Surveillance and control of food-borne human pathogens, such as Listeria monocytogenes, is a critical
aspect of modern food safety programs at food production facilities. This study evaluated contamination
patterns of Listeria species at a poultry food production facility, and evaluated the efficacy of procedures
to control the contamination and transfer of the bacteria throughout the plant. The presence of Listeria
species was studied along the production chain, including raw ingredients, food-contact, non-foodcontact
surfaces, and finished product. All isolates were sub-typed by pulsed-field gel electrophoresis
(PFGE) to identify possible entry points for Listeria species into the production chain, as well as identifying
possible transfer routes through the facility. The efficacy of selected in-house sanitizers against a
sub-set of the isolates was evaluated. Of the 77 different PFGE-types identified, 10 were found among
two or more of the five categories/areas (ingredients, food preparation, cooking and packing, bulk
packing, and product), indicating potential transfer routes at the facility. One of the six sanitizers used
was identified as unsuitable for control of Listeria species. Combining PFGE data, together with information
on isolate location and timeframe, facilitated identification of a persistent Listeria species
contamination that had colonized the facility, along with others that were transient.