Beutin Lothar, Marchés Olivier, Bettelheim Karl A, Gleier Kerstin, Zimmermann Sonja, Schmidt Herbert, Oswald Eric
Division of Emerging Bacterial Pathogens, Department of Biological Safety, Robert Koch Institute, 13353 Berlin, Germany.
Infect Immun. 2003 Jul;71(7):3995-4002. doi: 10.1128/IAI.71.7.3995-4002.2003.
Fecal samples from healthy children under 2 years of age living in Berlin, Germany (205 infants), and Melbourne, Australia (184 infants), were investigated for the presence of attaching and effacing (AE) Escherichia coli (AEEC) strains by screening for eae (intimin) genes. Twenty-seven AEEC strains were isolated from 14 children (7.6%) from Melbourne and from 12 children (5.9%) from Berlin. The 27 AEEC strains were classified as enterohemorrhagic E. coli (one strain, producing Shiga toxin 1), typical enteropathogenic E. coli (EPEC) (one strain carrying an EPEC adherence factor [EAF] plasmid), and atypical EPEC (25 strains negative for Shiga toxins and EAF plasmids). The AEEC were divided into 18 different serotypes, O-nontypeable and O-rough strains. Typing of their intimin genes revealed the presence of intimin alpha in 6 strains, intimin beta in 11 strains, intimin gamma in 7 strains, intimin zeta in 2 strains, and intimin eta in one strain. Analysis of HEp-2 cell adherence showed diffuse adherence or localized adherence-like patterns in 26 AEEC strains; local adherence was found only with the EAF-positive strain. Ten AEEC strains showed an AE property with the fluorescent actin staining (FAS) test. The introduction of an EAF plasmid (pMAR7) converted 11 FAS-negative AEEC strains to FAS positive and increased the FAS reaction in six FAS-positive AEEC strains, indicating that the genes needed for the AE phenotype were functional in these strains. Our finding indicates that atypical EPEC strains could play a double role as strains that naturally immunize against intimin in humans and as reservoirs for new emerging human pathogenic EPEC strains.
对居住在德国柏林(205名婴儿)和澳大利亚墨尔本(184名婴儿)的2岁以下健康儿童的粪便样本进行了调查,通过筛查eae(紧密素)基因来检测是否存在黏附性和脱屑性(AE)大肠杆菌(AEEC)菌株。从墨尔本的14名儿童(7.6%)和柏林的12名儿童(5.9%)中分离出27株AEEC菌株。这27株AEEC菌株被分类为肠出血性大肠杆菌(1株,产生志贺毒素1)、典型肠致病性大肠杆菌(EPEC)(1株携带EPEC黏附因子[EAF]质粒)和非典型EPEC(25株志贺毒素和EAF质粒均为阴性)。AEEC被分为18种不同的血清型、O-不可分型和O-粗糙型菌株。对其紧密素基因进行分型显示,6株中有紧密素α,11株中有紧密素β,7株中有紧密素γ,2株中有紧密素ζ,1株中有紧密素η。对HEp-2细胞黏附的分析显示,26株AEEC菌株呈现弥漫性黏附或局部黏附样模式;仅在EAF阳性菌株中发现局部黏附。10株AEEC菌株在荧光肌动蛋白染色(FAS)试验中表现出AE特性。引入EAF质粒(pMAR7)使11株FAS阴性的AEEC菌株转变为FAS阳性,并增强了6株FAS阳性AEEC菌株的FAS反应,表明AE表型所需的基因在这些菌株中具有功能。我们的发现表明,非典型EPEC菌株可能发挥双重作用,既是人类中针对紧密素天然免疫的菌株,又是新出现的人类致病性EPEC菌株的储存库。