Caracterização de amostras de Escherichia coli isoladas de bezerros com e sem diarreia : pesquisa de fatores de colonização e toxinas / Characterization of Escherichia coli strains isolated of diarrheic and healthy calves : a colonization factors and toxins study

AUTOR(ES)

Claudia de Moura

DATA DE PUBLICAÇÃO

2005

RESUMO

Infections caused by Escherichia coli are the most cause of diarrhea in animals, bovines and cattle, being thus responsible for important economic losses in farms. In this work, 58 strains isolated from calves with diarrhea and 43 strains isolated from healthy calves were studied for PCR analysis about the virulence factors eae, EAF, K99, F41, CS31A, F17, STa, LT-II, VT1, VT2, Hly, Ehly, CDT, CNF1, CNF2 and EAST1. We utilized techniques in vitro for the VT and Ehly production and serological assays for detecting serogroups. Of the studied strains, 31 of them were positive for colonization factors, being 28 isolated from diarrheic calves and five isolated from healthy calves, where 26 were CS31A+, eleven F17 and an association between CS31A/F17 was found in six strains from diarrheic calves. The eae gene was present in 43 strains, where 35 were isolated from calves with diarrhea and no E. coli were positive for the FC K99, F41 and EAF. About the toxin genes, the most frequent was VT1 in 43 strains, being 24 of diarrheic origin and 19 from healthy calves. Forty strains were EAST1, with of them 17 isolated from diarrheic calves, ten strains were VT2, being six isolated from healthy calves. Eight strains were Ehly, six CDT, four CNF2 and only two strains LT-II. Twenty E. coli showed association of eae/VT1 and 13 are CS31A/VT1 positive. No strains were positive for STa, Hly and CNF1. The production of VT and Ehly were positive in in vitro assays. Eleven strains were negative for all the genes probes. We detected 35 serogroups between E. coli studied. To our knowledge, this is the first description of an association between CS31A and VT1. The association between eae gene and VT1 toxin show that calves should be considered VTEC reservoir in Brazil for human infection

ASSUNTO(S)

virulencia (microbiologia) pcr bovino escherichia coli diarrhea reação de cadeia da polimerase diarreia escherichia coli virulence factors calves

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