Background: This study examines the prevalence of primary resistance to antiretroviral drugs in patients diagnosed with HIV infection during 2002 to 2005 and determines the clinical and epidemiological characteristics of this population.
Methods: A prospective analysis of genotypic resistance was carried out in 125 patients by gene sequencing (88.0% diagnosed in 2002, 28.9% in 2003-2004, and 87.9% in 2005). Thirteen patients had a diagnosis of recent primary infection.
Results: Sixteen patients (12.8%) carried viruses with at least one drug-resistance mutation; among them, 4 had recent infection (30.8%) and 12 chronic infection or infection of unknown duration (10.7%). Six patients (4.8%) presented at least one resistance mutation to nucleoside/tide reverse transcriptase inhibitors, 9 patients (7.2%) to non-nucleoside/ tide reverse transcriptase inhibitors inhibitors and 2 patients (1.6%) to protease inhibitors. One patient (0.8%) harbored a multidrug-resistant variant. The frequency of primary resistance was higher in patients with HIV subtype B (15.5%), in the homosexual/bisexual population (17.9%), and in patients diagnosed in 2005 (17.9%). Prevalence increased from 9.3% in 2002 to 16.3% in 2005 in chronically infected patients or those with unknown duration of the infection.
Conclusions: Primary resistance to antiretroviral drugs is high in both recent and chronic HIV infection and has increased in recent years. Genotype resistance testing in patients with a diagnosis of HIV infection is recommended before beginning antiretroviral therapy.