Characteristics of adherence of enteroaggregative Escherichia coli to human and animal mucosa

Abstract

An Escherichia coli strain (serotype 0127a:H2) that had been isolated from a child with diarrhea in Thailand and that was negative for the virulence factors of the four categories of diarrheagenic E. coli (enterotoxigenic, enteropathogenic, enteroinvasive, and enterohemorrhagic) and that showed an aggregative pattern of adherence to HeLa cells was investigated for adherence to native or Formalin-fixed human and animal mucosa. The hemagglutinating activity and adherence ability of the bacteria were resistant to D-mannose and were strictly regulated by environmental conditions. Genetic data supported the close relation between the hemagglutinating activity and adherence ability. In accordance with the adherence pattern on tissue-cultured cells, the bacteria adhered to human and animal mucosa, as evidenced by a direct gold-labeling analysis. In human intestines, Formalin-fixed mucous coatings, epithelial cells of colonic mucosa, epithelial cells of ileal single lymphoid follicles and Peyer's patches, and the absorptive cells ofjejunal or ileal vili provided adherence targets. Adherence to M cells in the Peyer's patch-associated epithelium was also confirmed. The adherence levels to native jejunal or ileal human villi were low, as was the case with the corresponding Formalin-fixed villi. In human urinary tract, the superficial epithelial cells of both native and Formalin-fixed ureter provided striking adherence targets. In animal (porcine and rabbit) small intestines, the bacteria adhered to the native villi to a lesser extent than to the Formalin-fixed villi. The adherence levels were compared with those'of enterotoxigenic E. coli with colonization factor antigen (CFA)/I pili or CFA/II pili. The data suggested unique mucosa adherence characteristics of the enteroaggregative E. coli strain. The possibility of the adherence ability as a virulence factor was discussed. * Corresponding author. gative E. coli as a cause of pediatric diarrhea (2, 3). It has also been shown that enteroaggregative E. coli causes characteristic lesions in rabbit and rat ileal loops and possesses a 55to 65-MDa plasmid coding for the production of smooth lipopolysaccharide and pili; the plasmid also confers upon its host bacterial cells the ability to adhere to HEp-2 cells in an aggregative pattern (34). In previous experiments using Formalin-fixed or native human small intestinal or ureteral mucosa, we investigated the adherence sites and levels of bacterial enteropathogens Vibrio cholerae 01 (37, 38, 41), V. cholerae non-O1 (39), Vibrio parahaemolyticus (35, 42), and enterotoxigenic E. coli with colonization factor antigen (CFA)/I pili or CFAIII pili (36, 40). In this study, we used native or Formalin-fixed mucosa of human small intestines, human ureters, and animal (porcine and rabbit) small intestines to test 'the adherence ability of an enteroaggregative E. coli strain isolated from a child with diarrhea in Thailand. We found that the strain can adhere to both native and Formalin-fixed mucosa in an adherence manner that is very different ...

The significance of enteroaggregative Escherichia coli in the etiology of hospitalized diarrhoea in Calcutta, India and the demonstration of a new honey-combed pattern of aggregative adherence

“…These results are in tandem with recent reports which are beginning to indicate that the pathogenicity of EAggEC is mediated by a toxin because they do not induce the attaching and effacing lesion characteristic of EPEC [14]. Further, experimental EAggEC infection in isolated rabbit and porcine intestinal loops appear to indicate the EAggEC may elaborate a toxin that damages enterocytes [15]. It has recently been demonstrated that EAggEC elaborate a low molecular mass partially heat-stable enterotoxin which induces ion transport alterations consistent with a secretory response [3].…”

Enteroaggregative Escherichia coli

“…Knutton et al (1992) showed that 44 different EAggEC isolates adhered to human adult colonic mucosa but none of six isolates adhered to ileal mucosa. Yamamoto et al (1991), using a single isolate of EAggEC, found low levels of adhesion to native jejunal and ileal mucosa and high levels of adhesion to formalin-fixed colonic mucosa. The same group also investigated the adhesion of EAggEC to native unfixed jejunal tissue from a child.…”

“…Knutton et al (1992) identified an isolate that showed the typical aggregative phenotype but did not produce the characteristic fibrillar bundles on EM and did not hybridize with a DNA probe. Others have identified EAggEC isolates that do not hybridize with probes that have high specificity for the aggregative phenotype (Baudry et al 1990;Yamamoto et al 1991;Debroy et al 1994a). Czeczulin et al (1995) probed EAggEC strains with probes for both AAF/I and AAF/II fimbriae, and have found strains that do not hybridize with either probe, suggesting the existence of more aggregative adherence-associated fimbriae.…”

Expression of antigenically distinct fimbriae with hemagglutination and HeLa cell adherence properties by an enteroaggregative Escherichia coli strain belonging to the enteropathogenic serogroup

“…Apart from the HeLa cell adherence properties (Ad), the EAggEC strains usually exhibit mannose-resistant hemagglutination (MRHA) activities towards erythrocytes of human and certain other species [8]. Further, Yamamoto et al [9] have demonstrated unique adherence charac-teristics of these strains to both native and formalin-fixed human and animal mucosa. The cellular adherence properties of EAggEC appear to correlate well with the expression of fimbriae encoded by 55-65 MDa plasmids [8].…”