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last
update October 2002
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| Pneumocystis
Pneumonia: Chest X-Rays |
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Pneumocystis
carinii pneumonia
(PCP) is the most common opportunistic infection in HIV disease.
It manifests as fever, nonproductive cough, and dyspnea. The chest
x-ray usually shows diffuse interstitial infiltrates, but it may
be normal in early infection. PCP is generally diagnosed by induced
sputum examination. Treatment is with trimethoprim-sulfamethoxazole
(TMP-SMX) or intravenous pentamidine. These drugs are given in
combination with corticosteroid therapy if there is evidence of
significant respiratory dysfunction. The total duration of therapy
is three weeks.
Primary PCP prophylaxis is recommended in patients with a CD4
count less than 200, and secondary prophylaxis is recommended
in patients with a prior history of PCP. TMP-SMX is the drug of
choice. The dose is a double- or single-strength tablet once a
day. TMP-SMX is also effective in protection against toxoplasmosis,
isosporiasis, salmonellosis, and pneumococcal and hemophilus infections.
Adverse reactions to TMP-SMX are common in HIV-infected patients,
but the drug can often be successfully reintroduced through a
desensitization process.
Alternatives to TMP-SMX include dapsone, atovaquone, and aerosol
pentamidine. Dapsone is dosed as 100 mg per day. It can cause
hemolysis in patients with glucose 6-phosphate dehydrogenase (G6PD)
deficiency, so this condition should be ruled out before initiating
therapy. Atovaquone is considerably more expensive than TMP-SMX
and dapsone. Aerosol pentamidine, which requires special equipment
for administration, is given monthly.
Primary or secondary PCP prophylaxis can be safely discontinued
in HIV-infected patients if their CD4 count rises above 200 for
at least three months on combination antiretroviral therapy.
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