Al Hilali Samer A, Almohana Ali M
Department of Microbiology, College of Medicine, Kufa University, Iraq Najaf Kufa p.o. Box(18), Iraq.
Indian J Med Microbiol. 2011 Oct-Dec;29(4):383-8. doi: 10.4103/0255-0857.90171.
Enteropathogenic Escherichia coli (EPEC) are among the most important pathogens infecting children worldwide and are one of the main causes of diarrhoea. The study was carried out to investigate the occurrence of EPEC as a cause of infectious diarrhoea in children younger than 2 years of age and characterize their virulence genes.
During the study period, a total of 656 faecal specimens from children with diarrhoea and 54 from healthy children were analyzed. E. coli isolates were serotypically identified with EPEC polyvalent and monovalent antisera. The isolated EPEC were examined for the presence of the attaching and effacing (eaeA), bundle-forming pilus (bfpA), Shiga like toxins (stx₁ and stx₂), enterohaemorrhagic E. coli enterohaemolysin (EHEC hlyA) and EPEC adherence factor (EAF) genes by the PCR assay.
The study has shown that 22 (3.4%) had diarrhoea due to EPEC, while no EPEC isolates were detected in asymptomatic children. The highest number of the EPEC isolated belonging to polyvalent 2. The primers encoding virulence genes were subjected to all the EPEC isolates. Only 9.1%, 27.3%, and 9.1% isolates gave positive re sults with intimin (eaeA), bfbA and (EAF) genes, respectively. None of the isolates were positive for stx₁, stx₂, and hlyA genes. Typical EPEC (eaeA⁺, bfpA⁺) was diagnosed in two isolates, while, atypical EPEC was manifested in four isolates.
According to the results, the frequency of EPEC isolates in Najaf was lower than what has been suspected and the investigation including the use of molecular technique and serotyping, are necessary to allow precise identification and epidemiological study of these pathogens.
肠致病性大肠杆菌（EPEC）是全球感染儿童的最重要病原体之一，也是腹泻的主要病因之一。本研究旨在调查2岁以下儿童感染性腹泻中EPEC的发生率，并对其毒力基因进行特征分析。
在研究期间，共分析了656份腹泻儿童的粪便标本和54份健康儿童的粪便标本。使用EPEC多价和单价抗血清对大肠杆菌分离株进行血清型鉴定。通过聚合酶链反应（PCR）检测分离出的EPEC是否存在紧密黏附素（eaeA）、束状菌毛（bfpA）、志贺样毒素（stx₁和stx₂）、肠出血性大肠杆菌溶血素（EHEC hlyA）和EPEC黏附因子（EAF）基因。
研究表明，22例（3.4%）腹泻儿童是由EPEC引起的，而无症状儿童中未检测到EPEC分离株。分离出的EPEC中，多价2型数量最多。对所有EPEC分离株进行编码毒力基因的引物检测。分别只有9.1%、27.3%和9.1%的分离株在紧密黏附素（eaeA）、束状菌毛（bfpA）和（EAF）基因检测中呈阳性结果。所有分离株的stx₁、stx₂和hlyA基因均为阴性。在两株分离株中诊断出典型EPEC（eaeA⁺，bfpA⁺），而在四株分离株中表现为非典型EPEC。
根据结果，纳杰夫EPEC分离株的频率低于预期，包括使用分子技术和血清分型在内的调查对于准确鉴定这些病原体并进行流行病学研究是必要的。
