The Relationship Of The GyrA, PraC And MtrCDE Gene Of Neisseria Gonorrhoeae With Drug Resistance

604 strains of Neisseria gonorrhoeae which have been separated in three cities of china, changchun, zhanjiang and xi'an, from 1993 to 2001. The following phenotypes have been researched, there are antimicriobia resistance, plamid profile, auxiotype, PEN/TET resistance and 3 -lactamase.We have assayed minimal inhibitory concentration (MIC) of 8 antibiotics to these strains using agar dilution method. Plasmid profile of drug resistant strains was determined by extraction of plasmid and agarose gel electrophoresis. The frequency and patterns of mutations within the gyrA and praC genes were investigated part of resistant strains were appraised through PCR methods. Drug resistant correlation was analyzed using linear correlation and regression analysis, t test and X2 test. Results shows that of all the 604 strains, 6 strains (1.0%) are classified into PPNG strain and 116 strains (19.2%) belong to PP/TRNG . Of the three most useful quinolone kind drugs, cinrofloxacin has the best effect, 62% (417/604) separated strains are sensitive to it. 13.2% (80/604) separated strains are resistant to actinospectacin. 13.4% (81/604) separated strains show decrease of sensitivity to ceftriazone and 2.2% (13/604) strains are totally resistant to it.Tolerance correlation analysis demonstrates that cinrofloxacin, ofloxacin and norfloxacin are positively correlate to drug tolerance (r=0.9,P<0.05). In PPNG strains, penicillin and economycin are negatively correlated to drug tolerance (r=0.6 P<0.05). Ceftriaxone and Azithromycin are negatively correlated to drug resistance, either (r=0.6, P <0.05). Drug resistance analysis in different areas show that sensitivity of quinolone kinds of drugs in Zhanjiang is lower than that of north China(Xi'an and Changchun) (P<0.05). Drug resistance ratio checked out in Xi'an area is higher than that in Chuangchun and Zhanjing). Sensitivity to other kinds of drugs has no obvious difference. We also have analyzed the relationship between drug resistance and plamid profile, auxotype, phenotype of PEN/TET drug resistance and P -lactamase. We suggest that Many kinds of extensively used drugs before are no longer suitable to the treatment of gonorrhea. Much attention should be paid to the appearance of drug resistant strains to Ceftriaxone, Actinospectacin and Azithromycin.in order to investigate gyrA,praC gene of Neisseria gonorrhoeae in relation to acquired resistance, 76 QRNG strains that have high level CIP resistance are selected.selected 18 N. gonorrhoeae strains were investigated for the frequency and patterns of mutations within the gyrA and praC genes. To identify mutations in the gyrA and praC genes of the gonococcal mutants, the quinolone resistance determining regions of the gyrA and praC genes were amplified by polymerase chain reaction (PCR) and the PCR products were directly sequenced. The strains were analyzed for genetic relationship by pulsed-field gel electrophoresis (PFGE) and Nhel enzyme digest. The result shows that only 2 strains in the controlled 18 sensitive strains have single gyrA mutation. There is no praC mutation. But in drug resistancegroup, 89%(16/18) strains developed single mutation from Ser-91 to Phe or double mutation including praC. gyrA in 88.9% (15) strains have mutation from Ser-91 to Phe and Asp-95 to Gly. 72% praC mutations are from Asp-86 to Asn. The strains were analyzed for genetic relationship by pulsed-field gel electrophoresis (PFGE). PFEG analysis shows that ten strains have the same mutation pattern in the gyrA and praC genes, and the PFEG fingerprint maps in the strains from different areas are different. Results from this study suggest that gyrA mutations plus a praC mutation(s) play an important role in the development of high-level fluoroquinolone resistance in N. gonorrhoeae .Resistance of NG to erythromycin and Triton X-100 is due to overexpression of the mtrCDE-encoded efflux pump mediated by mtrR gene, which encodes a transcriptional represser that modulates expression of the mtrCDE operon. Accordingly, we questioned whether clinical...