Abstract
Multiple nucleoside resistance involves specific genetic changes in the HIV‐1 reverse transcriptase gene, such as Q151M mutation and an insertion of two serine aminoacids at RT codon 69. Among 432 patients failing antiretroviral therapy, five (1.15%) harboured viruses with Q151M mutation into the RT gene and no viruses were identified harbouring insertion at codon 69. Also we have studied the long‐term benefit of HIV genotypic testing with the failure to reach a viral load below 50 copies/ml within 1 year of antiretroviral therapy using as the primary end‐point. A group of 64 HIV‐positive antiretroviral multiexperienced patients were examined, all of them failing the current ART. HIV‐RNA changed –0.8 log at month 4 and +0.1 log and –0.5 log at months 8 and 12, respectively. The proportion of patients with viral load below 50 copies/ml was 19.3, 32.8, and 28.1% at months 4, 8, and 12, respectively. In multidrug‐experienced patients, genotype‐guided therapy is not in fact able to achieve complete viral suppression in more than 30% of patients after 1 year of ART. The development of more precise resistance tests and interpretations are needed for better control of HIV replication. Other metabolic/pharmacokinetics factors of poor drug adherence should also be assessed. J. Clin. Lab. Anal. 15:127–130, 2001. © 2001 Wiley‐Liss, Inc.