Medical Microbiology and Immunology Test 4
A healthcare provider is teaching a student about malaria and its mode of transmission. Which of the following statements made by the student would indicate a need for additional teaching?
"A bite from the deer tick is the most common mode of transmission"
The human gastrointestinal system is the site for many of the organisms we have considered in this class. Pick one organism from each list (Q24, answers 1-5, Q25, answers 1-5 that is not normally find in human intestine.
24. Babesia microti 25. Mycobacterium tuberculosis
A mother takes her baby to the pediatrician as she is worried about the general droopiness and weak feeding activity of her baby. The baby is also suffering from constipation. During questioning about feeding, the pediatrician learns that the mother had previously fed her baby honey from locally produced honey. Which of the diseases below would be the most likely diagnosis? A. Botulism B. Tetanus C. Leprosy D. Lymphogranuloma venereum E. Tuberculosis
A. Botulism
Which of the following genera contains species that have a dimorphic or biphasic life cycle? A. Chlamydia B. Borrelia C. Treponema D. Bartonella E. Rickettsia
A. Chlamydia
Which of the following pathogens can be detected within the cytoplasm of peripheral blood leukocytes based on the presence of morulae? A. Ehrlichia chaffeensis B. Chlamydia trachomatis C. Borrelia burgdorferi D. Treponema pallidum E. Rickettsia rickettsiae
A. Ehrlichia chaffeensis
A 19-year old man presents with a painless sore on his penis. The physician informs him that he has developed a highly infectious lesion, commonly known as a chancre, which is a sign of A. Primary syphilis B. Secondary syphilis C. Tertiary syphilis D. Congenital syphilis E. Latent syphilis
A. Primary syphilis
Which of the following statements is generally true for obligate anaerobes? A. They lack superoxide dismutase and catalase enzymes B. They are all gram-negative organisms C. They contain superoxide dismutase and catalase enzymes D. They all produce neurotoxins E. They are all rod-shaped
A. They lack superoxide dismutase and catalase enzymes
Which of the following is NOT true regarding Mycobacteria? A. Waxy cell wall with high protein content B. Bacillus C. Aerobe D. Slow growing E. Require specialized growth medium for isolation
A. Waxy cell wall with high protein content
The protein synthesis inhibitor, doxyclycline, is used to treat which of the following? A. Lyme Disease B. Ehrlichiosis C. Rocky Mountain spotted Fever D. All of the Above E. None of the three diseases listed above
All of the Above
The lifecycle of Plasmodium falciparum is comprised of both sexual and aseual phases that occur in independent host animals. Which of the following is the site of the sexual reproductive phase?
Anopheles midgut
The human being is the only known reservoir of infection in leprosy except for the fact that naturally occurring disease with organisms indistinguishable from Mycobacterium leprae has also been detected in:
Armadillos
This common food-borne pathogen is estimated to cause almost a million cases of abdominal cramps and diarrhea each year. These symptoms typically occur 8-22 hours after consumption of food that has been improperly stored following cooking. In most instances the disease is self-limiting and is over within 24 hours. The pathogen responsible is? A. Clostridium botulinum B. Clostridium perfringens C. Clostridium difficile D. Clostridium tetani E. Ehrlichia chaffeensis
B. Clostridium perfringens
Which of the following is a correct pairing of parasite and microscopic structure? A. Cyclospora cayatensis and flagellae B. Entamoeba histolytica and engulfed red blood cells C. Giardia lamblia and cilia D. Plasmodium falciparum and hypnozoites E. Plasmodium vivax and kinetoplasts
B. Entamoeba histolytica and engulfed red blood cells
Multiple diagnostic tests are available for determining whether a particular pathogenic organism is present or not. What test is based on detecting DNA of a particular pathogen? A. Complement Fixation B. Polymerase Chain Reaction C. Enzyme-linked Immunosorbent Assay D. Latex bead agglutination E. Fluorescent Antibody
B. Polymerase Chain Reaction
Mycoplasma pneumonie is a bacterium that: A. causes a severe respiratory infection that nearly always requires hospitalization B. adheres to respiratory epithelial cells via a specialized tip structure C. is a very rare cause of "walking pneumonia" D. is surrounded by both inner and outer membranes E. cannot be grown on solid agar medium
B. adheres to respiratory epithelial cells via a specialized tip structure
Which of the following is caused by the action of a neurotoxin that prevents the release of the neurotransmitter acetylcholine into the synapse? A. gas gangrene B. flaccid paralysis C. erythema migrans D. condyloma lata E. spastic paralysis
B. flaccid paralysis
The petechial rash characteristic of the spotted fever group of Rickettsiae: A. spreads from the trunk to extremities B. is referred to as erythema migrans C. spreads from the extremities to the trunk D. is referred to as condyloma lata E. is spread by a mosquito vector
B. is referred to as erythema migrans
Which if the following bacterial genera produces endospores?
Bacillus and Clodstridum
A 47 year old man who is diagnosed with lymphoma picked up his daughter at the airport from her recent trip to Mexico. Three days later he developed a headache, vomiting, and abdominal pain that worsened to include bloody diarrhea. He informed his physician that his daughter had spent most of her time in Mexico working on a pig farm. Stool sample reveals the presence of cysts and large, ciliated organisms. What is the most likely cause of the disease?
Balantidium coli
A 12 year old girl presented with a 4 day history of fever, headache, and malaise. Physical exam revealed a pustular lesion on her right hand and enlarged tender lymph nodes in the right cervical and axillary regions. Her symptoms developed two weeks after she had been bitten by her kitten. Silver staining demonstrated pleomorphic organisms. Bacteriologic cultures revealed a bacterium with a fastidious growth requirements. Serologic testing confirms the presence of antibodies against the causative agent. What was the most likely cause?
Bartonella henselae
Giardia lamblia typically results in a self-limiting diarrheal disease 1-2 weeks after exposure to contaminated water or foodstuffs. Which of the following animals is know to be a non-human reservoir for this parasite?
Beavers
A mother takes her baby to the pediatrician as she is worried about the general droopiness and week feeding activity of her baby. The baby is also suffering from constipation. during questioning about feeding, the pediatrician learns that the mother had previously fed her baby raw honey from a local apiary. Which of the following diseases below would be the most likely diagnosis?
Botulsim
Which of the following species causes diarrhea and colitis that is associated with disruption to the normal intestinal microbiota following broad spectrum antibiotic use? A. Clostridium botulinum B. Clostridium perfringens C. Clostridium difficile D. Clostridium tetani E. Ehrlichia chaffeensis
C. Clostridium difficile
The activity of the following toxins is/are produced following spore germination of a pathogen and results in diarrhea and damage to the intestinal mucosa that may result in pseudomembranous colitis?
C. difficule toxins
At this year's Thanksgiving lunchtime meal, your grandparents cover the turkey with foil so that it will be warm throughout the afternoon and evening. You inform them that this is not a good idea because it may allow the growth and toxin production of a common food-borne pathogen. This organism is
C. perfringens
The Nagler test is used to identify which of the following species?
C. perfringens
A female infant was born at a gestation age of 26 weeks was transferred to the neonatal ICU. Her treatment included assisted ventilation, intravenous fluids, and broad spectrum antibiotics. On the fifth postnatal day, the infant became clinically unstable, and a review of her peripheral blood smear showed the presence of a dimorphic organism (Image 8). Blood culture on Sabouraud agar isolated a gram-positive, ovoid-shaped organism. Despite appropriate clinical management the infant died on the 12th day of her life. What is the most likely cause of her infection?
Candida albicans
A freshman student presents to the Student Health Center after a week of exhibiting a dry hacking cough and other signs of mild respiratory tract infection. After physical examination, the physician informs the student that it is very likely a common bacterial cause of community acquired pneumonia and that multiple residents of the same residence hall had similar symptoms. A suitable specimen is collected but no growth on rich solid or liquid medium is observed, even after a month of incubation. Which of the following is the most likely pathogen?
Chlamydophila pneumoniae
Which of the following bacterial species is a gram positive spore-forming and toxin-producing bacterium that contributes to approximately 15,000 deaths per year, primarily in elderly residents in nursing homes?
Clostridium difficile
A 35 year old male with a history of chronic intravenous drug use presented to the emergency department with right upper limb pain an swelling. On clinical examination severe edema of the upper limb, erythema, blistering of the arm and crepitus over the shoulder and arm was noted (image 13). An X-ray of the affected limb revealed gases trapped within the soft tissues (image 14). The patient was started on broad-spectrum antibiotics and underwent arm and forearm fasciotomy to remove necrotic tissues. Cultures of tissue specimens obtained intraoperatively revealed the presence of an anaerobic, gram-positive bacillus. What is the most likely cause of the infection?
Clostridium perfringens
Which of the following bacteria would be expected to LACK the enzymes Superoxide dismutase and catalase?
Clostridium tetani
How are Leptospira species transmitted from their animal reservoirs to humans?
Contact with urine from an infected animal
A 69 year old man presented to University Hospital complaining of progressively more severe headaches over several weeks, and sudden persistent hearing loss. Examination of the cerebrospinal fluid (CSF) showed the presence of numerous leukocytes and budding yeast cells (Image 9). An India-ink preparation of the fresh CSF revealed the mutinous capsule of the organism as a translucent halo surrounding the budding yeast (image 10). What is the most likely cause?
Cryptococcus neoformans
A 27-year-old female who recently returned from a camping trip to Martha's Vineyard complains of fever, headache and general fatigue. Blood smears reveal a replicating parasite attached together forming a structure looking like a "Maltese cross". What is the most likely parasite? A. Entamoeba histolytica B. Plasmodium vivax C. Plasmodium falciparum D. Babesia microti E. Toxoplasma gondii
D. Babesia microti
Depending on serovar (serologic variant), this pathogen has been linked to pelvic inflammatory disease and urethritis, lymphogranuloma venereum, ophthalmia neonatorum and blindness. What is the pathogen? A. Neisseria gonorrhoeae B. Borrelia burgdorferi C. Bartonella henselae D. Chlamydia trachomatis E. Ureaplasma urealyticum
D. Chlamydia trachomatis
Which of the following bacterial species is a Gram positive spore-forming and toxin-producing bacterium that contributes to more than 10,000 deaths per year, primarily in residents of nursing homes? A. Clostridium perfringens B. Clostridium novyi C. Clostridium tetani D. Clostridium difficile E. Clostridium botulinum
D. Clostridium difficile
A 25-year old man presents with moist erythematous lesions noted as condyloma lata. The rapid plasma reagin (RPR) test is performed. This test is an indirect test and detects antibodies to which of the following? A. Borrelia burgdorferi B. Bartonella henselae C. Treponema pallidum D. Host cardiolipin E. Neisseria gonorrhoeae
D. Host cardiolipin
A male student reports to Student Health at the start of the Fall semester complaining of fever, chills, severe headaches and loss of consciousness. The student reports that he recently returned from Africa where he was working as a volunteer teacher at a district school. Cerebral malaria is suspected but initial blood smear testing fails to identify the parasite in the sample. What is the most likely explanation? A. Malaria parasites can only be detected in the cerebral spinal fluid of such patients B. Factors released by the parasite cause the blood cells to lyse prior to microscopic identification C. Co-infection with Staphylococcus aureus results in rapid killing of the malaria parasite D. Malaria parasites promote RBCs to stick to endothelial cells sequestering them from the peripheral blood supply E. Incorrect preparation of thin and thick blood smears
D. Malaria parasites promote RBCs to stick to endothelial cells sequestering them from the peripheral blood supply
Which of the following is associated with fish tank granuloma? A. Mycobacterium leprae B. Mycobacterium tuberculosis C. Mycobacterium bovis D. Mycobacterium marinum E. Mycobacterium ulcerans
D. Mycobacterium marinum
Based on their mode of antibacterial action, Beta lactam antibiotics including penicillin and cephalosporins are INEFFECTIVE against which of the following organisms? A. Chlamydia trachomatis B. Treponema pallidum C. Neisseria gonorrhoeae D. Mycoplasma pneumoniae E. Clostridium perfringens
D. Mycoplasma pneumoniae
The Elementary body (EB) of pathogens with the dimorphic or biphasic life cycle: A. is larger than the reticulate body (RB) B. replicates by binary fission C. grows on complex, nutrient-rich solid medium D. is the infectious form of the organism E. is the most metabolically active form
D. is the infectious form of the organism
A 37 yo female currently living on the streets of NYC presents at a local clinic complaining of fever, headaches, profuse night sweats, and a persistent cough. Diagnostic testing is consistent with primary, active tuberculosis. The attending physician initiates combination therapy using the DOTS regimen to limit the likelihood of antibiotic resistance developing. DOTS stands fro:
Directly observed treatment, short-course
Which of the following describes the organism that causes Gas gangrene? A. Gram positive rod B. Produces endospores under adverse conditions C. Toxin producer D. Lacks catalase activity E. All of the above
E. All of the above
Which of the following is a tick-borne disease that is not uncommon in Missouri and is caused by an intracellular pathogen that replicates inside endothelial cells? A. Lyme disease B. Trachoma C. Ehrlichiosis D. Syphilis E. Rocky Mountain Spotted Fever
E. Rocky Mountain Spotted Fever
In the United States, the DaPT vaccination is given to children ages 2, 4, 6 months and 4 years. The letter T refers to: A. Tuberculin B. Trachoma antigen C. Typhoid polysaccharide D. Toxoplasmin E. Tetanus toxoid
E. Tetanus toxoid
Which of the following pathogens can be detected within the cytoplasm of peripheral blood leukocytes based on the presence of moraulae?
Ehrlichia Chaffeensis
A 28 year old woman presents with a 12 day history of abdominal pain accompanied by blooding diarrhea with thick mucus. Her medical history reveals she recently returned from an extended vacation in South America where she often consumed food preparedly street vendors. Stool examination for O&P (ova and parasites) reveals these organisms (image 17). Colon biopsy identified characteristic flask-shaped lesions (image 18). What is the most likely cause?
Entamoeba histolytica
A healthcare provider is evaluating a blood sample from a patient presumptively diagnosed with malaria under the microscope. Which of these cellular characteristics should the health care provider anticipate?
Erythrocytes containing ring-like structures
The organisms associated with the development of gas gangrene is best described by which of the following sets of characteristics?
Gram positive bacillus, toxin-producing, spore-forming, superoxide dismutase negative
A 9 year old girl presented to her local clinic in Los Angels with a slight fever, dry cough, and myalgia. Chest X-ray showed a widened mediastinum and extensive diffuse infiltrates consistent with pneumonia. QuantiFERON Gold test was negative. A blood smear revealed numerous macrophages containing yeast cells. Patient justify revealed she had recently returned from visiting her grandparents in central Missouri where she spent several hours in an abandoned chicken coop playing with newborn puppies. What is the most likely cause?
Histoplasma capsulatum
A 25 year old man presents with moist erythematous lesions noted as condylomalata. The rapid plasma reagin (RPR) test is performed. This test is an indirect test and detects antibodies of which of the following?
Host cardiolopin
37 year old HIV positive female presents at the University Hospital complaining of fever, headache, profuse night sweats, and a persistent cough. Diagnostic testing is consistent with primary, active tuberculosis. The attending physician initiates combination therapy including isoniazid. Isoniazid is a bactericidal antibiotic that acts by:
Inhibiting flagellum activity
How is Mycobacterium leprae cultured in the laboratory?
It cannot be grown in lab
An otherwise healthy 29 year old woman visits the Boone County Department of Public Health and Human Services for a tuberculin skin test (TST) because she is required to have one before starting her new job as a health care worker. Two days after receiving an intra-dermal PPD injection she returns to the clinic with a positive induration at the injection site measuring 18 mm. She has no overt symptoms of TB, and her chest X-ray findings are normal. The nurse assessing the woman recored a diagnosis of
Latent TB infection
Which of the following diseases can be contacted as a water-borne infection resulting from drinking of water contaminated with rodent urine (that contains the pathogen)?
Leptospirosis
Which of the following disease can progress to stage where treatment-resistant arthritis develops, that is believed to result from an auto-immune like response due to similarity between a pathogen surface protein and a human protein?
Lyme disease
A female student reports to Student Health at the start of the fall semester complaining of fever, chills, severe headaches and loss of consciousness. The student reports that she recently returned from Africa where she was working as a volunteer teacher at a district school. Cerebral malaria is suspected but initial blood smear testing fails to identify the parasite in the sample. What is the most likely explanation?
Malaria parasites promotes RBCs to stick to endothelial cells sequestering them from the peripheral blood supply
Which of the following genera contains species that frequently exhibit a characteristic "fried-egg" like appearance under appropriate culture conditions?
Mycoplasma
Which state typically has the highest number of cases of Rocky Mountain Spotted Fever each year?
North Carolina
The most likely lifestyle of organisms lacking these enzymes is
Obligate anaerobe
A 44 year old man was admitted to the University Hospital with fevers and chills. Fever episodes occurred every 48 hours, which high peaks followed by abrupt resolution. He recently returned from Pakistan where he spent two months visiting friends and relatives. On further examination he was found to have jaundice, tachycardia, and hepatosplenomegaly. His peripheral blood smear is shown in Image 15. What is the most appropriate conclusion?
Red blood cells are infected with Plasmodium falciparum
A 57 year old man presented with a 7 year history of diffuse skin infiltration associated with sensory loss in his left hand. His face had multiple nodular lesions that coalesced in to plaques, especially on the forehead, ears, nose, and lips (image 21). He had weakness in the muscles on the left side of his face and loss of eyebrow hair and eyelashes. Skin smear stained according to the Ziehl-Neelsen method revealed acid-fast bacilli in clumps (image 22). Nerve damage typically associated with his pathogen results from
Replication of the bacterium within Schwann cells
Multi-drug resistant tuberculosis (MDR TB) is caused by tubercle bacilli that are resistant to which of the following major first line medications?
Rifampin and isoniazid
A 28 year old woman comes to the physician because of a fever, mild headache, and sore throat. Her temperature is 39 C (102 F), and her pulse if 90/min. Her medical history revealed she had developed a painless genital ulcer which spontaneously healed several weeks ago. Physical examination shows generalized lymphadenopathy and a diffuse, bronze-colored, maculopapular rash covering her body, palms, and toes. What is the most likely diagnosis?
Secondary syphilis
A 43 year old HIV positive female presents to the clinic with a productive cough, fever, and general fatigue. Acid-fast staining of a sputum sample revels numerous small bacilli (image 11). Chest X-ray reveals a cavitary lesion within the upper right lobe and generalized interstitial infiltrates throughout both lungs (image 12). PPD test shows an induration that measures >20mm What is the most likely cause?
Secondary tuberculosis
A 55 year old farmer clearing a field injures his hand on a rusty nail. Several days later his jaw feels tighter and suffers from increased perspiration and back spasms. When he visits his family physician, his doctor informs that he has not visited his office for more than 15 years. A likely diagnosis is
Tetanus
The life cycle of Babesia microti comprises an exogenous sexual phase with multiplication in Ixodes scapularis (deer tick) and an endogenous asexual phase with multiplication in the vertebrate host. In strict biological terms the tick is considered
The definitive host
A 49 year old HIV positive male presents to the clinic complaining of fever, night sweats, cough and weight loss over the past several weeks. Suspecting the patient may have developed secondary TB, the physician orders a chest x-ray and tuberculin skin test (TST). While the results of the chest x-ray are consistent with secondary TB, the patient's TST test is negative. What is the most likely reason for the negative TST test?
The person's memory T-cell population has been destroyed by HIV co-infection
Image 16 illustrates an example of inflammation of the eye associated with the leading preventable cause of blindness in the world. Amongst the causes of the loss of sight is the long term mechanical abrasion of the cornea. The disease is called
Trachoma
Which if the following enzymatic reactions may result in urogenital tract inflammation during a bacterial infection?
Urea breakdown
Which of the following toxin(s) are important to the pathogenesis of gas gangrene
alpha and PLO toxins
Identify the cell type that is most commonly associated with Mycoplasma pneumoniae
ciliated epithelial cells
A 37 year old HIV positive female presents at University Hospital complaining of fever, headache, profuse night sweats, and a persistent cough. Diagnostic testing is consistent with primary, active tuberculosis. The attending physician initiates combination therapy including isoniazid. Isoniazid is a bactericidal antibiotic that acts by:
disrupting cell wall synthesis
Identify the cell type that is most commonly associated with Rickettsia Rickettsiae
endothelial cells
Which of the following is caused by the action of a neurotoxin that prevents the release of the neurotransmitter acetylcholine into the synapse?
flaccid paralysis
In the complement fixation test, which of the following is true
in a positive test, complement is fixed/tied up by antibodies binding to pathogen antigen
Rifampicin is used in the treatment of several medically important pathogens including M. tuberculosis, S. aureus, N. Meningitidis, and C. pneumoniae. The mechanism of action of rifampicin involves:
inhibition of RNA synthesis
The elementary body (EB) of bacterial pathogens with the dimorphic or biphasic life cycle:
is the infectious form of the organism
The form of leprosy associated with severe disfigurement of the face is
lepromatous
Which of the following species have been recently assigned to the genus Chlamoydophila?
psittaci and pneumoniae
With many infectious diseases, more severe conditions will often develop in individuals who are immunocompromised or immunosuppressed. Of the pathogens discussed in class, which is most likely to be responsible for the benign tumors observed in Image 33.
• B. henselae
A 17 year old boy presented with a 10-day history of joint pain, fever, and headache. On examination at presentation, he was noted to have a characteristic rash on both arms (Image 1). During a walk in a forest 3 weeks before presentation, he recalls being bitten by numerous ticks, which was removed several hours later. What is the most likely cause?
• Borrelia burgdorferi
A 46 year old male veterinarian who specializes in exotic birds (image 34) was admitted to University Hospital complaining of increasing weakness, generalized muscle pains, fever, chills, and night sweats for the previous five days. For the last two days he had a dry cough, anorexia, and a constant ache in his lower right back. Chest X-ray showed extensive infiltration in both lungs (image 35). Blood and sputum cultures were negative on conventional bacteriologic media. A presumptive diagnosis of bacterial pneumonia was made, and the patient showed improvement following a course of erythromycin. Examination of paid serum samples revealed a 16-fold rise in antibodies against an intracellular pathogen. What is the most likely cause of the patient's condition?
• C. psittaci
A recent outbreak of an STD involved over 90 men who have sex with other men. Symptoms include inguinal lymphadenopathy (image 23), painful genital ulcers and bloody proctitis with mucopurulent discharge and constipation. Many of these patients were concurrently infected with other STD-agents, including HIV, and reported engaging in unprotected anal intercourse. The diagnosis in this outbreak was confirmed by a PCR test, which revealed genotype L2 of
• C. trachomatis
Which of the following genera has no detectable peptidoglycan (by techniques such as electron microscopy), yet is sensitive to inhibitors of peptidoglycan synthesis and contains the genes for the proteins necessary to make peptidoglycan?
• Chlamydia
A 42 year old man with a history of subcutaneous black tar heroin use presented to the hospital with slurred speech, diplopia (double vision), upper body muscle weakness, and dysphagia (difficulty swallowing). The physical examination showed bilateral ptosis (drooping eyelids), a sluggish pupillary response to light, and multiple skin abscesses on his arms and legs (Images 5&6). Gram stain of the abscesses isolated an organism that grows exclusively under anaerobic conditions (Image 7). What is the most likely cause of the patient's condition?
• Clostridium botulinum
A 7 year old girl is brought into the clinic complaining of fever, headache, muscle pains and conjunctival infection (red eyes). On physical exam the physician noted a macular rash on her lower extremities (Image 24). Microscopic examination of the blood sample revealed characteristic intracytoplamic inclusion bodies within the monocytes (image 25). What is the most likely infectious agent?
• Ehrlichia chaffeensis
A 26 year old male who is planning to immigrate to the United States must undergo a routine chest X-ray as part of a standard medical assessment prior to admission. The patient's chest film reveals the presence of a calcified peripheral nodule (image 36, red arrow) and a calcified right hilar node (image 36, blue arrow) consistent with previous healing of infection with Mycobacterium tuberculosis. The lesions detected on chest X-ray are referred to as a:
• Ghon complex
A 40 year old man, who has been recently diagnosed with HIV, develops a generalized rash (images 27&28) accompanied by fever, malaise and bloody diarrhea. His peripheral blood smear and bone marrow aspirate are show in Images 29&30. Blood culture at room temperature on Sabouraud agar grows organisms producing hyphae. What is the mist likely cause?
• Histoplasma capsulatum
A 24 year old HIV positive male was admitted to he hospital with a 20 day history of fever, night sweats and rapid loss. On admission, the patient reported having shortness of breath. High-resolution computed tomography of the chest (image 26) showed innumerable tiny, well- defined nodules throughout the kings and pleural surfaces. Sputum culture isolated a slow-growing, acid fast bacillus. The patient was diagnosed with which of the following conditions?
• Miliary tuberculosis
A 32 year old male from Bairnsdale, Australia presents to the Royal Melbourne Hospital with an extensive ulcer on his left ankle (Image 3). Patient history reveals the lesions started approximately 3 months earlier as a painless papule on the skin. Diagnosis was confirmed by Polymerase Chain reaction (PCR) and the identification of acid-fast bacilli within the infected tissue (Image 4). Which of the following factors contributors most to the pathogenesis of the patient's condition?
• Mycoalactone
A previously well 34 year old man presented with a 3 month history of multiple plaques on his face, groin, and penis, and legs (Image 2). The patient was heterosexual and reported a history of multiple unprotected sexual encounters over the preceding 2 years. A rapid plasma reagin (RPR) test was positive. Treatment with penicillin was initiated, and the cutaneous lesions resolved within 2 weeks. What is the most likely diagnosis?
• Secondary syphillis
A 34 year old Iranian woman presented with a 4-month history of a rash on her back. Physical exam revealed multiple hypo pigmented, atrophic lesions with well-defined borders (Image 31). The lesions were hairless and anesthetic and had developed over many months. Histopathological exam of a skin-biopsy specimen revealed granulomatous inflammation with numerous activated macrophages and lymphocytes. Acid-face stain of the biopsy specimen is shown in image 32. What is the most likely diagnosis
• Tuberculoid leprosy
The life cycle of Plasmodium falciparum comprises an exogenous sexual phase with multiplication in certain Anopheles mosquitoes and an endogenous asexual phase with multiplication in the vertebrate host. In strict biological terms the mosquito is considered
• the definitive host
