空肠弯曲菌喹诺酮类抗生素敏感性检测及其耐药机理分析

Antibiotics susceptibility and genetic characteristics analysis for quinolone resistant Campylobacter jejuni isolated from China

目的了解我国不同宿主来源空肠弯曲菌对喹诺酮及氟喹诺酮类抗生素的耐药现状,分析耐药菌株的耐药机制。方法利用96孔琼脂稀释法分析不同来源空肠弯曲菌对萘啶酸、环丙沙星两种抗生素的最小抑菌浓度(MIC)。对102株检测耐药的菌株和27株敏感菌株通过基因测序的方法分析其耐药机制。结果234株空肠弯曲菌中共筛查到218株(93.16%)萘啶酸耐药菌株,其中鸡粪和鸭粪来源菌株耐药率均为100.00%,腹泻病人粪便来源菌株耐药率是97.96%,食品动物来源菌株耐药率是97.83%,牛粪来源菌株耐药率是77.97%,耐药率差异有统计学意义(P<0.05),鸡粪和鸭粪来源菌株耐药率最高;211株(90.17%)环丙沙星耐药菌株,其中鸡粪和鸭粪来源菌株耐药率均为100%,腹泻病人粪便来源菌株耐药率是91.84%,食品动物来源菌株耐药率是95.65%,牛粪来源菌株耐药率是77.97%,耐药率差异有统计学意义(P<0.05),鸡粪和鸭粪来源菌株耐药率最高。所有的耐药菌株gyrA基因的喹诺酮类耐药决定区(QRDR)都存在Thr-86-Ile点突变。gyrB基因相关区域测序显示不存在有意义突变。结论我国分离空肠弯曲菌菌株对萘啶酸、环丙沙星耐药严重,gyrA基因QRDR内的Thr-86-Ile突变能引起空肠弯曲菌对喹诺酮类及氟喹诺酮类抗生素高水平耐药。

According to CLSI,agar dilution method was used to analyze the minimum inhibitory concentrations(MIC)of the nalidixic acid and ciprofloxacin for the isolates from different sources.Mutations in the quinolone resistant determining region(QRDR)of gyrA and gyrB were examined by DNA sequencing of 102 resistant C.jejuni isolates and 27 sensitive isolates.The results showed that 218 isolates(93.16%)were resistant to nalidixic acid among the entire tested 234 isolates.Among these,the resistant rates of the isolates from chicken feaces,duck feaces,human feaces,food animal and cow feaces were 100.00%,100.00%,97.96%,97.83%and 77.97%,respectively.The 211 isolates(90.17%)were resistant to ciprofloxacin.Among these,the resistant rates of the isolates from chicken feaces,duck feaces,human feaces,food animal and cow feaces were 100.00%,100.00%,91.84%,95.65%and 77.97%,respectively.The differences were both statistically significant.All of the resistant isolates on the QRDR of gyrA had Thr-86-Ile mutation.However,the point substitutions in gyrB gene were synonymous mutations.The results indicated that the C.jejuni isolates in this study showed highly resistant to nalidixic acid and ciprofloxacin.The Thr-86-Ile mutation on the QRDR of gyrA can cause highly resistant to quinolone and fluoroquinolone for C.jejuni.