河南省人源产ESBLs鼠伤寒沙门菌单相变异株的分子特征研究

目的 分析河南省腹泻病例粪便标本中产超广谱β内酰胺酶(ESBLs) 的鼠伤寒沙门菌单相变异株耐药情况,并研究其分子学特征。方法 对河南省腹泻粪便中分离的124株鼠伤寒沙门菌单相变异株沙门菌,通过肉汤稀释法进行抗生素敏感性试验并筛选产ESBLs菌株;PCR方法检测β-内酰胺酶编码基因携带情况,采用质粒接合试验分析耐药基因的水平转移情况,应用脉冲场凝胶电泳(PFGE)进行亲缘关系分析。结果 124株鼠伤寒沙门菌单相变异株沙门菌耐药严重,其中有16株为产ESBLs菌株。16株产ESBLs菌株均携带CTX-M型耐药基因,并检测出OXA型和TEM型耐药基因;其中9株菌可将CTX-M基因通过质粒转移到大肠埃希菌J53,药敏分析发现其他抗生素的耐药性可以发生共转移。16株产ESBLs 鼠伤寒沙门菌单相变异株沙门菌经XbaⅠ酶切后共分为14种带型,无明显的优势带型。结论 检出产ESBLs 的鼠伤寒沙门菌单相变异株沙门菌基因型具有多样性,耐药基因可通过接合性质粒在不同菌属间播散。

Molecular characteristics of extended spectrum β-lactamase producing monophasic Salmonella Typhimurium isolated from humans in Henan Province

We investigated the resistance of monophasic Salmonella Typhimurium producing extended spectrum β-lactamase in the feces from people with diarrhea in Henan Province, and studied its molecular characteristics. A total of 124 strains of monophasic Salmonella Typhimurium isolated from the fecal samples were tested for antimicrobial susceptibility through the broth dilution method, and ESBL producing strains were screened. PCR was used to detect carriers of β-lactamase encoding genes. Plasmid transfer tests were used to analyze the transfer of drug-resistance genes, and pulse field gel electrophoresis was used to analyze the genetic relationships. A total of 16 strains were confirmed as ESBL producing strains in the 124 monophasic Salmonella Typhimurium strains. The 16 isolates all carried different types of CTX-M gene drug resistance, and some carried OXA type and TEM type resistance genes. The CTX-M gene of nine strains was transferred to E. coli J53 through plasmids, and drug sensitivity analysis indicated that resistance to other antibiotics was co-transferred. After XbaⅠ digestion, the 16 strains of ESBL producing Salmonella were divided into 14 bands, and no dominant type was identified. The results demonstrated that the genotypes of ESBL producing strains are diverse, and the resistance genes can be disseminated among different bacteria through conjugated plasmids.