Study Of Ciprofloxacin Resistance And Mutations In ParC Genes In Clinical Isolates Of Neisseria Gonorrhoeae In Zibo Region

Objective To investigate the occurrence of ciprofloxacin resistance among Neisseria gonorrhoeae strains in Zibo region during 2003 to 2004 and determine the frequency and patterns of mutations in parC gene in the high-level ciprofloxacin resistance isolates, and to provide a fast and valid method for detecting drug-resistance in Neisseria gonorrhoeae.Methods A total of 51 gonococcal isolates were collected in Zibo region for Neisseria gonorrhoeae. The the minimal inhibitory concentrations(MICs ) of ciprofloxacin were detected by agar dilution method primers coding for parC gene were designed by DNA Star softwarewe and the gene fragment was amplified by PCR. Mutations in parC genes in 30 ciprofloxacin-resistant strains(MICs 4-32μg/ml) and 3 ciprofloxacin-sensitive strains(MICs<1.0μg/ml) in Zibo region were identified by direct sequencing of the amplified products for possible mutations. Results In the 51 clinical isolates, only 6(11.76%) were found to be susceptible to ciprofloxacin (MIC <1.0μg/ml), the whole resistance rate was 88.24%. In 24 success sequenced ciprofloxacin-resistant strains (MICs ranging from 4 to 32μg/ml) , the mutations had amino acid substitutions of Asp→Asn, Ser→Asn, Ser→Pro, Glu→Lys at codon 86,87,88,91 of parC respectively. The most common parC alteration, Asp-86 to Asn was found in 19 strains (79.17%).Conclusion The resistants trains of Neisseria gonorrhoeae to ciprofloxacin in Zibo region were serious, Mutations in high-level ciprofloxacin resistance strains were diversity . PCR and direct DNA sequencing appears to be a promising method for the rapid detection of mutations in parC gene, making up the deficiency of routine drug-susceptive tests.