1.
A patient presents with a brain abscess. The dominant organism is an anaerobe normally found as part
of the oral flora. Which of the following best fits that description?
A. 
B. 
C. 
D. 
2.
A 23-year-old male who has recently started working on a sheep farm in Nova Scotia develops pneumonia
shortly after helping with lambing. His cough produces little sputum, and a saline-induced sputum sample
shows no predominant organism either with Gram stain or with acid-fast stain. It is established that he
acquired the pneumonia from parturition products from the sheep. Which agent is most likely to be the
cause of his pneumonia?
A. 
B. 
C. 
D. 
E. 
3.
A 3 year old presents with difficulty breathing and will not lie down to be examined. You suspect acute
bacterial epiglottitis and examine the child’s epiglottis, which is highly inflamed. Which vaccine are you
most likely to find that the child is missing?
A. 
B. 
C. 
D. 
Streptococcus pneumoniae (conjugate vaccine)
E. 
4.
A 22-year-old cystic fibrosis patient presents with fever and increasing dyspnea. A Gram-negative
organism is found in unusually high numbers in the mucus. Which virulence factor is most important
in colonization and maintenance of the organism in the lungs?
A. 
B. 
Pyocyanin (blue-green pigment)
C. 
D. 
5.
Exotoxin A most closely resembles the action of which other microbial toxin?
A. 
Heat-labile toxin (LT) of Escherichia coli
B. 
C. 
D. 
E. 
6.
A 36-year-old immigrant who lived in a crowded resettlement camp before coming to the United States
now has a cough that has been bothering him for several weeks. He has also lost 10 pounds. Which of
the following factors is known to be most important in triggering the granulomatous reaction to wall off
and contain the infection?
A. 
B. 
C. 
Purified protein derivative (PPD)
D. 
E. 
7.
Patient develops diarrhea 5 days after starting antibiotic treatment for a serious staphylococcal infection.
What is the most likely causative agent?
A. 
B. 
C. 
D. 
8.
A patient develops mild gastroenteritis a few days after having a variety of sushi at a party. There is
no blood or pus in the stool. Which causative agent is most likely to have caused this illness?
A. 
B. 
C. 
D. 
9.
Yersinia pestis may be transferred by
A. 
B. 
C. 
D. 
10.
A patient had surgery 2 months ago to put in a pace maker. He felt fine for 1 month, but over the past
month, he has been feeling worse. He is running a low-grade fever, tires easily, and has worsening heart
murmurs. Which of the following staphylococcal organisms causes sub-acute bacterial endocarditis
that occurs 2 months or more after heart surgery?
A. 
B. 
Staphylococcus epidermidis
C. 
Staphylococcus haemolyticus
D. 
Staphylococcus saprophyticus
11.
A previously healthy 6 month old now looks limp. He cannot hold his eyes open, pupils do not react,
and he cannot hold his head up. What is the proper treatment?
A. 
Send him home on amoxicillin and clindamycin (to stop the toxin production quickly)
B. 
Give him a dose of equine botulinum immunoglobulin
C. 
Monitored supportive care with antibiotics, and botulinum immunoglobulin
D. 
Monitored supportive care with human botulinum immunoglobulin
E. 
Monitored supportive care with no antibiotics and no antitoxin
12.
A 78-year-old man develops a high fever, cough producing a blood-tinged sputum, and difficulty breathing.
Sputum shows organism consistent with Streptococcus pneumoniae. What is the most important virulence
factor?
A. 
B. 
A phospholipase allowing Streptococcus pneumoniae To escape the phagosome quickly
C. 
D. 
13.
Which of the following organisms grows in 40% bile?
A. 
B. 
C. 
D. 
14.
A patient recently returned from Africa has been febrile for several days and now has abdominal pain.
His blood cultures grow out Salmonella typhi. What was the most likely source of his infection?
A. 
B. 
C. 
Contact with baby goats on a farm and then eating without washing hands
D. 
A food preparer with bad personal hygiene
E. 
15.
A preterm (33-week) infant girl is born at home to a 16-year-old mom after 22 hours of labor after the
rupture of the membranes. A friend helped the mother deliver the baby. The now 4 day old infant now
shows signs of sepsis. What is the best description for the most likely causative agent? All organisms
in the answer choices are Gram-positive, catalase-negative cocci found in pairs or short chains.
A. 
Non-hemolytic organisms found as part of the normal fecal flora; resistant to bile and optochin;
carries a high level of drug resistance
B. 
Alpha-hemolytic diplococcic sensitive to both bile and optochin
C. 
Beta-hemolytic cocci in chains and carrying Lancefield’s Group B antigen
D. 
Alpha-hemolyticcocci in chains; resistant to bile and optochin
16.
A patient has a gastric ulcer not induced by non-steroidal anti-inflammatory agents. Which characteristic
appears to play a central role in the ability of the organism to survive transit of the lumen to colonize the
stomach?
A. 
Phospholipase C production
B. 
C. 
Micro aerophilic lifestyle
D. 
17.
A54-year-old man develops a pyogenic infection along the suture line after knee surgery. The laboratory
gives a preliminary report of a beta-hemolytic, catalase-positive, coagulase-positive, Gram-positive coccus.
The most likely causative agent is
A. 
B. 
C. 
Staphylococcus epidermidis
D. 
E.