Abstract

PIP: There are quite a few pathogens which can cause pneumonia. Identifying the agent of infection simplifies therapy by allowing the appropriate treatment to be targeted with a minimum amount of toxic drugs. Empirical therapy is ideally reserved for settings in which the patient is not acutely ill, there is a high probability of a single, easily treated pathogen, and rapid diagnostic facilities are available if treatment fails. Empirical therapy, however, is often necessary in many AIDS-endemic regions where diagnostic tests are unavailable due to limited resources. In such circumstances, a treatment algorithm independent of extensive diagnostic testing and targeted against locally prevalent pathogens is called for. Malin and colleagues have reported finding Pneumocystis carinii pneumonia (PCP) among 33% of 64 patients in Zimbabwe observed with diffuse pneumonia unresponsive to penicillin. Untreated PCP is lethal. Further, despite three negative sputum smears for Mycobacterium tuberculosis, the organism was the most common pathogen ultimately identified, confirming previous reports and highlighting the importance of anti-TB therapy. The high incidence of PCP raises concerns that in certain parts of Africa treatment algorithms which do not consider PCP may need to be re-evaluated. Different patient selection criteria among studies with discordant results may partially explain the differences in the incidence of PCP in different parts of Africa. Otherwise, regional environmental differences, host genetic variation, and differences in the virulence of various strains of P. carinii may play a role. Data on the incidence of PCP in HIV-infected infants in Africa would provide insights into the role of P. carinii as a pathogen. The authors note that if the incidence of PCP is rising, even in selected areas, then prophylaxis in such areas with co-trimoxazole may be a cost-effective management approach which may also decrease the incidence of bacterial infections. Alternatively, early empirical therapy with co-trimoxazole at high doses may be an effective approach for treating both PCP and bacterial infections before the initiation of empirical anti-TB therapy.