腹泻病人中志贺菌的耐药性和Ⅱ类整合子

Drug resistance and class 2 integron in Shigella from patients with acute diarrhea

目的:研究志贺菌的耐药表型、携带的耐药基因及整合子的流行现状。方法:对2008年-2009年从闵行区腹泻病患者大便标本分离的63株志贺菌,用KB法测定其对9种抗生素的药物敏感情况;PCR筛查整合子种类;长片段扩增Ⅱ类整合子可变区并测序。结果:63株志贺菌均表现出明显的多重耐药和交叉耐药现象,福氏志贺菌对复方新诺明、氨苄青霉素、四环素和萘啶酸的耐药率达90%以上。宋内氏志贺菌对复方新诺明和四环素的耐药率达85%以上。92.1%(58/63)的志贺菌中检出II类整合子,未检出I类整合子。58株II类整合子保守区阳性的标本,可变区扩增亦全部阳性,大小约3 kb～4 kb之间。测序结果显示耐药菌株含有编码对磺胺类抗生素耐药的基因dfrA1、对链丝菌素耐药的基因sat1和对氨基糖甙类抗生素耐药的基因aadA1。结论:多重耐药和交叉耐药在志贺菌中广泛存在;耐药志贺菌携带II类整合子,II类整合子与耐药表型之间存在一定关联。

Objective： To study the drug resistance phenotype,drug resistance gene and integrons of Shigella isolated from patients with diarrhea.Methods：Sixty three strains of Shigella were isolated from stools of diarrhea patients between 2008 and 2009 in Minhang district.The KB method was used to determine the susceptibility of Shigella to Ampicillin（AMP 10 μg）,Amoxicillin（AMC 10μg）,Cephalothin（KF30 μg）,Cefotaxime（CTX30 μg）,Tetracycline（TE30 μg）,Nalidixic acid（NA 30 μg）,Trimethoprim-sulfamethoxazole（SXT25 μg）,Ciprofloxacin（CIP 5μg） and Gentamicin（GN 10μg）.PCR was used for screening integrons and sequence were analyzed for class 2 integrons.Results：All the 63 strains showed obvious multi-drug and cross resistance to the antibiotics available in the study.In addition,the resistance of S.flexneri to Trimethoprim-sulfamethoxazole,ampicillin,Nalidixic acid and Tetracycline accounted for more than 90%.The drug resistance of Shigella sonnei to Trimethoprim-sulfamethoxazole and Tetracycline reached above 85%.Class 2 Integrons were present in 92.1% of isolates.Class 1 was not observed in any isolate.Sequence analysis showed dfrA1-sat1-aadA1 gene cassettes were present in drug-resistant strains.Conclusion：Multi-drug and cross resistance to the antibiotics of Shigella occurred most of the isolated strains.Correlation existed between Class 2 integrons and resistance patterns.