RESUMEN
AIMS: The aim of this study was to evaluate drug resistance patterns among Iranian people living with HIV who have taken antiretroviral therapy for 9-15 months. METHODS: A cross-sectional study was conducted between December 2015 and May 2016. Two hundred fifty-two blood samples were collected from all eligible HIV-infected patients at fourteen healthcare settings, located in major provinces in Iran. The samples were examined for presence of drug resistance strains and viral load level. Moreover, a phylogenetic tree, using neighbor joining, was constructed and HIV subtypes were determined. RESULTS: The most common subtypes were CRF35-AD (47.6%) and A1 (42.8%), followed by 45_CPX (4.8%) and C (4.8%). The resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs), nucleoside reverse transcriptase inhibitors (NRTIs), and protease inhibitors was reported as 19.2, 19.2, and 10.3%, respectively. M184I/V mutation was the most frequent (31.6%) mutation among NRTI-based regimens. Moreover, K103E/N was the most frequent (34.2%) NNRTI mutation. CONCLUSIONS: This is the first study to illuminate the emergence of the CPX genotype among Iranian patients. The drug resistance rate of NNRTIs was similar to that of NRTIs. By assessing drug resistance, it is possible to evaluate the efficacy of treatment and patient adherence to treatment.