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Increased In Vitro Adherence and On-Farm Persistence of Predominant and Persistent Listeria monocytogenes Strains in the Milking System

Permanent URL:
http://handle.nal.usda.gov/10113/49759
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Abstract:
Dairy farms are a reservoir for Listeria monocytogenes, and the reduction of this pathogen at the farm level is important for reducing human exposure. The objectives of this research were to study the diversity of L. monocytogenes strains on a single dairy farm, assess strain dynamics within the farm, identify potential sources of L. monocytogenes in bulk tank milk and milk filters, and assess the adherence abilities of representative strains. A total of 248 L. monocytogenes isolates were analyzed by pulsed-field gel electrophoresis (PFGE). Combined AscI and ApaI restriction analysis yielded 40 PFGE types (strains). The most predominant strains were T (28.6%), D (22.6%), and F (14.9%). A high level of heterogeneity of strains among isolates from fecal (Simpson's index of diversity [SID] = 0.96) and environmental (SID = 0.96) samples was observed. A higher homogeneity of strains was observed among isolates from milk filters (SID = 0.71) and bulk tank milk (SID = 0.65). Six of 17 L. monocytogenes isolates (35.3%) were classified in an in vitro assay as having a "low adherence ability," 9 (52.9%) were classified as having a "medium adherence ability," and 2 (11.8%) were classified as having a "high adherence ability." The L. monocytogenes strains that were predominant and persistent showed significantly better adherence than did strains that were only sporadic, predominant, or persistent (P = 0.0006). Our results suggest that the milking system was exposed to several L. monocytogenes strains from different sources. Only 3 strains, however, were successful in persisting within the milking system, suggesting that some strains are more suitable to that particular ecological environment than others.
Author(s):
Latorre, Alejandra A. , Van Kessel, Jo Ann S. , Karns, Jeffrey S. , Zurakowski, Michael J. , Pradhan, Abani K. , Boor, Kathryn J. , Adolph, Evin , Sukhnanand, Sharinne , Schukken, Ynte H.
Subject(s):
Listeria monocytogenes , milking equipment , animal pathogenic bacteria , dairy farming , strains , milk tanks , bacterial adhesion , pulsed-field gel electrophoresis , feces , species diversity , filters , in vitro studies , food pathogens , milking parlors , polymerase chain reaction , pathogen identification , New York
Format:
p. 3676-3684.
Note:
Includes references
Source:
Applied and environmental microbiology AEM 2011 June 1, v. 77, no. 11
Language:
English
Publisher:
American Society for Microbiology
Year:
2011
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.