Investigation for possible source(s) of contamination of ready-to-eat meat products with Listeria spp. and other pathogens in a meat processing plant in Trinidad

ABSTRACT

In 2003, there was a recall of three processed (chicken franks, spice ham and turkey ham ready-to-eat (RTE) meat products by a large processing plant in Trinidad as a result of contamination by Listeria monocytogenes. The study was conducted to investigate the possible source(s) of Listeria contamination of recalled RTE meat products and to determine the prevalence of Listeria spp., Salmonella spp., Escherichia coli and Campylobacter spp. in the products and air within the plant. Raw and processed meat products, as well as food contact surfaces were also tested for Salmonella spp., Listeria spp. and Campylobacter spp. initially after thorough clean-up and close-down of the plant. Faecal and effluent samples from the piggery, in close proximity to the plant, were tested for the presence of Salmonella spp., Listeria spp. and Campylobacter spp. Air samples and food contact surfaces were negative for the tested organisms. Ten (58.8 per cent) of the 17 effluent samples and 4 (11.8 per cent) of the 34 faecal samples were positive for Campylobacter coli. Of the 11 raw meat products tested, 10 (90.9 per cent) were positive for E. coli and Listeria spp. either singly or in combination. Of the 32 processed RTE products tested, 11 (34.4 per cent) were positive for E. coli, Salmonella spp., Listeria spp. and Campylobacter spp. in combination or singly. Eleven (61.1 per cent) of 18 processed products contained unacceptable levels of aerobic bacteria using international standards. Four months later, following the implementation of recommended cleaning, sanitizing and hygienic practices at the plant, pre- and post-processed products were sampled and Listeria spp. were identified in 4 (80.0 per cent) of the 5 raw products and in 1 of the 5 (20.0 per cent) finished products. It was concluded that the close proximity of the piggery to the processing plant was not the probable source of Listeria contamination of the recalled meat products.