Internal-Medicine

224 10: Infection
66. (F) Shigella causes an invasive diarrhea with
blood and has an incubation period of more
than 16 hours. Potato and egg salad, lettuce,
and raw vegetables are common food sources.
(Kasper, p. 904)
67. (C) Vibrio cholerae causes profuse watery diarrhea
with an incubation period of more than
16 hours. Shellfish are a common source.
(Kasper, p. 912)
68. (H) B. cereus causes an early onset of food poisoning
when found in fried rice. This occurs
within 1–6 hours and, like staphylococcal food
poisoning, is characterized by vomiting. The
enteric form of B. cereus food poisoning is
characterized by watery diarrhea and occurs
8–16 hours after ingestion of contaminated
food such as meat, vegetables, dried beans, or
cereals. (Kasper, p. 758)
69. (D) The location of infection, the possibility of
tick exposure, and the nonspecific nature of the
presentation are consistent with a rickettsial
infection, likely RMSF. (Kasper, p. 1000)
70. (B) The diagnosis is usually made by proximal
to distal “milking of the urethra” and showing
evidence of a purulent or mucopurulent discharge.
Other methods include examining a
urethral swab or the sediment from the first
20–30 mL of voided urine (after the patient has
not voided for several hours). Dysuria without
inflammation may represent a functional
problem and usually does not benefit from
antibiotics. (Kasper, p. 764)
71. (E) Doxycycline is the treatment of choice, with
tetracycline as the second choice. There is insufficient
evidence to determine the exact role of
fluoroquinolones in RMSF. Beta-lactam antibiotics,
erythromycin, and aminoglycosides are
of no value. Sulfa-containing drugs may actually
exacerbate the condition. Glucocorticoids
have not been shown to be helpful, but meticulous
control of volume status is important.
(Kasper, p. 1001)
72. (B) Although all the skin problems listed have
been described with M. pneumoniae infection,
the only clearly linked entity is erythema multiforme.
(Kasper, p. 1009)
73. (B) C. trachomatis causes 30–40% of cases in the
United States. The exact prevalence depends on
the effectiveness of Chlamydial control programs
in the population. The other organisms
can all cause urethritis in men. (Kasper, p. 763)
74. (A) HSV and C. albicans are the common causes
of vulvar infection. Although they can cause
dysuria, it is of the “external” variety (i.e., secondary
to urine passing over the inflamed
vulvar area). The other infections cause “internal
dysuria” and/or vaginal discharge. (Kasper,
p. 765)
75. (A) Pulmonary and systemic microcirculation are
the primary targets of the disease. The resultant
damage results in increased vascular permeability.
This can cause edema, decreased plasma
volume, decreased albumin, prerenal azotemia,
and even hypotension. Involvement of the pulmonary
microcirculation can result in noncardiogenic
pulmonary edema. (Kasper, p. 1000)
76. (E) Empiric treatment should include coverage
for both Chlamydial infection (with azithromycin)
and N. gonorrhoeae infection (usually with ceftriaxone).
There are numerous alternatives for
N. gonorrhoeae infection, such as oral cefixime
(not available in the United States), oral
ciprofloxacin, or intramuscular (IM) ceftriaxone.
However, resistance to penicillin is too
common to allow the routine use of this drug.
(Kasper, p. 765)
77. (D) There is a definite midwinter spike in bacteremia
in adults, but not in children. Invasive
disease is highest in children under 2 years of
age. Bacteremia is more common in certain
groups (e.g., Native Americans, Native Alaskans,
African Americans), suggesting a genetic predisposition.
Up to 40% of healthy children and
10% of healthy adults are asymptomatic