Prevalence of genotypic and phenotypic HIV-1 drug-resistant strains among patients who have rebound in viral load while receiving antiretroviral therapy in the UNAIDS–Drug Access Initiative in Abidjan, Côte dʼIvoire

Objective: To determine the prevalence of genotypic and phenotypic antiretroviral (ARV) drug-resistant HIV-1 strains among patients with viral load rebound while receiving ARV therapy in Abidjan Cote dIvoire. Methods: Between August 1998 and April 2000 we selected all patients (n = 241) who had received ARV drug therapy for at least 6 months in the UNAIDS-Drug Access Initiative (DAI) in Abidjan. We analyzed for genotypic and phenotypic drug resistance among 97 (40%) of the 241 patients who had a rebound in plasma viral load defined as an initial decrease of >0.5 log(10) copies/ml followed by a subsequent increase of >0.25 log(10) copies/ml. Results: Of the viruses isolated from the 97 patients 86 (88.7%) had usable sequences and 68 (79%) of the 86 patients had genotypic resistance to at least one reverse transcriptase inhibitor (RTI) or protease inhibitor (PI). Resistant mutations were found for zidovudine in 50 (78%) of 64 patients who had received the drug 11 (68.7%) of 16 patients on lamivudine for nevirapine in two (2%) for indinavir in one (1%) and for ritonavir in one (1%). Phenotypic resistance to at least one nucleoside RTI was seen in 45 (56%) of the 80 patients tested to non-nucleoside RTIs in eight (10%) and to PIs in one (1.3%). Multivariate regression analysis showed factors associated with resistance to be initial treatment with dual therapy (P = 0.04) compared with highly active antiretroviral therapy and maximal initial viral load response (P = 0.006). Conclusion: Our results demonstrate a high prevalence of ARV drug resistance associated with dual ARV therapy. These results indicate the limited role for dual ARV therapy. (authors)