MMSC438 Exam 2
1. A bloody stool sample is received in the laboratory and D. Escherichia coli
plated to routine stool culture media. The following re- 0157:H7
sults arerecorded by the laboratory scientist 24 hours
after plating the patient sample:Blood agar: beta-he-
molytic coloniesMacConkey: Only lactose fermenting
colonies are presentSMAC: 2+ clear colonies present-
Further testing reveals: Oxidase negative, indole pos-
itive, MUG negative, motileThe most likely identifica-
tion is:
A. Yersinia enterocolitica
B. Salmonella spp.
C. Shigella spp.
D. Escherichia coli 0157:H7
2. A liter of watery stool is submitted to the laboratory for A. Vibrio cholerae
enteric pathogen screening. Colonies from the blood
agar plateproduce an oxidase positive result. Yellow
colonies are observed on the thiosulfate citrate bile
salts sucrose agar. What is the most likely pathogen?
A. Vibrio cholerae
B. Campylobacter jejuni
C. Salmonella enterica Typhimurium
D. Yersinia enterocolitica
3. Two hours after eating a meal consisting of ham, pota- A. Enterotoxin B of Staphy-
to salad and green peas, vomiting and nausea develop lococcus aureus
in the absence of diarrhea. The symptoms are most
likely due to ___________.
A. Enterotoxin B of Staphylococcus aureus
B. Neurotoxin of Clostridium botulinum
C. Type A toxin of Clostridioides difficile
D. Enterotoxin of Escherichia coli
, MMSC438 Exam 2
4. While on a medical study abroad trip to Kenya, an A. Blood
outbreak of typhoid fever occurs. A patient is seen in
the clinic complaining of symptoms consistent with
typhoid for the past three days. What specimen type
would be most appropriate for culture of the suspect-
ed pathogen?
A. Blood
B. Sputum
C. Stool
D. Urine
5. Tympanocentesis (the drainage of fluid from the mid- B. Otitis media
dle ear) is performed on a 4-year-old girl. A viral
pathogen is identified.The most likely diagnosis is:
A. Otitis externa
B. Otitis media
C. Epiglottitis
D. Sinusitis
6. When examining stool culture plates, suspected C. Non-lactose fermenting
pathogens can best be identified as: colonies on MacConkey
A. Green colonies on thiosulfate citrate bile salts su- agar.
crose (TCBS) agar.
B. Non-hemolytic colonies on blood agar.
C. Non-lactose fermenting colonies on MacConkey
agar.
D. Obligate anaerobic colonies on egg yolk agar.
7. Pseudomembranous colitis______________. D. All of the above.
A. Is toxin mediated.
B. Is most frequently caused by Clostridioides difficile.
C. Occurs after administration of broad spectrum an-
1. A bloody stool sample is received in the laboratory and D. Escherichia coli
plated to routine stool culture media. The following re- 0157:H7
sults arerecorded by the laboratory scientist 24 hours
after plating the patient sample:Blood agar: beta-he-
molytic coloniesMacConkey: Only lactose fermenting
colonies are presentSMAC: 2+ clear colonies present-
Further testing reveals: Oxidase negative, indole pos-
itive, MUG negative, motileThe most likely identifica-
tion is:
A. Yersinia enterocolitica
B. Salmonella spp.
C. Shigella spp.
D. Escherichia coli 0157:H7
2. A liter of watery stool is submitted to the laboratory for A. Vibrio cholerae
enteric pathogen screening. Colonies from the blood
agar plateproduce an oxidase positive result. Yellow
colonies are observed on the thiosulfate citrate bile
salts sucrose agar. What is the most likely pathogen?
A. Vibrio cholerae
B. Campylobacter jejuni
C. Salmonella enterica Typhimurium
D. Yersinia enterocolitica
3. Two hours after eating a meal consisting of ham, pota- A. Enterotoxin B of Staphy-
to salad and green peas, vomiting and nausea develop lococcus aureus
in the absence of diarrhea. The symptoms are most
likely due to ___________.
A. Enterotoxin B of Staphylococcus aureus
B. Neurotoxin of Clostridium botulinum
C. Type A toxin of Clostridioides difficile
D. Enterotoxin of Escherichia coli
, MMSC438 Exam 2
4. While on a medical study abroad trip to Kenya, an A. Blood
outbreak of typhoid fever occurs. A patient is seen in
the clinic complaining of symptoms consistent with
typhoid for the past three days. What specimen type
would be most appropriate for culture of the suspect-
ed pathogen?
A. Blood
B. Sputum
C. Stool
D. Urine
5. Tympanocentesis (the drainage of fluid from the mid- B. Otitis media
dle ear) is performed on a 4-year-old girl. A viral
pathogen is identified.The most likely diagnosis is:
A. Otitis externa
B. Otitis media
C. Epiglottitis
D. Sinusitis
6. When examining stool culture plates, suspected C. Non-lactose fermenting
pathogens can best be identified as: colonies on MacConkey
A. Green colonies on thiosulfate citrate bile salts su- agar.
crose (TCBS) agar.
B. Non-hemolytic colonies on blood agar.
C. Non-lactose fermenting colonies on MacConkey
agar.
D. Obligate anaerobic colonies on egg yolk agar.
7. Pseudomembranous colitis______________. D. All of the above.
A. Is toxin mediated.
B. Is most frequently caused by Clostridioides difficile.
C. Occurs after administration of broad spectrum an-
