SPECIFICITY OF THE BAX POLYMERASE-CHAIN-REACTION SYSTEM FOR DETECTIONOF THE FOODBORNE PATHOGEN LISTERIA-MONOCYTOGENES

The polymerase chain reaction (PCR) can be used for rapid and specific detection of foodborne pathogens. One commercial kit, the Qualicon BA X system uses PCR to detect Listeria monocytogenes in enrichment cultu res derived from food and environmental samples. The specificity and s ensitivity of the BAX system for detecting L. monocytogenes were chara cterized by using both pure and mixed cell cultures, and optimal condi tions for production of cell lysates were determined. The BAX system w as highly specific for L. monocytogenes, and no interference was seen in the presence of either other Listeria species or microbes from othe r genera. The assay detected L. monocytogenes at 10(5)-10(6) colony-fo rming units/mL. This sensitivity is adequate for detecting viable cell s after enrichment but prevents false-positive signals from nonviable cells.