title: Genotypic and phenotypic resistance testing of HIV-1 in routine clinical care.
abstract: Data on genotypic and phenotypic resistance testing of HIV-1 in the routine clinical setting are lacking. In a retrospective single-center study, all patients (n = 102) for whom genotypic resistance typing (GRT) and phenotypic resistance typing (PRT) were performed during the calendar year 2002 were examined. GRT and PRT results were concordant for 79% of the drugs, being highest for nevirapine (92%) and lowest for didanosine (57%). Concordance of results for protease inhibitors was lowest for lopinavir (78%) and highest for indinavir (88%). Discordant results for lamivudine were observed in 16% of patients; 90% of these results corresponded to high-level resistance by PRT and susceptibility by GRT. Overall, HIV loads were lower and CD4+ cell counts higher after therapy following resistance testing, but a significant association with the number of active drugs as predicted by GRT or PRT could not be identified. In a subgroup of 43 patients with virological failure under antiretroviral therapy and sufficient follow-up data, HIV loads were significantly lower after 3 and 6 months. More patients with HIV loads <400/ml had 2 or more active drugs according to PRT (21/29 [75%]) than according to GRT ([15/29 [52%]; p = 0.109. This was also found for HIV loads <50/ml (PRT 16/22 [72%], GRT 10/22 [42%]; p = 0.103), although the differences were not statistically significant. There was no discernable difference between GRT and PRT in the clinic-based population, but the numbers of resistance tests performed are not sufficient to draw definitive conclusions.
authors.affiliation: Division of Infectious Diseases & Hospital Epidemiology, Department of Internal Medicine, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland.
authors.forename: H H
authors.initials: HH
authors.lastname: Hirsch
authors.forename: H
authors.initials: H
authors.lastname: Drechsler
authors.forename: A
authors.initials: A
authors.lastname: Holbro
authors.forename: F
authors.initials: F
authors.lastname: Hamy
authors.forename: P
authors.initials: P
authors.lastname: Sendi
authors.forename: K
authors.initials: K
authors.lastname: Petrovic
authors.forename: T
authors.initials: T
authors.lastname: Klimkait
authors.forename: M
authors.initials: M
authors.lastname: Battegay
mesh_terms: D000328:Adult; D000368:Aged; D000554:Ambulatory Care Facilities; D019380:Anti-HIV Agents / Q000494:pharmacology / Q000627:therapeutic use; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D019562:Viral Load
chemical_list: D019380:Anti-HIV Agents