September 29, 2016
2 min read

High level of drug resistance found among Mexican patients with HIV

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Patients in Mexico with HIV had a high level of pretreatment drug resistance, according to recent study results.

“Ours is the first survey of pretreatment HIV-drug resistance with national representativeness done in Mexico in accordance with WHO guidelines,” Santiago Ávila-Ríos, PhD, of the Centre for Research in Infectious Diseases, Mexico City, and colleagues wrote. “Our survey showed high levels of pretreatment HIV-drug resistance in Mexico, with dominance of resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs).”

The researchers used Sanger sequencing and next-generation virus sequencing to assess plasma specimens from ART-naive patients with HIV (n = 264) at 25 clinics across Mexico. Median follow-up was 9.4 months, and the researchers used univariate and multivariate logistic regression to examine relationships between demographics and pretreatment drug resistance.

According to the Sanger method, pretreatment resistance to any ART occurred among 41 patients (15.5%; 95% CI, 11.4-20.5) and resistance to NNRTIs was observed in 28 patients (10.6%; 95% CI, 7.2-15). Thirteen patients had “at least low-level” pretreatment resistance to Sustiva (efavirenz, Bristol-Myers Squibb), and 23 showed resistance to Atripla (tenofovir/emtricitabine/efavirenz, Bristol-Myers Squibb/Gilead Sciences), according to the researchers.

Next-generation sequencing indicated 38 patients (14.4%; 95% CI, 10.4-19.2) had pretreatment-resistance to any ART, while 26 (9.8%; 95% CI, 6.5-14.1) were resistant to NNRTIs, Ávila-Ríos and colleagues wrote.

At a median follow-up of 8 months after initiating ART, 72% of participants who started NNRTIs (n = 135) achieved viral suppression vs. 40% of patients on protease inhibitor regimens (n = 25; P = .0045). Patients who initiated NNRTIs with pretreatment drug resistance had significantly lower viral suppression (OR = 0.24; 95% CI, 0.07-0.74) than patients who did not have NNRTI resistance.

“Although recommendation for a national change in first-line ART from NNRTI to a different class is debatable, given the high efficacy of NNRTI-based regimens in the Mexican setting in individuals without pretreatment resistance to NNRTI, we recommend the integration of baseline HIV-drug resistance testing for initial ART follow-up and for its feasibility to be examined,” Ávila-Ríos and colleagues wrote. “If baseline HIV genotyping for all individuals starting ART is not feasible, targeting specific populations for HIV-drug resistance tests such as women and their male partners, or the possibility of intensifying the monitoring of plasma viral load should be considered and included in further cost-effectiveness analyses.”

Raph L. Hamers, MD, PhD, of the departments of global health and internal medicine, Academic Medical Center of the University of Amsterdam, and Roger Paredes, MD, PhD, of the HIV Unit and irsiCaixa AIDS Research Institute, Hospital Universitari Germans Trias i Pujol, the Universitat Autonòma de Barcelona, wrote in an accompanying editorial that the findings indicate low- and middle-income countries should make an effort to minimize HIV-drug resistance.

“Investments in the global HIV response should emphasize sustained viral suppression with ART not only to improve survival and reduce HIV transmission, but also to prevent large-scale HIV-drug resistance,” they wrote.

Ávila-Ríos and colleagues also recommend standardized national drug resistance surveys. – by Andy Polhamus