Transmitted HIV drug resistance in antiretroviral-treatment-naive patients from Poland differs by transmission category and subtype.

Objectives: The surveillance of HIV-transmitted drug resistance mutations (t-DRMs), including temporal trends across subtypes and exposure groups, remains a priority in the current management of the epidemic worldwide.

Methods: A cross-sectional analysis of 833 treatment-naive patients from 9 of 17 Polish HIV treatment centres. Partial pol sequences were used to analyse drug resistance with a general time reversible (GTR)-based maximum likelihood algorithm used for cluster/pair identification. Mutation frequencies and temporal trends were investigated.

Results: t-DRMs were observed in 9% of cases (5.8% for NRTI, 1.2% NNRTI and 2.0% PI mutations) and were more common among heterosexually infected (HET) individuals (13.4%) compared with MSM (8.3%, P = 0.03) or injection drug users (IDUs; 2.9%, P = 0.001) and in MSM compared with IDUs (P = 0.046). t-DRMs were more frequent in cases infected with the non-B variant (21.6%) compared with subtype B (6.6%, P < 0.001). With subtype B a higher mutation frequency was found in MSM compared with non-MSM cases (8.3% versus 1.8% for IDU + HET, P = 0.038), while non-B variants were associated with heterosexual exposure (30.4% for HET versus 4.8% for MSM, P = 0.019; versus 0 for IDU, P = 0.016). Trends in t-DRM frequencies were stable over time except for a decrease in NNRTI t-DRMs among MSM (P = 0.0662) and an NRTI t-DRM decrease in HET individuals (P = 0.077). With subtype B a higher frequency of sequence pairs/clusters in MSM (50.4%) was found compared with HET (P < 0.001) and IDUs (P = 0.015).

Conclusions: Despite stable trends over time, patterns of t-DRMs differed notably between transmission categories and subtypes: subtype B was associated with MSM transmission and clustering while in non-B clades t-DRMs were more common and were associated with heterosexual infections.