Molecular and Phenotypic Characterization of Escherichia coli O26:H8 among Diarrheagenic E. coli O26 Strains Isolated in Brazil

Molecular and Phenotypic Characterization of Escherichia coli O26:H8 among Diarrheagenic E. coli O26 Strains Isolated in Brazil

Author Piazza, Roxane M. F. Google Scholar
Delannoy, Sabine Google Scholar
Fach, Patrick Google Scholar
Saridakis, Halha O. Google Scholar
Pedroso, Margareth Z. Autor UNIFESP Google Scholar
Rocha, Leticia B. Google Scholar
Gomes, Tania A. T. Autor UNIFESP Google Scholar
Vieira, Monica A. M. Autor UNIFESP Google Scholar
Beutin, Lothar Google Scholar
Guth, Beatriz E. C. Autor UNIFESP Google Scholar
Institution Inst Butantan
French Food Safety Agcy
Universidade Estadual de Londrina (UEL)
Universidade Federal de São Paulo (UNIFESP)
Ctr Univ Sao Camilo
BfR Fed Inst Risk Assessment
Abstract Escherichia coli strains of serogroup O26 comprise two distinct groups of pathogens, characterized as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC). Among the several genes related to type III secretion system-secreted effector proteins, espK was found to be highly specific for EHEC O26:H11 and its stx-negative derivative strains isolated in European countries. E. coli O26 strains isolated in Brazil from infant diarrhea, foods, and the environment have consistently been shown to lack stx genes and are thus considered atypical EPEC. However, no further information related to their genetic background is known. Therefore, in this study, we aimed to discriminate and characterize these Brazilian O26 stx-negative strains by phenotypic, genetic, and biochemical approaches. Among 44 isolates confirmed to be O26 isolates, most displayed flagellar antigen H11 or H32. Out of the 13 nonmotile isolates, 2 tested positive for fliC(H11), and 11 were fliC(H8) positive. the identification of genetic markers showed that several O26:H11 and all O26:H8 strains tested positive for espK and could therefore be discriminated as EHEC derivatives. the presence of H8 among EHEC O26 and its stx-negative derivative isolates is described for the first time. the interaction of three isolates with polarized Caco-2 cells and with intestinal biopsy specimen fragments ex vivo confirmed the ability of the O26 strains analyzed to cause attaching-and-effacing (A/E) lesions. the O26:H32 strains, isolated mostly from meat, were considered nonvirulent. Knowledge of the virulence content of stx-negative O26 isolates within the same serotype helped to avoid misclassification of isolates, which certainly has important implications for public health surveillance.
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Date 2013-11-01
Published in Applied and Environmental Microbiology. Washington: Amer Soc Microbiology, v. 79, n. 22, p. 6847-6854, 2013.
ISSN 0099-2240 (Sherpa/Romeo, impact factor)
Publisher Amer Soc Microbiology
Extent 6847-6854
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000327504200002

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