Background The continuing spread of drug-resistant gonococci has posed a challenge for successful treatment worldwide. Recently third-generation cephalosporins-resistant strains were isolated in Japan. Guangdong Province in South China has one of the highest gonococcal resistance rates in China and a large number of international migrants. We investigated the invitro antimicrobial susceptibility and genotypes of N gonorrhoeae strains isolated in Guangzhou, the capital city, from 2001 to 2009.
Methods MICs to penicillin, ceftriaxone, tetracycline, ciprofloxacin, and spectinomycin were determined by agar plate dilution and susceptibilities were interpreted according to WHO standards. ß-lactamase production was determined by paper acidometric testing. The resistant plasmids were determined for penicillinase-producing N gonorrhoeae (PPNG) and high-level tetracycline resistant N gonorrhoeae (TRNG) by PCR and the isolates were genotyped.
Results Of 1132 consecutive gonococci isolated from 2001 to 2009, no ceftriaxone and spectinomycin resistant strains were found, but the prevalence of strains less susceptible to ceftriaxone rose from 18.2% to 38.5%. The MIC90 for ceftriaxone showed intermediate sensitivity (0.06–0.125 μg/ml) and spectinomycin near the resistant level (16–32 μg/ml). The resistance to penicillin, tetracycline and ciprofloxacin increased from 81.8%, 84.5% and 72.5% in 2001 to 90.1%, 91.4% and 98.7% in 2009, respectively. A total of 313 (27.7%) PPNG and 486 (42.9%) TRNG strains were detected. 206 (18.2%) strains were both PPNG and TRNG. PPNG rose from 21.8% to 29.8% and TRNG rapidly increased from 27.2% to 56.3%. Genotyping TEM-1 gene showed 267 (99.6%) PPNGs in 2001–2008 carried the Asian-type ß-lactamase plasmids and one African-type in 2008. Genotyping of tetM gene showed that all 486 TRNGs were Dutch variants.
Conclusion Gonorrhoea resistance continues to be a major public health problem in Guangzhou. The emergence of an African gonorrhoea resistance variant may be related to the large African diaspora in Guangzhou, migration of Chinese to Africa, or other migration patterns. More research is needed to determine what practices, systems, and behaviours contribute to escalating resistance patterns.
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