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Fluoroquinolone resistance among Neisseria gonorrhoeae isolates from Shanghai, China: Detection of quinolone resistancedetermining region mutations
Reprint requests: Dr Zhou Xiaoming, Department of Epidemiology, Shanghai Public Health Clinical Centre CaoLang Road 2901, Shanghai 201508, P.R. of China e-mail: xmzhou@shmu.edu.cn, ztj1127@yahoo.com.cn
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Received: ,
Abstract
Background & objectives:
Fluoroquinolone has a broad spectrum of antimicrobial activity, and is widely used for gonorrhoea treatment. However, its efficacy can be compromised by the drug-resistance property of Neisseria gonorrhoeae isolates. Most resistant cases of N. gonorrhoeae are associated with mutations in the quinolone-resistance-determining-region (QRDR) within genes of gyrA and parC. This study was undertaken to describe resistance profile of N. gonorrhoeae to fluoroquinolones in Shanghai, P.R. of China, and also associated resistance mutations in gyrA and parC.
Methods:
Eighty N. gonorrhoeae isolates were collected from Shanghai Skin Disease & Sexually Transmitted Disease Hospital or DongFang Hospital during April 2005 to April 2006 in Shanghai, P.R. of China. The minimum inhibitory concentrations (MIC) of fluoroquinolones for these isolates were determined by an agar dilution method. Mutation patterns within gyrA and parC were determined by direct sequencing or by using established restriction fragment length polymorphisms (RFLP) methods.
Results:
Ninety five per cent (76 of 80) of isolates were resistant, 3.75 per cent (3 of 80) intermediate resistant, and 1.25 per cent (1 of 80) were sensitive to fluoroquinolone drug ciprofloxacin. Sequencing and RFLP analysis of gyrA and parC revealed that all resistant isolates had dual mutations of S91F and D95A/G/N in gyrA. Some isolates had an extra mutation within parC either of D86N, S87N or E91A/G. Mutation patterns for gyrA and parC were signifififificantly (P<0.05) associated with MICs level.
Interpretation & conclusions:
Mutations of S91F and D95A/G/N in gyrA combined with S87N in parC was the most prevalent mutation pattern of fluoroquinolone resistant N. gonorrhoeae isolates. This mutation pattern was associated with a high level of quinolone resistance (MIC >16.0 μg/ml) which can serve as a maker for quinolone-resistance prediction in Shanghai, P.R. of China.
