Submitted to: International Association for Food Protection Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/10/2005
Publication Date: 8/14/2005
Citation: Van Kessel, J.S., Karns, J.S., Gorski, L.A., Perdue, M.L. 2005. Subtyping Listeria monocytogenes from bulk tank milk using automated repetitive element-based PCR. In: International Association for Food Protection Proceedings, August 14-17, 2005, Baltimore, MD. p. 14.
Technical Abstract: A total of 65 L. monocytogenes strains from raw milk were analyzed using an automated repetitive element-based PCR system to examine the utility of this system for serotype grouping and to determine if regional relationships could be identified. Results of the similarity analysis revealed three primary clusters. Isolates in Cluster 1 represented serogroups 1/2a, 1/2b, 4b, 3b, and 4c. Cluster 2 exclusively contained serogroup 1/2a isolates, although two 1/2a isolates were also found in each of Clusters 1 and 3. Cluster 3 contained only 4 isolates from serogroups 1/2a (2), 1/2b (1), and 4c (1). Clusters 1 and 2 were separated at a relative similarity of 86% and these two clusters had <65% similarity with Cluster 3. Cluster 3 isolates were shown to be more similar to Cluster 1 and 2 isolates than to L. ivanovii and L. seeligeri, and less similar to Cluster 1 and 2 isolates than L. welshimeri, L. grayi, and L. innocua. When rep-PCR fingerprints of the L. monocytogenes 1/2a isolates were compared, regional grouping was not apparent. However, discrimination between isolates suggests that this method might have utility in tracking L. monocytogenes 1/2a. This would be useful for tracking isolates across regions or within smaller ecological niches. It appears that the automated rep-PCR method used could not discriminate between serotypes 1/2b and 4b, but has the potential for discriminating between L. monocytogenes 1/2a isolates and may be useful for differentiating 1/2a isolates from other serovars and for tracking isolates within this serotype.