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Control of Escherichia coli 0157:H7 in the Ruminant Gut and in the Farm Environment. - OZ0702(3)

New control methodologies are needed to prevent the survival of E. coli 0157 in cattle and on farms. Joint work at RR1 and ADAS, Bridgets will combine investigations in vivo and in vitro to produce these. The objective is to prevent the exposure of the food chain to animals or their products infected with E.coli 0157, reducing the infectious challenge to food hygiene controls, and to eliminate environmental contamination and animal-to-animal transmission. The numbers of commensal and serotype 0157 strains of e. coli in ruminant gut compartments and their relationship will be determined, and cattle in controlled husbandry regimes carrying E.coli 0157 will be identified for tests of the effectiveness of new ethods, not involving antibiotics, to eliminate this pathogen. The potential for use of safe, non-pathogenic commensal E. coli populations in ruminants as a model for E. coli will be confirmed. Interventive dietary approaches tested will include the use of existing and new strains of probiotic bacteria isolated at RRI and the NADC, Ames, la, USA, a range of plant glycosides, recently shown at RRI to selectively inhibit growth and survival of commensal and serotype 0157 strains of E.coli, and different protein supplements. The most promising treatments in each of these groups will be tested with cattle in vivo. Cattle carrying E. coli 0157 will be tested on-farm and cattle at ADAS Bridgets will be used in controlled husbandry studies using the commensal E. coli model. Finally, the effectiveness of a mixed acid/alcohol treatment to reduce survival of E. coli 0157 in the farm environment will be tested in vitro at RRI and in vivo at ADAS.
These novel processes are the most promising currently avaliable for control of E. coli 0157 in cattle and on farms. Reduced carriage of E. coli 0157 could prevent spread of the pathogen on the farm, at market and in abbatoirs. The work will confirm whether commensal E. coli can be used to model E. coli 0157, facilitating tests on further measures which may be developed in future. The results will provide the basis for demonstrations by ADAS to advisors, farmers and others for practical application and advice concerning the interventive methods developed. They will also be presented in reports to MAFF, and published in trade and scientific journals worldwide.
A corresponding proposal is being submitted by Richard Laven (ADAS Bridgets)
1) Investigate the relative importance of different gut compartments in the carriage of commensal and VTEC serotype 0157 E. coli, by comparing population sizes and strain profiles present in bovine rumen, colon and faeces samples, and attached bacteria from samples of gut epithelium from the rumen and colon, obtained from abattoirs (ADAS).
2) Identify cattle at, or on farms near, ADAS Bridgets shedding E. coli 0157 (ADAS)
3) Test potential for use of existing and newly identified probiotic bacteria to suppress growth of pathogenic VTEC E. coli in the ruminant gut. This will involve in vitro work at RRI to be followed by in vivo tests at ADAS and on those farms identified in 2 (above) as having E. coli 0157.
4) Investigate novel methods for dietary control of pathogenic VTEC E. coli in the ruminant gut. In vitro work at RRI wil investigate the selective inhibitory effects of plant glycosides, and promising compounds will subsequently be tested in vivo by ADAS and on cattle identified as having E. coli 0157.
5) Investigate the effects of N or protein supplements on the populations of E. coli 0157 in the ruminant gut. This work will be performed partly in vitro under appropriate containment conditions at RRI and partly with animals at ADAS identified in 2 (above) and using a commensal E. coli model at ADAS Bridgets.
6) Investiagte the effectiveness of organic acid/ethanol treatments upon E. coli numbers in the farm environment, through work in vitro (RRI, U. Aberdeen), followed by on-farm tests at ADAS.
7) Throughout the work, evaluate the use of commensal strains of E. coli especially the rumen strain F318, as a model for E. coli 0157.
Time-Scale and Cost
From: 1999

To: 2002

Cost: £397,096
Contractor / Funded Organisations
Rowett Research Institute
Animal Health              
E.coli O157              
Plants and Animals              
Fields of Study
Animal Health