Study On The Genes Of Ciprofloxacin-resistance In Neissria Gonorrhoeae Epidemic Strains In LinFen Region

Objective To investigate the occurrence of ciprofloxacin(cip) resistance among Neisseria gonorrhoeae strains in Linfen region in 2006 and determine the frequency and patterns of mutations in gyrA gene in the ciprofloxacin resistance isolates, and to provide a fast and valid method for detecting drug-resistance in Neisseria gonorrhoeae.Methods A total of 33 gonococcal isolates were collected in Linfen region for Neisseria gonorrhoeae. In vitro, susceptibility tests of ciprofloxacin were performed in 33 isolates , gyrA gene were amplified by polymase chain reaction(PCR)assay and the PCR products were directly sequenced in order to see if there were mutations in gyrA gene.Results The 33 clinical isolates demonstrated 100% resistance to ciprofloxacin. The gyrA gene containing quinolone resistance-determining region (QRDR)were amplified by PCR in all clinical isolates. The mutations had amino acid substitutions of Ser to Phe at codon 91(33 strains),and Asp to Gly,Asn,Ala at codon 95 of gyrA respectively. The most common gyrA alteration at codon95, Asp-95 to Gly was found in 19 strains (63.3 %).Conclusion The resistants trains of Neisseria gonorrhoeae to ciprofloxacin in Linfen region were serious, and ciprofloxacin treatment for the treatment of NG infections in Linfen Region should not be recommended. The results from this study suggested that mutations in gyrA gene play an important role in the development of fluoroquinolone resistance in Neisseria gonorrhoeae. Mutations in gyrA gene at 95 codon were diversity .PCR and direct DNA sequencing appears to be a promising method for the rapid detection of mutations in gyrA gene, making up the deficiency of routine drug-susceptive tests.