Characterization of Enteropathogenic and Enteroaggregative Escherichia coli Isolated from Diarrheal Outbreaks

Abstract

Virulence characteristics of diarrheal outbreak-associated Escherichia coli O55:NM, O126:NM, and O111:NM were examined. The E. coli O55:NM strains were atypical enteropathogenic E. coli (EPEC), while the E. coli O126:NM and O111:NM strains should be classified as enteroaggregative E. coli (EAggEC). The contributions of EPEC and EAggEC to the human disease burden in Japan might be significantly greater than is currently appreciated.There are six categories of Escherichia coli that cause diarrhea: enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli, enteroaggregative E. coli (EAggEC), enteroinvasive E. coli, and diffusely adherent E. coli (21). EPEC causes characteristic attaching-and-effacing lesions (A/E), which can be observed by intestinal biopsy in both human patient (19) and animal (29) models. A/E is characterized by loss of microvilli, intimate adherence of bacteria between epithelial cell membranes (27,30), and cytoskeletal changes such as actin polymerization directly beneath the adherent bacteria (15). Generally, EPEC causes infantile diarrhea in developing countries and sporadic diarrhea in developed countries (21). EAggEC, on the other hand, is an enteric pathogen defined by its distinctive aggregative or "stackedbrick" pattern of adherence to cultured human epithelial cells (22). EAggEC associates mainly with persistent diarrhea in developing countries (21). Only two reports in Japan have described diarrheal outbreaks caused by EAggEC or EPEC. Itoh et al. (11) reported the isolation of EAggEC from the stools of patients with severe diarrhea in elementary and junior high schools. Makino et al. (18) reported the isolation of EPEC from a mass outbreak. In this paper, we describe three cases of diarrheal outbreaks in Japan caused by E. coli belonging to the traditional EPEC serotype.Chromosomal DNA-embedded agarose plugs for pulsedfield gel electrophoresis (PFGE) analysis were prepared by using the CHEF Bacterial DNA Plug Kit (Bio-Rad, Hercules, Calif.) and were digested with XbaI (Nippon gene; Osaka, Japan) at a concentration of 30 U/plug for 4 h at 37°C. The plugs were applied to a 1% PFC Grade Agarose (Bio-Rad) gel. Electrophoresis was performed in 0.5ϫ Tris-Borate EDTA buffer at 14°C using a CHEF DR-II PFGE apparatus (BioRad) under the following conditions: voltage, 6 V/cm; block 1, 11 h, with initial switching time of 4 s to final switching time of 8 s; block 2, 9 h, with initial switching time of 8 s to final switching time of 50 s. The HEp-2 cell assay was performed following the method described by Craviotto et al. (4), with modifications involving 3 or 6 h of incubation (15). The E. coli isolates were examined for the presence of the following virulence genes by PCR: stx1 (Shiga toxin) and stx2 (16), eaeA (E. coli attaching and effacing) (12), bfpA (bundle-forming pilus) (9), perA (EPEC plasmid-encoded regulatory region) (8), astA (EAggEC heat-stable enterotoxin) (28), aggR (transcriptional activator for EAggEC aggregative adherence fimbria I expression) ...

Virulence Markers of Enteroaggregative Escherichia coli Isolated from Children and Adults with Diarrhea in Brasília, Brazil

“…The strains from children with diarrhea were very frequently found to be of the EPEC classical serogroups, while such strains were very rarely recovered from adults. EAEC strains from children have previously been reported to belong to EPEC serogroups (6,17,35,49). Rosa et al (35) found that most of the EAEC strains from children with diarrhea belonged to EPEC serogroups, and similar to our findings, they showed that the most frequent serogroups were O86 and O125.…”

Escherichia coli Pathotypes in Pakistan from Consecutive Floods in 2010 and 2011

“…[18][19][20][21][22] On the other hand typical EPEC, a wellrecognized cause of infantile diarrhea, 4 contributed much less during the current study compared with atypical EPEC in previous studies. 23,24 Similar results have been observed in Bangladesh where the majority of ETEC producing LT, followed by LT + ST and ST producing were predominantly associated with flood associated diarrheal cases 25 compared with previous studies from China, India, Mexico, Myanmar, and Pakistan where strains predominantly produced ST. 26 The association of EAEC with diarrhea has not been frequently reported, 27 however in our study EAEC is one of the most frequently isolated pathotype in sporadic cases, whereas EPEC is from flood affected cases. Furthermore, younger children ( 5 years of age) are more often affected by EAEC than older children in both the flood affected and non-flood affected areas (Table 4).…”

DiarrheagenicEscherichia coliandShigellaStrains Isolated from Children in a Hospital Case-Control Study in Hanoi, Vietnam

“…EAggEC is an increasingly recognized enteric pathogen and is the cause of acute or persistent diarrhea in children and adults in both developed and developing countries (36). A growing number of reports have described EAggEC outbreaks (19,69,72), and many reports have implicated EAggEC as a cause of sporadic diarrhea (41,46). EPEC is an important cause of childhood diarrhea in developing countries (30,48).…”