Prevalence of antiretroviral drug resistance and resistance-associated mutations in antiretroviral therapy-naïve HIV-infected individuals from 40 United States cities

Background: Transmission of drug-resistant HIV strains to antiretroviral therapy (ART)-naïve subjects can negatively impact therapy response. As treatment strategies and utilization of antiretroviral drugs evolve, patterns of transmitted mutations may shift. Method: Paired genotypic and phenotypic susceptibility data were retrospectively analyzed for 317 ART-naïve, HIV-1-infected subjects from 40 small and major metropolitan cities in the Northeastern, Midwestern, Southern, Southwestern, and Northwestern United States during 2003. Results: Using current (January 2007) PhenoSense cutoffs, HIV-1 from 8% of subjects had reduced susceptibility to >1 drug. By class, <1% had reduced susceptibility to protease inhibitors (PIs), and 1 % had reduced susceptibility to nucleoside reverse transcriptase inhibitors (NRTIs); reduced susceptibility to >1 non-nucleoside reverse transcriptase inhibitor (NNRTIs) was seen in 7% of subjects, with 4% of all subjects having reduced susceptibility to all NNRTIs. IAS-USA-defined NRTI, NNRTI, and/or major PI HIV-1 drug resistance-associated mutations were detected for 10% of the subjects. HIV risk factors included homosexual contact (74%), heterosexual contact (28%), and injectable drug use/transfusion/other (7%). Reduced susceptibility to >1 drug was significantly higher (p = .034) for white subjects than African Americans and Hispanics/others. Conclusion: The high prevalence of drug resistance in these ART-naïve subjects suggests that transmitted resistance is occurring widely within the United States. HIV genotyping and/or phenotyping for antiretroviral-naïve patients seeking treatment should be considered, especially if the therapy will include an NNRTI.