MMSC438 Exam 2
A bloody stool sample is received in
the laboratory and plated to routine
stool culture media. The following re-
sults arerecorded by the laboratory sci-
entist 24 hours after plating the pa-
tient sample:Blood agar: beta-hemolyt-
ic coloniesMacConkey: Only lactose fer-
menting colonies are presentSMAC: 2+
D. Escherichia coli 0157:H7
clear colonies presentFurther testing re-
veals: Oxidase negative, indole positive,
MUG negative, motileThe most likely
identification is:
A. Yersinia enterocolitica
B. Salmonella spp.
C. Shigella spp.
D. Escherichia coli 0157:H7
A liter of watery stool is submitted
to the laboratory for enteric pathogen
screening. Colonies from the blood agar
plateproduce an oxidase positive result.
Yellow colonies are observed on the thio-
sulfate citrate bile salts sucrose agar. A. Vibrio cholerae
What is the most likely pathogen?
A. Vibrio cholerae
B. Campylobacter jejuni
C. Salmonella enterica Typhimurium
D. Yersinia enterocolitica
Two hours after eating a meal consisting
of ham, potato salad and green peas,
vomiting and nausea develop in the ab-
sence of diarrhea. The symptoms are
most likely due to ___________. A. Enterotoxin B of Staphylococcus au-
A. Enterotoxin B of Staphylococcus au- reus
reus
B. Neurotoxin of Clostridium botulinum
C. Type A toxin of Clostridioides difficile
D. Enterotoxin of Escherichia coli
, MMSC438 Exam 2
While on a medical study abroad trip to
Kenya, an outbreak of typhoid fever oc-
curs. A patient is seen in the clinic com-
plaining of symptoms consistent with ty-
phoid for the past three days. What spec-
imen type would be most appropriate for A. Blood
culture of the suspected pathogen?
A. Blood
B. Sputum
C. Stool
D. Urine
Tympanocentesis (the drainage of fluid
from the middle ear) is performed on a
4-year-old girl. A viral pathogen is identi-
fied.The most likely diagnosis is:
B. Otitis media
A. Otitis externa
B. Otitis media
C. Epiglottitis
D. Sinusitis
When examining stool culture plates,
suspected pathogens can best be iden-
tified as:
A. Green colonies on thiosulfate citrate
bile salts sucrose (TCBS) agar. C. Non-lactose fermenting colonies on
B. Non-hemolytic colonies on blood agar. MacConkey agar.
C. Non-lactose fermenting colonies on
MacConkey agar.
D. Obligate anaerobic colonies on egg
yolk agar.
Pseudomembranous coli-
tis______________.
A. Is toxin mediated.
B. Is most frequently caused by Clostrid-
D. All of the above.
ioides difficile.
C. Occurs after administration of broad
spectrum antimicrobials.
D. All of the above.
A bloody stool sample is received in
the laboratory and plated to routine
stool culture media. The following re-
sults arerecorded by the laboratory sci-
entist 24 hours after plating the pa-
tient sample:Blood agar: beta-hemolyt-
ic coloniesMacConkey: Only lactose fer-
menting colonies are presentSMAC: 2+
D. Escherichia coli 0157:H7
clear colonies presentFurther testing re-
veals: Oxidase negative, indole positive,
MUG negative, motileThe most likely
identification is:
A. Yersinia enterocolitica
B. Salmonella spp.
C. Shigella spp.
D. Escherichia coli 0157:H7
A liter of watery stool is submitted
to the laboratory for enteric pathogen
screening. Colonies from the blood agar
plateproduce an oxidase positive result.
Yellow colonies are observed on the thio-
sulfate citrate bile salts sucrose agar. A. Vibrio cholerae
What is the most likely pathogen?
A. Vibrio cholerae
B. Campylobacter jejuni
C. Salmonella enterica Typhimurium
D. Yersinia enterocolitica
Two hours after eating a meal consisting
of ham, potato salad and green peas,
vomiting and nausea develop in the ab-
sence of diarrhea. The symptoms are
most likely due to ___________. A. Enterotoxin B of Staphylococcus au-
A. Enterotoxin B of Staphylococcus au- reus
reus
B. Neurotoxin of Clostridium botulinum
C. Type A toxin of Clostridioides difficile
D. Enterotoxin of Escherichia coli
, MMSC438 Exam 2
While on a medical study abroad trip to
Kenya, an outbreak of typhoid fever oc-
curs. A patient is seen in the clinic com-
plaining of symptoms consistent with ty-
phoid for the past three days. What spec-
imen type would be most appropriate for A. Blood
culture of the suspected pathogen?
A. Blood
B. Sputum
C. Stool
D. Urine
Tympanocentesis (the drainage of fluid
from the middle ear) is performed on a
4-year-old girl. A viral pathogen is identi-
fied.The most likely diagnosis is:
B. Otitis media
A. Otitis externa
B. Otitis media
C. Epiglottitis
D. Sinusitis
When examining stool culture plates,
suspected pathogens can best be iden-
tified as:
A. Green colonies on thiosulfate citrate
bile salts sucrose (TCBS) agar. C. Non-lactose fermenting colonies on
B. Non-hemolytic colonies on blood agar. MacConkey agar.
C. Non-lactose fermenting colonies on
MacConkey agar.
D. Obligate anaerobic colonies on egg
yolk agar.
Pseudomembranous coli-
tis______________.
A. Is toxin mediated.
B. Is most frequently caused by Clostrid-
D. All of the above.
ioides difficile.
C. Occurs after administration of broad
spectrum antimicrobials.
D. All of the above.
