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Vancomycin resistant enterococci in Swedish broilers

emergence, epidemiology and elimination

Nilsson, Oskar (2011). Vancomycin resistant enterococci in Swedish broilers. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2011:51
ISBN 978-91-576-7595-8
[Doctoral thesis]

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Abstract

Vancomycin resistance enterococci (VRE) are an important cause of nosocomial infections. Presence of VRE in farm animals constitute a reservoir of resistance that can spread to humans via the food-chain and is due to extensive use of the growth promoter avoparcin conferring cross-resistance to vancomycin.

Since 2000, the occurrence of VRE among Swedish broilers has increased in the absence of any obvious selective pressure as avoparcin has not been used since 1984. Also, the increased occurrence seemed to be due to spread of one clone of VRE.

The work of this thesis confirms that the increased occurrence of VRE is caused by the spread of one predominant clone. Both the predominant and the minority clones are E. faecium with plasmid mediated vanA gene.

The vanA gene is transferrable from the predominant and several of the minority clones. Thus, the predominance of one clone is not due to that the resistance is untransferable from the clones. It also confirms that VRE among Swedish broilers have a potential for zoonotic spread of the vanA gene. Plasmid addiction systems are most likely not involved in the retention of the vanA gene as there is a near absence of such systems among VRE from Swedish broilers. Decreased susceptibility to the ionophore narasin can be co-transferred with the vanA gene from the predominant and some of the minority clones. Thereby the use of narasin for coccidial prophylaxis could contribute to retention of the vanA gene. The traits are probably located close to each other so when retaining the decreased susceptibility to narasin, the enterococci also retain the vanA gene.

Broilers arriving to the farms are colonized with VRE persisting in the broiler houses. Differences in occurrence of VRE among farms indicate that the occurrence of VRE can be reduced. Furthermore, a reduction in the contamination of the broiler houses can be achieved by disinfection with a method combining steam and formaldehyde. Subsequently, this could reduce the occurrence of VRE in Swedish broiler production on the whole.

Further research should focus on the role of narasin in the VRE epidemiology as well as exploring the possibility to eliminate VRE from Swedish broiler production.

Authors/Creators:Nilsson, Oskar
Title:Vancomycin resistant enterococci in Swedish broilers
Subtitle:emergence, epidemiology and elimination
Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :2011
Volume:2011:51
Number of Pages:59
Papers/manuscripts:
NumberReferences
I.Nilsson, O., Greko, C., Top, J., Franklin, A., Bengtsson, B. (2009). Spread without known selective pressure of a vancomycin-resistant clone of Enterococcus faecium among broilers. Journal of Antimicrobial Chemotherapy 63(5), 868-872
II.Nilsson, O., Greko, C., Bengtsson, B., Englund, S. Genetic diversity among VRE isolates from Swedish broilers with the coincidental finding of transferrable decreased susceptibility to narasin. (manuscript)
III.Nilsson, O., Greko, C., Bengtsson, B. (2009). Environmental contamination by vancomycin resistant enterococci (VRE) in Swedish broiler production. Acta Veterinaria Scandinavica 51, 49
IV.Nilsson, O., Greko, C., Vågsholm, I., Bengtsson, B. Survival of vancomycin resistant Enterococcus faecium under laboratory and field conditions – a pilot study to investigate if eradication from broiler farms is possible? (manuscript)
Place of Publication:Uppsala
Publisher:Dept. of Clinical Sciences, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-7595-8
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L70 Veterinary science and hygiene - General aspects
L Animal production > L73 Animal diseases
Subjects:Obsolete subject words > VETERINARY MEDICINE > Veterinary epidemiology
Agrovoc terms:broiler chickens, streptococcus faecium, antibiotics, resistance to antibiotics, genes, epidemiology, sweden
Keywords:VRE, epidemiology, broiler, vancomycin, vanA, Enterococcus faecium, disinfection, gene transfer, narasin, plasmid addiction system
URN:NBN:urn:nbn:se:slu:epsilon-e-95
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-95
ID Code:8125
Department:(VH) > Dept. of Clinical Sciences
External funders:Stiftelsen Lantbruksforskning
Deposited By: Oskar Nilsson
Deposited On:12 May 2011 10:52
Metadata Last Modified:02 Dec 2014 10:46

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