Purpose: The objectives of this study were to conduct longitudinal sampling of 2 ready-to-eat (RTE) meat processing facilities to probe the ecology of E. coli O157:H7, S. enterica, and L. monocytogenes, to identify harborage sites where pathogens persist, and to assemble a set of isolates from harborage sites.
Methods: Briefly, sponge samples of environmental sites, food contact surfaces, and finished products were collected from the 2 facilities over a 6 month period. Up to 55 sites in each facility were sampled monthly with 3 sponge samples (for individual pathogens) taken from adjacent locations at each site. Samples were processed following modified versions of the USDA-FSIS Microbiology Laboratory Guidebook protocols 4.05, 5.05, and 8.07 for isolation of S. enterica, E. coli O157:H7, and L. monocytogenes, respectively.
Results: Five samples from Facility B (1.5%) were positive for S. enterica, but no sampling site produced S. enterica on more than 1 occasion. L. monocytogenes was detected in 11.2% of the samples collected from Facility A, while 14.7% of the samples from Facility B were positive for L. monocytogenes. Ten and 12 sites tested positive for L. monocytogenes on more than 1 sampling date in Facility A and Facility B, respectively. E. coli O157:H7 was not isolated from either facility over the course of the study, and S. enterica was not detected in Facility A.
Significance: These data suggest that E. coli O157:H7 and S. enterica are likely only transiently present in RTE meat processing facilities, while environmental persistence of L. monocytogenes in RTE meat plant harborage sites may be more common.