Pneumocystis carinii Pneumonia
Prevention of Exposure
Although some authorities recommend that HIV-infected persons at risk
for P. carinii pneumonia (PCP) not share a hospital room with a patient who
has PCP, data are insufficient to support this recommendation as standard
practice.
Prevention of Disease
Adults and adolescents who have HIV infection (including those who are
pregnant) should be administered chemoprophylaxis against PCP if they have
a CD4+ T-lymphocyte count of <200/µL, unexplained fever (>100
F [37.7 C]) for >2 weeks, or a history of oropharyngeal
candidiasis. Trimethoprim-sulfamethoxazole (TMP-SMZ) is the preferred
prophylactic agent. One double-strength tablet/day is the preferred
regimen. However, one single-strength tablet/day also appears to be
highly effective and may be better tolerated. TMP-SMZ may confer
cross-protection against toxoplasmosis and many bacterial infections. For patients who have an adverse reaction that is not life-threatening,
treatment with TMP-SMZ should be continued if clinically feasible; for those
who have discontinued such therapy, its reinstitution should be strongly
considered. Whether it is best to reintroduce the drug at the original
dose or at a lower and gradually increasing dose or to try a desensitization
regimen is unknown. If TMP-SMZ cannot be tolerated, alternative prophylactic
regimens include dapsone, dapsone plus pyrimethamine plus leucovorin, and aerosolized pentamidine administered by the Respirgard II™ nebulizer
(Marquest, Englewood, CO). Regimens that include dapsone plus pyrimethamine
also are protective against toxoplasmosis but not against most bacterial
infections. Because data regarding their efficacy for PCP prophylaxis are
insufficient for a firm recommendation, the following regimens generally
cannot be recommended for this purpose: aerosolized pentamidine administered
by other nebulization devices currently available in the United States,
intermittently administered parenteral pentamidine, oral
pyrimethamine/sulfadoxine, oral clindamycin plus primaquine, oral atovaquone,
and intravenous trimetrexate. However, the use of these agents may be considered
in unusual situations in which the recommended agents cannot be administered.
Prevention of Recurrence
Adults and adolescents who have a history of PCP should be administered
chemoprophylaxis with the regimens indicated above to prevent recurrence
(AI).
Notes:
Pediatric Notes
Children born to HIV-infected mothers should be administered prophylaxis
with TMP-SMZ beginning at 46 weeks of age (15). Prophylaxis
should be discontinued for children who are subsequently found not to be
infected with HIV. HIV-infected children and children whose infection status
remains unknown should continue to receive prophylaxis for the first year
of life. The need for subsequent prophylaxis should be determined on the
basis of age-specific CD4+ T-lymphocyte count thresh-olds (15,16, Table 1).
Children who have a history of PCP should be administered lifelong chemoprophylaxis to prevent recurrence (AI).
Note Regarding Pregnancy
Chemoprophylaxis for PCP should be administered to pregnant women as well
as to other adults and adolescents. TMP-SMZ is the recommended
prophylactic agent. Because of theoretical concerns regarding possible
teratogenicity associated with drug exposures during the first trimester,
providers may choose to withhold prophylaxis with TMP-SMZ during the first
trimester. In such cases, aerosolized pentamidine may be considered because
of its lack of systemic absorption and the resultant lack of exposure of
the developing embryo to the drug.
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