Listeria monocytogenes in spreadable raw sausage and raw sausage batter - Occurrence and quantitative detection

Because of a possible human health risk spreadable raw sausages with a Listeria (L.) monocytogenes contamination level above 1,0 x 10(2) c.f.u./g have to be recalled from market (according to BgVV). Therefore in this study industrially produced raw sausages were examined if they are contaminated with L. monocytogenes. The plate counts from a total of 4430 samples including raw sausage batters and spreadable raw sausages from three producers were examined according to EN ISO 11290 (2):1998. In 98,3 % of these samples L. monocytogenes was not detectable and the investigated L.m. plate counts never exceeded 100 c.f.u./g. By the examination of 562 samples the selective BCM(R) LMP medium (BIOSYNTH) was used in addition to the PALCAM medium (MERCK). Eighteen (3,2 %) samples were found to be positive by the use of the EN ISO method. More positive samples (27/4,4 %) were detected by using the BCM(R) LMP medium. All suspected colonies from the BCM(R) LMP medium appeared after 24 to 48 hours and were confirmed as L. monocytogenes by PCR, tests according to EN ISO 11290-2:1998 as well as with the RAPID' L.MONO medium (BIORAD). Based on our studies, the BCM(R) LMP medium is suitable for a selective and fast enumeration of L. monocytogenes from spreadable raw sausages and raw sausage batters.