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Title: Generation of airborne listeria from floor drain

Author
item Berrang, Mark
item FRANK, JOSEPH - University Of Georgia

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2011
Publication Date: 1/23/2012
Citation: Berrang, M.E., Frank, J. 2012. Generation of airborne listeria from floor drain [abstract]. 2012 International Poultry Scientific Forum, January 23-24, 2012, Atlanta, Georgia. p.4.

Interpretive Summary:

Technical Abstract: Listeria monocytogenes can colonize in floor drains in poultry processing plants and further throughout processing facilities, remaining present even after cleaning and disinfection of the plant. Therefore, during wash down, workers exercise caution to prevent escape and transfer of drain microflora to food contact surfaces. The objective of this study was to examine the extent to which an inadvertent water spray into a colonized floor drain can cause the spread of airborne Listeria. Non-virulent L. innocua was used to inoculate a PVC (poly vinyl chloride) model floor drain resulting in approximately 108 cells per mL of PBS (phosphate buffered saline) and 106 attached cells per cm2 inner surface. Each model drain was subjected to a 2 s spray of tap water at 68.9 kPa from a distance of one meter. Airborne cells were collected by means of sedimentation plates filled with modified oxford (MOX) agar which were placed on the floor and walls of a contained room at incremental horizontal and vertical distances of 0.6, 1.2, 2.4 or 4 m from the drain. Sedimentation plates were exposed for 10 min. A mechanical sampler was used to collect air by impaction on the surface of MOX agar to measure the number of cells per liter. The experiment was conducted in triplicate rooms for each replication. Listeria was detected on sedimentation plates on walls as high as 2.4 m above the floor and 4 m from the drain. Plates on the floor were less contaminated with increased distance from the drain; at 0.6 m more than 50 colony forming units (CFU) were detected while at 2.4 m an average of 2.6 CFU were detected. Plates set at the height of a low bench, 2.4 m from the drain were also found positive for Listeria. Results from the mechanical air sampler revealed an average of 0.3 CFU per L of air. A 2 s accidental spray with a water hose into a contaminated area can cause airborne spread of Listeria resulting in the potential for cross contamination of food contact surfaces, equipment and exposed product.