Prevalence of integrase strand transfer inhibitors (InSTIs) resistance mutations in InSTIs-naive and -experienced HIV-1 infected patients: a single Center experience

Integrase strand transfer inhibitor resistance (InSTI) rates are low. However, genotypic resistance test is not routinely performed in many centres. The aim of this study is to evaluate the prevalence of InSTI related mutations in our large Cohort. We examined all integrase genotypic resistance tests 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. 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), the overall prevalence of major RAMs was 11.7%. Among them, 10 harboured N155H, four Q148H, two Q148R, two Y143C/S and two T66A/I/T respectively. A novel mutation at a recognized resistance site (E92K) was identified in one raltegravir-experienced patient. The overall prevalence of InSTI mutations in our Cohort was low, particularly in naïve patients indicating no transmitted RAMs, while in InSTIs-experienced patients the rate of RAMs was high (11.7%). We support an implementation of surveillance of InSTI resistance.