Probelia((TM)) PCR system for rapid detection of Salmonella in milk powderand ricotta cheese

The Probelia(TM) Salmonella sp. PCR amplification and detection kits (Sanof i Diagnostics Pasteur, Marnes La Coquette, France) were evaluated for the r apid and specific detection of Salmonella agona artificially inoculated int o skim milk powder and ricotta cheese. The Probelia(TM) results were compar ed with those obtained using the Australian Standard Method. Using a pure c ulture of Salm. agona, the detection limit of Probelia(TM) was between 8 an d 79 cfu ml(-1), equivalent to 0.2-2 cfu per PCR reaction. Detection of Sal m. agona inoculated in skim milk powder (at 5-10 cfu g(-1), stored at 5, 15 or 25 degrees C) and ricotta cheese (at 1-2, 10-20 and 100-200 cfu per 25 g) was effected by using non-selective enrichment prior to the PCR determin ations. For all of the 40 milk powder samples and 12 ricotta cheese samples , the Probelia(TM) results were consistent with those using the Australian Standard Method. Using Probelia(TM), Salmonella was detected to genus level in the dairy products within 24-28 h, whereas the cultural technique requi red 3-4 d for presumptive positive isolates and further time for confirmati on.