Contribution of the BFP pilus to the hybrid adherence phenotype of an Enteropathogenic Escherichia coli strain

• Grant number: 09/04635-5
• Support type: Scholarships in Brazil - Master
• Effective date (Start): September 01, 2009
• Effective date (End): July 31, 2011
• Field of knowledge: Biological Sciences - Microbiology - Biology and Physiology of Microorganisms
• Principal researcher: Tânia Aparecida Tardelli Gomes do Amaral
• Grantee: Bruna Gil Garcia
• Home Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

The employment of new laboratory techniques has allowed the recognition of new agents of infectious diarrhea, among which are the different diarrheagenic Escherichia coli (DEC) pathotypes. We have previously demonstrated that one of these pathotypes, enteropathogenic E. coli (EPEC), is an important infantile diarrhea agent in our community. EPEC promote a characteristic lesion in intestinal cells known as attaching and effacing lesion (A/E lesion) and carry the EAF plasmid encoding the Bundle-forming pilus (BFP), which mediates bacterial-bacterial or bacterial-enterocyte adhesion. In HeLa and HEp-2 cells in vitro, these interactions result in formation of compact bacterial microcolonies characterizing the so called localized adherence (LA) pattern. We have also shown the occurrence, in our community, of strains of another DEC pathotype, enteroagregative E. coli (EAEC), which are emerging pathogens. EAEC is characterized by the formation, in HeLa/HEp-2 cells, of the aggregative adherence (AA) pattern. The identification of LA and AA-expression leads to the identification of E. coli strains as EPEC or EAEC, respectively. Curiously, in recent epidemiologic studies, we have isolated some E. coli strains that co-expressing LA and AA, which could thus be classified as either EPEC or EAEC. In a preliminary analysis, we verified that these strains are potentially pathogenic due to their ability in producing A/E lesions and expressing BFP; however, these strains were devoid of the adhesins described so far that are associated with the AA phenotype. Furthermore, in more prolonged assays, one selected strain (E. coli 99245) formed a mature biofilm on both biotic and abiotic surfaces, as often seen with EAEC strains. In this study, we intend to contribute to the characterization of the structures involved in the hybrid adherence phenotype(LA/AA) in a selected strain (E. coli 99245), emphasizing the analysis of the roe of BFP in both the expression of the LA and the AA patterns and in biofilm formation.