Using strain typing to characterise a fluoroquinolone-resistant Neisseria gonorrhoeae transmission network in southern California.

OBJECTIVE

We investigated the initial outbreak of fluoroquinolone-resistant Neisseria gonorrhoeae (QRNG) in southern California with analysis of transmission using strain typing.

METHODS

Surveillance for QRNG was conducted between 2000 and 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 to 261) and negatively associated with travel history: AOR 0.05, (95% CI 0.0 to 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.