HealthDay News — According to a study published in The Lancet Infectious Diseases, a significant number of patients with HIV have strains of the virus that are resistant to both older and newer drugs.

The researchers looked at 712 HIV patients worldwide whose infection was not controlled by antiretroviral drugs. They found that 16% of patients whose infection was resistant to modern drugs had HIV mutations linked with resistance to older drugs — thymidine analogues.

Among patients whose HIV had this mutation, 80% were also resistant to tenofovir, the main drug in most modern HIV treatment and prevention programs, the researchers reported.

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“We were very surprised to see that so many people were resistant to both drugs, as we didn’t think this was possible,” lead author Ravindra Gupta, of University College London, said in an institution news release.

“Mutations for thymidine analogue resistance were previously thought to be incompatible with mutations for tenofovir resistance, but we now see that HIV can be resistant to both at once. This emphasizes the need to check the genetic profile of patient’s virus before prescribing first-line treatments, as they may have already developed resistance to other treatments that they did not mention having taken.”


Gregson J, et al. “Occult HIV-1 Drug Resistance To Thymidine Analogues Following Failure Of First-Line Tenofovir Combined With A Cytosine Analogue And Nevirapine Or Efavirenz In Sub Saharan Africa: A Retrospective Multi-Centre Cohort Study”. The Lancet Infectious Diseases. 2016. doi: 10.1016/S1473-3099(16)30469-8

Llibre JM. “Time To Get Serious With HIV-1 Resistance In Sub-Saharan Africa”. The Lancet Infectious Diseases. 2016. doi: 10.1016/S1473-3099(16)30447-9

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