Internal-Medicine

Answers and Explanations
1. (A) In tetanus, an acute onset is usual. The
median onset is 7 days, and 90% present within
14 days of injury. The organism is an anaerobic,
motile Gram-positive rod. It has the ability to
survive for years in the form of spores, which are
resistant to disinfectants and heat. Tetanus can
occur in nonimmunized individuals, or those
who have neglected their booster shots.
Penicillin, or metronidazole, is used in treatment,
but their efficacy is not clear. (Kasper, p. 842)
2. (D) EIA is an excellent screening test for HIV
infection as it is positive in over 99.5% of cases.
However, it lacks specificity, and in low risk
populations, only about 10% of EIA positive
results are true positives. Recent influenza
vaccination, acute viral infections, and liver
disease are common causes for false positives.
The Western blot test is more specific and is
the usual confirmatory test, although even
more specific tests are now available. (Kasper,
pp. 1100–1101)
3. (A) S. aureus causes more than 50% of cases of
native valve endocarditis in drug abusers. The
onset is usually acute, and the tricuspid valve
is the most commonly affected. In staphylococcal
tricuspid endocarditis, septic pulmonary
emboli are common. Frequently, no murmur
is heard. (Kasper, p. 732)
4. (C) HSV-2 genital infections may be associated
with fever, malaise, and anorexia. Vesicular
lesions usually ulcerate rapidly and become
covered with exudate. There is a 90% chance of
recurrent symptoms in the first year following
a primary infection. HSV-1 genital infections
are similar, but the chance of recurrence is less.
(Kasper, p. 1037)
5. (D) The presence of IgG antibodies by the indirect
immunofluorescence test indicates recent or
prior EBV infection. IgM antibodies indicate
recent infection only. Heterophil antibodies are
present in 50% of children and 90–95% of adolescents
and adults with infectious mononucleosis.
Monospot tests are the best diagnostic tools
but may not turn positive until the second or
third week of the illness. Specific EBV antibodies
and cultures are rarely used. (Kasper, p. 1047)
6. (B) Current recommendations suggest that
mild diarrhea be treated with oral rehydration
alone, but when enteric symptoms such as
cramps are bothersome, treatment with loperamide
or bismuth subsalicylate is warranted.
More severe infections with severe diarrhea,
severe pain, or fever should be treated with
antibiotics such as fluoroquinolones or
trimethoprim-sulfamethoxazole. (Kasper, p. 728)
7. (B) Pain referring to either or both lower quadrants
is common when oophoritis is present.
Fever usually accompanies oophoritis. Sterility
is not a consequence of mumps oophoritis.
(Kasper, p. 1154)
8. (B) Mycoplasmas have no cell walls and have
filtration characteristics of viruses, but morphologically
are closer to bacteria. The typical
M. pneumoniae infection produces an influenzalike
respiratory illness characterized by
headache, malaise, fever, and cough. If pneumonia
occurs, physical examination can be
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