Frequency of Contamination with Listeria Monocytogenes of Raw Dried Cured Vacuum Packed Sausages

The aim of this study was to collect actual data concerning the frequency of contamination with Listeria monocytogenes of some raw dried cured vacuum packed sausages, which are very popular in Bulgaria produced from Oct. 2004 till May 2008. 148 vacuum-packed samples were taken from 9 different food business operators during all seasons of the year. The samples were analyzed according to the USDA method for meat foods. Ten specimens were positive for presence of Listeria monocytogenes, which is equal to 6,75% of all tested samples. In two other raw dried cured sausages L. welshimeri and L.innocua were found, but these species are not pathogenic for consumers. In the period before the official implementation of the HACCP system (01.01.2006) in Bulgaria, 52 samples were examined and 5 Listeria monocytogenes isolates were found (~10%). 2,5 years after the HACCP implementation, 96 specimens from the same meat factories were tested and 5 Listeria monocytogenes isolates (5,2%) were detected. Samples taken from lots, produced in winter time were contaminated with Listeria monocytogenes more often (7 of all 10) than specimens taken during other seasons. Data was discussed through the point of view of the effectiveness of hygienic practices and HACCP system application. Also, application of the ‘microbiological criterion’ set in the COMMISSION REGULATION (EC) No 2073/2005 for ready-to-eat foods unable to support the growth of L. monocytogenes was considered.