Pulmonary

A 55 yo man is hospitalized with severe abdominal pain associated with nausea and vomiting. Lab studies show marked elevations of serum amylase and lipase. He has a history of heavy alcohol use. During hospitalization, his condition deteriorates and he develops severe respiratory distress. There are crackles bilaterally on physical examination and infiltrates bilaterally on chest x-ray. The patient's fails to improve with mechanical ventilation and 100% oxygen and dies 4 days later due to progressive respiratory failure. Which of the following autospy finding is most likely in this patient?

Alveolar hyaline membranes > This patient with *pancreatitis* and subsequent respiratory failure likely has *acute respiratory distress syndrome* (ARDS). Pancreatitis is a major risk factor for ARDS as it results in the release of large amounts of inflammatory cytokines and pancreatic enzymes into the circulation, which leads to infiltration of neutrophils into the pulmonary interstitium and alveolar spaces. Diffuse injury to the alveolar epithelium and pulmonary microvascular endothelium results in a leaky alveolocapillary membrane and significant pulmonary edema. > ARDS is typically characterized by progressive hypoxemia refractory to oxygen therapy and diffuse interstitial edema in the absence of cariogenic causes. During the first 1-6 days, interstitial and idntraalveolar edema, inflammation, and fibrin deposition cause the alveoli to become lined with waxy *hyaline membranes*. These membranes consist of fibrin exudate and inspissated protein-rich edema fluid mixed with the remnants of necrotic epithelial cells.

___________________ is a polyene anitfugnal similar to nystatin used for *systemic mycoses*. It is administered intravenously and never used for simple mucocutatneous infection due to many toxic side effect

Amphotericin B

A 55 yo man comes to the ED due to sudden onset of dyspnea. He is a truck driver and just returned from a long trip. The patient's medical history is significant for hypertension, hyperlipidemia, diabetes mellitus type 2, and chronic kidney disease. Blood pressure is 110/70 mmHg and pulse is 110/min. Physical examination shows a moderately overweight man with tachypnea. Lungs are clear on auscultation. ECG shows sinus tachycardia. His serum creatinine is elevated. Ventilation/perfusion scanning is ordered. Which of the following findings will be most helpful to confirm the suspected diagnosis in this patient?

An area of perfusion defect without ventilation defect *Pulmonary embolism* (PE) should be suspected in this patient with a prolonged period of immobility (long trip) who now has acute onset of dyspnea and tachypnea, a normal lung examination, and sinus tachycardia on ECG. > In most patients, CT angiography, which requires contracts administration, is the diagnostic test of choice. > However, contrast used in CT studies should be avoided in patients with renal insufficiency (elevated creatinine) due to the increased risk of contrast-indcued nephropathy, in such patients, a *ventilation/perfusion scan* (V/Q) is the peered diagnostic study.

An 18 yo man comes to the ED with sudden-onset right-sided chest pain and dyspnea. The patient was at home watching a football game on television when his symptoms abruptly started. He now has pain with depth breaths. He has no the medical problems and takes no medication. The patient has smoked a pack of cigarettes daily for the past 2 years. His respirations are 24/min. Physical examination shows a thin, tall patient in acute distress. The right side of the chest is hyper resonant to percussion and lacks audible breath sounds. What condition most likely led to this patient's presentation?

Apical sub pleural blebs > This young male patent with sudden-onset unilateral chest pain, dyspnea, and absent breath sounds on examination likely has *primary spontaneous pneumothorax (PSP). PSP is no traumatic and is found in patients without preexisting pulmonary disease (eg. cystic fibrosis). It occurs when a large change in the alveolar or intrapleural pressure results in a break in the visceral pleura and subsequent trapping of air between the parietal and visceral spaces. The superficial alveoli in the apices experiences greater pressure changes (due to the weight of the lungs pulling down on the apical tissue), predisposing them to the formation of *subpleural blebs* The blebs then can spontaneously rupture through the visceral pleura, frequently while the patient is at rest. > Tall, thin males around the age of 20 are most commonly affected. Although the most important risk factor is *smoking*, taller individuals also appear to be at higher risk due to more negative intrapleural pressure in the lung apices.

A 64 yo man is brought to the ED after a motor vehicle accident where his chest hit the steering wheel. His temp is 98 F, BP is 132/78, pulse is 76, and respirations are 14. The patient has no known chronic medical problems and takes no medication. Physical exam reveals mild tenderness over the lower right chest. Imaging of the neck and chest shows no fractures of dislocations. However, the chest x-ray reveals pleural thickening and calcifications along the posterolateral middling regions and diaphragm. There is also a small right-sided pleural effusion. This patient most likely has a history of exposure to which of the following agents? (Asbestos, Beryllium, Coal dust, Nitrous dioxide, organic dust, silica)

Asbestos > This older adult patient, who is incidentally found to have *pleural thickening* with calcification of the posterolateral middling zones and diaphragm, likely has *asbestos-related* pleural *disease*. These *calcified lesions *pleural plaques)* are one of the hallmarks of asbestos exposure and usually affect the parietal pleura. > Asbestos-realted pleural disease presents with pleural thickening, calcified lesions (pleural plaques) of the posterolateral middling zones and diaphragm, and occasionally benign pleural effusions. Many patients are asymptomatic despite visible disease on imaging.

____________________ is a type of pneumoconiosis that can present with dyspnea on exertion, but the chest x-ray is more likely to reveal an interstitial pattern of involvement most prominent in the lower zones. *Pleural plaques* may also be noted. Histology shows ferruginous bodies - fusiform rods with a translucent asbestos center and an iron-containing coating.

Asbestosis

A 34 yo woman comes to the office for evaluation of recurrent transient pulmonary infiltrates. The patient has history of bronchial asthma and has had several exacerbations over the past years, particularly during the winter months. She is currently asymptomatic. She has no other medical problems and has never traveled outside the U.S her medications include albuterol as needed and medium-dose inhaled glucocortocids. Temp is 98.8 F, physical examination is unremarkable. Complete blood count shows eosinophil. A chest Ct scan reveals proximal bronchiectasis. The patin's condition is most like related to colonization with which of the following?

Aspergillus fumigateurs > *Aspergillus fumigateurs* is a low virulence fungus that generally does not cause significant infections except in immunocompromised or deliberated patients. It may, however, colonize the bronchial mucosa. > Patients with asthma or cystic fibrosis in particular may develop an allergic *hypersensitivity* reaction to the fungus. > The result is *allergic bronchopulmonary aspergillosis (ABPA), which occurs in 5%-10% of corticosteroid-depndent *asthmatics*. > Patients with ABPA have very high serum IgE levels, *eosinophilia*, and IgE plus IgG serum antibodies to Aspergillus. > There is intense airway inflammation and mucus plugging with exacerbations and remissions. Repeated exacerbations may produce transient pulmonary infiltrates and proximal *bronchiectasis*

___________________ can colonize old lung cavities (eg. those formed by tuberculosis) to form a "fungal ball". Symptoms include cough, dyspnea, and hemoptysis.

Aspergillus fumigatus

_________________ is a macrolide antibiotic that acts by inhibiting the material 50S ribosomal subunit as do all the macrolide antibiotics, chloramphenicol, and linezolid.

Azithromycin

_________________ is a type of pneumoconiosis that may present with dyspnea and ill-defined nodular or irregular opacities on chest x-ray. Histology reveals noncaseating epithloid granules without obvious, associated particles.

Berylliosis

uA 35 yo African American is being evaluated for exertional dyspnea and dry cough. She has no significant pas medical history and takes no medication. She works as a bird keeper part time at a local zoo. Chest x-ray shows bilateral hilar adenopathy and reticular pulmonary infiltrates. Serum ACE levels and calcium levels are elevated. PPD testing is negative. Bronchoscopy is arranged to help determine the diagnosis. Which of the cell times is most likely to predominate in this patient's brocnhoalvelar lavage fluid?

CD4+ lymphocytes > CD4+ T helper cells are the predominant crypt of lymphocyte found in sarcoid granulomas. Intralveoalr and interstitial accumulation of CD4+T cells i

A 46 yo man comes to the physician due to 3 days of fever, shortness of breath, pleuritic chest pain, and cough productive of green sputum. He has smoked a pack of cigarettes daily for 20 years. On examination, there are crackles at the base of the left lung. Chest x0ray reveals a left lower-lobe consolidation. Microscopic analysis of a sputum sample shows gram-positive, lancet cocci in pairs. Which of the following characteristics are these bacteria likely to demonstrate?

Bile solubility > Streptococcus pneumoniae are gram-positive, alpha hemolytic, optochin-sensitve, bile soluble diplococci. > Virdans group stretopoccic are also alpha hemolytic, but they are optochin-resistant and bile insoluble. > Streptococcus pyogenes (Group A streptococcus) appear as gram-positive cocci in chains with bacitracin susceptibility.

A 36 yo woman comes to the physician due to dyspnea and weakness. She has no other medical problems. her moth had similar symptoms and died at age 42. After an extensive work-up, lung biopsy is performed. Light microscopy of the tissue sample shows medical hypertrophy, intimal fibrosis, and decreased intraluminal diameter of the small branches of the pulmonary artery. The patient is subsequently scheduled for lung transplantation. Which of the following medications is indicated for management of her condition during the waiting period?

Bosentan > Bosentan is a competitive antagonist of endothelia receptors used for treatment of idiopathic pulmonary arterial hypertension > *Pulmonary hypertension* causes specific morphologic findings in the branches of the pulmonary artery, including increased arteriolar smooth muscle thickness (*medial hypertrophy*), *intimal fibrosis*, and significant *luminal narrowing*. In the setting of severe hypertension, lesions can progress to form interlacing tufts of small vascular channels called *plexiform lesions*. > These changes can occur in both pulmonary hypertension due to underlying lung, vascular, or cardiac disease and in idiopathic or familial pulmonary arterial hypertension (PAH).

A 26 yo medical student is exposed to a patient who suffers from active pulmonary tuberculosis infection. Two years later, the asymptomatic medical student presents with a chest radiograph finding of a small calf iced lesion in the right lung field. What cell contributed most to the containment of the infection?

CD4+ T lymphocytes and macrophages > Pulmonary tuberculosis infection is controlled through the action of CD4+ TH1 lymphocytes and macrophages. These cells work together to contain M. tuberculosis within a caseous granuloma, which offers the macrophages inside an opportunity to kill the raining organisms if the necrotic area is small enough.

______________________ are yeast that form peudohyphae.

Candida > Candida infection is usually not associated with pulmonary infiltrates or lymphadenopathy

A 3 yo boy who recently immigrated to the US is brought to the pediatric emergency department with fever, malaise, and a swollen right knee. He is hypotensive and tachycardic. His past medical history is significant for a recent episode of otitis media and several vaccinations that are not up to date. Arthrocentesis of his right knee shows cloudy synovial fluid. Gram stain of the aspirate reveals pleomorphic, Gram-negative cocobacilli. Cultures performed on a blood agar plate supplemented with a disk containing hematin and NAD+ grow colonies only near the disk. The pathogenicity of the organism responsible for this patient's condition is most likely related to which of the following virulence factors? (Capsule, cytotoxic exotoxin, Fimbiae, Hemolysins, hyaluronidase)

Capsule > Haemophilus influenzae is a blood-loving organism that requires both X factor (hematin) and V factor (NAD+) to grow. The phatogenicity of H influenzae depends on the presence of an antiphagocytic polysaccharide capsule. The type B strain is the most invasive and virulent and has a capsule consisting of liner polymer of polyribitol phosphate. > Unecapsualted (nontypable) H influenzae is part of the normal flora and causes primarily local infections.

A 50 yo non-smoking female is found to have a round lesion in the right upper lobe of her lung. Transthoracic biopsy is scheduled to obtain tissue for histological examination. Which of the following would favor the diagnosis of hamartoma in this patient?

Cartilage tissue in the biopsy sample > Hamartomas are the most common benign lung tumors. They present as asymptomatic peripherally located "coin lesion" in patients 50-60 years old. These tumors are composed of disorganized cartilage, fibrous and adipose tissue.

Gram-postive bacteria are inoculated under the skin of experimental animals and then the infection is treated with antibiotics. Bacteria isolated from the injection site several days later assume a spherical configuration when placed in an isotonic solution and disintegrate rapidly when placed in a hypotonic solution. Which of the following antibiotic was most likely used in this experiment? (Chloramphenicol, azithromycin, ciprofloxacin, cefuroxime, doxycycline)

Cefuroxime > Under normal circumstances, Gram-postive organism would not be destroyed by variations in tonicity within a certain range due to their intact peptidoglycan cell wall. > Cefuroxime is a second generation cephalosporin. > Cephalosporins are beta-lactam antibiotics and are related to penicillins. Vancomycin is another example of an antibiotic that inhibits cells all synthesis.

A 42 yo woman comes to the office with a nonproductive cough and worsening SOB with exertion. The patient has a history of primary pulmonary HTN and underwent lung transplantation 8 months ago. She states that she has not missed any doses of her transplant medications. A chest x-ray revels surgical evidence of her transplant but clear lung fields. Pulmonary function testing demonstrates a force expiratory volume in 1 second (FEV1), 67% of her best post transplant FEV1. Her forced vital capacity remains largely unchanged. A lung biopsy shows areas of total fibrotic obstruction in the terminal bronchioles. The patient's condition is most likely caused by which of the following?

Chronic transplant rejection > This patient with cough, dyspnea, obstructive findings on spirometry, and fibrotic destruction of the small airways likely has *chronic transplant rejection*. Lung transplantation may be complicated by both acute and chronic rejection. Chronic rejection is a major cause of morbidity and mortality and occurs in almost half of all patients within 5 years of transplantation. These patients commonly presents with dyspnea and a dry cough. > Chronic rejection affects the small bronchiole producing the obstructive lung disease known as *bronchiolitis obliterns*. Initially, histopathology shows lymphocytic inflammation and destruction of the epithelia of the small airways. Subsequently, fibrinopurlent exudate and granulation tissue are found in the lumen of the bronchiole, which ultimately results in fibrosis, scaring, and the progressive alliteration of small airways. NOTE: > Acute rejection usually occurs within the first 6 months. It is frequently asymptomatic and commonly discovered on the surveillance biopsies. Histopathology demonstrates perivascular and interstitial monocular cell infiltrates.

__________________ is an antibiotic in the flurorquinolone class of antibiotics. The fluroquinolones act by inhibiting bacterial DNA gyrate thereby leading to bacterial DNA damage and bacterial death. These agents have no effect on the cell wall.

Ciprofloxacin

A 41 yo man comes to the ED complaining of fever, weigh loss, and a productive cough. He reports drinking 12-18 beers a day. Physical examination shows poor dentition. A foul-smelling sputum sample is expectorated and sent for Gram stain and culture. His chest x-ray show abscess. Which of the following antibiotics would be the most appropriate treatment for this patient's condition?

Clindamycin > Streptococcus pneumoniae is the most common cause of community-acquired pneumonia in the general patient population. However, alcoholic are significantly increased risk for *aspiration pneumonia* )infection with oral flora) because alcohol intoxication impairs the gag and cough reflex. Alcoholic with poor oral hygiene have increased numbers of oral bacteria, further increasing this risk. In addition, alcohol may impair the phagocytic and/or bactericidal action of alveolar macrophages, predisposing to infection. > Pulmonary infection in alcoholic patients very commonly include anaerobic oral flor (Bacteroides, Prevotella, Fusobacerium, and Peptrostreptococcus) admixed with aerobic bacteria. Necrotizing infections and lung abscesses may result. > Of the antibiotic choices given, clindamycin has the most activity against oral anaerobes and also covers aerobic Gram-postive organisms such s S. pneumoniae. > Similar to macorlides, clindamycin works primarily by binding to the 50s ribosomal subunit in bacteria and disrupting protein synthesis.

___________________ pneumoconiosis can present with exertion dyspnea and nodular interstitial opacities on chest x-ray. Histology of nodal and perilymphatic lung tissue shows accumulations of coal dust-laden macrophages (coal macules).

Coal worker's

_________________ also causes disseminated mycosis in immunocompromised patients. In tissue sections, it is visualized as large, thick-walled spherules containing endospores.

Coccidiodies immitis

A 45 yo man comes to the ED due to several days of cough and fever. His temperature si 101.2 F, blood pressure is 117/76, pulse is 92/min, and respirations are 18/min. Physical examination of the right lung reveals occasional rales and decreased breath sounds at the base. A chest x-ray demonstrates a lung infiltrate, hilar adenopathy, and right-sided pleural effusion. Lung tissue obtained from this patient showing endospores. Was is most likely the cause of this patient's condition?

Coccidioides immitis > Coccidioides immitis infection can be asymptomatic or it can cause pulmonary disease ranging from flulike illness to chronic pneumonia. It causes disseminated disease in immunocompromised patents. Spherules containing endospores are found in the tissue samples.

A 42 yo previously healthy man comes to the ED due to several hours of dyspnea. He is long-haul truck driver and became acutely short of breath during a 36 hour trip. The patient smokes a pack of cigarettes daily and drinks a 6 pack of beer on the weekends. Pulmonary examination reveals vesicular breath sound bilaterally with the overlying areas resonant to percussion. CT pulmonary angiogram shows right lower lobe pulmonary artery occlusion consistent with pulmonary embolism but no evidence of pulmonary infarction. Which of the following is the most likely reason for the lack of tissue necrosis in this patient?

Collateral circulation > The lung is supplied by *dual circulation* from the pulmonary and bronchial system (collateral circulation). As a result, lung infarction only rarely develops as a complication of pulmonary embolism (PE) > When a clot occludes the pulmonary artery, the bronchial artery can continue to supply nutrients to the tissue.

___________________ is an encapsulated yeast that causes meningoencephalitis and pulmonary cryptococcosis primarily in immunocompromised patients, particularly those with HIV infection. However, it is found extracellular as its large, polysaccharide capsule inhibits phagocytosis by macrophages.

Cryptococcus neoformans

____________________ takes the form of a budding yeast with a thick capsule. This yeast also grows abundantly in soil containing *bird (pigeon) droppings*. However, this fungus tends to cause disease (meningoencephalitis and pulmonary disease) in the immunocompromised.

Cryptococcus neoformans

uWORLD: A 35 yo man who received a kidney transplant one year ago comes to the ED with pleuritic chest pain and cough. He is found to have a low-grade fever. Chest x-ray reveals an infiltrate in the lower lobe of the right lung. The patient is started on broad-spectrum antibiotics, including vancomycin, ceftriaxone, and azithromycin. Despite these measure, his condition worsens over the next several days. Bronchoscopy with bronchoalveolor lavage is performed. Mucicarmine staining of his bornchoalveloar fluid reveals red staining. What is the most likely cause of this patient's condition?

Cryptococcus neoformans > Cryptococcus neoformans is a yeast that has an antiphagocytic polysaccharide capsule, a major virulence factor. Methenamine silver stain can identify the yeast form of Cryptococcus, seen in tissue as round cell with narrow-based buds. The polysaccharide *capsule* appears as a clear, unstained zone with *india ink* and stains *red* with mucicarmine.

A 63 yo man comes to the ED with a 1 week history of progressively worsening SOB and cough. The SOB worsens when the patient lies flat in bed, and he needs to prop himself up with 3 pillows to sleep well at night. He has HTN and Type 2 DM and was treated 2 weeks ago for a MI with 2 stents placed in the left anterior descending artery. His BP is 120/80, pulse is 92, and respirations are 22. The patient's pulse ox shows 89% on room air. Chest auscultation reveals bilateral crackles at the lung bases and a third heart sound. Which of the following factor most likely accounts for this patient's dyspnea?

Decrease lung compliance > In left ventricular failure, fluid accumulation in the lung interstitum results in decreased compliance. > Dyspnea, bibasilar crackles, and presence of a S3 sound in a patient who had a recent Mi suggests *left heart failure*. > The presence of fluid in the pulmonary interstitum causes distortion (Swelling) of the affected tissue, increasing resistance to movement (*decreased lung compliance*). As a result, the negative pressure generated during normal inspiratory effector is not sufficient to adequately distend the lungs, resulting in poor gas exchange and SOB. Other causes of reduced compliance include pulmonary fibrous and insufficient surfactant.

Researchers conduct a series of experiments to determine how pathogenicity is transmitted among different strains of Streptococcus pneumoniae. In the first experiment, they injected nonvirulent strain A into the peritoneal cavity of the laboratory mice and observe no ill effect. In the second experiment, researchers subject virulent strain B to a detergent agent that kills and lyses the bacterial cells. They then inject the lysate into the peritoneal cavity of a new group of mice and again observe no ill effects. During the third experiment, they inject live strain A bacteria in combination with the killed strain B lysate, resulting in death of the mice. Which of the following genetic processes most likely accounts for the observed findings of these experiments?

Direct uptake of extracellular DNA > Certain strains of Streptococcus pneumoniae express capsular polysaccharides that inhibit phagocytosis, making it a successful pathogen. Strains lacking the capsule are not pathogenic; however, S pneumoniae is able to obtain new genetic material from the environment that is released following the death and lysis of neighboring bacterial cells. > This process, known as *transformation*, allows the bacterium to *take up exogenous DNA* fragments, integrate the DNA into its genome, and express the encoded proteins. Through this method, nonvirulent strains of S pneumoniae that do not form a capsule can acquire the genes that code for the capsule and therefore *gain virulence* > Bacteria that have the innate capacity to undergo transformation are said to be naturally competent and include Haemophilus, streptococcus, Bacillus, and Nisseria species.

An infant is evaluated at the office after developing prominent oral thrush, interstitial pneumonia, and severe lymphopenia during the first year of life. The patent was born full-term to a 25 yo woman who received no prenatal care and is an IV drug abuser. She breastfed her son for the first mouth but then switched to formula feedings. The mother is currently unwilling to undergo any kind of testing. She tells the heath care provider, "Just take care of my son". Which of the following prenatal interventions would have most likely prevented this infant's condition? (Enzyme inhibitor drug, interferon therapy, killed vaccine, live attenuated vaccine, prenatal vitamins, toxoid vaccine, viral component vaccine)

Enzyme inhibitor drug > Oral thrush, interstitial pneumonia, and severe lypmhopenia during the first year of life are consistent with mother-to-child *vertical transmission of HIV-1*. The risk of HIV infection occurring in an infant born to an HIV-postive mother who received no prenatal *antiretroviral therapy* (ART) can be as high as 35%. ART during pregnancy reduces the risk of perinatal transmission to 1%-2%. All pregnant women with HIV should take ART, regardless of their CD4 cell count or viral load.

A 38 yo man comes to the office with reports of dyspnea on exertion and decrease exercise tolerance. His medical history is unreliable, the has no history of childhood asthma or cough. He has never smoked and has no known occupational exposures. The patient has gained almost 100 lb over the past 4 years since leaving the military due to a sedentary lifestyle. Re currently weights 297 lb and BMI of 41. His respiratory rate is 22/min and use ox is 93% on room . His respiratory rate is 22/min and pulse 93% on room air at rest. Physical exam is notable for central obesity. Lungs and clear and auscultation bilaterally. What changes to FVC1, FVC, ERV, RV, and TLC are most likely to be seen on PFT?

FEV1: Decrease FVC: Decrease ERV: Decrease RV: Normal TLC: Decrease > This young patient presenting with respiratory symptoms and *central obesity* without a history of pulmonary pulmonary disease likely has obesity-related *restrictive lung disease*

A 32 yo man is hospitalized following a motor vehicle accident during which he sustained bilateral femur fractures, pelvic fracture, and urethral injury. The patient has no other intraabdominal or chest injury. On the third day of his hospitalization, he reports shortness of breath. The patient's temperature 98.8 F, heart rate is 110 and regular, respirations are 20, and oxygen saturation is 84% on room air. He appears confused and agitated. Physical examination shows a petechial rash on his chest. ECG shows sinus tachycardia with no ischemic changes. Which of the following histologic changes has most likely taken place in this patient lung tissue?

Fat micro globules in pulmonary arterioles > Fat embolism syndrome should be strongly suspected in a patient with severe long bone and/or pelvic fractures who develops acute-onset neurologic abnormalities, hypoxemia, and a petechial rash. Occlusion of the pulmonary micro vessels by fat globules is an early histologic finding of this syndrome.

A 56 yo African American woman with a history of HTN is brought to the ED because of three days of pyuria and back pain. On physical examination, she has a temperature of 102.6 F, a blood pressure of 70/40, a pulse of 130, and respirations of 28. She is confused and her skin is diffusely warm to the touch. She has suprapubic and costovertebral angle tenderness, but no rashes or edema. Her complete blood count demonstrates leukocytosis with increased neutrophils, but is otherwise normal. Coagulation studies are normal. Her urinalysis is positive for leukocyte esterase and nitrites and has numerous bacteria. Several hours later she becomes increasingly hypoxic requiring mechanical ventilation. Her respiratory symptoms are most likely due to which of the following pathology conditions?

Fluid accumulation in the alveolar spaces > This patient with fevers, hemodynamic instability, tachypnea, and evidence of a urinary tract infection has urospesis which is likely complicated by *acute respiratory distress syndrome (ARDS). *Sepsis* and pulmonary infection are the two most common *risk factors* for ARDS. > During sepsis, cytokines such as tumor necrosis factor, interleukin (IL)-1, IL-6, and IL-8 begin to circulate in response to the infection, causing activation of the pulmonary epithelium. This results in increased recruitment and extravasation of neutrophils into the lung tissues provoking an inflammatory response that leads to capillary damage and the leakage of protein and fluid into the alveolar space. > As more alveolar space becomes *fluid-filled* patients develop worsening hypoxia and respiratory failure. More than half the cases of ARDS present within 24 hours of the inciting risk factor (eg. pneumonia, sepsis, trauma)

*Vancomycin* is active only against ____________________ bacteria and thus does not provide good coverage against anaerobes.

Gram-postive

____________________ is a systemic vasculitis of small and medium-sized arteries. It presents with involvement of upper respiratory tract (sinusitis, nasal obstruction, epistaxis, otitis), lung (hemoptysis) and kidney *rapidly progressing glomerulonephritis). Presence of cANCA is typical.

Granulomatosis with polyangiitis (Wegener's)

A 65 yo male dies in the hospital of an overwhelming pulmonary infection. Autospy shows a right lower lung lobe that is pale, firm, and airless. Histologically, the alveoli are filled with exudate containing neutrophils, fibrin and some fragmented RBCs. The patient died during which phase of his disease?

Gray hepatization > In Gray hepatization, RBCs disintegrate

____________________ is endemic to the Mississippi and Ohio River and found in bird and bat droppings. Patients with this often have a history of cleaning bird coops or caving.

Histoplasma capsulatum

uA 54 y/o man diagnosed with HIV infection 2 years ago develops a cough, low-grade fever, and hepatosplenomegaly. He has lost 3.6 kg (8 lb) over the past month. Histology findings show small ovoid bodies within a macrophage. What fungi is most likely the cause of this patient's condition

Histoplasma capsulatum > Histoplasma capsulatum can survive intracellular within macrophages. It causes a disseminated mycosis in immunocompromised patients. The clinical feature include systemc syndromes, (fever and weight loss), painful oral ulcers, lymphadenopathy, and hepatosplenamegaly.

A 63 yo man comes to the office for evaluation of 3 months of increasing cough with occasional hemoptysis, night sweats, and unintentional weigh loss. He recently migrated from South Africa, where he worked in the gold mines. The patient has a history of silicosis diagnosed 10 years ago. Vital signs show a low-grade fever. Exmianaiton reveals diffuse, fine crackles with right upper lobe predominance. Chest x-ray shows diffuse small nodules, hilar adenopathy with prominent calcifications, and a right upper lobe cavitary lesion. Sputum is sent for appropriate staining and culture. This patient's increased susceptibiliy to the current infection is best explained by which of the following factors?

Impaired macrophage function > *Silicosis* is distinguished by clacficaiton of the rim of hilar nodes (Eggshell calcification) and birefringent silica particles surrounded by fibrous tissue on histology. It has long been associated with increased risk of *tuberculosis* > Silicosis impairs the *macrophage* effector arm of cell-mediated immunity, which is integral to the immune response against mycobacteria. It is thought that macrophage phagolysosomes are disrupted by internalized silica particles, causing release of the particles and viable mycobacteria, which inhibits the immune system's ability to control the infection. This extracellular release of lysosomal enzymes is thought to contribute to alveolar and interstitial lung injury in silicosis. Prolonged exposure of macrophage to silica particles also appears to increase macrophage apoptosis.

A 34 yo man who recently emigrated from Southeast Asia comes to the physician due to persistent cough, night sweats, and weight loss from several weeks. He smokes a pack of cigarettes a day and consumes alcohol on weekends. Chest x-ray shows a right upper-lobe infiltrate. Despite antibiotic treatment for pneumonia, his symptoms worsen. Microscope should granulomas. Which of the following substance contribute most to the development of this patient's observed microscopic lesions?

Interferon-y > This patient's lung biopsy show *epitheloid macrophages* and *multinucleated giant cells*, which are the predominant cells found in *granulomas*. Granulomas often form after tissue macrophages encounter pathogens or substance that cannot be easily digest or removed. > In Mycobacterium tuberculosis infection, bacteria that becomes engulfed by macrophages are able to evade intracellular killing and survive and reproduce within phagolysosomes. However, the macrophages are still able to present mycobacterial antigens to naive T hyper cells. > Concomitant *macrophage IL-12* secretion induces the T helper cells to differentation into the *TH1 subtype*. > Mature TH1 cells then produce *interferon-y*, which activates macrophages, improving their ability to kill ingested mycobacteria. > In addition, activated macrophages produce TNF-alpha, which acts to recruit additional monocytes and macrophages to the area. These infiltrating cells cluster in a circular fashion around the remaining M tuberculosis organism, walling them in. For most individuals, this granulomatous response successfully limits the actor from spreading and erectly controls the infection.

A 45 yo woman is evaluated for progressive external dyspnea and fatigue. She also reports episodic pain and bluish discoloration of the finger and toes on cold exposure that improves with rewarming. Physical examination shows tightening of skin over the fingers. Cardiac examination reveals an accentuated second heart sound over the upper left sternal border. The abdomen is soft with mild hepatomegaly. There is bilateral lower extremity pitting edema. Pulmonary function test results are as follows: Normal FEV1/FVC

Intimal thickening of pulmonary arterioles > This patient's accentuated second heart sound indicates elevated pulmonary artery pressure (*pulmonary arterial hypertension [PAH]), which in turn has caused *cor pulmonale* and symptoms of right-sided heart failure (lower extremity edema and hepatomegaly with pulmonary edema). Her *sclerodactyly* (skin thickening and tightening over the fingers due to collagen deposition) and *Raynaud phenomenon* (cold-induced digital vasospasm) are features suggestive of CREST syndrome, which is localized variant of systemic scerlosis. > Both diffuse and limited forms of systemic sclerosis variants develop due to increase deposition of collagen in tissue. Increase production of collagen and extracellular matrix protein by fibroblasts. > All tissue can be affected, but the earliest damage is seen in small arterioles and capillaries. Microvascular injury of pulmonary arterioles lead to narrowing of the lumen and increased pressure in pulmonary circulation. It leads to hypertrophy of the right ventricle, with subsequent development of right-sided congestive heart failure. ANSWER/OBJECTIVE > Pulmonary hypersion develops in patients with *systematic sclerosis* as a result of damage to the pulmonary arterioles. It manifests with an accentuated pulmonary component of the second heart sound and signs of right-sided heart failure due to for pulmonale.

A 62 yo man comes to the physician because of recent weight loss, cough, and occasional hemoptysis. His past medical history is significant for poorly controlled diabetes mellitus and chronic obstructive pulmonary treated with bronchodilators and oral corticosteroids. Chest x-ray shows pulmonary infiltrates and an area of cavitation in the right upper lobe. Sputum microscopy shows acid-fast bacilli. Which of the following is the most accurate statement concerning this patient's pulmonary infection?

It originated from reactivation of an old infection > Primary tuberculosis causes the formation of Ghon foci in the lower lungs. Secondary (Reactivation) tuberculosis occurs in patients with prior tuberculosis infection that never cleared completely. Reactivation tuberculosis occurs most often in immunosuppressed patients and is characterized by apical cavitary lesions and hemoptysis.

A 65 yo man comes to the physician due to fevers, chills, chest pain, and a productive cough for the last 2 days. He drinks 6-10 beers daily an has a 45 pack year smoking history. His temperature is 104.4 F, blood pressure is 100/70, pulse is 95, and respirations are 28. On examinations, he is in mild respiratory distress. There are crackles and decreased breath sounds in the right upper lobe. His chest x-ray shows a large right upper lobe infiltrate. Sputum examination shows encapsulated gram-negative bacilli. Sputum culture grows pink-colored mucoid colonies on MacConkey agar. What organism is most likely the cause of this patient's condition? (Chlamydia, Klebsiella, Legionella, Mycoplasma, Pseudomonas, Stap aureus, Streph pneumoniae)

Klebsiella pneumoniae > Klebsiella is an encapsulated, lactose-fermenting, gram-negative bacillus the appears mucoid in culture. It causes pneumonia in subjects with impaired host defenses, espiscally alcoholics. Klebsiella pneumonia is characterized by tissue necrosis and early abscess formation with production of thick, mucoid, blood-tinged sputum (currant jelly sputum)

_______________ is an occasional cause of septicemia and purulent meningitis in neonates

Listeria monocytogenes

A 54 yo Caucasian male is hospitalized with spiking fevers and productive cough. He was diagnosed with right lower lobe pneumonia one week ago and received a short course of oral antibiotics, but his condition has failed to improve since then. CXR shows a round density with an air-fluid level in the lower lobe of the right lung. Which contributed most to the observed lung lesion in this patient?

Lysosomal content release by macrophages > Pulmonary abscesses are local suppurative collections within lung parenchyma that result in necrosis of the surrounding lung tissue. If the abscess cavity communicates with an air passage, the semiliquid exudate within will partially drain, creating an air-containing cavity that can be identified on chest radiograph. > Histologically, suppurative destruction of the lung parenchyma within the abscess cavity is seen. This destruction occurs to a large extent secondary to the release of lysosomal enzymes by neutrophils and macrophages. The lysosomal enzymes severe to digest the offending pathogens and tissue debris, as well as to chemotactically summon additional neutrophils or macrophages to the area. Occasionally, however, the enzymes will also damage the surrounding parenchyma, setting the stage for abscess formation. > Tissue damage and resultant abscess formation is primarily caused by lysosomal enzymes release from neutrophils and macrophages.

_________________ is found in the cell wall of *Streptococcus* species. It binds to the factor H to prevent opsonization and destruction of streptococci by the alternative complement pathway.

M protein

A 62 yo woman comes to the physican with sought and dyspnea. She electorates copious amounts of pale tan-colored fluid. Chest x-ray reveals a pulmonary infiltrate that is subsequently biopsied. Histological examination shows columnar mucin-secretin cells that line the alveolar spaces without invading the storm or vessels. This patient's condition is best categorized under which of the following disease processes?

Malignant neoplasm > *Adenocarcinoma in situ* (formerly known as bronchioloalveolar carcinoma) is one of the major subtypes of lung subtypes of lung adenocarcinoma, the most common type of lung cancer in the U.S. > The tumor arises form the alveolar epithelium and is located at the periphery of the lung. > It is considered a pre invasive lesion characterized by *growth along interact alveolar septa* without vascular or stromal invasion. > Microscopic examination reveals *well-differentiated, dysplastic columnar cells* with or without intracellular mucin (compare to normal lung). The tumor has a tendency to undergo erogenous spread (along the airways) and can progress to invasive disease if not resected.

A 64 yo man comes to the office due to 4 weeks of progressive dyspnea. for the past several months, he has had a nonproductive cough and felt fatigue. His medical problems include degenerative joint disease and peptic ulcer disease. He smoked 2 packs of cigarettes daily for 38 years but quite 4 years ago. On exam, there are decreased breath sounds and percussive dullness at the base of the right lung. Chest CT reveals a right-sided pleural effusion and diffuse nodular thickening of the pleura. On thoracentesis, blood fluid is obtained. Pleural biopsy shows proliferation of epitheloid-type cells that are joined by desmosomes, contain abundant monofilaments, and are studded with very long microvilli. Which of the following is the most likely diagnosis?

Mesothelioma > Malignant mesothelioma is a rare neoplasm that arises from the pleura or peritoneum. It is strongly associated with asbestos exposure. Hemorrhagic pleural effusions and pleural thickening are characteristic. Histopathology reveals tumor cells with numerous, long slender microvilli and abundant tonofilaments. > *Mesothelioma* is rare malignant neoplasm arising from mesothelial cells, which line body cavities (eg, pleural, peritoneal, pericardial). > *Asbestos* exposure is the primary risk factor. Individuals involved in asbestos mining and industrial applications (eg, insulation, shipbuilding) are at risk of mesothelioma. Symptoms include dyspnea and chest pain. > *Hemorrhagic* pleural effusion are frequently present. > Histopathology will show tumor cells with numerous, *long slender microvilli* and abundant *tonofilaments*. Immunohistochemical markers (eg, pancytokeratin) are useful in diagnosis.

A 44 yo man comes to the ED with a 3-day history of fever, chills, malaise, dyspnea, and a cough productive of "greenish" sputum. The patient has no prior medical problems and has never been hospitalized. He has a 25-pack-year smoking history and drinks 4-5 beers a week. His temperature is 103 F, blood pressure is 130/80, pulse is 98, and respiration are 20. On examination, dullness to percussion, crackles, and egophony are present at the right lung base. The remainder of the examination is normal. Chest x-ray shows a dense infiltrate occupying the entire right lower lobe. Which of the following most likely accounts for the color of this patient's sputum? (Epithelial necrosis, hemolysis, high bacterial load, mucopolysaccharides, myeloperoxidase)

Myeloperoxidase > The middle-age man presenting with new-onset fevers, productive cough, and a dense lobar infiltrate likely has community-acquired *pneumonia* (CAP). CAP in otherwise healthy individuals is most commonly caused by Streptococcus pneumoniae, the most common bacterial etiology worldwide. Tobacco use further increases its risk. In non elderly patients, pneumococcal pneumonia presents with abrupt-onset fevers, rigors, tachypnea, and productive cough with *consolidation* in one lobe of the lungs > Neutrophil *myeloperoxidase* is responsible for the *green* color of pus and sputum in bacterial infections. It is a blue-green heme-based pigmented molecule contained with the zoophilic granules of neutrophils and catalyzes the production of hypochlorous acid from chloride and hydrogen peroxide fudging the phagocytic respiratory burst.

A 54 yo woman comes to the hospital due to a week of progressive fever and headache. She also had dyspnea, productive cough, fatigue, and night sweats. The patient underwent a renal transplant 2 years ago and is on immunosuppressive therapy. Her temperature is 101 F, blood pressure is 130/80, pulse is 90, respirations is 18. On examination, she is lethargic and has patch lung crackles with normal heart sounds and no focal neurological deficit. Her leukocyte count is 14,000. Chest x-ray reveals several nodules but no parenchymal infiltrate. Brain MRI shows a 1.2 cm ring-enchanting focal lesion with surrounding edema in the right frontal lobe. Sputum Gram stain is taken. What is the most likely the cause of the patient's condition?

Nocardia asteroides > Nocardia, weakly staining *gram-postive*, catalase-costive, rod-shaped bacteria found in soil and healthy gingiva. They form partially acid-fast, breaded *branching filaments* (resembling fungal hyphae but not as wide). > *Nocardiosis* typically affects the *lungs brain, or skin* and is mostly seen in *immunocompromised* patients. The *pulmonary form can result in cavitary infiltrates often initially misdiagnosed as tuberculosis; however, Mycobacterium tuberculosis would not appear as filaments of gram-positive organisms. > The other common presentation for nocardiosis is *brain abscess*. > The treatment of choice is trimethoprim-sulfamethoxazole.

_______________ is the drug of choice for oropharyngeal candidiasis in patients without advanced immunodeficiency. It acts acts by binding to ergosterol in the fungal cell membrane, causing the formation of pores and leakage of fungal cell contents.

Nystatin > Nystatin is not absorbed from the GI tract and is administered as an oral "swish and swallow" agent.

Several students returning from a cave exploration trip to the Central US develop fever, cough, and malaise. Pulmonary infiltrates and hilar adenopathy are apparent on CXRs. Lung tissue specimens would most likely show:

Ovoid cells within macrophages > Histoplasma capsulate is a dimorphic fungus that is found as mold in soil. It is also present in bird and bat droppings, and is endemic to the Mississippi and Ohio River basins. Patients may report a history of exploring caves (exposure to bats) or cleaning bird cages or coops. > H. capsulate is transmitted by the respiratory route when bird or bat droppings containing fungal spores are inhaled. In the lungs, the fungus is ingested by macrophages, and is seen on light microscopy as small intracellular oval bodies. The immune reaction is Histoplasma closely resembles that included by M. tuberculosis: a cellular response with formation of granulomata. Because the fungus largest histiocytes and the reticuloendothelial system, it may cause lymphadenopathy and hepatosplenomagly. > While the majority of immunocompetent hosts remain asymptomatic, some may develop acute pulmonary dais (cough, fever, pleurisy chest pain and pulmonary infiltrates). Furthermore, individuals with underling lung disease may develop chronic pulmonary histoplasmosis, a condition that clinically resembles tuberculosis (patients present with cough, malaise, weight loss and cavitation in the upper lung lobes). Disseminated disease occurs in immunocompromised individuals.

A 45 yo man comes to the office for evaluation of a persistent cough and dyspnea on exertion. He has been a coal miner for the past 15 years and has been exposed to large quantities of dust while working underground. A lung biopsy reveals fine carbon particles within the patient's respiratory bronchioles and alveolar ducts. Which of the following defense mechanisms is most directly responsible for clearing particles from this portion of the patient's respiratory tract?

Phagocytosis > This patient has *coal workers pneumoconiosis*, a form of interstitial lung fibrosis secondary to long-term inhalation of coal particles. > The pneumoconioses are diseases resulting form the inhalation of fine dust particles that reach the respiratory bronchioles and alveoli. Particles that lodge in this region are normally cleared by alveolar macrophages. High particulate burden can cause the excessive release of cytokines from macrophages, resulting in progressive pulmonary fibrosis.

A 62 yo man is brought to the ED due to the sudden onset of high fever and shaking chills. Twelve hours before presentation, he had experienced SOB and cough. The patient has smoked 1 pack daily for 40 years. His vaccination record is unknown. Exam shows dullness to percussion over the left side of the chest. CXR reveals consolidation in the left upper lobe. Gram stain of the sputum shows gram-positive diplocci. Small alpha-hemolytic colonies grow in a blood agar plate. Which of the following is the major virulence factors of the bacteria causing the disease in this patient?

Polysaccharide capsule > The primary virulence factor of Streptococcus pneumonia (Without which it cannot cause disease) is a polysaccharid capsule that inhibits phagocytosis > This patient with fever, cough, and a consolidation on chest x-ray has *pneumonia*. Typical bacterial etiologies of community-acquired pneumonia (CAP) include *Streptococcus pneumoniae,* Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, and Staphylococcus aureus. > Atypical pneumonia (due to Mycoplasma pneumoniae, Chlamoydophila pneumonia, and Legionella) is less likely in this patient, particularly given the acute onset and severity of his symptoms as well as the lobar consolidation on chest x-ray. > S pneumoniae, the most common cause of CAP, are gram-positive diplococci that exhibits *partial (alpha) hemolysis on blood agar (green colonies)* and are bile-solute and opochin-senstive.

A 48 yo male who died in a motor vehicle accident is found to have a small fibrotic focus in the lower lobe of the right lung and a calcified lymph node in the right lung hills. These autopsy findings are most consistent with which of the following?

Primary exposure to M. tuberculosis > The finding of a fibrotic focus in the lower lobe of a lung in conjunction with a calf iced lymph node can occur in a variety of settings, with M tuberculosis infection one of the more likely. In M. tuberculosis infection, a lower lobe lung lesion (Ghon focus) accopamied by ipsilateral hilar adenopathy is described as a Ghon complex. The Ghon complex occurs during initial infection with M. tuberculosis.

________________ in the cell wall of staphylococcus aureus helps prevent opsonization by binding the Fc region of immunoglobulins. S aureus is a common cause of tracheitis, which has a clinical presentation (eg, stridor, fever, respiratory distress) similar to epiglottitis

Protein A

A 58 yo man comes to the physician due to exertion dyspnea and cough. His symptoms started 6 months ago and have progressively worsened. His other medical problems include recurrent pyelonephritis, peptic ulcer disease, and rheumatoid arthritis. the patient had taken a medication for rheumatoid arthritis for many years, but stopped 1 year ago as the drug failed to improve his worsening hand arthritis. he does not use tobacco, alcohol, or illicit drugs. Physical examination shows joint diseases consistently with rheumatoid arthritis. Chest x-ray show diffuse pattern. What is the a likely explanation for this patient's pulmonary symptoms?

Pulmonary fibrosis > Pulmonary fibrosis presents with gradually progressive dyspnea and bilateral reticulonodular opacities on chest x-ray. Pulmonary function tests reveal a restrictive pattern and lung biopsy shows patch interstitial lymphocytic inflammation and fibrosis of the alveolar walls. > Rheumatoid arthritis can causes a variety of pulmonary manifestations; the most common is a form of interstitial lung disease similar to idiopathic interstitial pneumonia. > Methotrexate is a drug frequently used for rheumatoid arthritis treatment that can also cause interstitial pneumonitis and fibrosis.

A 32 yo man is hospitalized with nausea, vomiting, and severe abdominal pain. he has a history of heavy alcohol use and was admitted to the hospital for acute pancreatitis a year ago. He has continued to drink alcohol since his last hospitalization and had a party last weekend, during which he consumed an entire fifth of liquor. His temperature is 101 F, blood pressure is 110/80, pulse is 104, and respirations are 20. His abdominal examination is notable for marked tenderness in the epigastric region. His serum lipase is 2392 U/L. On the second day of hospitalization, he develops SOB and progressive hypoxemia. Chest x-ray reveals new bilateral opacities. 24 hour fluid intake is 2800 mL and urine output is 1800. Which parameter is most likely to be normal in this patient? (Capillary permeability, lung compliance, pulmonary capillary wedge pressure, ventilation to perfusion matching, work of breathing)

Pulmonary capillary wedge pressure > This patient's signs and symptoms suggest *acute respiratory distress syndrome* (ARDS), for which pancreatitis is a major risk factor. > ARDS is characterized by diffuse injury to the pulmonary microvascular endothelium and alveolar epithelium, resulting in increase pulmonary capillary permeability and leaky aveolocapillary membrane. The result in noncardiogenic pulmonary edema with a *normal* (6-12 mmHg) pulmonary capillary wedge pressure* (PCWP). An elevated PCWP would be more suggestive of cardiogenic pulmonary edema (eg, decompensated left ventricular failure). Although patients receiving large volume resuscitation can develop volume overload, this patient's adequate urine output makes this less likely. >The interstitial and idntraalveolar edema, inflammation, and hyaline membrane formation that occurs as a result of ARDS cause lung compliance to decrease, the work of breathing to increase, and the oxygen diffusion capacity of the lung to decrease. More severe involvement or atelectasis of regional alveoli can cause ventilation to perfusion mismatch with decreased ventilation in areas of maintained perfusion.

A 54 yo man comes to the physician due to SOB that has been slowly worsening over the last 6 months. He also has a persistent nonproductive cough. The patient does not use alcohol, tobacco, or illicit drugs. His temperature 98 F, blood pressure is 132/78, pulse is 74/min, and respirations are 16/min. Physical examination reveals fine crackles bilaterally on pulmonary auscultation and drumstick shaped finger. Chest x-ray shows diffuse reticular opacities. Pulmonary function testing reveals decreased forced vital capacity, increased FEV1/FVC ratio, and expiratory flow rates that are higher than normal when corrected for lung volume. This patient's supernormal expiratory flow rates are best explained by an increase in which of the following parameters?

Radial traction on airway walls > Interstitial lung disease is associated with decreased lung volumes and increased lung elastic recoil caused by fibrotic interstitial tissue. The increased elastic recoil results in increased radial traction *outward pulling* on the airways, leading to increased expiratory flow rates when correct for the low lung volume. > This patient's presentation (progressive dyspnea, fine crackles, clubbing, and diffuse reticular opacities) is consistent with ILD. Most interstitial lung diseases cause progressive pulmonary fibrosis with thickening and stiffening of the pulmonary interstitium. This causes increased lung elastic recoil, as well as *airway widening* due to increased outward pulling (*radial traction*) by the surrounding fibrotic tissue. > The resulting decrease in airflow resistance leads to supernormal expiratory flow rates *higher than normal when corrected for lung volume*.

A 35 yo woman comes to the office due to a 3 month history of progressive dyspnea on exertion, nonproductive cough, and fatigue. She has a history of seasonal allergies for which she takes over-the counter antihistamines. The patient ascribes her symptoms to smoking cigarettes and has cut down from a pack of a day to 3-4 cigarettes daily. Her mother has rheumatoid arthritis. Biopsy show non-caseating granuloma. This patient has which of the following conditions?

Sarcoidosis > This patient likely has sarcoidosis, a chronic multi system disorder that leads to non-caveating granuloma deposition in various organs. It typically affects *young adults*, is more common in African Americans, and affects *women* more than men. Any organ can be affected, but the *lungs* are intimately involved in most cases. > patients often present with insidious onset of respiratory symptoms (eg. cough, dyspnea, chest pain) accompanied by fatigue, fever, and weight loss. The disease may also be incidentally decide in asymptomatic patients with typical chest x-ray findings (eg. bilateral hilar lymphadenopathy, reticular opacities).

A 23 yo African American female is being evaluated for fatigue and a nodular rash on her bilateral lower extremities. Chest X-ray demonstrates lung nodules and hilar fullness. Transbronchial biopsy findings include large epithelia cells, occasional giant cells and no areas of necrosis. Which of the following is the cause of this patient's condition?

Sarcoidosis > This vignette describes a typical presentation of sarcoidosis, an inflammatory disease of unknown etiology that leads to development of non-caseating granulomas in many organs and tissues. In sarcoidosis, non-caveating grandmas consist of aggregates of epithelioid cells (activated macrophages) and multinucleate giant cells consistent with chronic granulomatous inflammation. > The typical patient is a young black woman with non-specific complaints of fever, malaise and eight loss. Lung involvement is present in the majority of patients, and manifests lineally with cough, dyspnea, and chest pain. Skin involvement is varied in presentation ranging from macules to plaques to erythema nodosum (painful skin nodules). Chest X-ray is essential for diagnosis. In stage I of sarcoidosis, it classically reveals bilateral hilar lymphadenopathy. ---> Stage IV is characterized by lung fibrosis.

A 35 yo African American female presents to your office with arthralgia and tender, deep nodules on her legs. She has no significant PMH. There is hepatomegaly on physical exam. CXR reveals enlarged hilar lymph nodes, and bloodwork reveals an elevated ACE level. Skin PPD testing shows no observable induration after 48 hours. Liver biopsy in this patient would most likely demonstrate:

Scattered granulomas > Sarcoidosis can cause arthralgia, and skin changes occur in 30-50%. A variety of skin lesions are possible, including subcutaneous nodules (erythema nodosum), erythematous plaques, or macules that are slightly reddened and scaling. > Liver biopsy shows changes in up to 75% of cases. Scattered granulomas are the most common liver pathology finding.

___________________ infection occurs when patients who have been primarily infected incompletely eliminate the M. tuberculosis bacilli within Ghon foci or extra pulmonary sites. The organism that remain then mobilize form these foci during periods of immunosuppression to cause active disease. Patients who take chronic corticosteroids, anti-TNF agents (eg. infliximab or etanercept), calcineurin inhibitors (eg, cyclosporine), or who are HIV-postive are at increased risk for reactivation tuberculosis. In the lung, the typical pathologic finding associated with secondary infection is an *apical cavitary lesion*.

Secondary M. tuberculosis

A 55 yo woman comes to the physician with fever cough, and night sweats for the past 2 weeks. Chest imaging shows a nonspecific pulmonary lesion. Transthoracic needle aspiration is performed. The specimen is cultured and grows several bacterial species, including Peptostrptococcus and Fuobacterium. Which of the following predisposing factors is most likely responsible for this patient's condition? (Mitral valve prolapse, Occult malignancy, Penetrating chest trauma, Seizure disorder, Tobacco smoking, Urinary infection)

Seizure disorder > Peptostreptococcus and Fusobacerium are anaerobic bacteria that are part of the normal mouth flora. The presence of these organisms in this patient's lung lesion is highly suggestive of a developing *lung abscess*. As the abscess evolves, it typically forms a cavitary lesion with an identifiable *air-fluid level* on imaging. Symptoms are often indolent and include fever, night sweats, weight loss, and cough productive of *foul-smelling sputum* (indicative of anaerobes) > Risk factors for lung abscess include conditions that increase aspiration risk, such as *alcoholism, drug abuse, seizure disorder, stroke, and dementia*

A 53 yo man comes to the office due to 7-8 months of SOB. He states that he feels most short of breath when chopping wood for his fireplace. Several of his coworkers have experienced similar symptoms. he has a history of HTN and type 2 DM. Pulmonary examination reveals diffuse fine crackles. Chest x-rays reveals nodular densities in both lungs that are most prominent in the apical regions. Calcifications of the hilar lymph nodes is also seen. Bronchoscopy with transbronchial biopsy of a calcified node is performed, and polarized microscopy shows birefringent particles surrounded by dense collagen fibers. This patient most likely has a history of exposure to which of the following substance?

Silica > This middle-aged adult, presenting with dyspnea on exertion, nodular densities on x-ray, calcified hilar lymph nodes, and birefringent particles on biopsy, has silicosis. *Silicosis* is one of the several pneumonicoses, a group of interstitial lung diseases caused by the inhalation of mineral dusts. It is frequently asymptomatic but can present with dyspnea on exertion and productive cough. Symptoms usually present 10-120 years after intimal exposure. Silicosis is distinguished by calcification of the rim of hilar nodes (*eggshell calcification*) and *birefringent* silica *particles* surrounded by fibrous tissue on histology.

______________________ usually arises from the major bronchi. On chest imaging, it is seen as a hilar mass. Pathology shows flat, oval-shaped cells with scant cytoplasm and hyper chromatic nuclei. Neuroendocrine markers such as *chromogranin* and *synaptophysin* are usually positive.

Small cell carcinoma

A 72 yo man comes to the office after several days of mild headache and lethargy. He has also had weakness, chronic cough, and decreased appetites. He drinks 2 or 3 beers each weekend and has a 40 pack year smoking history. Temperature is (98.6 F), bP 120/84 and pulse is 78 and respirations are 24/min. Lung examinations show mildly prolonged expiration with end-expiratory wheezes. Labs show hyponatremia. Chest x-ray reveals overinflated lung fields and 2.5 cm left hilar mass. Biopsy of the mass would most likely show?

Small cell lung cancer > A neuroendocrine malignancy associated with several paraneoplastic syndromes. It is the most common cause of syndrome of inappropriate antidiuretic hormone (SIADH) due to ectopic secretion of antidiuretic hormone. SIADH is characterized by *hyponatremia*, decreased serum osmolality, and urine osmolality > 100.

______________________ arises from he major bronchi. Imaging will show a hilar mass. Histologically, it is characterized by *keratinization* and *intercellular bridges*. This tumor can sometimes present as a cavitary lung lesion.

Squamous cell carcinoma

Coagulase is an enzyme produced by ________________ that activates prothrombin, resulting int he conversion of fibrinogen to fibrin. This process leads to fibrin-coating of the organism and resistance to phagocytosis.

Staph aureus

A 34 yo HIV-postive man comes to the ED with sudden-onset fever, chills, productive cough, and left-sided chest pain that worsens with deep breathing. His symptoms began 3 days ago. Physical examination shows bronchial breath sounds over the left lower lung. His most recent CD4+ lymphocyte count measured 1 month ago was 800 cells/uL. Which of the following organism is most likely responsible for they patient's symptoms? (Strep. pneumoniae, mycoplasma pneumoniae, pneumocystis jiroveci, staph aureus, legionella, moraxella catarrhalis, mycobacterium tuberculosis)

Streptococcus pneumoniae > The most common cause of community-acquired pneumonia is immunocompetent hosts (which would include an HIV+ patient with normal CD4+ counts) is Streptococcus pneumoniae. NOTE: > Because he is HIV+, it might be assumed that the cause is an AIDS-related opportunistic pathogen such as Pneumocystis jirvoveci. HOWEVER, the normal CD+ lymphocyte count for adults ranges from 400-1400 cells/uL; *counts <200 cells/uL are associated with a significantly increased risk of P jiroveci infection.*

A 3 yo male experiences recurrent sinusitis and one episode of severe pneumonia. As a part of his evaluation, Candida extract is injected intradermally. 48 hours later he returns with a firm nodule measuring 16 mm in diameter in the location where the extract was injected. Which of the following cell types is responsible for the response observed in this patient?

T-lymophcytes > Contact dermatitis, granulomatous inflammation, the tuberculin skin test and the Candidia extract skin reaction are all examples of delayed-type hypersensitivity reactions (DTH). > The cells that mediate DTH reactions are TH1-lymphocytes that realize interferon-g to cause recruitment and stimulation of macrophages . > DTH reactions take days to reach their peak activity; this is in contrast to other hypersensitivity reaction which causes clinical effects within minutes of antigen exposure.

A 56 yo Caucasian male presents to the ED with a six hour history of burning substernal pain. His past medical history is unremarkable and he takes no medications. He smokes two packs of cigarettes every day and consumes alcohol occasionally. An ECG performed in the ED reveals ST segment elevation in lead I and V3-V6. During the next several hours, the patient develops progressive shortness of breath. He is unable to lie still in the bed and insisting on sitting up. Which of the following histologic features is most likely to be newly present in this patient's lung tissue?

Transudate accumulating in the alveolar lumen > Prolonged, burning substernal pain and ST segment elevations in leads I and V3-V6 is strongly suggestive of anterolateral left ventricle infarction. Common consequences of left ventricle infraction include left ventricular failure, cariogenic acute pulmonary edema, pulmonary venous hypertension (congestion), and transudate of plasma into the lung interstitum and alveoli.

_________________ presents with malaise, weight loss, low-grade fever and cough. Chest X-ray shows *patchy* or *nodular infiltrates*, cavities, or calf iced nodules. Histology reveals caseating granulomas

Tuberculosis

uWORLD: A 45 yo man is involved in a motor vehicle collision and suffers a right femoral shaft fracture. He has no other significant injuries. Upon arrival at the host pail, the patient undergoes open reduction and internal fixation of the right femur. On the third postoperative day, he comes tachycardia and tachypenic and has pleuritic chest pain. His temperature is 97F, blood pressure is 120/70 and pulse is 98. PaO2 of 65. Which is the most likely cause of this patient's hypoxemia?

Ventilation/perfusion mismatch > Sudden-onset tachypnea and chest pain in a hospitalized patient should raise suspicion for *pulmonary embolism* (PE). This patient has 2 important risk factors for PE: *immobilization* (causes venous stasis) and *recent surgery* (inflammation induces a hyper coagulable state). The risk of PE can be as high as 50% after an orthopedic procedure. Thrombi most commonly originate in the deep veins of the pelvis and the lower extremities before emboli zing to the lungs. Although the risk of *fat embolism* is also increased following a long bone fracture, this patient lacks the typical skin and neurologic findings. > Thrombic occlusion of the pulmonary circulation leads to increase blood flow to the remainder of the lung, causing a *ventilation/perfusion (V/A) mismatch*. The resulting ischemic injury also causes inflammation, leading to surfactant deficiency and atelectasis in the surrounding lung regions. This leads to high volume of deoxygenated blood traversing poorly ventilated lung regions, causing right-to-left intrapulmonary shunting which often results in *hypoxemia*.

Cells of ___________________, which show *glandular* or *papillary elements* have short and plump microvilli that distinguish adenocarcinoma from mesothelioma.

adenocarcinoma

*Metronidazole* has excellent coverage against ____________ but does NOT cover ________ organism.

anaerobes; aerobic. > Adequate coverage against both aerobic streptococci and anaerobes is essential of successful treatment of lung abscesses.

A 65 yo man comes to the ED due to an episode of hemoptysis that occurred early this morning. The patient estimates that he coughed up about 100 mL of blood. Prior to this episode he was in his usually state of health and felt well, with no fevers, night sweats, or weight loss. He has had occasional episodes of blood-tinged sputum over the past few months. The patient's past medical history is significant for tuberculosis (TB) that was effectively treated several years ago. He had smoked a pack of cigarettes daily for 45 years but quite 4 years ago. A representative cut of the CT scan, shown in the image below, demonstrates changes consistent with prior TB infection, including an old left upper lobe cavity. Compared to prior scans, the main difference is that the cavity now appears to be filled with a round mass. Which of the following best describes this patient's condition? (Allergic, colonizing, contagious, invasive, malignant)

colonizing > *Aspergillus fumigatus* is a mold that is widely present in organic matter. It forms septet hyphae. The spores are inhaled with the air and are typically cleared by the mucus and ciliated epithelium of the respiratory tract. In individuals with suppressed immune defenses, Aspergilus causes a wide spectrum of disease. > This patient likely has hemoptysis due to an *aspergilloma (mycetoma)*, which represents Aspergillus *colonizaiton*. Aspergilomas develop in old lung cavities *from tuberculosis, emphysema, sarcoidosis)

A 52 yo man is being evaluated for persistent nonproductive cough and exertion dyspnea that has progressed over the past year. Lately he has had difficulty accomplishing normal daily activities. The patient has no significant past medical history and takes no medications. He does not use tobacco, alcohol, or illicit drugs. Spirometry shows a forced vital capacity (FVC) that is 40% of the predicted value and a FVC1 to FVC ratio of 87%. A CT guided lung biopsy is performed, and histopathology sows dense fibrosis, fibroblast proliferation, and cyst formation, which are most prominent in the subpleural regions. Which is the most likely diagnosis?

idiopathic pulmonary fibrosis > This patient presenting with slowly progressive external dyspnea and dry cough, a restrictive profile on PFT, and international fibrosis with cystic air space enlargement likely has IPF, a type of idiopathic interstitial pneumonia. > The pathologic findings of IPF are termed "usual interstitial pneumonia (UIP)" and show patch involvement with dense fibrosis and fibroblastic foci. Alveolar wall collapse leads to formation of cystic space (honeycombing) lined by hyper plastic type II pneumocytes or bronchiolar epithelium (honeycomb fibrosis). These findings are more predominant in the sub pleural & paraseptal spaces.

Mononuclear interstitial pulmonary infiltrates are found in the early stages of various ___________________ diseases

interstitial lung

A 34 yo immigrant from Eastern Europe presents to your office with a three-month history of productive cough, night sweats and low-grade fever. Sputum cultures grow budding yeast that form germ tubes at 37 C. The most likely site of this organism before entering the sputum is?

oral cavity > Canaida give rise to tree hyphae, termed "Germ tubes", when incubated at 37 C for 3 hours. Morphologically, all Candida fungi are yeasts, seen in tissue sections as single cells with *pseudohyphae*. > Candida albicans is the most common opportunistic mycosis. It is also a frequent colonizer of human skin and mucous membrane. (Candida contributes to the normal flora off skin, mouth, vagina, and intestine).

A 65 yo man comes to the office due to several weeks f nonproductive cough. The patient also has anorexia and unintentional weight loss. His medical history includes hypothyroidism due to Hashimoto thyroiditis and a 50 pack year smoking history. Examination shows an enlarged, right supraclavicular lymph node. An imaging study shows a large mediastinal mass causing tracheal deviation. Histopathology of a lymph node after biopsy demonstrates clusters of small, ovoid cells with scant cytoplasm and a high mitotic count. Immunohistochemical staining is positive for chromogranin. The patient most lily suffers from which of the following conditions?

small cell lung carcinoma > Small cell carcinoma is strongly associated with smoking and is usually centrally located. This tumor arises form the primitive cell of the basal layer of the bronchial epithelium. Immunohistochemcial stains are frequently positive for neuroendocrine markers (eg. neuron-specific enolase, chromogranin, synaptophysin)

Complete collapse of a lung usually occurs following obstruction of a *mainstem bronchus* (eg. central lung tumors in chronic smokers). As the air trapped in the lung gradually gets absorbed into the blood, there is loss of lung volume due to *alveolar collapse* (i.e., atelectasis), which causes the trachea to deviate ________________ the affected side.

toward HOWEVER > Tension pneumothorax or a large pleural effusion will cause tracheal deviation *away from* the affected lung because the excess air or fluid pushes against the mediastinal structures.

Drug X, a laboratory -synthesized antimicrobial agent, is a D-alaine-D-alanine analog that block bacterial peptidoglycan cross-linking and resists degradation by bacterial enzymes. Antimicrobial diffusion disks with drug X are added to several agar plates, each which contains colonies of a single organism with the appropriate growth medium. The plates are then inverted and incubated for 18 hours alongside control plates with the same organism but no antimicrobial disks. The control plates all show organism growth. In the plates with the diffusion disks, resistance to drug X is detmerined by measuring the zone of complete growth inhibition around the disk. Which of the following bacteria is most likely to be resistant to drug X? (Actinomyces israelii, Borrelia burgdorferi, Helicobacter pylori, Mycoplasma hominis, Pasteurella mutlocida)

> The new antibiotic drug X inhibits synthesis of the *peptidogylcan cell wall* found in both gram-positive and gram-negative orngaims. This cell wall is essential for survival of these organism because it acts as a permeability barrier and protects them from destruction by osmotic stressors. > All organisms in the Mycoplasma genus, including Ureaplasma, lack peptidoglycan cell walls and are therefore resistant to agents that attack the peptidoglycan cell wall such as penicillins, cephalosporins, carbapenems, and vancomycin. > Mycoplasma infection can be treated with anti-ribosomal agents (Eg. tetracycline, macrocodes)

_____________ is an antiviral drug effective against herpes simplex virus (1 and 2) and varicella zoster virus. It is a necloside analog that is converted into acyclo-GTP in infected cells, which inhibits viral DNA polyermase.

Acyclovir

A 55 yo woman comes to the physician because of a persistent cough and recent, unintentional weight loss. She has never smoked and has no history of exposure to industrial pollutants. Physical examination reveals decreased breath sounds and dullness to percussion at the left lung base. Imaging suites show an irregular mass in the lower lobe of her left lung and a left-side pleural effusion. A diagnostic thoracocentesis is performed and he aspirated fluid is sent for cytological evaluation. If a malignancy is diagnosed it is most likely to be?

Adenocarcinoma > Adenocarcinoma is the most common lung cancer in the vernal pollution. It is also the most common subtype in women and nonsmokers. It is locked peripherally and consists of tumor cells that form glandular or papillary structures. > In constrast, squamous cell carcinoma and small cell carcinoma have a strong association with smoking.

A 35 yo man comes to the ED with recurrent hemoptysis, weight loss, and low-grade fevers for several weeks. he says he lost 7 kg over the past 3 months. He recently emigrated from Central America. The patient's temperature is 100 F, blood pressure is 110/70, pulse is 78, and respirations are 18. A chest x-ray demonstrates right lung apical infiltrative and cavitary lung lesions. Sputum cultures grow acid-fast bacilli. he is placed in respiratory isolation and started on antibiotic therapy. The cavitary lesions seen in this patient most likely formed through which of the following pathogenic mechanisms?

Aggregation of activated leukocytes. > Mycobacterium tuberculosis infection characteristically demonstrates granulomatous inflammation with caseous necrosis. Granuloma formation assets in disease containment and occurs mainly through an interaction among macrophage, multinucleate giant cells, and CD4 T lymphocytes. Extensive macrophage activation can also result in collateral tissue damage, resulting in caseous necrosis with formation of cavitary lung lesions.

Patients with asthma are at risk for developing an allergic reaction to A. fumigates called _____________________. Signs and symptoms include cough, dyspnea, wheezing, fever, and migratory pulmonary infiltrates.

Allergic bronchopulmonary aspergillosis

_______________________ causes pulmonary disease in immunocompromised patients. This fungus is seen in tissue sections as *septate hyphae* with V-shaped branching.

Aspergillus fumigatus

A 56 yo man comes to the physician for a follow-up appointment. His medical problems include HTN and osteoarthritis for which he takes amlopdine daily and ibuprofen as needed. He was employed as a construction worker for over 30 years and recently received a latter from his employer stating that he had significant exposure to asbestos early in his cancer. The patient is now concerned about his risk of developing cancer. Which malignancy is likely to develop? (Acute leukemia, bronchogenic carcinoma, gastric carcinoma, malignant mesothelioma, transitional cell carcinoma)

Bronchogenic carcinoma > Asbestos is naturally occurring mineral with insulating properties used in shipbuilding, construction, and textile industries. Inhalation of fine asbestos fibers in occupational and non-occupational settings causes epithelial cell injury, activation of macrophages, and chronic interstitial inflammation and fibrosis. > Patients with a long history of asbestos exposure are at risk for developing asbestosis, plural disease, and malignancies such as bronchogenic carcinoma and mesothelioma. *Bronchogenic carcinoma* is the most common malignancy in this population, followed by *mesothelioma*

A 53 yo man comes to the ED due to progressively worsening SOB, nonproductive cough and low-grade fevers over the past 2 weeks. He has not had a runny nose or sore throat and does not recall any sick contacts. He received a lung transplant for idiopathic pulmonary fibrosis 4 months ago. His medications include immunosuppressants and trimethoprim-sulfamethoxazole. His temperature is 100 F. Chest x-ray reveals diffuse interstitial infiltrates bilaterally. A decrease in pulmonary function is noted on testing. Which characteristics the organism most likely responsible for this patient's current condition?

Enveloped double-stranded DNA virus > Transplant patients are at risk of a variety of unusual infections due to their immunocompromised state. *Cytomegalovirus (CMV)* is particularly common in patients with lung *transplants* (typically occurring within the first few months after transplant). Most but not all transplant centers practice universal prophylaxis for lung transplant recipients (eg. valganciclovir). > CMV is an *enveloped double-stranded DNA* virus belonging to the Herpesvirdiae family. > Histopathology of lung biopsy from patients with CMV *pneumonitis* (most common form of tissue-invasive CMV following lung transplant) may show enlarged cells with *intranuclear and intracytoplasmic inclusions* (viral particles); there is often a surrounding halo (*owl's eye*)

A 63 yo man is brought to ED after recent onset of high fever, confusion, headache, watery diarrhea, and mildly productive cough. He has been smoking two packs daily for more than 30 years and has been diagnosed with chronic bronchitis. Otherwise, his PMH is not significant. His temperature is 104 F, blood pressure is 100/70, pulse is 91/min, and respirations are 28/min. Sputum Gram staining reveals numerous neutrophils but no bacteria. Which of the following is the mostly likely cause of this patient's disease?

Legionella pneumophila > Legionnaires' disease has a propensity to affect smokers and is characterized by very high fever, diarrhea, headache, and confusion. Laboratory studies frequently show hyponatremia. L. pneumophilia is a gram-negative rod that is often not detected on Gram stain. > Diagnosis can be difficult because the signs/symptoms are not specific. Should be suspected in a patient with radiographic evidence of pneumonia, high fever, and accompany GI symptoms such as diarrhea. Acquiring a diagnostic sputum sample is difficult and unreliable, often showing few or no bacteria since unique LPS chains on the outer membrane inhibit Gram staining. > Diagnosis is most commonly made by testing for Legionella antigen in the urine. > Can cause a life threatening pneumonia if not recognized and treated properly. Treatment is the respiratory fluroquinolones (i.e. levofloxacin) or newer macrocodes (ie. azithromycin)

A 56 yo smoker with a persistent dry cough comes to the physician due to recent-onset headaches and dyspnea. He also complains of having a "puffy face" for 2 weeks but denies any other medical problems. He has no shoulder pain. Physical examination shows symmetrical facial swelling and conjunctival edema. His pupils are equal, round, and reactive to light. Dilated vessels are seen over this neck and upper trunk. Heart sounds are clear. This patient's condition is most likely caused by which of the following?

Mediastinal mass > Intrathroacic spread of bronchogenic carcinoma may lead to compression of the superior vena cava, causing impaired venous return form the upper part of the body. Signs and symptoms include dyspnea, facial swelling, and halted collateral veins in the upper trunk. > This patient's symptoms are consistent with impaired venous return from the upper body. The superior vena cava provides venous drainage from the head, neck, upper trunk, and upper extremities. It is formed by the union of the right and left brachiocephalic veins behind the 1st costal cartilage on the right. It has thin walls and is easily compressed by mediastinal masses. > Compression of the superior cava causes a combination of symptoms called *superior vena cava syndrome*. Affected patients complain of dyspnea, cough, and *welling of the face*, neck, and upper extremities. Headaches, dizziness, and confusion may occur due to cerebral edema and elevated intracranial pressure. > Dilated collateral veins may be seen in the upper torso. Lung cancer, followed by non-Hodgkin lymphoma, is the most common cause of superior vena cava dyrnome.

A 45 yo man comes to the ED due to 2 weeks of chest pain and cough. He has a history of advanced HIV and has taken his antiretroviral medications inconsistently over the past few months. Temperature is 100.6 F. Crackles are heard on pulmonary examination. CD4 cell count is 98/mm. Chest x-ray reveals nodules and hilar lymphadenopathy. A bronchoscopy is performed. Mucicarmine staining of the patient's bronchoalveolar fluid shows budding yeast forms with thick capsules. Symptomatic infection with the organism causing this patient's condition most common manifests as which of the following?

Meningoencephalitis > Budding yeasts with thick capsules are chracerstic of Cryptococus neoformans, which typically affects only *immunocompromised* patients (*opportunistic pathogen*). C neoformans is present in soil and pigeon droppings; it is transmitted by the respiratory route but not acquired via person-to-person contact. > In individuals with an impaired cellular immune response, C neoformans can cause symptomatic disease, most commonly *meningoencephalitis*

In ___________________ constitutional symptoms (eg. night sweats, weight loss, fever) and chest x-ray finding (eg. upper lobe infiltrates with cavitation)

Mycobacterium tuberculosis

Bacteria isolated from the lung tissue of a 32 yo Caucasian male fail to depolarize with HCL and alcohol after staining carboifuchsin. Which of the following cell wall components is most likely responsible for this atoning phenomenon?

Mycolic acid > The acid-fast stain identifies organism that have mycelia acid present in their cell walls, including Mycobacterium and some Nocardia species. > Acid-fast staining is carried out by applying an aniline dye (eg, carbolfuchsin) to a smear and then decolorizing with acid alcohol to reveal whether the organisms present are "acid fast".

A 23 yo male is being evaluated for persistent cough and a pulmonary infiltrate detected on chest X-ray. 3 mL of this patient's blood is added to an anticoagulated tube and placed into iced water. Several minutes later clumping is detected inside the tube, but it rapidly uncoagulates when the tube is warmed while being held it in the observer's hand. Which of the following organisms is most likely responsible for this patient's condition?

Mycoplasma pneumonia > The question stem is describing the effect of cold agglutinins. As their name implies, cold agglutinins cause the agglutination or clumping of RBCs when a sample of blood containing cold agglutinins is chilled. > Cold agglutinins are antibodies that are produced in response to Mycoplasma pneumoniae infection. These antibodies are directed against antigen in the cell membrane of M. pneumoniae that happen to be homologous to antigens that are present on the surface of human erythrocytes. > The cold agglutinins are responsible for the transient anemia that can be documented in many patients with M. pneumonia infection. > Cold agglutinins are also associated with Epstein-Barr virus infection and hematologic malignancies in addition to infection with Mycoplasma pneumoniae.

______________________ typically causes atypical penuomina characterized by a persistent nonproductive cough, pharyngitis, ear pain, and constitutional symptoms (eg. fever, headache, malaise). Chest x-ray classically reveals a diffuse interstitial infiltrate.

Mycoplasma pneumoniae

Health authorities are investigating an outbreak of respiratory infections among a group of military recruits. Fifteen recruits reported persistent cough, low-grade fever, and malaise. Apart from the low-grade fever, physical examination was largely unremarkable. Chest x-rays were all notable for pulmonary infiltrates that appeared more severe than what would have been expected based on assessment of the patient's clinical status. Sputum specimens were obtained, and the causative organism required a complex acellular medium enriched with cholesterol to grow. Which of the following organism is the most likely cause of the outbreak?

Mycoplasma pneumoniae. > Mycoplasma pneumoniae is the causative agent of "walking pneumonia" an infection typically characterized by a nagging nonproductive cough, low-grade fever, and malaise. Often, the chest x-ray suggests a severe pneumonia even though the patent appears relatively well. > *Mycoplasma species require cholesterol supplementation* to grow on artificial media.

A 42 yo man comes to his primary care physican due to daytime sleepiness. He often falls asleep during meetings and while watching television and has even fallen asleep while driving. The patient does not feel refreshed when waking and has occasional morning headaches. He has no had abnormal dreams or visual hallucinations when falling asleep or on walking. The patient has no significant past medical history and is a lifetime non-smoker. He drinks 2 or 3 beers on Friday nights. Blood pressure is 148/100, pulse is 78 and BMI is 32. Cardiopulmonary examination shows no abnormalities. Arterial blood gas analysis is normal. What is this patient's most likely diagnosis?

Obstructive sleep apnea > Obstructive sleep apnea is due to relaxation of oropharyngeal muscle one with occlusion of the upper airway. Symptoms include daytime sleepiness, *headaches*, and depression. > Complications include systemic and pulmonary hypertensions, right heart failure, and an increased risk for cardiac events. NOTE > Obesity hypoventilation syndrome by restricted expansion of the chest wall due to severe obesity. his leads to hypoventilation with a chronically elevated PCO2 and reduced PO2. > This patient's normal blood gases and mild obesity are not consistent with obesity hypoventilation.

A 78 y/o nursing home resident is brought to the ED because of fever, chest pain, and a productive cough. His temperature is 39.4 (10 F), BP is 106/62 mmHg, pulse is 112/min, and respirations and 35/min. Chest x-ray reveals a left lower lobe infiltrate. Sputum microscopy shows numerous lancet-shaped gram-positive diplococci. He dies despite aggressive hydration and antibiotic treatment. This patient's death might have been prevented if he had received a vaccine containing which of the following components? (Killed bacteria, Live attenuated bacteria, Outer polysaccharide covering, recombinant surface protein, unconjugated toxoid)

Outer polysaccharide covering > The elderly and young children are at high risk for invasive pneumococcal disease and should be vaccinated against Streptococcus pneumoniae. The pneumococcal polysaccharide vaccine is an unconjugated vaccine that induces a relatively T-cell-indpendent response. In contrast, the pneumococcal conjugate vaccine contains polysaccharide material attached to a protein antigen, which allows for a more robust T-cell-dependent response.

A 30 yo woman comes to the ED with acute-onset of SOB. Analysis of the patient's expiratory gases reveals the following Tracheal pO2 = 150 mmHg Alveolar pO2 = 145 mmHg Alveolar pCO2 = 5 mmHg What best explains the results of the patient's pulmonary gas analysis?

Poor alveolar perfusion > Normal tracheal pO2 is 150 mmHg and normal alveolar pO2 is 104 mmHg. The equilibration of O2 in a normal individual at rest is perfusion-limited. Situations where O2 equilibration can become diffusion-limited include disease states such as emphysema and pulmonary fibrosis, and physiologically in states of very high pulmonary blood flow, such as during exercise.

A 54 yo man comes to the office due to daytime sleepiness and lack of energy. The symptoms began 6 months ago and have progressively worsened so that he feels "completely drained" by the end of the day. The patient's wife mentions that he snores loudly. His past medical history is unremarkable, although he has not been a physician in over 10 years. The patient does not use tobacco or alcohol, and he works in the warehouse of an agricultural supply company. BMI is 34. Physical examination shows a narrow oropharynx and a large neck circumference. The patient is at increased risk of developing which of the following? (Bronchiectasis, Hypertropic cardiomyoatphy, Laryngeal carcinoma, Narcolepsy, Pulmonary hypertension).

Pulmonary hypertension > Obstructive sleep apnea presents in obese individuals with excessive daytime sleepiness and signs of nocturnal upper airway obstruction (eg. snoring, gasping). The condition is associated with systemic hypertension. Prolonged, untreated obstructive sleep apnea can also cause pulmonary hypertension and right heart failure. > This patient, an obese man with loud snoring, daytime sleepiness, and suggestive examination findings (eg, thick neck, narrow airway) most likely has *obstructive sleep apnea* (OSA). > OSA is characterized by recurrent obstruction of the upper airway during sleep; each nocturnal episode of reduced ventilation causes transient *hypercapnia* and *hypoxemia*.

A 45 yo man comes to the urgent care clinic because of fever, severe headache, myalgia, and pleuritic chest pain. He has had these symptoms for several days. Physical examination shows fever and mild tachycardia. Lung auscultation reveals mid crackles. Radiographic examination is consistent with segmental pulmonary infiltrates. The patient fails to respond to empiric antibacterial antibiotic therapy. Microscopic examination of lung tissue obtained from this patient shows spherules packed with endospores. This patient' history is most likely to reveal which of the following?

Recent travel to Arizona > Cocidiocides immitis is a dimorphic fungus that has a mold form (hyphae) and a endosperm form (spherules containing endospores, a unique characteristic of Coccidiodies) at body temperature. > C. immitis is endemic to the southwestern US (i.e., southern and central California, Arizona, New Mexico, and western Texas), northern Mexico, and some regions of Central and South America. > C. immitis is transmitted by spore inhalation. Spores are formed by fragmentation of hyphae. Once inside the lung, the spores turn into spherules that contain endospores. The spherules subsequently rupture and release endospores that disseminate to other organs and tissues. Each endospore is capable of forming a new spherule.

A 74 yo previously healthy Caucasian male comes to his physician's office complaining of abrupt onset fever, headache, myalgia, malaise, cough, and throat pain. His two granddaughters missed several days of school because of similar symptoms. Examination demonstrates mild hyperemia of the throat without any exudate, and the patient is sent home on conservative management. Fiver days later, he is admitted to the hospital with progressive dyspnea, chest pain, and productive cough. Which of the following pathogens is most likely to be isolated form this patient's sputum? (Listeria, klebsiella, Staph aureus, nontuberculous mycobacteria, cytomegalovirus)

Staphylococcus aureus > The patient's presenting signs and symptoms and report of similarly ill household children are consistent with influenza infection. Individuals infected with influenza A tend to experience abrupt onset fever, headache, myalgia, and malaise; signs and symptoms gradually improve over a period of two or five days. > A subset of patients stricken by influenza go on to develop secondary bacterial pneumonia characterized by recurrent fever, dyspnea, and productive cough. The elderly are particularly at risk for this complication. > In order, the pathogen most often responsible for secondary bacterial pneumonia are Strep pneumonia, Straph Aureus, and Haemophilus influenzae.

The presence of numerous neutrophils in the alveolar fluid would be consistent with an *exudate*, which occurs in the setting of an _______________ or _______________

acute bacterial or aspiration pneumonia

A 27 yo medical student is coughed on by a patient who suffers from an active pulmonary TB infection. The student has never been exposed to M. tuberculosis before. Which of the following would most likely happen during the first week after exposure?

intracellular bacterial proliferation > Mycobacteria are phagocytosed by alveolar macrophages, and the sulfated virulence factor expressed by M. tuberculosis allows for intracellular bacterial proliferation. > Continued proliferation eventual kills the macrophage and ashes cellular lysis, allowing M. tuberculosis to be phagocytize by and infect additional macrophages. > Virulence factors expressed by the mycobacterium promote the recuriment of additional native, inactivated macrophages and also undermine the immunologic intracellular signaling between antigen presenting cells and helper T-cells. > Eventually, antigen carrying macrophages or dendritic cells migrate to the lymph nodes and induce a helper T-cell response. However, this occurs approximately 2-4 weeks following the intimal infection.