Microbiology Exam 3 Review

(a) Yersinia pestis

A 12 y/o male living in Nevada suddenly found a burrow in his yard while playing. Twenty-three hours later, the child becomes acutely ill, with temperature of 39.3° C prostration and septic. Multiple tender nodular lesions are palpated his right axilla. A blood culture reveals a cocci0bacillary organism on the gram stain, with bipolar ends. Which pathogenic organism would likely induce his sudden toxic presentation? (a) Yersinia pestis (b) Chlamydia pneumoniae (c) Mycoplasma pneumoniae (d) Rickettsia rickettsii (e) Chlamydia psittaci

(b) Use of tampons

A 16 y/o female was well until 2 days prior to her admission, when she had fever (39.9° C) and vomiting. On the morning of admission, she had loose stools, continued fever, and vomiting. Her pediatrician noted that she was hypotensive (BP 76/48 mmHg), heart rate of 120 bpm, and a temperature of 38° C. An erythematous rash was prominent on her trunk. The GI tract was a potential site of the infection. Considering her clinical history, which additional information could be useful? (a) Illegal drug use (b) Use of tampons (c) Pregnancy test

(d) Neisseria meningitidis

A 19 y/o male college student presents with fever, chills, malaise, headache, photophobia, and confusion with numerous petechiae on his extremities and trunk. On examination, he has positive Brudzinski and Kernig signs. A lumbar puncture reveals increased leukocytes, particularly PMN neutrophils, increased protein, and decreased glucose levels. Gram-staining of the CSF reveals Gram-negative cocci in pairs. Which of the following is the most likely causative agent for the infection in this patient? (a) Bordetella pertussis (b) Francisella tularensis (c) Haemophilus influenzae (d) Neisseria meningitidis (e) Yersinia pestis

(d) Campylobacter jejuni

A 19 y/o presents with severe abdominal cramps and painful diarrhea that is treated with what appears to be blood. The patient is afebrile. He denies having consumed shellfish, hamburger, unpasteurized milk, or apple cider. He attended a picnic where barbecued chicken was served, and he recalls discarding some of the chicken because it was undercooked. This patient's gastroenteritis is most likely due to what organism? (a) Vibrio cholerae (b) Vibrio parahaemolyticus (c) Vibrio vulnificus (d) Campylobacter jejuni (e) Escherichia coli Strain O157:H7

(d) Has a polyribosyl-ribotol capsule

A 2 y/o Amish-boy non-immunized presents with difficult with swallowing and respiration. Lateral neck XR showed a thumb-sign characteristic of epiglottitis. The organism causing his illness most likely is: (a) Produces very potent exotoxins (b) Grows alone in Blood agar (c) Is an anaerobic catalase-positive (d) Has a polyribosyl-ribotol capsule

(d) Chemoprophylaxis with rifampin

A 20 y/o male college student living in a dormitory presents with fever and chills, intense headache, vomiting, and stiff neck. His temperature is 39.2° C and pulse is 140/min. After examination, the clinical diagnosis of meningitis is made. Gram stain smears made of CSF shows PMN leukocytes, intracellular Gram-negative diplococci, and a few extracellular Gram-negative diplococci. A culture of CSF grows colonies of Gram-negative diplococci that are oxidase-positive. The isolated pathogen is identified as Neisseria meningitidis Group B. Which of the following prophylactic measures may be taken by other students staying in the dormitory to prevent transmission of the infection? (a) Chemoprophylaxis with vancomycin (b) Immunization with tetravalent meningococcal polysaccharide vaccine (c) Chemoprophylaxis with oral penicillin (d) Chemoprophylaxis with rifampin (e) No prophylaxis is available

(c) A toxin-related disease

A 21 y/o previously healthy college student was brought to the ED with fever, increased heart rate, low arterial blood pressure, and respiratory distress. Blood cultures were negative, but a MRSA was cultured from sputum. He developed diffuse purport of the skin and necrotizing pneumonia, and died within 24 hours after arriving at the ED. What is the most likely reason for the complicated and fatal outcome of this infection? (a) A multi-drug resistant organism (b) An immunocompromised patient (c) A toxin-related disease

(a) Vibrio parahaemolyticus

A 25 y/o woman presents with a 24-hour history of diarrhea and abdominal pain. She returned from a vacation in Florida where she had consumed undercooked seafood. Based on clinical history and presentation, the organism most likely causing disease in this patient will be which of the following? (a) Vibrio parahaemolyticus (b) Campylobacter jejuni (c) Helicobacter pylori (d) Escherichia coli (e) Shigella

(d) Perform test for N. gonorrhea and Chlamydia trachomatis NOTE: (e) No need to notify the health department of the patient's infection - FALSE Patient diagnosed with gonorrhea, chlamydia, syphilis, and anthrax has to be reported to the health department

A 27 y/o man comes to your office complaining of pain with urination and a discharge from his penis. He reports having both insertive and receptive anal sex with two men in the last 2 months but says that he always uses condoms when having anal sex. He also reports both giving and receiving oral sex. Physical examination is notable for purulent urethral discharge. Which of the following would be part of the recommended management of this patient? (a) Treat him with metronidazole 500 mg for 14 days (b) Admit him to the hospital for parental therapy (c) Arrange to see him in two weeks (d) Perform test for N. gonorrhea and Chlamydia trachomatis (e) No need to notify the health department of the patient's infection

(c) Fastidious GNB

A 28 y/o woman is evaluated in February for persistent paroxysms of cough, followed by emesis. On physical examination, she is afebrile and chest auscultation is normal. Her leukocyte count is elevated with lymphocytosis. Which of the following best describes the organism causing her illness? (a) The major exotoxin associated with illness is tracheal cytotoxin (b) It grows easily on MacConkey agar (c) Fastidious GNB (d) Pertussis toxin is calmodulin-dependent

(d) Mouth

A 30 y/o female with history of rheumatic fever is diagnosed with mitral valve endocarditis. Blood cultures grew Streptococcus sanguinis. What is the most likely source of this organism? (a) Urethra (b) Stomach (c) Vagina (d) Mouth (e) Skin

(c) Tetanus

A 30 y/o male comes to the hospital complaining of "stiffness." He was fine until two days ago when he started to have trouble opening his mouth. Later the same day, his neck became stiff, and since then, he has had increasing trouble with respirations. On exam, he has a temperature of 101° F, his pulse is 11/min, his respirations are shallow and at 24/min. He appears flushed and is sweating profusely. He does appear quite rigid and his face appears to be in a grimace. His reflexes are all hyperactive. Which of the following is the most probably disease of this patient? (a) Food-borne botulism (b) Gram-negative sepsis (c) Tetanus (d) Toxin-mediated food poisoning

(d) Clostridium botulinum infection at the injection site

A 32 y/o injection-heroin user is "skin popping" because of exhausting all intravenous sites of infection. He has noted increased swelling and pain at an arm infection site during the past week and now also notes that his vision is blurred and his speech is slurred, and he has chills and feels weak and feverish. Which of the following is the most likely cause of his symptoms? (a) Clostridium sordellii injection site infection (b) Staphylococci infection at the injection site (c) Clostridium perfringens infection site abscess (d) Clostridium botulinum infection at the injection site (e) Streptococci infection at the injection site

(e) Clostridiodes difficile

A 35 y/o woman takes a 7-day course of antibiotics for an infection. The infection clears up; however, 2 weeks later, she develops watery diarrhea. The diarrhea is non-bloody. She also has anorexia, nausea, and cramping. On physical examination, her temperature is 39° C. There is diffuse tenderness in her abdomen. A stool sample reveals pus in her stool. Her condition deteriorates and pseudomembranes are seen on the mucosal surface with endoscopy. What is the most likely causative agent of this patient's condition? (a) Clostridium perfringens (b) Entrameoba histolytica (c) Salmonella (d) Giardia (e) Clostridiodes difficile

(a) Vibrio cholerae

A 36 y/o man presents with profuse "rice-watery" diarrhea and vomiting. The patient has a temperature of 38.9° C, pulse of 160/min, and RR of 40/min. The patient's history of significant for a recent business trip to India where he ingested a "sweet, watery drink" from a street vendor. Stool cultures are positive for Gram-negative, non-lactose fermenting, comma-shaped organisms that are oxidase-positive. The patient receives oral rehydration fluids containing sodium and glucose and is treated with tetracycline; he improved by the following day. What is the most likely cause of this patient's profuse diarrhea? (a) Vibrio cholerae (b) Vibrio parahaemolyticus (c) Vibrio vulnificus (d) Campylobacter jejuni (e) Escherichia coli Strain O157:H7

(e) All of the above can potentially cause meningitis NOTE: The results are not enough to know which organism.

A 4 y/o boy is brought to the ER because of vomiting and stiff neck. The symptoms are followed by a seizure. On physical examination, he is febrile and has signs of meningeal irritation. A lumbar puncture is done to determine if he has meningitis. The results are as follows. What organism is probably causing his meningitis? (a) Hemophilus spp. (b) Group B Streptococcus (c) Listeria monocytogenes (d) Neisseria meningitidis (e) All of the above can potentially cause meningitis

(e) He should be excluded from food preparation

A 45 y/o man with a history of blood culture-confirmed typhoid fever continues to have stool cultures that grow Salmonella typhi 18 months after his initial illness despite remaining well. Which of the following is the correct interpretation of this finding? (a) He needs a cholecystectomy (b) Do nothing because the patient feels well (c) He is not a chronic-carrier because his stool culture is positive more than 12 months after the initial infection (d) He does not need to be treated with antibiotics because he is a chronic-carrier (e) He should be excluded from food preparation

(a) Shigella dysenteriae

A 45 y/o woman presents with a 2-day history of abdominal cramps of bloody diarrhea. She has returned from vacation in India, where she ate many of the local foods. Her blood pressure is 120/80 mmHg, pulse rate is 84/minute, and temperature is 37.8° C. Stool examination reveals many PMN leukocytes and aerobic Gram-negative, non-motile organisms. From the stool culture, a Gram-negative rod was isolated that forms non-lactose fermenting colorless colonies on eosin-methylene blue (EMB) agar. What organism is the most likely cause? (a) Shigella dysenteriae (b) Escherichia coli (c) Vibrio cholerae (d) Vibrio parahaemolyticus (e) Campylobacter jejuni

(c) Alveolar macrophages

A 52 y/o obese female presents with fever, productive cough with rusty sputum of sudden onset. She smoked 1/2 pack per day and drinks alcohol. Radiograph showed a lingular infiltrate. Which one of the following defense mechanisms is defective in this patient? (a) Production of lysozyme (b) Presence of alveolar commensals (c) Alveolar macrophages (d) Production of antibodies

(e) Vibrio vulnificus

A 54 y/o man in Louisiana presents with a 2-day history of fever, chills, and diarrhea; he now has painful, hemorrhagic, bulls lesions on his lower extremities. His blood pressure is 60/40 mmHg. He consumed uncooked oysters 3 days earlier; 6 months ago, he was diagnosed with liver cirrhosis. Clinical samples from the bulbous lesions, blood, and stool are sent for microbiological investigations; the patient is placed on tetracycline. Stool and the samples from the skin lesions are inoculated on various media including thiosulfate-citrate-bile salts-sucrose (TCBS) agar. After 24 hours of incubation at 37° C, green colonies appear on the TCBS agar. Further study of the colonies show actively motile, Gram-negative curved rods that are oxidase-positive and ferment lactose; they grow in the presence of 6% sodium chloride. The isolate fails to grow in the absence of sodium chloride and is susceptible to compound O/129. Samples from the skin lesions and blood cultures also grow organisms with the same characteristics. What bacteria is most likely responsible for the patient's symptoms? (a) Vibrio fluvialis (b) Aeromonas hydrophila (c) Plesiomonas shigelloides (d) Vibrio parahaemolyticus (e) Vibrio vulnificus

(c) Pseudomembranous colitis

A 55 y/o man was treated for bacterial pneumonia and prescribed erythromycin for treatment. He presents a week later with severe diarrhea, lower abdominal cramping, fever, nausea, and dehydration. What is the diagnosis of this patient? (a) Botulism (b) Localized tetanus (c) Pseudomembranous colitis (d) Food poisoning

(a) As a non-suppurative sequelae

A 6 y/o female awakened with pain and swelling in the right ankle. Four weeks ago, she had a freebie illness with a sore throat and headache and was treated with amoxicillin. On admission, she had a warm, swollen right ankle, and a systolic heart murmur thought to be consist with mitral regurgitation. ASO titer was positive (>1:200 IU). How would you describe this illness process? (a) As a non-suppurative sequelae (b) As an acute bacterial infection (c) As bacteremia

(c) Simmons' citrate-positive

A 62 y/o alcoholic male presents with "currant jelly sputum" pneumonia. Sputum Gram-stain showed a Gram-negative organism. Which characteristic best describe the organism? (a) Lactose-negative (b) Requires NAD factor for growth (c) Simmons' citrate-positive (d) Oxidase-positive

(b) Moraxella catarrhalis

A 65 y/o man with COPD presents with a cough with copious purulent sputum, shortness of breath, a 3-day history of a low-grade fever. Gram stain of the sputum shows a high predominance of Gram-negative diplococci among many polymorphs, intracellular Gram-negative diplococci are also observed. The cocci are oxidase-positive, DNAse-positive, fail to ferment carbohydrates, reduce nitrate to nitrite, and grow on nutrient agar at 22° C. Which of the following bacterium is most likely causing the patient's symptoms? (a) Neisseria meningitidis (b) Moraxella catarrhalis (c) Neisseria lactamica (d) Neisseria sicca

(e) Toxins

A 69 y/o woman was treated for bacterial pneumonia and prescribed erythromycin for treatment. She presents a week later with severe diarrhea, lower abdominal cramping, fever, nausea, and dehydration. Stool examination and enzyme immunoassay of the patient's serum indicate infection by Clostridium difficile, which is a Gram-positive bacilli. The patient is prescribed metronidazole for the infection. Which of the following bacteria's component is the cause of the symptoms in this patient? (a) Capsule (b) Cell wall (c) Flagella (d) Spores (e) Toxins

(e) Escherichia coli Strain O157:H7

A 7 y/o presents with severe, bloody diarrhea. The diarrhea has been present for at least 2 days. He is having approximately 8 to 10 bowel movements/day and admits to pain on defecation. The day before the symptoms began, the patient consumed a hamburger that was cooked medium rare. The stool is positive for the presence of many white blood cells. On the second day, 4+ colonies are apparent on MacConkey-sorbitol agar; the colonies are sorbitol-negative. The organism is oxidase-negative. What is the most likely organism causing the gastroenteritis in this child? (a) Vibrio cholerae (b) Vibrio parahaemolyticus (c) Vibrio vulnificus (d) Campylobacter jejuni (e) Escherichia coli Strain O157:H7

(d) Skin

A 70 y/o woman with a prosthetic knee comes in complaining of fever and pain with swelling of the knee. You suspect a Staphylococcus epidermidis prosthetic joint infection. What is the most likely source of this patient's joint injection? (a) Vagina (b) Dental caries (c) Mouth (d) Skin (e) Colon

(d) Escherichia coli

A 72 y/o male with prostate disease presents with dysuria and fever. More than 100,000 colonies of a Gram-negative bacillus lactose fermenter, methyl-red positive, oxidase-negative, and is growing in MacConkey agar. Which one is the most likely pathogen? (a) Legionella pneumophila (b) Pseudomonas aeroginosa (c) Bordetella pertussis (d) Escherichia coli

(c) Clostridium perfringens

A 75 y/o woman with cellulitis of her lower left leg is seen in the emergency room. A CBC is notable for an elevated white cell count of 40,000/mm3 with a left shift. The Gram-stain is significant for Gram-positive "box-car"-shaped rods. The culture is significant for anaerobic Gram-positive rods that are lecithinase-positive, non-motile, and produce a double zone of hemolysis on anaerobic blood agar. Which of the following is the bacteria responsible for the infection of this patient? (a) Clostridium difficile (b) Clostridium botulinum (c) Clostridium perfringens (d) Bacteriodes fragilis (e) Fusobacterium spp.

(d) Antibiotic therapy

A patient presents with severe colitis associated with overgrowth of Clostridium difficile in the lower bowel. The most likely cause of this condition is: (a) Botulin food poisoning (b) A stomach ulcer (c) A compromised immune system (d) Antibiotic therapy (e) Mechanical blockage of the large intestine

(a) Bacitracin

A throat culture grew Beta-hemolytic, Gram (+) cocci chains in blood agar. An antibiotic disk test was ordered to identify the presence of a pathogenic organism. Which would be the antibiotic disk used? (a) Bacitracin (b) Novobiocin (c) Vancomycin (d) Optochin

(b) Mesenteric veins

Adult S. mansoni will be found in: (a) Intestines (b) Mesenteric veins (c) Perianal fold (d) Veins around the bladder (e) Liver parenchyma

(b) Rocky Mountain spotted fever NOTE: The rash starts in the extremities and can spread in Rocky Mountain spotted fever. In Lyme disease, the rash is usually confined at the bite-site.

After being bit by a tick in the southeastern United States, a young patient develops fever, headache, sore throat, nausea, and a rash on the lower parts of both arms and legs. Which of the following is high on the list of differential diagnoses? (a) Epidemic typhus (b) Rocky Mountain spotted fever (c) Lyme disease (d) Q fever

(d) C. perfringens

An 11 y/o boy with poorly controlled type I diabetes mellitus was admitted to the hospital with ketoacidosis and altered mental status 2 to 3 days after eating large meals that included chitterlings. His white blood cell count was 11,300 mm3 and his abdominal radiograph showed dilated loops of small bowel with gas in the bowel wall. His hospital course was notable for persistent hematemesis and increasing abdominal distention. Bloody ascites and necrotic jejunum and ileum were found at laparotomy. Which Clostridium organism is most likely responsible for the following syndrome? (a) C. difficile (b) C. tetani (c) C. sordellii (d) C. perfringens (e) C. botulinum

(b) Escherichia coli

An 80 y/o patient in an extended care facility complains of dysuria, left flank pain, and shaking chills. The patient has an elevated body temperature of 39.6° C. The patient also vomited twice in the past 8 hours. The nurse in charge of the patient reported that the patient's urine was foul smelling and turbid. The physical examination revealed left costovertebral angle tenderness. Urine was collected for culture/Gram-stain and urinalysis. The urinalysis was significant for the presence of protein (1+), bacteria (3+), >100 WBC/HPF, and 10 RBC/HPF. The urine culture was subsequently positive for >100,000 colonies/mL of Gram-negative bacilli that was lactose fermenter and was indole-positive. What is the most likely cause of this patient's infection? (a) Candida albicans (b) Escherichia coli (c) Staphylococcus aureus (d) Streptococcus agalactiae (e) Enterococcus faecalis

(c) Acid-fast organism

An organism found to have high-concentrations of mycolic acid will most likely be a(n): (a) Gram-positive organism (b) Gram-negative organism (c) Acid-fast organism (d) Fungus

(d) C. psittaci

Birds are the vector for transmission of? (a) B. quintana (b) M. pneumoniae (c) R. rickettsia (d) C. psittaci (e) Y. pestis

(a) Catalase test

Colonies from a skin lesion's exudate culture showed clusters of purple color cocci on Gran stain. Which lab test would aid confirming a preliminary diagnosis? (a) Catalase test (b) Oxidase test (c) Antibiotic susceptibility (d) Streptolysin O Ab (e) Coagulase test

(c) G. lamblia causes bloody diarrhea

Each of the following statements about Giardia lamblia is correct EXCEPT: (a) G. lamblia has both a trophozoite and cyst stage in its life cycle (b) G. lamblia is transmitted by the fecal-oral route from both human and animal sources (c) G. lamblia causes bloody diarrhea (d) G. lamblia can be diagnosed by the string test (e) The natural reservoir of G. lamblia is the beaver

(d) Hookworm infection can be diagnosed by finding larvae in the stool samples NOTE: Hookworm infection can be diagnosed by finding EGGS, not larvae, in the stool samples

Each of the following statements concerning hookworm infection is correct EXCEPT: (a) Hookworm infection can affect the lungs because of its lung transmission (b) Hookworm infection is acquired by humans when filariform larvae penetrate the skin (c) Hookworm infection is caused by a worm that feeds blood from out GI mucosa (d) Hookworm infection can be diagnosed by finding larvae in the stool samples

(e) Y. pestis NOTE: a. C. pneumoniae i. No animal vectors/Humans b. M. pneumonia i. No animal vectors/Humans c. R. rickettsia i. Transmitted by ticks d. C. psittaci i. Transmitted by birds

Fleas are the vector for transmission? (a) C. pneumoniae (b) M. pneumonia (c) R. rickettsia (d) C. psittaci (d) Y. pestis

(d) Mycoplasma pneumonia

High levels of cold agglutinins are associated with what organism? (a) Staphylococcus aureus (b) Pseudomonas aeruginosa (c) Legionella pneumophila (d) Mycoplasma pneumonia

(a) C. pneumoniae

Humans are the vector for transmission of? (a) C. pneumoniae (b) R. rickettsia (c) C. psittaci (d) Y. pestis

(e) All of the above

In blood agar (BA), the colonies showed the characteristic observed in the picture. If complicated, this infection could also cause: (a) Abscesses (b) Septic arthritis (c) Bacteremia (d) Intoxication (e) All of the above

(b) Beta-hemolytic Gram-positive cocci

In blood agar (BA), the colonies showed the characteristic observed in the picture. Preliminary, identify the organism. (a) Streptococcus pyogenes (b) Beta-hemolytic Gram-positive cocci (c) Staphylococcus aureus (d) Alpha-hemolytic cocci

(b) Adhesins, enzymes

In blood agar (BA), the colonies showed the characteristic observed in the picture. The infection became complicated and the patient developed fever, chills, and swelling of the knee. Septic arthritis was then diagnosed. Which virulence factors would have been involved in the origin of this disease? (a) Protein A, capsule (b) Adhesins, enzymes (c) Superantigens, catalase (d) Endotoxin (Lipid A)

(a) Demonstration of acid production from glucose and maltose

In cases of possible sexual abuse involving children, the identification of oxidase-positive, Gram-negative diplococci such as Neisseria gonorrhoeae requires which of the following? (a) Demonstration of acid production from glucose and maltose (b) A positive direct immunofluorescent reaction with monoclonal antibody against N. gonorrhoeae outer membrane protein (c) A positive particle agglutination using monoclonal antibody to N. gonorrhoeae (d) Identification of N. gonorrhoeae by two distinct methodologies

(d) Increased levels of neutrophils

Infection by parasites can be blocked by the host's natural (non-specific) defenses. However, specific defensed are also activated by parasites included all EXCEPT: (a) Production of parasite-specific IgG (b) IgE-mediated degranulation of mast cells (c) Eosinophil-mediated IgE-independent cytotoxicity (d) Increased levels of neutrophils (e) CTL responses to intracellular protozoa

(d) Hookworms

Infection with this nematode is characterized by blood loss due to release of anticoagulant: (a) Ascaris lumbricoides (b) Filariasis (c) Enterobious vermicularis (d) Hookworms (e) Trichinella spiralis

(a) Preferential activation of a CD4+ Th2 response

Intracellular growth of Leishmania within macrophages would require: (a) Preferential activation of a CD4+ Th2 response (b) Decrease in the intracellular levels of ROS (c) Active secretion of IGN-gamma by CD4+ Th1 cells (d) Class switching of anti-parasite IgM to IgG (e) Expression of Toll-like receptors

(c) Sporeless

Legionella pneumophila is a: (a) Extracellular pathogen (b) Catalase-negative (c) Sporeless (d) Encapsulated

(a) B. quintana

Louse are the vector for transmission of? (a) B. quintana (b) M. pneumoniae (c) R. rickettsia (d) C. psittaci (e) Y. pestis

(c) Nasal membrane

Match the organism with the anatomic area - Neisseria spp. (a) Large intestine (b) Small intestine (c) Nasal membrane (d) Urogenital tract (e) Skin

(e) Silver stain

Spirochetes can be observed using: (a) Gram stain (b) Ziehl-Neelsen stain (c) Wet mount (d) Acid-fast stain (e) Silver stain

(b) Reproduce via both asexual and sexual mechanisms

Sporozoa differ from other protozoa in that they: (a) Are unicellular organisms that reproduce intracellularly (b) Reproduce via both asexual and sexual mechanisms (c) All affect the GI tract (d) Are transmitted by spored (e) Are resistant to the host's immune mechanisms

(d) Continuous change of the outer glycoproteins to evade the immune system NOTE: Only T. brucei (African Trypanosomes) has continuous change of their outer glycoproteins.

The African and the American Trypanosomes share all of the following characteristics EXCEPT: (a) They have a single flagella that is attached to an undulating membrane (b) Growth in blood or spinal fluid (c) Transmission by blood-sucking bugs (d) Continuous change of the outer glycoproteins to evade the immune system (e) Restricted geographical distribution

(b) A sterile organ

The bladder is usually: (a) Colonized with normal microbiota (b) A sterile organ (c) Unprotected from infection (d) Normally infected by E. coli

(c) Bacteriodes fragilis

The large intestine is the site of the largest normal flora bacteria. Which of the following is found in the greatest number in the colon? (a) Escherichia coli (b) Lactobacillus spp. (c) Bacteriodes fragilis (d) Klebsiella pneumoniae

(b) A protease that forms pores on enterocytes NOTE: Amoebapore is the name of the protease.

The main virulence factor of Entamoeba histolytica is? (a) An enterotoxin that causes diarrhea (b) A protease that forms pores on enterocytes (c) Mechanical damage to the GI's mucosa (d) High motility and survival outside host

(a) Streptococcus pyogenes

The patient, a 7 y/o boy, was prescribed an antibiotic therapy for 5 days. Three weeks later, the boy developed rheumatic fever. Which is the pathogen of interest? (a) Streptococcus pyogenes (b) Streptococcus pneumoniae (c) Viridans group streptococci (d) Group D streptococci

(i) Acute complications: Pharyngitis, cellulitis (ii) Non-suppurative sequelae: Rheumatic fever (from pharyngitis), glomerulonephritis (from pH or skin) (iii) ASO Titer (Anti-Streptolysin O Antibody): This titer is to check for the causation of these conditions above, whether it was caused by hemolysin: Streptolysin O or not

The patient, a 7 y/o boy, was prescribed with antibiotic therapy for 5 days. Three weeks later, the boy developed rheumatic fever. Is there any association with pharyngitis and rheumatic fever? Regarding this organism, briefly explain or mention: (i) Acute complications (ii) Non-suppurative sequelae (iii) ASO titer

(c) Inhalation

There are three major forms of botulism. Which of the following is NOT one of the three major forms? (a) Food-borne (b) Infant (c) Inhalation (d) Wound

(a) Entamoeba histolytica

This parasite is characterized by phagocytized red blood cells and regular, rosary-beads chromatin. (a) Entamoeba histolytica (b) Trichomonas vaginalis (c) Giardia lamblia (d) Cryptosporidium parvum (e) Plasmodium falciparum

(c) Giardia lamblia

This parasite is characterized by polar flagella, two nuclei, and sucking disks that attach to GI mucosa. (a) Entamoeba histolytica (b) Trichomonas vaginalis (c) Giardia lamblia (d) Cryptosporidium parvum (e) Plasmodium falciparum

(a) Schistosoma mansoni

This parasite's eggs get entrapped in intestinal mucosa and activate inflammatory mechanisms that are the main cause of symptoms: (a) Schistosoma mansoni (b) Fasciola hepatica (c) Trichuris trichiura (d) Leishmania spp (e) Entamoeba histolytica

(a) In material contaminated with cat feces NOTE: (b) and (c) are true for Merozoites, not Oocysts

Toxoplasma gondii can be transmitted to a new host by infectious oocysts: (a) In material contaminated with cat feces (b) Encysted in undercooked meat (c) That can cross the placenta (d) All are true

(c) No infection is possible since humans are not T. saginata's intermediate hosts

Traveling through Guatemala on vacation, you stop at a taco kiosk near the road. You are very hungry but stop to think about the consequences of eating there. If you ingest Taenia saginata's eggs in your taco, you could: (a) Have an intestinal infection by a T. saginata worm (b) Have different types of tissues infected by the T. saginata larvae (cysticercosis) (c) No infection is possible since humans are not T. saginata's intermediate hosts

(e) Rehydration and electrolyte balance therapy

Treatment of Campylobacter jejuni enteritis, as well as most other forms of gastroenteritis, requires what? (a) Oral antibiotics (b) Anti-diarrhea and anti-nausea medication (c) IV antibiotics (d) Emergency care (e) Rehydration and electrolyte balance therapy

(d) Rickettsia

What causes Rocky Mountain spotted fever? (a) Fungus (b) Virus (c) Protozoa (d) Rickettsia

(a) Where sexual reproduction takes place

What is a definitive host? (a) Where sexual reproduction takes place (b) Where immature stages undergo essential development (c) Ensures continuity of parasite in nature (d) Serves as vehicle of transmission

(b) Where immature stages undergo essential development

What is an intermediate host? (a) Where sexual reproduction takes place (b) Where immature stages undergo essential development (c) Ensures continuity of parasite in nature (d) Serves as vehicle of transmission

(c) Ensures continuity of parasite in nature

What is defined as a reservoir host? (a) Where sexual reproduction takes place (b) Where immature stages undergo essential development (c) Ensures continuity of parasite in nature (d) Serves as vehicle of transmission

(d) Serves as vehicle of transmission

What is defined as a vector? (a) Where sexual reproduction takes place (b) Where immature stages undergo essential development (c) Ensures continuity of parasite in nature (d) Serves as vehicle of transmission

(b) Leptospira interrogans

Which of the following can survive in water contaminated with urine from infected animals for prolonged periods of time? (a) Treponema pallidum (b) Leptospira interrogans (c) Borrelia recurrentis (d) Borrelia burdogferis (e) Treponema pertuneu

(b) Leptospira interrogans

Which of the following has the highest antigenic variation? (a) Treponema pallidum (b) Leptospira interrogans (c) Borrelia recurrentis (d) Borrelia burdogferis (e) Treponema pertuneu

(b) Its life cycle involves two hosts

Which of the following is NOT correct regarding Cryptosporidium parvum? (a) It infects the epithelial cells of the upper small intestine (b) Its life cycle involves two hosts (c) Diagnosis is done by identification of oocytes stained with acid fast (d) It is considered an opportunistic infection (e) Transmission is by food or water contaminated with oocytes

(c) Adult worms reside as pairs in the liver parenchyma

Which of the following is NOT correct regarding Schistosoma spp. infection? (a) Intermediate host is a snail (b) Transmission is by exposure to water bodies (c) Adult worms reside as pairs in the liver parenchyma (d) The diagnosis is done by examination of feces or urine for characteristic eggs (e) The three species have different geographic distribution

(a) They contain mycolic acids

Which of the following is characteristic of Mycobacteria? (a) They contain mycolic acids (b) They are resistant to inactivation by heat (c) They all are extracellular pathogens (d) They are anaerobic (e) They are spore-forming

(d) Borrelia burdogferis

Which of the following organisms may be cultured from a skin biopsy of a rash? (a) Treponema pallidum (b) Leptospira interrogans (c) Borrelia recurrentis (d) Borrelia burdogferis (e) Treponema pertuneu

(c) Vaccination of all susceptible individuals

Which of the following preventative measures did NOT play a role in the eradication of Schistosoma in Puerto Rico? (a) Protection of water from contamination from contamination with fecal material (b) Proper treatment of sewage and used water (c) Vaccination of all susceptible individuals

(c) Enterobius vermicularis

Which type of helminth infection can NOT be diagnosed by examination of a fecal sample? (a) Trichuris trichiura (b) Ascaris lumbricoides (c) Enterobius vermicularis (d) Necator americanus (a) Strongyloides stercolaris

(e) Scotch Tape swab

You are asked to diagnose a 5 y/o patient who presents to the ER with insomnia, hyperactivity, and perianal itching. You suspect this kid has an Enterobius vermicularis infection, so you request the following test to the clinical lab: (a) Fecal sample analysis for characteristic cysts (b) Urinalysis (c) CBC+ eosinophil levels (d) Culture of the itching area (e) Scotch Tape swab

(e) Mycobacterium species

Ziehl-Neelsen staining is associated with which organism? (a) Treponema pallidum (b) Leptospira interrogans (c) Borrelia recurrentis (d) Borrelia burdogferis (e) Mycobacterium species