XVIII International AIDS Conference


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Primary drug resistance mutations (pDRM) at the two largest metropolitan areas of São Paulo, Brazil

R. Rodrigues1, V. Almeida2, J.L.P. Ferreira1, S.Q. Rocha3, T. Ragazzo2, L. Brigido1, Sao Paulo HIV Salvage Workgroup

1Instituto Adolfo Lutz, Virology, Sao Paulo, Brazil, 2Centro de Referencia DST/Aids de Campinas, Campinas, Brazil, 3Centro de Referencia DST/Aids de Sao Paulo, Sao Paulo, Brazil

Background: Free acess to ARV is part of Brazilian response to the AIDS epidemic and primary resistance is a concern since the introduction of HAART in late 1990s. Primary Drug Resistance Mutations (pDRM) surveillance has an important strategy to monitor ARV therapy efficacy. We evaluated naïve individuals from two major HIV Clinics in São Paulo.
Methods: Patients that agreed to participate were interviewed by clinical staff to access risk and partnership to ARV users. Blood samples were collected from May 2008 to November 2009. Clinical and laboratory information was obtained from clinical charts. HIV RNA polymerase was retrotranscribed and sequenced by nested PCR products at ABI3100.
Results: 243 HIV infected individuals were enrolled. Sequence from 230 (95%) samples was analyzed, mostly clade B (80%). Four females with previous exposure to MTCT prophylaxis, most (3/4) showing one or more DRM, were not included in pDRM prevalence estimate. Among the 226 naïve cases, according to Stanford CPR, the prevalence of pDRM was 8.9% (5.5%-13% CI95). IAS 2009 DRM or polymorphisms at resistance codons was detected in 14.2% (10%-19% CI95). Patients referring sexual partner on ARV therapy had similar number of pDRM, with no significant association to risk group or gender. Mutations to NNRTIs were the most common, 74% of pDRM cases, with two cases with three class resistance. Overall, pDRM were more observed among clade B (12.5% x 2.1%, p< 0.034).
Conclusions: Comparing to other studies in the area the prevalence of pDRM seems stable but the proportion of NNRTIs is a concern as NNRTIs based regimens are commonly used. No clear risk factor to pDRM, as partnership to ARV users could be determined. Although the numbers here are small, our data suggests that women exposed to MTCT prophylaxis may benefit from pre treatment genotype test.

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