de Faria Romero Soldi G, Ribeiro IC, Ahagon CM, et al. - Researchers sought to delineate major PI mutations among patients exposed to at least one PI. In addition, they investigated the predictors of mutation emergence and determined how the subtypes impacts resistance. From patients exposed to PI with virological failure, partial HIV-1 pol sequences (Sanger Sequencing) were genotyped from January 2014 to December 2017. At least one major PI mutation was identified in 27.5% (466/1696) of the cases, most commonly M46 (14.7%), V82 (13.8%) and I54 (13.3%). Mutations to nucleotide analog reverse transcriptase inhibitor (NRTI) were observed in 69.6% and mutations to non-NRTI were observed in 59.9%, of the 1,696 sequences. Full activity to darunavir was compromised in almost half of the cases among patients with PI-DRM. Hence they support efforts to detect failure at earlier time, particularly for HIV-1 subtype F that pointed association to the emergence of resistance, with potential impact in protease inhibitors sequencing. Furthermore, sufficient adherence to allow PI-DRM emergence may be reflected by NRTI mutations.