Comparative In Vitro Activity of Sita(cid:976)loxacin Against Neisseria gonorrhoeae Isolated from Thai Patients
Visanu Thamlikitkul MD1, Chakkraphong Seenama BSc1, Surapee Tiengrim MSc2
Affiliation : 1 Division of Infectious Diseases and Tropical Medicine, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand 2 Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
Objective : To investigate the in vitro activity of sita(cid:976)loxacin compared to that of ceftriaxone, ce(cid:976)ixime, and cipro(cid:976)loxacin against
Neisseria gonorrhoeae isolated from Thai patients.
Materials and Methods : Antimicrobial susceptibility testing of ceftriaxone, ce(cid:976)ixime, cipro(cid:976)loxacin, and sita(cid:976)loxacin in 52 strains
of N. gonorrhoeae isolated from Thai patients was performed by disk diffusion method and agar dilution method to determine the
inhibition zone diameters and minimum inhibitory concentrations [MICs] of ceftriaxone, ce(cid:976)ixime, cipro(cid:976)loxacin, and sita(cid:976)loxacin.
Results : All N. gonorrhoeae isolates were susceptible to ceftriaxone (MIC ≤0.025 mg/L, zone diameter ≥35 mm) and ce(cid:976)ixime
(MIC ≤0.025 mg/l, zone diameter ≥31 mm). All N. gonorrhoeae study isolates were resistant to cipro(cid:976)loxacin (MIC ≥1 mg/l, zone
diameter ≤27 mm). The inhibition zone diameters of sita(cid:976)loxacin against N. gonorrhoeae study isolates were 41 mm or more
in 35 isolates (67%), and ranged from 28 to 40 mm in 17 isolates (33%). When the interpretative inhibition zone diameter of
resistance to cipro(cid:976)loxacin (27 mm or less) was applied to sita(cid:976)loxacin, no N. gonorrhoeae study isolates were considered resistant
to sita(cid:976)loxacin. The MIC50 and MIC90 of sita(cid:976)loxacin against N. gonorrhoeae study isolates was 0.06 and 0.12 mg/L, respectively.
When the interpretative MIC of cipro(cid:976)loxacin resistance (more than 1 mg/L) was applied to sita(cid:976)loxacin, no N. gonorrhoeae study
isolates were considered resistant to sita(cid:976)loxacin.
Conclusion : Sita(cid:976)loxacin is active against cipro(cid:976)loxacin-resistant N. gonorrhoeae. A clinical study in sita(cid:976)loxacin therapy to treat
gonococcal urethritis caused by cipro(cid:976)loxacin-resistant N. gonorrhoeae should be considered.
Keywords : In Vitro Activity, Neisseria gonorrhoeae, Sita(cid:976)loxacin, Fluoroquinolone
