Objective: We investigated the initial outbreak of QRNG in southern California with analysis of transmission using strain typing.
Methods: Surveillance for QRNG was conducted in 2000-2002 in southern California including epidemiology and strain typing by a combination of antibiogram, auxotype, serovar, Lip type, and amino acid alteration patterns in the quinolone-resistance determining region of GyrA and ParC. Combining epidemiological data with strain typing, we describe the emergence of QRNG outbreak strains using risk factor analysis and transmission networks.
Results: Two outbreak strains accounted for 82% of isolates. Both strains required proline, were Lip type 17c, had amino acid alterations 91 > Phe in GyrA and 87 > Arg in ParC, but they differed by their serovar, IB-3C8 versus IB-2H7, 2G2. Outbreak strains were positively associated with men who have sex with men (MSM), adjusted odds ratio (AOR) 23.9; 95% confidence interval (CI) 2.2-261 and negatively associated with travel history: AOR 0.05, (95% CI 0.0-0.6). Network analysis demonstrated that 17 cases were connected by sexual contacts and/or public venues including bars, bathhouses/sex clubs, and Internet sites.
Conclusions: QRNG may have become established among Californian MSM through an identified transmission network of southern Californian bars, bathhouses and Internet sites.