Huang David B, Mohamed Jamal A, Nataro James P, DuPont Herbert L, Jiang Zhi-Dong, Okhuysen Pablo C
University of Texas at Houston Health Science Center, Division of Infectious Diseases, Houston, TX, USA.
Baylor College of Medicine, Division of Infectious Diseases, Houston, TX, USA.
J Med Microbiol. 2007 Oct;56(Pt 10):1386-1392. doi: 10.1099/jmm.0.47161-0.
Enteroaggregative Escherichia coli (EAEC) is associated with diarrhoea among travellers to developing countries. EAEC virulence properties predisposing to illness are not clear. Sixty-four EAEC strains identified by a HEp-2 cell assay and isolated from faecal samples from US and European travellers to developing countries were studied for the prevalence of 11 putative virulence genes by PCR: 49 EAEC strains from adults with acute diarrhoea and 15 EAEC strains from adults without diarrhoea. E. coli strains from the stools of healthy travellers to the same region were used as controls. EAEC carrying aggR, aap, astA and set1A were identified individually more often in the stools of subjects with diarrhoea compared with those without diarrhoea (P<0.05). EAEC isolates with two or three of these genes were associated with diarrhoea compared with EAEC isolates without the presence of these genes (P<0.05). Subjects with diarrhoea who shed EAEC isolates positive for these genes were more likely than subjects shedding EAEC negative for these genes to pass stools with gross mucus (57 vs 14 %) and faecal leukocytes (40 vs 7 %) (P<0.05). This study shows the heterogeneity of gene profiles of EAEC strains found in the stools of international travellers and suggests that the presence of aggR, aap, astA or set1A, the number of genes present and stool characteristics may be markers for more virulent EAEC strains.
肠集聚性大肠杆菌（EAEC）与前往发展中国家的旅行者腹泻有关。EAEC导致疾病的毒力特性尚不清楚。通过HEp-2细胞试验鉴定并从美国和欧洲前往发展中国家的旅行者粪便样本中分离出的64株EAEC菌株，采用聚合酶链反应（PCR）研究了11个假定毒力基因的流行情况：49株来自急性腹泻成人的EAEC菌株和15株来自无腹泻成人的EAEC菌株。来自前往同一地区的健康旅行者粪便中的大肠杆菌菌株用作对照。与无腹泻者相比，腹泻者粪便中单独携带aggR、aap、astA和set1A的EAEC菌株更为常见（P<0.05）。与未携带这些基因的EAEC分离株相比，携带其中两个或三个基因的EAEC分离株与腹泻有关（P<0.05）。排出这些基因阳性的EAEC分离株的腹泻患者比排出这些基因阴性的EAEC分离株的患者更有可能排出带有大量黏液（57%对14%）和粪便白细胞（40%对7%）的粪便（P<0.05）。本研究显示了在国际旅行者粪便中发现的EAEC菌株基因谱的异质性，并表明aggR、aap、astA或set1A的存在、基因数量和粪便特征可能是更具毒力的EAEC菌株的标志物。
