title: Transmission cluster of multiclass highly drug-resistant HIV-1 among 9 men who have sex with men in Seattle/King County, WA, 2005-2007.
abstract: BACKGROUND
  From 2005 through 2007, Seattle health care providers identified cases of primary multiclass drug-resistant (MDR) HIV-1 with common patterns of resistance to antiretrovirals (ARVs). Through surveillance activities and genetic analysis, the local Health Department and the University of Washington identified phylogenetically linked cases among ARV treatment-naive and -experienced individuals.
  
  
  METHODS
  HIV-1 pol nucleotide consensus sequences submitted to the University of Washington Clinical Virology Laboratory were assessed for phylogenetically related MDR HIV. Demographic and clinical data collected included HIV diagnosis date, ARV history, and laboratory results.
  
  
  RESULTS
  Seven ARV-naive men had phylogenetically linked MDR strains with resistance to most ARVs; these were linked to 2 ARV-experienced men. All 9 men reported methamphetamine use and multiple anonymous male partners. Primary transmissions were diagnosed for more than a 2-year period, 2005-2007. Three, including the 2 ARV-experienced men, were prescribed ARVs.
  
  
  CONCLUSIONS
  This cluster of 9 men with phylogenetically related highly drug-resistant MDR HIV strains and common risk factors but without reported direct epidemiologic links may have important implications to public health. This cluster demonstrates the importance of primary resistance testing and of collaboration between the public and private medical community in identifying MDR outbreaks. Public health interventions and surveillance are needed to reduce transmission of MDR HIV-1.
authors.affiliation: HIV/AIDS Epidemiology Unit, HIV/AIDS Program, Public Health-Seattle & King County, 400 Yesler Way, Seattle, WA 98104, USA. susan.buskin@kingcounty.gov
authors.forename: Susan E
authors.initials: SE
authors.lastname: Buskin
authors.forename: Giovanina M
authors.initials: GM
authors.lastname: Ellis
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Pepper
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Frenkel
authors.forename: Steven A
authors.initials: SA
authors.lastname: Pergam
authors.forename: Geoffrey S
authors.initials: GS
authors.lastname: Gottlieb
authors.forename: Carrie
authors.initials: C
authors.lastname: Horwitch
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Olliffe
authors.forename: Karen
authors.initials: K
authors.lastname: Johnson
authors.forename: Peter
authors.initials: P
authors.lastname: Shalit
authors.forename: Corinne
authors.initials: C
authors.lastname: Heinen
authors.forename: Margot
authors.initials: M
authors.lastname: Schwartz
authors.forename: Robert W
authors.initials: RW
authors.lastname: Wood