Usefulness of genotypic analysis of resistance to nucleoside analogues in the clinical setting

The introduction of drug resistance testing during clinical care of patient s infected with the human immunodeficiency virus (HIV) is still a matter fo r discussion. Thirty-seven HIV-infected subjects who had positive plasma vi raemia despite undergoing antiretroviral therapy were tested for the presen ce of genotypic mutations linked to resistance to nucleoside analogues. Thi rty (81.1%) individuals showed one or more mutations conferring drug resist ance. Eight harboured mutants at codons 215 and 41, which confer resistance to zidovudine and are associated with the worst prognosis. One individual carried the codon 69-SSS insertion, which confers multidrug resistance. Sev en (18.9%) subjects did not show any mutation, but all of them failed to ad here to the treatment regimen and/or experienced diarrhea that likely cause d malabsorption of the drugs. Clinicians referred to the resistance profile when they adjusted or prescribed subsequent combination regimens for their patients.