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A total of 220 enteroadherent Escherichia coli were identified from 729 Egyptian children with diarrhea using the HEp-2 adherence assay. Enteropathogenic E.coli (EPEC = 38) was common among children

We analyzed a randomly selected group of 30 diffusely adherent (DAEC), 30 enteropathogenic, 30 enteroaggregative, and five Shiga toxin-producing Escherichia coli strains isolated from children with diarrhea. Enterotoxigenic E. coli (ETEC) colonization factors (CFs) were evaluated by a dot-blot assay using 21 CF-specific monoclonal antibodies. Out of 95 non-ETEC strains, three DAEC were found to express coli surface antigen 20 (CS20). No other E. coli expressed CFs. We confirmed the three CS20-positive strains as ETEC-negative by repeat PCR and as toxin-negative by ganglioside-GM1-enzyme-linked immunosorbent assay. To our knowledge, this is the first study that has identified currently recognized CFs in non-ETEC diarrheagenic E. coli strains identified using molecular methods. CFs may be an unrecognized relevant adherence factor in other E. coli, which may then play a role in pathogenesis and the immune response of the host.

The innate immune response to enteropathogenic bacteria includes chemokine-induced polymorphonuclear neutrophil (PMN) migration across mucosal epithelia leading to bacterial clearance and resolution of infection. Among these bacteria, diffusely adherent Escherichia coli expressing Afa/Dr fimbriae (Afa/Dr DAEC), causing childhood diarrhea, can promote IL-8-dependent PMN transmigration across cultured intestinal epithelial cell monolayers via MAPK pathway activation. However, interactions between PMN and Afa/Dr DAEC are poorly documented and constitute the aim of the present study. Using the human PLB-985 cell line differentiated into fully mature PMN, we described the coordinated response to various E. coli. The rapid and strong release of reactive oxygen species and preformed intragranular mediators (myeloperoxidase and IL-8) is followed by a later TNF-α, IL-1β, and IL-8 synthesis. The use of wild-type (IH11128, C1845, LF82), control (AAEC185), and recombinant (AAEC185 bearing Dr or F1845 fimbriae, AdLF82, or type 1 pili) bacterial strains allowed us to demonstrate that late IL-8 hyperproduction is triggered by type 1 pili but not by Dr or F1845 fimbriae; MAPKs (p38, ERK, Src) and NF-κB activations are implicated in this response. Thus, in the course of Afa/Dr DAEC intestinal infection, epithelium- and neutrophil-derived IL-8 could, at least in part, control the flow of neutrophils through the lamina propria. Afa/Dr DAEC-induced IL-8 hyperproduction by PMN might thus be important for inducing and perpetuating local inflammation, and this self-amplifying loop might play a role in the pathogenesis of inflammatory bowel diseases such as Crohn’s disease.

Background Enteropathogens cannot be identified in 40% to 50% of subjects with travelers’ diarrhea (TD). Methods We used polymerase chain reaction (PCR) methods to look for the presence of two bacterial causes of diarrhea in a large group of international travelers after failing to detect a pathogen by conventional tests. DNA was isolated from the diarrheal stool and subjected to PCR from 162 subjects from whom we earlier failed to identify a pathogen in a previous study and included 54 from Antigua, Guatemala, 39 from Guadalajara, Mexico, 29 from Kolkata, India, and 40 from Goa, India. Gene products for enterotoxigenic Escherichia coli (ETEC)—LT (heat‐labile enterotoxin) and ST (heat‐stable enterotoxin)—and diffusely adherent E coli (DAEC), afa/dr (Afa fimbrial and Dr nonfimbrial family of adhesins), were used. Results At least one gene product was identified in diarrhea stool samples of 47 of 162 (29%) subjects. ETEC virulence genes (LT, ST) were found in 34 (21%) samples studied, with rates of occurrence ranging from 8% in Goa to 39% for the samples from Guatemala ( p = 0.0006). A large number of ST‐only strains explained the high ETEC rate in Guatemala. DAEC afa / dr family of adhesions was identified in between 8 and 14% of the samples. Conclusions ETEC and DAEC were implicated in nearly one‐third of the subjects initially diagnosed as pathogen negative. Direct PCR results from stools are consistent with the previous assumption that most undiagnosed TD is bacterial in nature and also highlights the potential value that PCR can add to studies designed to evaluate treatment and preventive interventions for TD, including vaccines.

Diarrhoeagenic Escherichia coli (DEC) were sought in stool specimens from 72 adults and children aged over 3 years, who presented with diarrhoea at a hospital in Accra, Ghana, and 72 matched controls. Only diffusely-adherent E. coli were significantly associated with disease in these older individuals (P=0.029). We additionally tested 53 specimens from infants among whom DEC were collectively associated with disease (P=0.012). Enteropathogenic, enterotoxigenic and enteroaggregative E. coli, the most commonly isolated pathotypes from infants with diarrhoea, were frequently recovered from healthy adults. Asymptomatic carriage of DEC by older individuals in Accra may place young children at risk for diarrhoea.

We have previously shown that some Escherichia coli strains isolated from children with diarrhea present the so-called 'localized and diffused adherence (LA/DA) pattern' in which both localized adherence (LA) and diffused adherence (DA) are expressed simultaneously. in the present study, we show that the LA adherence of these strains is genetically and phenotypically similar to that so far described for enteropathogenic E. coli (EPEC) as determined by DNA hybridization and electron microscopy. On the other hand, the DA is encoded by genes not homologous to the DAEC or AIDA-I DNA probes. in addition, the LA/DA strains are able to invade eukaryotic cells both in vitro and in vivo. in the rabbit ileal loop assay their invasion capacity goes beyond the enterocyte and reaches the muscularis mucosae as determined by transmission electron microscopy. These findings suggest that the LA/DA adherence pattern may be linked to a new E. coli virulence category which in the case of the strains studied may be associated to other virulence traits that enable them to more deeply invade the intestinal mucosa. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved. Universidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, Brazil Universidade Federal de São Paulo, Div Pediat Gastroenterol, São Paulo, Brazil Universidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, Brazil Universidade Federal de São Paulo, Div Pediat Gastroenterol, São Paulo, Brazil Web of Science

Escherichia coli from 138 fecal samples from aboriginal children, in whom no other enteric pathogen was isolated (including enterovirulent E. coli), were examined for HEp-2 cell adhesion. Twenty-five (36.8%) of 68 children with diarrhea and 32 (45.7%) of 70 without diarrhea had diffusely adherent isolates, which were thus not associated with diarrhea (P.25). However, after age stratification, childrenor = 18 months showed a significant association of diffusely adherent E. coli with diarrhea (Por = .05). Enteroaggregative E. coli were isolated from 12 children with diarrhea (17.6%) and 15 without diarrhea (21.4%); thus, there was no association with diarrhea (Por = .5). Sixteen children with diarrhea (23.5%) and 6 without diarrhea (8.6%) carried isolates that caused detachment of the HEp-2 cell monolayer from the glass coverslip when examined in the adhesion assay and were significantly associated with diarrhea (Por = .05). These isolates, termed cell-detaching E. coli, were different from all recognized classes of enterovirulent E. coli.

A DNA probe to detect genes conferring localized adherence of enteropathogenic Escherichia coli (EPEC) to Hep-2 cells was evaluated by using E. coli isolates from the stools of Peruvian infants with and without diarrhea. The probe was both sensitive and specific and revealed that Hep-2 adherence (because of the EPEC adherence factor [EAF] was more frequent in some O serogroups of EPEC than in others. Those serogroups in which EAF is almost always found have been designated class I EPEC; serogroups in which EAF is rarely found have been designated class II. Both class I (EAF-positive) and class II EPEC are associated with diarrheal disease.

A cohort of 452 rural children was followed longitudinally for 13 mo to ascertain the role of HEp-2 cell adherent Escherichia coli and other pathogens in causing acute (less than or equal to 14 d) and persistent (greater than 14 d) diarrhea. Aeromonas, Campylobacter jejuni, E. coli manifesting localized adherence to HEp-2 cells and enterotoxigenic E. coli were significantly associated with acute diarrhea. E. coli strains that exhibit aggregative adherence, so-called enteroaggregative E. coli, a newly-described category of diarrheagenic E. coli distinct from enterotoxigenic, enteroinvasive, enterohemorrhagic, and enteropathogenic E. coli, were found significantly more often in patients with persistent diarrhea (29.5%) than with acute diarrhea (12.8%) (P = .0052) or controls (9.9%) (P = .0006).