Virulence features of atypical enteropathogenic Escherichia coli identified by the eae+ EAF-negative stx− genetic profile

Abstract

This study characterized 76 atypical enteropathogenic Escherichia coli (aEPEC) strains, previously classified by the eae(+) EAF-negative stx(-) genotype, isolated from children with diarrhea in Brazil. Presence of bfpA and bfpA/perA was detected in 2 and 6 strains, respectively. The expression of bundle-forming pilus (BFP), however, was observed by immunofluorescence in 1 bfpA and 3 bfpA/perA strains, classifying them as typical EPEC (tEPEC). The remaining 72 aEPEC strains were characterized by serotyping, intimin typing, adherence patterns to HEp-2 cells, capacity to induce actin aggregation (fluorescent actin staining test), and antimicrobial resistance. Our results show that aEPEC comprise a very heterogeneous group that does not present any prevalence or association regarding the studied characteristics. It also suggest that tEPEC and aEPEC must not be classified only by the reactivity with the EAF probe, and that the search of other markers present in pEAF, as well as the BFP expression, must be considered for this matter.

Phenotypic and Genotypic Characterization of Antimicrobial Resistance in Enterohemorrhagic Escherichia Coli and Atypical Enteropathogenic E. Coli Strains from Ruminants

“…Atypical EPEC are an important cause of diarrhea in developing and developed countries and can be isolated from human beings and animals. 1 As a result of its epidemiologic importance, the frequency of antimicrobial resistance in human and animal VT-producing E. coli ( VTEC), including EHEC, has been the subject of many studies. 12,14 In contrast, only a limited number of studies of the frequency of antimicrobial resistance have focused on atypical EPEC from human beings 1 and, to the authors' knowledge, none on atypical EPEC from ruminants.…”

“…?show "fnote_aff1"$^! "content-markup(./author-grp [1]/aff|./author-grp [1]/dept-list)> Attaching and effacing Escherichia coli (AEEC) are a cause of diarrhea in humans and animals. These bacteria cause a characteristic attaching and effacing (AE) lesion in the gut mucosa because of the intimate bacterial adhesion to the enterocytes and effacement of the brush border microvilli.…”

Prevalence and Characteristics of the O122 Pathogenicity Island in Typical and Atypical Enteropathogenic Escherichia coli Strains

“…The main difference between tEPEC and aEPEC is the presence of the EPEC adherence factor (EAF) plasmid in tEPEC (8,21). This plasmid encodes the bundle-forming pilus (BFP), which mediates localized adherence to intestinal cells (9), which is an essential property to differentiate tEPEC from aEPEC strains (1,7,21).Formation of the attaching-and-effacing (AE) lesion is the major virulence mechanism of EPEC and an additional virulence property of enterohemorrhagic E. coli (EHEC) strains, a subset of STEC strains (9). This lesion consists of intimate bacterial adherence to the intestinal epithelial cells, cytoskeleton remodeling, and microvillus effacement (9).…”

Quorum sensing em Escherichia coli enteropatogênica atípica.

“…Este padrão de adesão caracteriza-se pela formação de microcolônias frouxas das bactérias sobre determinadas regiões da superfície celular, observado após 6 h de interação bactéria-célula epitelial (RODRIGUES et al, 1996;PELAYO et al, 1999;SCALETSKY et al, 1999;VIEIRA et al, 2001;DULGUER et al, 2003;GOMES et al, 2004;ABE et al, 2009). …”

“…adesão difusa (AD), adesão agregativa (AA), algumas amostras são incapazes de se aderir às células epiteliais, não aderentes (NA), e amostras cujo padrão de adesão é considerado indeterminado (IND) (VIEIRA et al, 2001;DULGUER et al, 2003;NUNES et al, 2003;ROBINS-BROWNE et al, 2004;ABE et al, 2009). …”