Objective: To determine the introduction of HIV-1 genetic forms and to examine transmission clusters and resistance to antiretroviral inhibitors among newly diagnosed patients from the Basque Country, Spain, during 2004-2007.
Methods: A total of 261 samples, corresponding to 47.5% heterosexuals, 37.9% men who have sex with men (MSM), and 11.1% intravenous drug users were analyzed in protease and reverse transcriptase to examine phylogenetic relationships and drug resistance-associated mutations.
Results: Subtype B was detected in 220 (84.3%) samples and non-B subtype variants in 41 (15.7%) samples. Nearly half (47%) of the sequences grouped in transmission clusters. One of these comprised 14 individuals, 12 of them MSM, with the T215D revertan mutation. In largest transmission clusters, the percentage of MSM was higher than heterosexuals (P < 0.001). Resistance mutations were detected in 29 (11.1%) patients: 20 (7.6%) of them to nucleoside reverse transcriptase inhibitor; 6 (2.3%) to nonnucleoside reverse transcriptase inhibitor (NNRTI); and 1 each to protease inhibitors, protease inhibitor plus NNRTI, and nucleoside reverse transcriptase inhibitor plus NNRTI, respectively.
Conclusions: Our findings underscore recommendations for HIV-1 genotyping in newly diagnosed patients not only to provide information on transmitted drug resistance as an issue in public health and as a guide to future therapy but also to document transmission clusters and to increase the necessary preventive measures.