High-risk behavior and potential transmission of drug-resistant HIV among injection drug users.

Evidence of increasing prevalence of drug resistance among recent HIV seroconverters indicates a growing public health concern and warrants an examination of the problem from a prevention perspective. Among 638 HIV-infected injection drug users (IDUs) completing 2731 visits between December 1996 and February 2000 in an ongoing cohort study in Baltimore, Maryland, factors associated with unprotected sex and needle sharing were determined. Participants were classified as being at higher or lower risk of HIV and of drug-resistant HIV transmission based on viral load, antiretroviral therapy use, and reported high-risk behavior. Stored plasma of those at higher risk of drug-resistant HIV transmission was tested for resistance by VirtualPhenotype (Vircolab, Rockville, MD). Women were nearly twice as likely as men to engage in unprotected sex, and IDUs were more likely to have unprotected sex if their sexual partners were also HIV infected. IDUs were at higher risk of HIV and drug-resistant HIV transmission at 19% and 6% of all visits, respectively. Participants were infected with drug-resistant HIV at 14% of visits when they were at higher risk of HIV transmission. Intensive risk reduction counseling is needed and must be integrated into routine HIV clinical care.