Medical progress: Pneumocystis pneumonia

Pneumocystis pneumonia remains a serious cause of sickness and death in immunocompromised patients. The epidemiology of this infection is only beginning to emerge, but it includes the transmission of organisms between susceptible hosts as well as probable acquisition from environmental sources. Lung injury and respiratory impairment during pneumocystis pneumonia are mediated by marked inflammatory responses in the host to the organism. Trimethoprim-sulfamethoxazole with adjunctive corticosteroid therapy to suppress lung inflammation in patients with severe infection remains the preferred treatment. However, accumulating evidence of mutations of the gene that encodes dihydropteroate synthase in pneumocystis has aroused concern about the potential for the emergence of resistance to sulfa agents, which have been the mainstay of prophylaxis and treatment of pneumocystis pneumonia. An improved understanding of the basic biology of pneumocystis has helped to define new targets for the development of drugs to treat this important infection.