Transmitted Antiretroviral Drug Resistance in Individuals with Newly Diagnosed HIV Infection: South Carolina 2005-2009

Objectives: The transmission of drug-resistant human immunodeficiency virus 1 (HIV-1) has important implications for the antiretroviral management of newly diagnosed individuals, increasing the risk of suboptimal treatment outcomes. The study objective was to characterize rates and factors associated with transmitted drug-resistant HIV-1 infection among newly diagnosed South Carolina (SC) residents. Methods: This study utilized surveillance genotypic data from antiretroviral therapy (ART)-naive individuals newly diagnosed with HIV-1 infection from June 2005 through December 2009. Multivariable negative binomial regression was used to model the association between the presence of major mutations and sociodemographic characteristics. Results: Of the 1,277 study participants, 14.4% (184/1,277) had HIV-1 variants with major antiretroviral drug mutations. Of these individuals, 126 had non-nucleoside reverse transcriptase inhibitor-associated mutations (NNRTI), 54 had nucleos(t)ide reverse transcriptase inhibitor-associated mutations (NRTI), 37 had protease inhibitor-associated mutations (PI). Nineteen (10.3%) individuals had dual class-associated mutations (NNRTI and PI in seven, NNRTI and NRTI in seven, and NRTI and PI in five individuals), and seven (3.8%) individuals had triple drug class-associated mutations (PI, NNRTI, and NRTI). The multivariable negative binomial regression models indicated that age at HIV diagnosis had a significant negative association with total number of mutations (rate ratio [RR] 0.88, 95% confidence interval [CI] 0.80-0.96, P value = 0.005) and total number of reverse transcriptase (RT) mutations (RR 0.88, 95% CI 0.80-0.97, P value = 0.006) present. Conclusion: Prevalence of transmitted drug resistance is consistently high among newly diagnosed HIV-infected individuals in SC. It is important to continue genotypic surveillance to facilitate effective HIV treatment and empiric post-exposure prophylaxis regimens. Key Words: antiretroviral therapy, HIV drug resistance, protease inhibitors, reverse transcriptase inhibitors, surveillance