Abstract
Recent reports demonstrate the transmission of drug-resistant HIV-1 variants to newly infected individuals, although estimates of the prevalence of drug resistance among populations from different geographic regions are highly varied. The interpretation and comparison of available study results are confounded by the lack of consensus regarding the nomenclature and reporting of antiviral resistance. This report re-evaluates previously presented and published data using uniform criteria for genotypic and phenotypic drug resistance. Treatment-inexperienced and recently or chronically infected populations are reviewed. The prevalence of transmitted drug resistance ranges from 1% to 11% among recently infected persons using these criteria. Programmes to monitor and characterize drug resistance among newly infected persons and their source partners are essential to evaluate the selection processes that influence the transmission of certain genetic variants of HIV. Temporal trends in the prevalence of transmitted drug resistance among diverse populations are necessary to evaluate the potential need for selective and generalized drug resistance screening programmes among newly infected, treatment-naive patients.