2021年西安市食源性腹泻患者致泻大肠埃希菌耐药性及分子分型

目的 了解2021年西安市食源性腹泻患者致泻大肠埃希菌（DEC）的感染状况、致病型分布、耐药性及分子分型特征。方法 收集西安市5家哨点医院腹泻患者粪便标本，进行DEC分离和PCR毒力基因分型鉴定，采用微量肉汤稀释法和脉冲场凝胶电泳（PFGE）对分离株进行药敏试验和分子分型，结果采用SPSS 19.0软件进行统计学分析。结果 389份粪便标本检出DEC阳性40份，阳性检出率为10.28%（40/389）。共分离到41株DEC，以肠产毒性大肠埃希菌（ETEC）和肠集聚性大肠埃希菌（EAEC）为主，分别占41.46%（17/41）和39.02%（16/41）。ETEC以estIa/estIb基因型为主（70.59%，12/17），EAEC以astA/pic基因型为主（87.50%，14/16）。40株菌（97.56%，40/41）对至少1种抗生素耐药，对氨苄西林、四环素、头孢噻肟和萘啶酸耐药率均超过50%，多重耐药率为56.10%（23/41）。41株DEC聚类分析得到40种带型，相似度为62.0%~100.0%。结论 2021年西安市食源性腹泻患者中DEC检出率较高，主要致病型为ETEC和EAEC，PFGE带型较为分散，菌株耐药及多重耐药现象比较严重。

Antimicrobial resistance and molecular typing of diarrheagenic Escherichia coli among patients with foodborne diarrhea in Xi’an City in 2021

Objective To investigate the infection status， pathogenic types， antimicrobial resistance and molecular typing of diarrheagenic Escherichia coli （DEC） isolated from patients with foodborne diarrhea in Xi’an City in 2021.Methods Fecal samples from patients with diarrhea were collected from 5 sentinel hospitals for DEC isolation and the pathogenic types of DEC were confirmed via PCR to detect virulence genes. Antimicrobial susceptibility testing and molecular typing were performed using the broth microdilution method and pulsed field gel electrophoresis （PFGE）. The results were statistically analyzed using SPSS software 19.0.Results Among the 389 fecal samples collected from patients with diarrhea， 40 were DEC-positive， with a positivity rate of 10.28%. A total of 41 DEC strains were identified in this study. Enterotoxigenic E. coli （ETEC） and enteroaggregative E. coli （EAEC） were predominant， accounting for 41.46% （17/41） and 39.02% （16/41） of cases， respectively. The gene types estIa/estIb （70.59%， 12/17） and astA/pic （87.50 %， 14/16） were dominant in ETEC and EAEC， respectively. Forty strains （97.56%， 40/41） were resistant to at least one antibiotic， and the resistance rates to ampicillin， tetracycline， cefotaxime， and nalidixic acid were greater than 50%. The multidrug resistance rate was 56.10% （23/41）. Cluster analysis revealed 40 PFGE patterns from the 41 DEC strains. The similarity of these patterns was 62.0%-100.0%.Conclusion The detection rate of DEC in patients with foodborne diarrhea in Xi’an City in 2021 was relatively high， with the major pathotypes being ETEC and EAEC. The PFGE patterns of the strains were diverse. Finally， the antimicrobial and multidrug resistance of the strains was relatively severe.