Background: The aim of the present study is to asses the prevalence of resistances in a group of patients with virological failure establishing the relationship between the appearance of mutations and the given antiretroviral therapy along with other variables used in these patients follow-up.
Patients and method: Samples belonging to 88 patients were selected either with viral load levels above 30.000 copies/ml after reaching undetectable viral load levels, or with persistently detectable levels above 1.000 copies/ml. Resistances were tested by means of Line Probe Assay (LiPA). The history of patients' antiretroviral treatments was reviewed.
Results: Mutations were observed in 52,6% of cases for reverse transcriptase (RT) an in 81,8% for the protease genes, being T215Y and V82A the most frequently detected ones. Mutations coferring resistance to the given antiretrovirals appeared in 33 cases. No statistical significance was observed between the presence of mutations and the administered therapy. In the multivariate analysis we found for LiPA RT a greater risk of appearance of mutations according to patient motility (OR = 4,0).
Conclusions: the prevalence of resistance mutations in patients with virologic failure is placed around 50% in both genes. A consensus in the definition of virologic failure in HIV infected patients is urged.