Agricultural Research Service (ARS) scientists have pinpointed the primary source of Listeria monocytogenes contamination in commercial chicken cooking plants: incoming raw poultry. The findings will help processing facilities focus their sanitation processes to reduce cross-contamination. For the 21-month study, scientists from ARS and the University of Georgia tested a new commercial cooking facility before and after processing began. The plant was free of L. monocytogenes when first constructed.
Potential sources of L. monocytogenes were tested by taking samples of soil and water around and near the facility exterior, and by testing heavily traveled floor surfaces following personnel shift changes. Samples were also collected and tested from incoming air from air vent filters and from monthly swabs of incoming raw meat. Floor drains in the facility were sampled approximately monthly to determine at what point the plant would become colonized with the bacteria.
Within four months of operation, L. monocytogenes was detected in floor drains, indicating that the organism had been introduced from some outside source. No L. monocytogenes was recovered from any floor samples in the plant entryways, locker room or cafeteria. Likewise, the organism was not detected on air vent filters during the survey. The only tested source found to be consistently positive for L. monocytogenes was incoming raw poultry meat.