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Virulence profiling and multi locus sequence typing of Escherichia coli strains of serogroups O145 and O63 isolated from human infections in Brazil

Grant number: 17/14735-3
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): October 01, 2017
Effective date (End): September 30, 2019
Field of knowledge:Biological Sciences - Microbiology
Principal Investigator:Luis Fernando dos Santos
Grantee:Adriene Maria Ferreira Cavalcanti
Home Institution: Instituto Adolfo Lutz (IAL). Coordenadoria de Controle de Doenças (CCD). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

In most countries Escherichia coli of serogroups O145 and O63 are associated with Shiga toxin-producing Escherichia coli (STEC). STEC strains belonging to these serogroups harbor beyond stx genes for Shiga toxins (Stx) production, the eae gene, a virulence marker defining Enteropathogenic E. coli pathotype (EPEC). In Brazil O145 and O63 E. coli strains are often recovered from cases of human diarrhea and are found to belong to EPEC pathotype. In the STEC pathotype there is a strong association between serogroups O145 and O63 and stx2f gene subtype. However, this specific stx subtype are not routinely sought in Public Health Laboratories in Brazil, including the National Reference Laboratory, so the classification of O145 and O63 Brazilian isolates as EPEC may represent a diagnostic limitation as only eae gene are searched and confirmed in laboratorial routine, rendering the identification of O145 and O63 strains as EPEC. There is also a possibility that O145 and O63 E. coli isolated in Brazil represent strains that loss stx genes, as such genes are located in the genome of lambda bacteriophages and are thus subjected to excision. In order to investigate the real identity and the virulence potential of O145 and O63 E. coli strains isolated in Brazil, this project aims to search for stx2f gene subtype in a collection of strains from clinical sources previously classified as EPEC. A panel of virulence markers, some of which are specific of the STEC pathotype and Multi Locus Sequence Typing will also be performed. The expected results will allow comparisons of O145 and O63 Brazilian strains with strains from other countries bringing advances and enlarging the body of knowledge about virulence and epidemiology of diarrheagenic Escherichia coli strains. (AU)