Background:
Quinolone resistance determining regions (QRDR) can be used as molecular markers for rapid detection of quinolone resistance in N. gonorrhoeae, especially in areas where culture-based susceptibility testing is not done. We used QRDRs in the gyrA and parC genes to characterize resistant isolates from Marion County Health Department Public Health Laboratory (MCHDPHL) in Indianapolis, IN.

Objective:
To test the feasibility of integrating a PCR-based resistance assay into clinical care and use as an epidemiologic tool.

Method:
In 2005 MCHDPHL received 28,827 gonorrhea (GC) cultures; 1138 (3.9%) were positive. Minimal Inhibitory Concentrations (MICs) for ciprofloxacin for all isolates were determined using E-tests. QRNG samples were analyzed for point mutations in the QRDRs of gyrA and parC using polymerase chain reaction and Roche LightTyper^TM fluorescence melt curve analysis.

Result:
Of the 1138 GC-positive samples, 60 (5.3%) had high-level resistance (MIC > 1.0 &mug/ml), and 5 (0.4%) showed intermediate resistance (0.094-0.75 &mug/ml). Of 34 samples analyzed for gyrA and parC mutations, all 32 high-level QRNG isolates had mutations in both gyrA and parC. The 2 intermediate QRNG isolates showed no mutations. Within the 32 high-level resistant strains, 2 major groups could be identified: 83% had an MIC > 32 &mug/ml and 17% had an MIC of 3-6 &mug/ml. The two groups were similar in risk, race and age. Zip code analysis was limited by small numbers of patients.

Conclusion:
Molecular resistance testing in GC-infected patients identified all high level QRNG and findings were similar to that found in other city sentinel surveillance studies.

Implications:
Optimizing and integrating real-time high throughput non-culture based molecular assays into clinical care may better define the local epidemiology of resistant organisms and help guide appropriate therapeutic decisions.