[Clinical utility of drug resistance testing]

Emergence of drug resistant HIV-1 is one of the major causes of the anti-retrovirus treatment failure. There are two types of clinical tests to identify the drug resistance. One is nucleotide sequencing of the drug target genomes (genotyping) and the other is measuring drug susceptibility of patient derived HIV-1 in vitro (phenotyping). Several retrospective studies have shown correlation between drug resistance test results and treatment outcome. The numbers of prospective randomized cohort studies have been also performed to clear the usefulness of drug resistance genotyping and phenotyping. Most of these studies have shown significant decrease of plasma virus level in the cases treated with genotypic and/or phenotypic guides. These results clearly support usefulness of genotyping and phenotyping in managing anti-HIV-1 treatment.