Regua-Mangia Adriana H, Gomes Tânia A T, Vieira Mônica A M, Irino Kinue, Teixeira Lúcia M
Departamento de Ciências Biológicas, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil.
Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil.
J Med Microbiol. 2009 Apr;58(Pt 4):414-422. doi: 10.1099/jmm.0.006502-0.
Enteroaggregative Escherichia coli (EAEC) strains have been implicated as emerging aetiological agents of diarrhoea worldwide. In the present study, 43 EAEC strains were serotyped and characterized according to random amplification of polymorphic DNA profiles, PFGE, multilocus enzyme electrophoresis (MLEE) and the presence of putative virulence genes (hly, aero, kps, fim, aggA, aafA, aggR, astA, she, aap, shf and pet). The EAEC strains consisted of a diversity of serotypes including eight O-non-typable and 35 O-typable strains arranged into 21 O : H combinations. Amplification of specific genes revealed that all strains carried at least two of the virulence sequences investigated. fim, aggR and aap were the most frequent genes in both groups studied. hly, aero and aggA sequences were more prevalent in the diarrhoeal group. kps occurred exclusively in strains isolated from symptomatic children and showed strong association with diarrhoeal disease. The molecular approaches used to investigate the relatedness among EAEC strains revealed a high degree of polymorphism, suggesting that these micro-organisms have a non-clonal origin. A closer relationship was observed among EAEC strains sharing O : H types. No significant clustering could be identified related to the virulence traits investigated; however, the she locus showed clonal distribution by MLEE typing. These results are in accordance with previous findings in revealing the conservation of particular EAEC factors, despite the high degree of diversity related to both genotypic and phenotypic markers.
肠集聚性大肠杆菌（EAEC）菌株已被认为是全球腹泻新出现的病原体。在本研究中，根据多态性DNA谱的随机扩增、脉冲场凝胶电泳（PFGE）、多位点酶电泳（MLEE）以及假定毒力基因（hly、aero、kps、fim、aggA、aafA、aggR、astA、she、aap、shf和pet）的存在情况，对43株EAEC菌株进行了血清分型和特征分析。EAEC菌株包括多种血清型，其中8株O型不可分型，35株O型可分型菌株，分为21种O:H组合。特定基因的扩增显示，所有菌株至少携带两种所研究的毒力序列。fim、aggR和aap是所研究的两组中最常见的基因。hly、aero和aggA序列在腹泻组中更为普遍。kps仅出现在有症状儿童分离的菌株中，且与腹泻疾病密切相关。用于研究EAEC菌株间相关性的分子方法显示出高度的多态性，表明这些微生物具有非克隆起源。在共享O:H类型的EAEC菌株之间观察到更密切的关系。未发现与所研究的毒力特征相关的明显聚类；然而，she位点通过MLEE分型显示出克隆分布。这些结果与先前的发现一致，即尽管在基因型和表型标记方面存在高度多样性，但特定的EAEC因子具有保守性。
