title: Declining trend in transmission of drug-resistant HIV-1 in Amsterdam.
abstract: OBJECTIVE
  Symptomatic primary HIV infections are over-represented in the mainly hospital-based studies on transmission of resistant HIV-1. We examined a more general population for the prevalence of resistant HIV-1 strains among primary infections.
  
  
  METHODS
  From 1994 to 2002 primary infections were identified within the Amsterdam Cohort Studies (ACS) among homosexual men and drug users, and at the Academic Medical Center (AMC). Whereas primary HIV-1-infected AMC patients, often presented with symptoms of acute retroviral syndrome, ACS participants largely seroconverted during follow-up and thus brought also asymptomatic primary infections to our study.
  
  
  METHODS
  Reverse transcriptase (RT) and protease sequences were obtained by population-based nucleotide sequence analysis of the first HIV RNA-positive sample available. Subtypes were identified by phylogenetic analysis. Mutations were identified based on the IAS-USA resistance table.
  
  
  RESULTS
  A total of 100 primary HIV-1 infections were identified (32 AMC and 68 ACS). Transmission of drug-resistant strains decreased over calendar time, with 20% [95% confidence interval (CI), 10-34%] of infections bearing drug-resistant mutations before 1998 versus only 6% (95% CI, 1-17%) after 1998. No multi-drug resistance pattern was observed. The median plasma HIV-1 RNA level of the first RNA positive sample was significantly lower for the individuals infected with a resistant strain versus those infected with wild-type, suggesting a fitness-cost to resistance. Four of seven non-B subtypes corresponded with the prevalent subtype in the presumed country of infection, and none showed resistance mutations.
  
  
  CONCLUSIONS
  The transmission of drug-resistant HIV-1 strains in Amsterdam has decreased over time. Monitoring should be continued as this trend might change.
authors.affiliation: Municipal Health Service Amsterdam, The Netherlands. dbezemer@gggd.amsterdam.nl
authors.forename: Daniela
authors.initials: D
authors.lastname: Bezemer
authors.forename: Suzanne
authors.initials: S
authors.lastname: Jurriaans
authors.forename: Maria
authors.initials: M
authors.lastname: Prins
authors.forename: Lia
authors.initials: L
authors.lastname: van der Hoek
authors.forename: Jan M
authors.initials: JM
authors.lastname: Prins
authors.forename: Frank
authors.initials: F
authors.lastname: de Wolf
authors.forename: Ben
authors.initials: B
authors.lastname: Berkhout
authors.forename: Roel
authors.initials: R
authors.lastname: Coutinho
authors.forename: Nicole K T
authors.initials: NK
authors.lastname: Back
mesh_terms: D000328:Adult; D015331:Cohort Studies; D024882:Drug Resistance, Viral / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology / Q000235:genetics / Q000635:transmission*; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D012367:RNA, Viral / Q000032:analysis; D012307:Risk Factors
chemical_list: D012367:RNA, Viral