Pneumocystis carinii infections in transplant recipients

Pneumocystis carinii is an organism of uncertain taxonomy that causes diffuse pneumonitis in malnourished infants and immunocompromised hosts. In transplant recipients, the infection most commonly presents from 2 to 6 months after transplantation with symptoms of dyspnea, fever, and dry cough lasting from a few days to a few weeks. A diagnosis is most readily and safely achieved by examination of material obtained by bronchoalveolar lavage for cyst forms of the organism. The therapy of choice is intravenous trimethoprim-sulfamethoxazole. Patients allergic to sulfa drugs are usually given parenteral pentamadine. Prophylaxis with oral trimethoprim-sulfamethoxazole is able to prevent pneumonia due to P carinii and is recommended for most transplant recipients, although the lowest effective dose and the optimal duration of therapy have not been determined. The currently high level of interest in this pathogen, stimulated by the epidemic of acquired immunodeficiency syndrome, should foster research that will increase our understanding and enhance our control over this pathogen.