Detection of cytotoxic necrotizing factor types 1 and 2 among fecal Escherichia coli isolates from brazilian children with and without diarrhea

The enteropathogenic role of cytotoxic necrotizing factor (CNF)-producing Escherichia coli was investigated by searching cnf genes among 2074 isolates from 200 children with and 200 without acute diarrhea in Brazil. Fourteen (7%) cases versus 10 (5%) control children carried at least one cnf positive isolate (P = 0.50) and most isolates expressed CNF type 1. DNA sequences of virulence factors of extraintestinal pathogenic E. coli (ExPEC) were detected in 78.6% of CNF1-producing isolates. Besides not being associated with human acute diarrhea, the CNF1-producing isolates here identified may represent potential ExPEC transitorily composing the normal intestinal flora.Instituto Adolfo Lutz Seção de BacteriologiaUniversidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Departamento de Microbiologia, Imunologia e ParasitologiaUNIFESP, EPM, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL

Typical and atypical enteropathogenic Escherichia coli bacterial translocation associated with tissue hypoperfusion in rats

Although enteropathogenic Escherichia coli (EPEC) are well-recognized diarrheal agents, their ability to translocate and cause extraintestinal alterations is not known. We investigated whether a typical EPEC (tEPEC) and an atypical EPEC (aEPEC) strain translocate and cause microcirculation injury under conditions of intestinal bacterial overgrowth. Bacterial translocation (BT) was induced in female Wistar-EPM rats (200-250 g) by oroduodenal catheterization and inoculation of 10 mL 10(10) colony forming unit (CFU)/mL, with the bacteria being confined between the duodenum and ileum with ligatures. After 2 h, mesenteric lymph nodes (MLN), liver and spleen were cultured for translocated bacteria and BT-related microcirculation changes were monitored in mesenteric and abdominal organs by intravital microscopy and laser Doppler flow, respectively. tEPEC (N = 11) and aEPEC (N = 11) were recovered from MLN (100%), spleen (36.4 and 45.5%), and liver (45.5 and 72.7%) of the animals, respectively. Recovery of the positive control E. coli R-6 (N = 6) was 100% for all compartments. Bacteria were not recovered from extraintestinal sites of controls inoculated with non-pathogenic E. coli strains HB101 (N = 6) and HS (N = 10), or saline. Mesenteric microcirculation injuries were detected with both EPEC strains, but only aEPEC was similar to E. coli R-6 with regard to systemic tissue hypoperfusion. In conclusion, overgrowth of certain aEPEC strains may lead to BT and impairment of the microcirculation in systemic organs.Universidade Federal de São Paulo (UNIFESP) Departamento de PediatriaUniversidade Federal de São Paulo (UNIFESP) Departamento de MicrobiologiaUniversidade Federal de São Paulo (UNIFESP) Departamento de CirurgiaUNIFESP, Depto. de PediatriaUNIFESP, Depto. de MicrobiologiaUNIFESP, Depto. de CirurgiaSciEL

Distribution of non-LEE-encoded type 3 secretion system dependent effectors in enteropathogenic Escherichia coli

Enteropathogenic Escherichia coli (EPEC) are important human gastroenteritis agents. The prevalence of six non-LEE genes encoding type 3 translocated effectors was investigated. The nleC, cif and nleB genes were more prevalent in typical than in atypical EPEC, although a higher diversity of genes combinations was observed in atypical EPEC.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo (UNIFESP) Departamento de Microbiologia, Imunologia e ParasitologiaUniversidade Estadual Paulista Julio de Mesquita Filho Instituto de Biociências Departamento de Microbiologia e ImunologiaUNIFESP, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL

Characterization of atypical enteropathogenic Escherichia coli strains that express typical localized adherence in HeLa cells in the absence of the bundle-forming pilus

The characterization of nine atypical enteropathogenic Escherichia coli strains expressing localized adherence in HeLa cells in the absence of the bundle-forming pilus revealed a diversity of serotypes, plasmids, and virulence genes. Although the strains lacked known E. coli adhesin genes, the identification of new adhesins could contribute to the characterization of similar enteropathogenic E. coli isolates.Universidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilInst Butanan, Lab Biol Cellular, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilWeb of Scienc

Phenotypic and genotypic characteristics of Escherichia coli strains of non-enteropathogenic E-coli (EPEC) serogroups that carry eae and lack the EPEC adherence factor and shiga toxin DNA probe sequences

This study was conducted to characterize the virulence potential of 59 Escherichia coli strains carrying eae and lacking the enteropathogenic E. coli adherence factor and Shiga toxin probe sequences. in hybridization studies, all strains carried the locus of enterocyte effacement (LEE)-associated DNA sequences. of the other 15 virulence DNA sequences tested, hly was the most frequent (44.1%); 17 combinations of these sequences were found, but strains carrying eae only (eae profile) were the most frequent (35.6%). Except for 1 cytodetaching strain, all others adhered to HeLa and Caco-2 cells, most of which (similar to 75.0%) showed variations of the localized adherence pattern. Actin accumulation was detected in 75.9% of the nondetaching strains. Most strains had LEE, probably inserted in pheU (49.2%), and presented a nontypeable intimin (83.1%). Translocated intimin receptor-derived DNA sequences correlated with enteropathogenic and enterohemorrhagic E. coli in 61.0% and 32.0% of the strains, respectively. Thirty-five different serotypes were found. Only strains with the eae profile were associated with diarrhea (P = .039).Universidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilUniv São Paulo, Inst Butantan, Lab Especial Microbiol, São Paulo, BrazilUniv São Paulo, Inst Adolfo Lutz, Secao Bacteriol, São Paulo, BrazilUniv São Paulo, Hosp Clin, Inst Crianca, São Paulo, BrazilUniv Estado Rio de Janeiro, Dept Microbiol, Rio de Janeiro, BrazilUniv London Imperial Coll Sci Technol & Med, Dept Biochem, London, EnglandUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilWeb of Scienc

Phenotypic and genotypic characteristics of shiga toxin-producing Escherichia coli strains isolated from children in São Paulo, Brazil

The biochemical and serological characteristics, virulence properties, and genetic relatedness of Shiga toxin-producing Escherichia coli (STEC) strains isolated in São Paulo, from April 1989 through March 1990, were determined. This is also the first report on clinic findings of human STEC infections in Brazil. The only three STEC strains identified in that period were lysine decarboxylase negative, belonged to serotype O111ac: non-motile, were Stx1 producers, carried the eae and astA genes, and 2 of them also presented the EHEC-hly sequence. The children carrying STEC were all boys, with less than two years old, and had no previous history of hospitalization. None of them presented blood in stools. Vomiting, cough and coryza were the most common clinical manifestations observed. Although the STEC strains were isolated during summer months, and presented similar phenotypic and genotypic characteristics, carbohydrate fermentation patterns and PFGE analysis suggested that these diarrheal episodes were not caused by a single clone.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Microbiologia, Imunologia e ParasitologiaUSP Hospital das Clínicas Instituto da CriançaUniversidade Estadual do Rio de JaneiroUniversidade Federal Fluminense Departamento de Microbiologia e ParasitologiaUNIFESP, EPM, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL