Foodborne Listeriosis 321lots teste

Foodborne Listeriosis 321
lots tested, with isolates from five lots matching the case isolate by serotyping and multilocus enzyme electrophoresis (MEE). Production line sampling revealed an increased contamination frequency of samples after mechanical removal (peeling) of the cellulose casing, and a swab sample taken from the conveyer belt onto which the peeled franks dropped yielded the same subtype. Another L. monocytogenes serotype, 1/2b, was isolated from product and environmental samples
in the room in which the cooked franks were cooled prior to peeling. The environmental investigation results provided strong evidence that the source of contamination was the processing environment, and that contamination occurred at the peeling step—after the cook step, which would inactivate L. monocytogenes. Isolation of this subtype from the plant environment over 4 months after the case occurred suggested its persistence in the processing area. The presence and persistence of L. monocytogenes in processing areas has proven to be a significant challenge to regulators and the food industry in the United States, as the contamination of ready-to-eat meat and poultry products after preparation of the finished product but before packaging led to three large, multistate listeriosis outbreaks over the following 12 years. This investigation provided early evidence that prevention of even low-level finished product contamination is critical to prevention of listeriosis, especially since L. monocytogenes grows well during storage of processed poultry products [69]
and appeared to have grown by several logs during home refrigeration of the frankfurters implicated here. In 1987, USDA–FSIS responded to increased knowledge of the association of L. monocytogenes with deli meats and other processed foods by initiating a monitoring program for ready-to eat meat and poultry products produced in federally inspected establishments (4). In 1989, USDA–FSIS established a zero tolerance policy for L. monocytogenes and other pathogens in ready to-eat meat and poultry products [3].