A COMPARISON OF THE HEALTH PROTECTION BRANCH AND THE ENZYME LINKED FLUORESCENT ASSAY METHODS FOR THE ISOLATION AND IDENTIFICATION OF LISTERIA SPP. AND LISTERIA MONOCYTOGENES FROM FOODS

Abstract

Abstract The conventional Health Protection Branch method (MFHPB-30) for the detection of Listeria monocytogenes is labor intensive and may require seven days to complete, depending on the initial levels of the organism in the food sample. Thus, there is a definite need for a rapid isolation and detection method. There are two commercially available versions of the enzyme linked fluorescent assay (ELFA) method for identifying Listeria from foods. One identifies Listeria to the genus level and the other to the species (L. monocytogenes) level, with both giving results within 50 h. In the present study, the two ELFA methods were compared to the HPB method to determine their efficiency.

For the genus-specific test, 326 uninoculated foods were compared by both the HPB and ELFA methods. When comparing the HPB method to the genus-specific ELFA method, the latter had a false-negative rate of 4.6%. There were no false positives. For the species-specific ELFA assay, of the 186 foods compared by the two methods, a false-negative rate of 8.1% and a false-positive rate of 3.8% was observed in the ELFA method as compared to the HPB method.