Increase in prevalence of Pneumocystis carinii mutations in patients with AIDS and P. carinii pneumonia, in the United States and China.

This study of Pneumocystis carinii dihydropteroate synthase (DHPS) mutations in patients with AIDS who have P. carinii pneumonia compares the change in the prevalence of such mutations in the United States, where sulfa-drug prophylaxis is widespread, to that in China, where it is infrequent. The DHPS gene from 145 US patients presenting during 1983-2001 and from 15 Chinese patients presenting during 1998-2001 was amplified by polymerase chain reaction and was sequenced. In the United States, 40% of patients had DHPS mutations; 38% received sulfa-drug prophylaxis. Mutation prevalence increased to 70% during 2000-2001, from 25% during 1994-1995 (P<.01). In China, 7% of patients had DHPS mutations; none received sulfa-drug prophylaxis. The prevalence of P. carinii DHPS mutations has markedly increased in the United States but remains low in China.