Transmission Cluster of Multiclass Highly Drug-Resistant HIV-1 Among 9 Men Who Have Sex With Men in Seattle/King County, WA, 2005-2007

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.