伤寒沙门菌多重耐药主动外排系统基因检测与序列分析

Multiple-antibiotic-resistant active efflux system gene identification and sequential analysis of Salmonella typhi

目的 :以聚合酶链反应 (PCR)检测伤寒沙门菌敏感株 2 75及其第 2代诱导耐药菌OM 2、182acrB主动外排基因并分析序列。方法 :参考伤寒沙门菌基因库序列 (No .AL6 2 72 6 7)设计引物 ,对伤寒沙门菌 2 75、OM 2、182PCR扩增acrB基因 ,以证实acrAB外排系统的存在 ,并对 3株伤寒沙门菌扩增所得的acrB测序并分析其序列。结果 :伤寒沙门菌 2 75、OM 2、182PCR均扩增出 4 4 9bp的产物带 ,序列分析示伤寒沙门菌 2 75、OM 2仅 2处碱基与参考序列不同 (同源性 99.5 5 % ) ,推定编码的氨基酸相同 (同源性 10 0 % ) ,伤寒沙门菌 182除 2处碱基不同外 ,另有 2处存在碱基插入 ,因其序列已被打乱 ,无法进行氨基酸推测。结论 :伤寒沙门菌存在主动外排系统 ,是产生高水平耐药及多重耐药的基础。

Objective: To detect by PCR and sequence the multiple antibiotic resistant efflux acrB gene in Salmonella typhi 275(a clinically isolated strain) and its induced resistant mutant OM2(RG1),182(RG2). Methods: The acrB gene of Salmonella typhi 275,OM2 and 182 were identified by PCR with the primers designed from Genebank(No. AL627267) and the DNA fragments were sequenced to confirm the existence of acrAB gene. Results: All the 3 strains ( Salmonella typhi 275,OM2 and 182) were acrB gene positive with 449 bp by PCR. Comparing with sequence of Salmonella typhi in the Genebank there were just 2 senseless base mutations in Salmonella typhi 275 and OM2 acrB (99.55% identity), 100% identity with the same amino acids. There were 2 bases insertation and 2 bases senseless mutation in Salmonella typhi 182 with no amino acids analysis because of the confused sequence. Conclusion: Multiple antibiotic resistant active efflux system exist in Salmonella typhi which is the bases of high level resistance and multiple antibiotic resistantce.