Atypical enteropathogenic Escherichia coli genomic background allows the acquisition of non-EPEC virulence factors

Atypical enteropathogenic Escherichia coli (aEPEC) has been associated with infantile diarrhea in many countries. The clonal structure of aEPEC is the object of active investigation but few works have dealt with its genetic relationship with other diarrheagenic E. coli (DEC). This study aimed to evaluate the genetic relationship of aEPEC with other DEC pathotypes. The phylogenetic relationships of DEC strains were evaluated by multilocus sequence typing. Genetic diversity was assessed by pulsed-field gel electrophoresis (PFGE). The phylogram showed that aEPEC strains were distributed in four major phylogenetic groups (A, B1, B2 and D). Cluster I ( group B1) contains the majority of the strains and other pathotypes [enteroaggregative, enterotoxigenic and enterohemorrhagic E. coli ( EHEC)]; cluster II ( group A) also contains enteroaggregative and diffusely adherent E. coli; cluster III ( group B2) has atypical and typical EPEC possessing H6 or H34 antigen; and cluster IV ( group D) contains aEPEC O55:H7 strains and EHEC O157:H7 strains. PFGE analysis confirmed that these strains encompass a great genetic diversity. These results indicate that aEPEC clonal groups have a particular genomic background - especially the strains of phylogenetic group B1 that probably made possible the acquisition and expression of virulence factors derived from non-EPEC pathotypes.

Molecular characterization and evaluation of antimicrobial susceptibility of enteropathogenic E. coli (EPEC) isolated from minas soft cheese

Foodborne disease caused by microorganisms is a problem of public health. Minas soft cheese is a national product manufactured using simple technology; it has high level of acceptance in the country making its production an important economic activity. Many microorganisms may be present in foods including the bacterium Escherichia coli (E. coli). Overall, E. coli is a harmless commensal bacterium; however, some strains may have a pathogenic potential. Several outbreaks of foodborne diseases associated with consumption of contaminated cheese have been reported, and the presence of pathogenic strains of E. coli has increased. The objective of this study was to isolate, evaluate the antimicrobial susceptibility, and characterize, by Multiplex PCR, the pathogenic E. coli strains isolated from Minas cheese commercialized in Rio de Janeiro. Thirty samples were analyzed and five strains of E. coli (EPEC) were identified. The assessment of antimicrobial susceptibility revealed 40% of the isolates resistant to ampicillin and 40% with intermediate resistance to ampicillin-sulbactam combination. These findings are a warning signal to health authorities since Minas cheese is a ready to eat food product, and therefore should not pose health risks to the population.

Co-ordination of pathogenicity island expression by the BipA GTPase in enteropathogenic Escherichia coli (EPEC)

BipA is a novel member of the ribosome binding GTPase superfamily and is widely distributed in bacteria and plants. We report here that it regulates -multiple cell surface- and virulence-associated -components in the enteropathogenic Escherichia coli (EPEC) strain E2348/69. The regulated components include bacterial flagella, the espC pathogenicity island and a type III secretion system specified by the locus of enterocyte effacement (LEE). BipA positively regulated the espC and LEE gene clusters through transcriptional control of the LEE-encoded regulator, Ler. Additionally, it affected the pattern of proteolysis of intimin, a key LEE-encoded adhesin specified by the LEE. BipA control of the LEE operated independently of the previously characterized regulators Per, integration host factor and H-NS. In contrast, it negatively regulated the flagella-mediated motility of EPEC and in a Ler-independent manner. Our results indicate that the BipA GTPase functions high up in diverse regulatory cascades to co-ordinate the expression of key pathogenicity islands and other virulence-associated factors in E. coli.

Detecção de Escherichia coli shigatoxigênica (STEC) e enteropatogênica (EPEC) em carcaças e fezes de suínos abatidos na região de Ribeirão Preto – SP e perfil de susceptibilidade dos isolados frente a diferentes antimicrobianos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Detecção de Escherichia coli shigatoxigênica (STEC) e enteropatogênica (EPEC) isoladas de búfalos leiteiros no Estado de São Paulo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Detection of Shiga toxigenic (STEC) and enteropathogenic (EPEC) Escherichia coli in dairy buffalo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Detecção de Escherichia coli shigatoxigênica (STEC) e enteropatogênica (EPEC) em peixes de pisciculturas e de vida livre

Pós-graduação em Microbiologia Agropecuária - FCAV

Análise molecular de estirpes de Escherichia coli enteropatogênica (EPEC) isoladas de animais e humanos

Pós-graduação em Microbiologia Agropecuária - FCAV

Determination of flagellar types by PCR-RFLP analysis of enteropathogenic Escherichia coli (EPEC) and Shiga toxin-producing E. coli (STEC) strains isolated from animals in Sao Paulo, Brazil

This study evaluated the polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) analysis of fliC for typing flagella antigen (H) of Shiga toxin-producing Escherichia coil (STEC) and enteropathogenic E. coli (EPEC) strains isolated from different animals. The molecular typing of the H type was efficient in the determination of 93 (85%) strains. Two nonmotile (H-) E. coil strains showed a PCR-RFLP electrophoretic profile that did not match known H type patterns. The fliC nucleotide sequence of strains B2N and 4a revealed a nucleotide substitution at the restriction site and a nucleotide insertion that generated a stop codon, respectively. The results of this study showed that PCR-RFLP analysis of fliC is faster, less laborious and as efficient for the determination of H type E. coli isolated from animals, compared to serotyping and that it is useful in determining H type in nonmotile strains and strains expressing non-reactive H antigens. Moreover, the fliC sequence of strain B2N suggests that we could have found a new flagellin antigen type. (C) 2010 Elsevier Ltd. All rights reserved.

EPA-SAB-EPEC.

Description based on: 95-003 (Mar. 1995); title from cover.

Clonal relationship among atypical enteropathogenic Escherichia coli strains isolated from different animal species and humans

Forty-nine typical and atypical enteropathogenic Escherichia coli (EPEC) strains belonging to different serotypes and isolated from humans, pets (cats and dogs), farm animals (bovines, sheep, and rabbits), and wild animals (monkeys) were investigated for virulence markers and clonal similarity by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The virulence markers analyzed revealed that atypical EPEC strains isolated from animals have the potential to cause diarrhea in humans. A close clonal relationship between human and animal isolates was found by MLST and PFGE. These results indicate that these animals act as atypical EPEC reservoirs and may represent sources of infection for humans. Since humans also act as a reservoir of atypical EPEC strains, the cycle of mutual infection of atypical EPEC between animals and humans, mainly pets and their owners, cannot be ruled out since the transmission dynamics between the reservoirs are not yet clearly understood.

Etiology of childhood diarrhea in the northeast of Brazil: significant emergent diarrheal pathogens

In a study conducted in Joao Pessoa, northeast of Brazil, 2344 Escherichia coli isolated from 290 infants with diarrhea and 290 healthy matched controls were analyzed for virulence traits. Enteroaggregative E. coli (EAEC) was the most prevalent pathogen associated to acute diarrhea. Based on the results of colony blot hybridization, serotyping, and HEp-2 cell adherence assays, strains were separated in categories as typical enteropathogenic E. coli (EPEC) (1.7%), atypical EPEC (a-EPEC) (9.3%), EAEC (25%), enterotoxigenic E. coli (10%), and enteroinvasive E. coli (EIEC) (1.4%). No enterohemorrhagic E. coli strains were isolated. Other enteropathogens were found, including Salmonella (7.9%), Shigella spp. (4.1%), thermophilic Campylobacter spp. (2.4%), Giardia lamblia (9.3%), and Entamoeba histolytica (5.8%). All enteropathogens were associated with diarrhea (P < 0.01). However, the association was lower for EPEC and EIEC (P < 0.03). Different pathogens associated with diarrhea may have been changing in Brazil where EAEC and a-EPEC seem to be the most prevalent pathogens among them. (C) 2010 Elsevier Inc. All rights reserved.

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

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. (C) 2009 Elsevier Inc. All rights reserved.