Use of rapid genomic deletion typing to monitor a tuberculosis outbreak within an urban homeless population.

Beginning in mid-2002, a large tuberculosis outbreak occurred among homeless persons in King County, Washington. In order to further monitor the outbreak following its peak in 2003, Mycobacterium tuberculosis isolates from all new King County tuberculosis (TB) patients in 2004 and the first half of 2005 (n = 220) were genotyped by using a rapid comparative genomics-based (genomic deletion-typing) approach, with confirmation by mycobacterial interspersed repetitive units and repetitive-sequence-based PCR (rep-PCR). Results were compared to retrospective genotypic data from 1995 to 2003.