Risk factors favoring the presence of Listeria monocytogenes in Colombian pork-meat processing plants

We tracked Listeria monocytogenes as a microbiological risk factor in pork processing plants. The five plants analyzed were located in main areas for meat processing in Colombia. Prevalence of L. monocytogenes was 11.46% (36/314), represented by serotypes 4b (6/36, 16.7%), 4d/4e (10/36, 27.8%), 4b/4d/4e (4/36; 11.1%), 3a (3/36, 8.3%), 3c (1/36, 2.8) and 1/2c/3c (9/36, 25%); 4/36 isolates (11.1%) were assumed as possible serotypes 4ab or 7. There was no tolerance to per-acetic acid and only 9/36 (25%) surface-isolates displayed tolerance (0.5-2% (v/v)) to alkyl dimethyl benzyl ammonium chloride. The risk factors analysis showed variations for each processing plant and found that surface and equipment had a higher degree of contamination, with the chopper and cutter at the highest risk. The general prevalence of L. monocytogenes in pork meat processing plants was 11.46%. All these results demonstrate deficiencies in the implementation and monitoring of cleaning and disinfection programs. Key words: Risk factors, L. monocytogenes, meat products, pork meat processing plants.