BACKGROUND

There are few large studies of transmitted drug resistance (TDR) prevalence and the drug resistance mutations (DRMs) responsible for TDR in the United States.

METHODS

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) and protease sequences were obtained from 4253 antiretroviral therapy (ART)-naive individuals in a California clinic population from 2003 to 2016. Phylogenetic analyses were performed to study linkages between TDR strains and selection pressure on TDR-associated DRMs.

RESULTS

From 2003 to 2016, there was a significant increase in overall (odds ratio [OR], 1.05 per year [95% confidence interval {CI}, 1.03-1.08]; P < .001) and nonnucleoside RT inhibitor (NNRTI)-associated TDR (OR, 1.11 per year [95% CI, 1.08-1.15]; P < .001). Between 2012 and 2016, TDR rates to any drug class ranged from 15.7% to 19.2%, and class-specific rates ranged from 10.0% to 12.8% for NNRTIs, 4.1% to 8.1% for nucleoside RT inhibitors (NRTIs), and 3.6% to 5.2% for protease inhibitors. The thymidine analogue mutations, M184V/I and the tenofovir-associated DRMs K65R and K70E/Q/G/N/T accounted for 82.9%, 7.3%, and 1.4% of NRTI-associated TDR, respectively. Thirty-seven percent of TDR strains clustered with other TDR strains sharing the same DRMs.

CONCLUSIONS

Although TDR has increased significantly in this large cohort, many TDR strains are unlikely to influence the activity of currently preferred first-line ART regimens. The high proportion of DRMs associated with infrequently used regimens combined with the clustering of TDR strains suggest that some TDR strains are being transmitted between ART-naive individuals.