Objective: To explore mechanisms of resistance to ciprofloxacin in Neisseria gonorrhoea(NG). Methods: A total of 102 isolates were collected

antibiotic susceptibility tests performed

accumulation of ciprofloxacin in isolates of NG was determined and gyrA and parC gene were amplified by PCR. The PCR products were assayed by SSCP. The PCR product which had the most common mutation was directly sequenced. Results: 72.5% were resistant to ciprofloxacin

20.6% showed reduced susceptibility

6.9% were susceptible and average accumulation of ciprofloxacin in the susceptible isolates was about 6ng/mg. However

in reduced-susceptiblity and rsistance isolates it was about 3ng/mg and 0.6ng/mg respectively. SSCP profiles revealed that the point mutations in gyrA gene occurred in all of isolates of reduced susceptibility and resistance

mutations (Ser-91→→Phe

Asp-95Asn) were most common

but the mutation points in parC gene only existed in the isolates which μ→→showed MIC 0.5g/ml. Double-point mutations(Ser-87Arg

Cys-104Tyr) were most common. Conclusion: The mechanisms of resistance to ciprofloxacin in NG were mainly involved in alteration of target molecules(GyrA and ParC) and resistance of membrane

and DNA gyrase was the main target molecule of ciprofloxacin

while the mutations in ParC were associated with high-level resistance to Ciprofloxacin quionolone.