Specificity of the BAX polymerase chain reaction system for detection of 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 BAX system uses PCR to detect Listeria monocytogenes in enrichment cultures derived from food and environmental samples. The specificity and sensitivity of the BAX system for detecting L. monocytogenes were characterized by using both pure and mixed cell cultures, and optimal conditions for production of cell lysates were determined. The BAX system was highly specific for L. monocytogenes, and no interference was seen in the presence of either other Listeria species or microbes from other genera. The assay detected L. monocytogenes at 10(5)-10(6) colony-forming units/mL. This sensitivity is adequate for detecting viable cells after enrichment but prevents false-positive signals from nonviable cells.