Internal-Medicine

Answers: 47–65 223
period is 14–18 days. Serum amylase is elevated
in most cases of mumps because of parotitis, not
pancreatitis. Other complications include thyroiditis,
myocarditis, and polyarthritis. (Kasper,
p. 1154)
56. (B) The most common cause of traveler’s diarrhea
worldwide is toxigenic E. coli. In North
Africa and Southeast Asia, Campylobacter infections
predominate. Other causative organisms
include Salmonella, Shigella, rotavirus, and the
Norwalk agent. The most common parasite
causing traveler’s diarrhea is Giardia lamblia.
(Kasper, p. 728)
57. (D) Histoplasma capsulatum is a dimorphic
fungus with worldwide distribution. In the
United States, it is particularly common in
Southeastern, mid-Atlantic, and Central states.
It is frequently found in soil enriched by droppings
of certain birds and bats. Caves are
common sites of infection. Most infections are
asymptomatic or mild and require no therapy.
Acute disseminated infection usually occurs in
patients with HIV infection or other immunocompromised
states, but chronic dissemination
can occur in immunocompetent patients.
Findings may include hepatosplenomegaly,
lymphadenopathy, anemia, and Addison’s disease.
Mediastinal fibrosis can result in superior
vena cava compression. Fibrosis can also
involve the pulmonary arteries, esophagus,
and pulmonary veins. Only rare nonviable
organisms are found on pathologic examination
in such cases. The prognosis is generally
poor. (Kasper p. 1179)
58. (C) This woman likely has native valve endocarditis,
probably in the setting of a previous
valvular abnormality. Streptococci cause over
half the cases of native valve endocarditis in
nonintravenous drug abusers. Of these, 75%
are viridans streptococci. Streptococcus bovis is
the most common nonviridans streptococcus
causing endocarditis and is usually found in
the older population (60 years), particularly if
bowel lesions are present. Staphylococcal
endocarditis is the next most common type,
but it is usually associated with a more acute
presentation. Enterococci cause about 6% of
cases in native valve endocarditis, but fungi
are rare causes. (Kasper, p. 732)
59. (E) Cytotoxic chemotherapy frequently results in
neutropenia and subsequently Gram-negative
bacillary infection. Pseudomonas, Staphylococcus,
Candida, and Aspergillus infections are also
common. (Kasper, p. 479)
60. (D) Selective immunoglobulin A (IgA) deficiency
predisposes to G. lamblia infection, hepatitis
virus, and S. pneumoniae. H. influenzae
infection occurs, but this is not as characteristic
as Giardia. (Kasper, p. 1944)
61. (D, F, G) Defects in the complement pathway
predisposes individuals to recurrent infections
with encapsulated organisms such as H.
influenzae, Neisseria species, or S. pneumonia.
(Kasper, p. 1928)
62. (B) All forms of T-lymphocyte deficiency/
dysfunction are characterized by candidal
infections. Candida species can cause thrush, skin
lesions, esophagitis, and cystitis. Hematogenous
spread can occur and disseminate the organism
widely in individuals with low CD4 counts.
(Kasper, pp. 1940–1941)
63. (D) Patients with myeloma have defects in
humoral immunity and are prone to recurrent
pneumonias due to S. pneumoniae. Lung infections
with S. aureus and Klebsiella pneumoniae
are also frequent. E. coli and other Gramnegatives
cause recurrent urinary tract infections.
(Kasper, p. 657)
64. (A) The preformed toxin of Staphylococcus
causes nausea within 1–6 hours of ingestion.
Ham, poultry, potato and egg salad, mayonnaise,
and cream pastries are common food
sources. (Kasper, p. 819)
65. (D) Enterotoxigenic E. coli causes 15–50% of
traveler’s diarrhea, depending on geographic
location. The incubation period is more than
16 hours, and water and many foods can be
the source. (Kasper, p. 728)