N. Rijpens et al., Rapid detection of stressed Salmonella spp. in dairy and egg products using immunomagnetic separation and PCR, INT J F MIC, 46(1), 1999, pp. 37-44
The rapid detection of an average of 5.9 stressed Salmonella cells in 25 g
of food product using immunomagnetic separation (IMS) and PCR is described.
For pasteurised egg yolk, egg yolk powder, ice-cream, whole egg, egg white
and cheeses made from pasteurised milk PCR was applied after 16 h of preen
richment in buffered peptone water (BPW) using IMS and alkaline lysis as sa
mple preparation method. For whole egg and egg white the BPW was supplement
ed with iron. For milk powder, and raw milk cheeses, the 16-h preenrichment
in BPW was followed by IMS and a 4-h enrichment in Rappaport-Vassiliadis b
roth. In the latter case, PCR was applied on the enrichment medium after ce
ntrifugation and alkaline lysis. For PCR the primers ST11 and ST15 (Aabo et
al., 1993) producing a fragment of 429 bp were used. An internal PCR contr
ol, designed to be co-amplified with the target DNA using the same primers
but producing a smaller fragment of 240 bp, was used. (C) 1999 Elsevier Sci
ence B.V. All rights reserved.