Resistance

Despite viral-load testing, high levels of drug resistance at first virologic failure were found in KwaZulu-Natal, South Africa.

Having NNRTI resistance at baseline more than doubles the risk for virologic failure on initial efavirenz-based regimens.

Data from the Women and Infants Transmission Study reinforce the importance of genotypic resistance testing in treatment-naive HIV-infected pregnant women.

A comprehensive report from the U.K. indicates a recent decline in the rate of transmitted drug resistance.

The development of triple-class resistance is rare in patients who initiate antiretroviral therapy with a regimen that includes either a potent NNRTI or a boosted PI.

Despite stable CD4-cell counts and viral loads, patients with detectable viremia on antiretroviral therapy accumulate resistance mutations and lose future treatment options.

In a small nationwide survey in the U.S., a striking 18% of recently infected adolescents had genotypic evidence of transmitted drug resistance.

Data from Germany support the new DHHS recommendation to perform genotypic resistance testing in all treatment-naive patients.

Two studies suggest that rates of nevirapine resistance can be reduced by adding AZT (with or without 3TC) to maternal and infant regimens.

Transmitted HIV-drug resistance appears to have increased over time in a large cohort from Europe and Canada, but what actually constitutes significant antiretroviral drug resistance?

Resistance testing before the initiation of antiretroviral therapy is increasingly important and cost-effective, given the rising prevalence of transmitted resistance among people with newly diagnosed HIV infection.

In a cohort of patients with extensive treatment experience and stable CD4-cell counts, genotypic resistance emerged slowly over a median follow-up of 9 months.

Approximately one quarter of patients developed resistance mutations during treatment interruption; the rate was particularly high (50%) among those on NNRTI-based regimens.

Two new studies suggest that 10% of treatment-naive patients in Europe — and 20% of treated patients in the U.K. specifically — have resistance to HIV drugs.

Ultrasensitive assays show that nevirapine resistance occurs in most women who receive single-dose treatment to prevent perinatal transmission; the resistance may persist for months or years.

In this retrospective cohort study, resistance rates were lowest in patients who received boosted-PI regimens and highest in those who received abacavir-based triple-NRTI regimens or single-PI regimens.

Two experts weigh in on whether to switch regimens in a patient with evidence of triple-class resistance.

For patients starting NNRTI-based regimens, drug-resistance mutations at baseline significantly increase the risk for virologic failure, especially if NNRTI resistance is present.

An expert’s take on the most clinically relevant findings from this year’s resistance meeting

Entecavir, a drug previously thought to have exclusive HBV activity, has now been shown to have anti-HIV activity and hence potentially to select for HIV resistance if not given with concomitant antiretroviral therapy.