Comparative In Vitro Activity of Ciprofloxacin and Sitafloxacin Against Neisseria gonorrheae

BACKGROUND: Most of Neisseria gonorrhoeae strains isolated from Thai patients are resistant to ciprofloxacin and ciprofloxacin is no longer recommended for therapy of gonococcal infection in Thailand. Sitafloxacin is a new generation of fluoroquinolones that contains in vitro activities against many bacteria that are resistant to ciprofloxacin. Sitafloxacin has a high concentration in urine. The objective of the study was to determine in vitro activity of sitafloxacin against ciprofloxacin-resistant N.gonorrheae. METHODS: Antimicrobial susceptibility tests for 52 strains of Neisseria gonorrhoeae isolated from patients attended Bangrak Hospital in Bangkok were performed. The tested antibiotics were ceftriaxone, cefixime, ciprofloxacin, and sitafloxacin. The minimum inhibitory concentrations (MICs) and inhibition zone diameters were determined by standard agar dilution and disk diffusion method, respectively, according to the Clinical and Laboratory Standards Institute (CLSI) 2013. RESULTS: All 52 N.gonorrheae isolates were susceptible to ceftriaxone (MIC < 0.025 mg/l, zone diameter > 35mm) and cefixime (MIC < 0.025 mg/l, zone diameter > 31mm). All N. gonorrheae isolates were resistant to ciprofloxacin (MIC > 1 mg/l, zone diameter < 27 mm). The inhibition zone diameters of sitafloxacin (5 microgram disk) against 52 isolates of N. gonorrhoeae were > 41 mm in 35 isolates (67%) and between 28 and 40 mm in 17 isolates (33%). If the cut-off value of inhibition zone diameter of resistance to ciprofloxacin (<27 mm) is applied, no isolates of N. gonorrheae is considered to be resistant to sitafloxacin. CONCLUSION: Sitafloxacin seems to be active against ciprofloxacin-resistant N. gonorrheae. A clinical study on therapy of gonococcal urethritis due to ciprofloxacin-resistant N. gonorrheae should be considered. DISCLOSURES: All authors: No reported disclosures.