The Ecology of Drug Resistance The perils of prophylaxing
against one disease only to introduce drug-resistant strains of
another bug were the topic of a poster at the annual conference
of the Infectious Disease Society of America (IDSA) in San
Diego. Researchers from the Universities of Maryland and Malawi
joined forces to find out which opportunistic infections were
striking people with HIV in Malawi and what drugs would be
useful for treating and preventing those infections. This was
done in preparation for a clinical trial of trimethoprim-
sulfamethoxazole (TS, Bactrim) to be used as prophylaxis against
salmonella and streptococcus, two pathogens that cause serious
intestinal and respiratory disease in Africans with HIV. Yet
there is a concern that, in Malawi at least, these organisms may
have developed resistance to TS. A further concern is that
widespread use of TS will produce cross-resistance to one of the
only affordable drugs left to treat malaria in the region,
sulfadoxine-pyrimethamine (SP). TS act