沙门菌监测点汤卜逊沙门菌分离株的分子分型和耐药性分析

Analysis on molecular typing of Salmonella thompson isolates and its drug resistance in Salmonella surveillance sites

目的应用分子分型技术对2007年上海和重庆市沙门菌监测点的50株汤卜逊沙门菌进行分子流行病学分析和抗生素敏感性测定,了解上海和重庆两地菌株的分子分型特征和药物敏感性特征。方法抗生素敏感性测定采用微量肉汤稀释法,分子分型方法包括脉冲场凝胶电泳(PFGE)和多位点串联重复序列分析(MLVA)。结果药敏试验显示78%的菌株存在多重耐药,其中磺胺甲恶唑和四环素的耐药率最高,其次是甲氧苄胺嘧啶;对头孢类抗生素(头孢噻肟、头孢三嗪、头孢他啶、头孢噻呋)均未产生耐药性。PFGE将50株菌分为15个带型,30株重庆分离株间有较高的相似性;MLVA分析显示除Sal16位点外,其余检测位点在所有待检菌株中没有差别。结论分子分型支持汤卜逊沙门菌引起的暴发以及散发。目前MLVA分型应用于汤卜逊沙门菌分子分型时,分型能力低于PFGE,需要进一步优化。

Objective To conduct molecular epidemiological analysis with molecular typing and drug susceptibility test to 50 strains of Salmonella thompson isolated in Chongqing and Shanghai. Methods The drug susceptibility test to 14 antibiotics was performed by mini broth dilution method. Molecular typing methods include pulsed field gel electrophoresis （PFGE） and multi-locus variable-number tandem repeat （VNTR） analysis （MLVA）. Results The results of drug susceptibility test indicated that 78% of the isolates were multidrug resistant. The most resistant antibiotics were sulfamethazole and tetracycline, followed by trimethoprim. All isolates were sensitive to cephalosporins （cefotaxime, ceftriaxone, ceftazidime and ceftiofur）. 15 PFGE patterns were identified in 50 isolates and 30 isolates from Chongqing were highly homologous. MLVA analysis shows that there were no variations at tested loci except for Sall6 loci. Conclusion The molecular typing analysis supported Salmonella thompson had caused outbreaks and sporadic cases. MLVA is less effective in subtyping Salmonella thompson than PFGE, which needs to be improved.