Emergence of Trimethoprim‐Sulfamethoxazole Resistance in the AIDS Era

Abstract

Trimethoprim-sulfamethoxazole (TMP-SMX) is widely used for Pneumocystis carinii pneumonia prophylaxis in human immunodeficiency virus (HIV)—infected patients, but little is known about the effects of this practice on the emergence of TMP-SMX—resistant bacteria. A serial cross-sectional study of resistance to TMP-SMX among all clinical isolates of Staphylococcus aureus and 7 genera of Enterobacteriaceae was performed at San Francisco General Hospital. Resistance among all isolates was Escherichia coli (24% in 1988 to 74% in 1995) and S. aureus (0% to 48%) obtained from HIV-infected patients. A rapid increase in the use of prophylactic TMP-SMX in HIV disease was also observed during this time in San Francisco and is likely responsible for the increase in TMP-SMX resistance.