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A case of bovine raw milk contamination with Listeria monocytogenes
Hunt, Karen; Drummond, Niall; Murphy, Mary; Butler, Francis; Buckley, James F.; Jordan, Kieran
During routine sampling of bulk raw milk on a dairy farm, the pathogenic bacteria Listeria monocytogenes was found to be a contaminant, at numbers < 100 cfu/ml. A strain with an indistinguishable pulsed-field gel electrophoresis pattern was isolated from the bulk milk two months later. Environmental swabs taken at the dairy environment were negative for the presence of L. monocytogenes, indicating a possible case of excretion of the L. monocytogenes directly into the milk. Milk samples were collected from the individual cows and analysed, resulting in the identification of L. monocytogenes excretion (at 280 cfu/ml) from one of the 4 mammary quarters of one dairy cow out of 180. When the infected cow was isolated from the herd, no L. monocytogenes was detected from the remaining herd. The pulsed-field gel electrophoresis pattern of the strain from the individual cow was indistinguishable from that originally isolated from the bulk milk. The infected cow did not show any clinical signs of disease, nor did the appearance of the milk have any physical abnormalities. Antibiotic treatment of the infected mammary quarter was found to be ineffective. This study shows that there can be risks associated with direct contamination of raw milk with L. monocytogenes. Teagasc Walsh Fellowship; Irish Department of Agriculture, Fisheries and Food, Food Institutional Research Measure (Irish Microbial Risk Assessment Network project); European Union (EU), 6th Framework Programme (BIOTRACER project).
Keyword(s): Listeria monocytogenes; Pulsed-field gel electrophoresis; Contaminated milk
Publication Date:
Type: Other
Peer-Reviewed: Yes
Language(s): English
Contributor(s): Teagasc Walsh Fellowship Programme; Department of Agriculture, Food and the Marine, Ireland; European Union
Institution: Teagasc
Publisher(s): Biomed Central
First Indexed: 2013-11-19 11:54:04 Last Updated: 2019-09-10 07:14:34