QUESTIONS
Select the best answer.
The next two questions are linked.
1 A 67-year-old diabetic woman is hospitalized with a
3-day history of fever, headache, diarrhea, dyspnea,
and a cough productive of scant sputum. A chest
radiograph reveals patchy, multilobar consolidation.
No organisms are seen on sputum Gram stain; how-
ever, culture of sputum and blood on buffered char-
coal yeast extract agar and blood agar are shown in the
photograph. Bacteria from the colonies, stained with
basic fuchsin, are also shown. Direct fluorescent anti-
body staining of cultured bacteria leads to a defini-
tive diagnosis. With which organism is this woman
infected? (A) Actinomyces israelii
(B) Corynebacterium diphtheriae
(C) Haemophilus influenzae
(D) Legionella pneumophila
(E) Nocardia asteroides
2 What is the source of infection for the patient in the
above question?
(A) Aerosolized spores from soil
(B) Aerosols from contaminated water
(C) Colonization of the upper airways
(D) Inapparent carrier of the organism
(E) Person with the same disease
3 A 5-year-old child died from severe septic shock,
disseminated intravascular coagulation, and cardiac
insufficiency following a sudden onset of fever, severe
headache, and vomiting. The causative agent, a
Gram-negative diplococcus, was isolated from blood
and cerebrospinal fluid (CSF) on Thayer–Martin agar
and was also identified in CSF by latex agglutination.
What is the most important virulence factor involved
in disease production by the etiologic agent in this
case?
1
Buxton_CH01.indd 1 7/1/2009 8:56:11 PM
, 2 Chapter 1
(A) Exotoxin production (A) Capsule
(B) Flagella (B) H antigen
(C) Lipooligosaccharide (C) Hemolysin
(D) Pili (D) Lipid A
(E) Polysaccharide capsule (E) Lipoteichoic acid
4 Vaccination against which bacterial species has been The next two questions are linked.
most successful at reducing the number of cases of
invasive diseases, including meningitis? 7 Infected pressure sores were observed on the buttock
(A) Escherichia coli K1 of an elderly, bedridden patient recently treated for a
(B) Haemophilus influenzae b malignancy of the rectum. Some of the lesions are con-
(C) Listeria monocytogenes spicuously necrotic, exceptionally painful to the touch,
(D) Neisseria meningitidis and readily give off a musty sweet odor. Moreover,
(E) Streptococcus pneumoniae these lesions seem to have developed overnight. A
Gram stain of the watery discharge from one of the
5 A 56-year-old renal transplant patient was hospitalized lesions reveals an abundance of bacteria (shown in the
following an abrupt onset of high fever (39.6 °C), con- photograph). What is the most likely diagnosis?
fusion, headache, diarrhea, a cough productive of scant
sputum, and shortness of breath. His chemistry profile
revealed hyponatremia. A chest radiograph showed lobar
infiltrates. Gram stain of sputum showed numerous neu-
trophils but failed to show any organisms. A urine anti-
gen test was positive for the causative agent. What is the
major virulence factor of the causative agent?
(A) Antiphagocytic capsule
(B) Cord factor
(C) Exotoxin production
(D) Intracellular growth
(E) Pyocyanin
6 A steer dies on a ranch in North Dakota and a vet-
erinarian is consulted. Histological sections of the
spleen from the deceased animal show evidence of a
bacterial causative agent (shown in the photograph).
The bacterium was also cultured aerobically on blood
agar. Which of the following substances is associated
with increased virulence of this isolate, and if detected,
would alarm the state health officials and result in a
more extensive investigation at the national level? (A) Clostridial gas gangrene
(B) Pseudomonas ecthyma gangrenosum
(C) Staphylococcal cellulitis
(D) Staphylococcal pyomyositis
(E) Streptococcal necrotizing fasciitis
8 Which virulence factor is most important when con-
sidering the pathology of this case?
(A) α-Toxin (lecithinase)
(B) Enterotoxin
(C) Pyocyanin
(D) Pyrogenic exotoxin A
(E) Streptolysin S
Buxton_CH01.indd 2 7/1/2009 8:56:12 PM
, Bacteriology 3
9 While planting a tree, a man punctured his foot
through his tennis shoe with the prongs of a rake.
He was not initially concerned with the wound and
washed it only superficially. At 4:00 AM, he awak-
ened with excruciating pain in the foot and sought
medical care at the emergency department. The lesion
was cleaned and excised of devitalized tissue and an
IV b-lactam antibiotic was administered, which sub-
sequently cleared the infection. A Gram stain of an
anaerobic culture taken from wound secretions is
shown. Of the following microbial groups, which is
most compatible with this case?
11 Of the following organisms, what is the patient most
likely infected with?
(A) Clostridium sp.
(B) Enterococcus
(C) Group A Streptococcus
(D) Meningococcus
(E) Methicillin-resistant Staphylococcus aureus
(MRSA)
(A) Actinomycetes 12 Based on these initial findings, what is the best antibi-
(B) Clostridia otic choice for the patient in the above case?
(C) Pseudomonads (A) Amoxicillin/clavulanate
(D) Staphylococci (B) Cephalexin
(E) Streptococci (C) Dicloxacillin
(D) Polymyxin B
The next three questions are linked. (E) Trimethoprim–sulfamethoxazole (TMP–SMZ)
10 A patient injured herself at home in the garden, and 13 A pediatric patient with a persistent cough is evalu-
after several days, the resulting skin lesion became ated for sinopulmonary disease. History and physical
infected and intensely painful and she sought medi- examination determines that the child suffers from
cal help. Culture of the wound grew Gram-positive nasal polyps and, possibly, chronic airway obstruc-
cocci that were b-hemolytic on blood agar. On nutri- tion. A sputum sample produces several bacterial spe-
ent agar, the organism produced effervescence when cies, including Haemophilus influenzae and a mucoid
hydrogen peroxide was added to the colonies (shown variety of Pseudomonas aeruginosa. Which of the fol-
in the photograph). What is the enzyme responsible lowing is the most likely diagnosis?
for this bubbling?
(A) Bronchiolitis
(B) Chronic obstructive pulmonary disease (COPD)
(C) Cystic fibrosis
(D) Interstitial pneumonia
(E) Sarcoidosis
Buxton_CH01.indd 3 7/1/2009 8:56:13 PM
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