Project

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Evolution of macrolide resistance of enterococci from faeces of calves fed with antibiotic contaminated cow's milk

Applicant Schällibaum Melchior
Number 63236
Funding scheme NRP 49 Antibiotic resistance
Research institution Agroscope Liebefeld-Posieux Eidg. Forschungsanstalt für Nutztiere & Milchwirtschaft (ALP)
Institution of higher education Research Institutes Agroscope - AGS
Main discipline Medical Microbiology
Start/End 01.03.2002 - 29.02.2004
Approved amount 161'986.00
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Lay Summary (English)

Lead
Lay summary
Evolution of macrolide resistance of enterococci in faeces of calves fed with antibiotic contaminated cow`s milk

Antibiotic containing milk from treated cows is usually fed to calves and pigs. A possible cause for selecting and disseminating resistance genes in dairy farms which could enter the food chain by contamination of raw milk during the milking process?

Background
In Switzerland the use of antimicrobial growth promoters in food producing animals is officially banned since July 1999. However the therapeutic and prophylactic use of an-tibiotics in animal production is still significant. The antibiotic containing milk produced during lactational treatments of bacterial infections and the withdrawal period (approximately 87`000 tons/year) is often fed to calves and pigs. In traditional Swiss dairy farms with tied housing calves are usually kept together with the milking cows in the same barn. It is not known, if and how this common practice of disposal of antibiotic contaminated waste milk on dairy farms may contribute to the selection and dissemination of resistant bacteria. It has been suggested, that in such antibiotic challenged environments resistant lactic acid bacteria such as enterococci and others which are found as part of the natural microflora in milk and milk products are selected and may enter the food chain by postsecretorial contamination of raw milk during the milking process and may participate in the communication systems which transfer resistance traits over the bacterial
species and genus borders, e.g. to human pathogens.

Aim
The objective of the project is to study the occurrence and behaviour of resistant enterococci in feces of calves fed with milk from cows which received intramammary treatment with spiramycin, an antibiotic which is often used for the treatment of intramammary infections in cows.

Significance
The results of this study will contribute to a scientifically based risk assessment concerning the input of resistance genes from primary milk production into the "human compartment" via the food chain. They may also be a basis on behalf of the responsible authorties for the use and disposal of antibiotic contaminated waste milk on dairy farms.



Direct link to Lay Summary Last update: 21.02.2013

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