Understanding HIV-1 Drug ResistanceFrenkel, Lisa M.*†; Tobin, Nicole H.*Therapeutic Drug Monitoring: April 2004 - Volume 26 - Issue 2 - p 116-121 Basel Proceedings Abstract Author Information Abstract: Infection with drug-resistant HIV-1 may result from the acquisition of mutant strains or from their selection within the individual; either can compromise the efficacy of antiretroviral therapy (ART). Drug-resistance testing is recommended to assist in the choice of ART. Herein, factors that contribute to the selection of drug-resistant virus and details important to the interpretation of the genotypic and phenotypic susceptibility test results are reviewed. From the Departments of *Pediatrics and †Laboratory Medicine, University of Washington, Seattle, WA. Received for publication September 30, 2003; accepted December 13, 2003. Reprints: Dr Lisa M. Frenkel, 4800 Sand Point Way, NE, 8G-1, Seattle, WA 98105 (e-mail: firstname.lastname@example.org). © 2004 Lippincott Williams & Wilkins, Inc.