Virulence factors in Escherichia coli strains isolated from water sources in pig farms in the state of Rio Grande do Sul, Brazil

摘要

Water coliform counts are routinely used as indicators of water potability. Several authors show high frequency of water contamination in pig farms, and tend to correlate this with the presence of diarrhea in piglets. The objective of the present work was to investigate virulence characteristics of E. coli strains isolate from water samples collected in pig farms with persistent problems of diarrhea in piglets. Thirty E. coli strains were isolated from water collected from 12 pig farms in the Stateof Rio Grande do Sul, Brazil, which showed persistent problems of diarrhoea in piglets. The hemolytic activity was determined using nutrient agar supplemented wilh 5 percent defibrinated equine blood. The samples were cultured in CFA and in Minca mediaand adhesion antigens were determined through a microagglutination technique using ovine, guinea pig, chicken and equine red blood cells, in the presence of mannose (MRHA) and guinea pig red blood cell in the absence of mannose (MSHA). Detection of the presence of 987P fimbria was performed by slide serum agglutination test using a polyclonal absorbed antiserum. Colicin production and typing was carried out. An ELISA test was used for LT-I toxin detection. Demonstration of plasmid profile was carried out using an electrophoretic test.