Shanxi Jinzhong Neisseria Gonorrhoeae In The Sensitivity Of The Four Types Of Antibiotics And Its Molecular Mechanism

Objective:To evaluate the susceptibility of Neisseria gonorrhoeae to four antimicrobial agents in Jinzhong of Shanxi.To analyses the machanisms of ciprofloxacin resistance,penicilin resistance and ceftriaxone resistance among Neisseria gonorrhoeae strains isolated.The role of MtrRCDE efflux system in gonococcal multidrug resistance.Methods:(1)Disk diffusion method was used to test susceptibility of antimicrobial agents including penicillin, tetracycline, ciprofloxacin, ceftriaxone. Thirty N.gonorrhoeae were collected to test the minimum inhibitory concentrations(MICs) of ciprofloxacin and penicillin by E test method.(2)Disk iodum method was used to test PPNG.(3)The penA,ponA,penB.gyrA ,parC genes and the inverted sequence within the mtrR promoter region were amplified by PCR.(4)The amplicons were directly analyzed by DNA sequencing.Results:(1)The positivity rates of resistant isolates to penicillin, tetracycline, ciprofloxacin, ceftriaxone were93.3%,80.0%,96.7%,0%.Positivity tates of multiple-resistant isolates to four antimicrobial agents were 83.3%.(2)There were 13β-lactamase negative srains and 15β-lactamase masculine starins within 28 penicilin-resistant starains.(3)There were no mutation in mosaic of penA gene within 15β-lactamase masculine and peniciline resistance strains.But there was A/T mutation in mtrR and Gly-101-Asp,Ala-102-Asp in penB.(4)We found a clinical isolate of Neisseria gonorrhoeae with reduced ceftriaxone sesceptibility that shows amultidrug-resistant phenotype.And we found mutation in mtrR,ponA,penB,gyrA and parC gene.(5)29 fluoroquinolone- resistant strains(MIC≥4mg/L) had double-point mutations in gyrA gene and a single or multi-point mutation(s) in parC gene.The most common mutations in parC were Ser-7-Arg and Tyr-104-Tyr.(6)All of the 20 strains which were multiple-resistant had mutations in a 13bp inverted sequence positioned within the mtrR promoter region,and the same mutation exhibited A/T a single base pair deletion in this tegion.Conclusion: (1)Positivity rate of multiple-resistance increases rapidly, and the resistance to ciprofloxacin also increases tapidly. Ceftriaxone should be the first choice in the treatment of gonorrhes at present in Jinzhong of Shanxi.(2)The mutation in penA,ponA and penB was related to penicilin resistance,especially in ponA.(3)Ceftriaxone resistance related with mutation in mtrR,penB,gyrA and parC, but penA.(4)Mutations in gyrA and parC genes play an important role in the development of fluoroquinolone resistance in N.gonorrhoeae.ParC gene was the most important reason of ciprofloxacin in high-level resistance in Neisseria gonorrhoese.(5)The mutation in mtrR was the reason to reduce penicilin,ceftriaxone and fluoroquinolone susceptibility. (6)Simultaneous mutations in fluoroquinolone target enzymes and the MtrRCDE efflux system as a fluoroquinolone-resistant mechanism in N.gonorrhoeae.