Single- and multidrug resistance mutations to reverse transcriptase and protease inhibitors - Human immunodeficiency virus type 1-infected patients from two geographical areas in Spain

Objectives: To describe the prevalence of genotypic resistance mutations, i ncluding single and multidrug resistance (MDR) to reverse transcriptase (RT ) and protease (PR) inhibitors in treated and untreated patients from two g eographical areas in Spain (Madrid and Galicia). Study Design/Methods: Resistance mutations to RT inhibitors were studied by line probe assay (LiPA) or by automated sequencing in 468 patients (Madrid , 268; Galicia, 200), and resistance mutations to PR inhibitors were studie d by automated sequencing in 295 patients (Madrid, 85; Galicia, 210). Results: The proportion of resistance mutations in treated and untreated pa tients results were higher by the LiPA method than by sequencing. By sequen cing, we detected resistance mutations to nucleoside analogue RT (NRT) inhi bitors and NRT inhibitors plus nonnucleoside RT (NNRT) inhibitors in 35.4% and 17.2% of treated patients, respectively. We also detected MDR to zidovu dine plus lamivudine in 13.9% of treated patients from Galicia, in 1.7% fro m Madrid (p < 0.001), and in 1.5% of untreated patients From Galicia. Also, we detected MDR to NRT inhibitors in 3.8% and to NNRT inhibitors in 9.1%. We found resistance mutations to PR inhibitors in 38.1%; of treated patient s and in 0.9% of untreated patients. Conclusions: These findings reinforce the usefulness of testing for resista nce mutations in some cases to evaluate their prevalence in a given populat ion and in the follow-up of treated patients.