Increased carriage of trimethoprim/sulfamethoxazole-resistant Streptococcus pneumoniae in Malawian children after treatment for malaria with sulfadoxine/pyrimethamine

Treatment of malaria with sulfadoxine/pyrimethamine and of presumed bacteri al infections with trimethoprim/sulfamethoxazole (cotrimoxazole) was assess ed to see if either increases the carriage of cotrimoxazole-resistant Strep tococcus pneumoniae in Malawian children. Children <5 years old treated wit h sulfadoxine/pyrimethamine, cotrimoxazole, or no antimicrobial agent were enrolled in a prospective observational study. Nasopharyngeal swabs were ta ken before treatment and 1 and 4 weeks later. Pneumococci were tested for a ntibiotic susceptibility by broth microdilution. In sulfadoxine/pyrimethami ne-treated children, the proportion colonized with cotrimoxazole-nonsuscept ible pneumococci increased from 38.1% at the initial visit to 44.1% at the 4-week follow-up visit (P = .048). For cotrimoxazole-treated children, the proportion colonized with cotrimoxazole-nonsusceptible pneumo cocci increas ed from 41.5% at the initial visit to 52% at the 1-week follow-up visit (P = .0017) and returned to 41.7% at the 4-week follow-up. Expanding use of su lfadoxine/pyrimethamine to treat chloroquine-resistant malaria may have imp lications for national pneumonia programs in developing countries where cot rimoxazole is widely used.