Human immunodeficiency virus drug resistance testing: State of the art in genotypic and phenotypic testing of antiretrovirals

Antiretroviral drugs have significantly reduced death rates from the acquir ed immunodeficiency syndrome in the United States. They are highly effectiv e in reducing viral replication, but their utility is threatened by rapid d evelopment of drug resistance. Although antiretroviral drug resistance test ing is available by either genotyping or phenotyping, no consensus guidelin es have been published regarding the appropriate use or interpretation of t hese new tests. Even though their role in clinical practice is not defined, it is important for clinicians to become familiar with relative advantages and disadvantages of genotypic and phenotypic testing and various mechanis ms of antiretroviral resistance.