Prevalence of Integrase Strand Transfer Inhibitors Resistance Mutations in Integrase Strand Transfer Inhibitors-Naive and -Experienced HIV-1 Infected Patients: A Single Center Experience.

Integrase strand transfer inhibitor (InSTI) resistance rates are low. However, genotypic resistance test (GRT) is not routinely performed in many centers. The aim of this study is to evaluate the prevalence of InSTI-related mutations in our large cohort. We examined all integrase GRTs performed as part of routine clinical practice at Spedali Civili General Hospital, University of Brescia from 2011 to 2016. Analysis was performed through the Stanford HIV Drug Resistance Database. A total of 341 patients were included. Genotypic resistance assays were performed in naive (48), ART-experienced but InSTI-naive (114), and both ART-experienced/InSTI-experienced (179) patients. No major resistance-associated mutations (RAMs) were detected in patients never exposed to InSTIs. Of 179 samples from patients exposed to InSTIs (mostly to raltegravir [RAL]), the overall prevalence of major RAMs was 11.7%. Among them, 10 harbored N155H, 4 Q148H, 2 Q148R, 2 Y143C/S, and 2 T66A/I/T, respectively. A novel mutation at a recognized resistance site (E92K) was identified in one RAL-experienced patient. The overall prevalence of InSTI mutations in our cohort was low, particularly in naive patients indicating no transmitted RAMs, although in InSTIs-experienced patients the rate of RAMs was high (11.7%). We support an implementation of surveillance of InSTI resistance.