EVALUATION OF RAPID DETECTION METHODS FOR LISTERIA IN TURKEY WASH

Authors: Wesley, Irene; TAKAHASHI, M - ADV ANALYTICAL TECH, INC; LASKY, S - ADV ANALYTICAL TECH, INC

Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/24/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Listeria monocytogenes is a human pathogen that continues to grow and multiply under both refrigeration and acidic conditions in ready to each meat products. Current rapid detection methods for Listeria require a long enrichment process (48 hours) prior to the rapid assay. There are a variety of new methods (flow cytometry, RT-PCR, etc.) being tested in an effort to improve the accuracy and reduce the time frame from sampling to assay results for Listeria detection. Irradiated turkey carcass wash solution was placed in a specialized LEB media (1 ml sample/9 ml media) in the presence or absence of a low level Listeria monocytogenes spike (1-4 cfu/ ml). These samples were incubated at 31 C for 17 hours (no agitation). Immunomagnetic beads coated with antibody specific to several of the Listeria spp. were then added with a one hour incubation at 37 C. This mixture was placed on an external magnetic system for 45 minutes to facilitate the separation of the bead bound bacteria from the turkey wash matrix. The captured bacteria were resuspended in buffer, labeled with a DNA specific fluorochromes (Syto 62) and enumerated for presence or absence using both traditional plate count methods and flow cytometry using the RBD 2000**TM cytometer. The IMS capture efficiency was determined by plating both the supernatant and the captured bacteria. The capture efficiency was greater than 98% (n=4). Based upon the results from the non-contaminated samples, an action level was set at 5000 counts/ml using the RBD 2000 to define the presence of L. monocytogenes contamination.