Surveillance on antibiotic susceptibility and plasmid-mediated resistance of Neisseria gonorrhoeae in Panyu Guangzhou

Abstract

Objective To monitor the minimum inhibitory concentration (MIC) of 5 antibiotics for Neisseria gonorrhoeae and its plasmid-mediated resistant strains,and to analyze the trend of drug resistant strains penicillinase-producing Neisseria gonorrhoeae (PPNG) and tetracycline-resistant Neisseria gonorrhoeae (TRNG).Methods Four hundred and thirty-six isolates of Neisseria gonorrhoeae were collected from Panyu Institute of Chronic Disease,Guangzhou from 2008 and 2012.The production of β-lactamase was determined by paper acidometric method.The agar dilution method was used to determine the MIC of spectinomycin,cefatriaxone,penicillin,tetracycline and ciprofloxacin.Results Out of 436 isolates,147 (33.72％) were plasmid-mediated PPNG strains and 222(50.92％) were TRNG strains.During the 5-year period,the prevalence of PPNG and TRNG ranged from 24.32％ to 45.59％ and from 21.31％ to 67.57％,with significant differences(x2=11.659,38.464,P all＜0.05).None of the strains were resistant to spectinomycin and ceftriaxone,but the ceftriaxone intermediate rate fluctuated from 26.13％ to 72.13％ with significant differences (x2=39.720,P＜0.01),and their MIC50 and MIC90 were all in the sensitive ranges.However,the MIC50 and MIC90 of penicillin,tetracycline and ciprofloxacin changed greatly,and were significantly higher than resistant standards,with the resistance rates of 76.37％ (333/ 436),88.76％ (387/436) and 94.26％ (411/436),respectively.Conclusions From 2008 to 2012,spectinomycin and ceftriaxone are both sensitive to Neisseria gonorrhoeae,and are recommended as the first-line antibiotics against gonorrhea.The MIC50 and MIC90 of penicillin,tetracycline and ciprofloxacin are unstable and rise above the resistant standards,indicating that it is inappropriate to use them as the first-line antibiotics in treatment of gonorrhea. Key words: Neisseria gonorrhoeae; Microbial sensitivity tests; Drug monitoring