The occurrence of atypical enteropathogenic Escherichia coli strains among children with diarrhea in Iran
The occurrence of atypical enteropathogenic Escherichia coli strains among children with diarrhea in Iran
复制标题
DOI：
10.1007/s10156-012-0526-0
复制
发表时间：
2013-08-01
影响因子：
2.2
通讯作者：
Pourshafie, Mohammad R.
中科院分区：
文献类型：
--
作者：
Bakhshi, Bita;Fallahzad, Soheil;Pourshafie, Mohammad R.
本研究的目的是调查典型和非典型肠致病性大肠杆菌（EPEC）菌株分离小于5岁的儿童的遗传多样性和2类整合子含量。对分离的菌株进行生化试验和血清学分型，并对每株菌株进行7种抗菌药物的敏感性试验。通过PCR分析和测序确认EPEC的身份及其2类整合子含量。大肠埃希菌的亚型分析通过脉冲场凝胶电泳（PFGE）分析进行。除庆大霉素外，其余6种抗菌药物均耐药。发现EPEC菌株中最流行的血清群为O 86和O 127血清群（37.7%）以及O 44、O 125和O 128血清群（42.8%）。我们的大多数EPEC分离株（60.7%）被鉴定为非典型。其中4株（14.2%）携带1 500或2 300 bp的2类整合子，分别对应dfrA 1-sat 1和dfrA 1-sat 1-aadA 1抗性基因盒阵列。PFGE分析表明，菌株之间存在广泛的多样性。没有PFGE聚类观察到根据形成菌毛（bfp）细菌，表明PFGE分析不能区分典型和非典型EPEC菌株。耐药菌株的高比例和EPEC分离株之间的大异质性，2类整合子的低患病率，表明需要检查在典型和非典型EPEC人群中赋予耐药性的其他机制。
The aim of this study was to investigate the genetic diversity and class 2 integron content of typical and atypical enteropathogenic Escherichia coli (EPEC) strains isolated from children less than 5 years of age. Biochemical tests and serogrouping were performed for identification of isolated strains, and each isolate was tested for susceptibility to 7 antimicrobial agents. The identity of EPEC and their class 2 integron content was confirmed by PCR analysis and sequencing. Subtyping of Escherichia coli spp. was performed through pulsed-field gel electrophoresis (PFGE) analysis. All EPEC strains were resistant to 6 antimicrobial agents except for gentamycin. The most prevalent serogroups among EPEC strains were found to be members of O86 and O127 serogroups (37.7 %) and O44, O125, and O128 (42.8 %). The majority of our EPEC isolates (60.7 %) were identified as atypical. Among the total 28 isolates, 4 (14.2 %) harbored a class 2 integron 1,500 or 2,300 bp in size, corresponding to dfrA1-sat1 and dfrA1-sat1-aadA1 resistance gene cassette arrays, respectively. PFGE analysis showed an extensive diversity among the isolates. No PFGE clustering was observed according to bundle-forming pilus (bfp) bacteria, suggesting that PFGE analysis could not discriminate between typical and atypical EPEC strains. The high ratio of antibiotic-resistant strains and the large heterogeneity among EPEC isolates with low prevalence of class 2 integrons signify the need to examine for other mechanism(s) involved in conferring resistance in typical and atypical populations of EPEC.