Journal of Bacteriology & Parasitology

Abstract

PDX-LIB, an Improvement on Selective Enrichment Media for Detection of Environmental Listeria spp.

Alan Olstein and Joellen Feirtag

PDX-LIB is a selective enrichment indicator broth developed for use as a diagnostic screening test for environmental Listeria spp. contamination. The test method was developed to provide a single step selective enrichment media incorporating a colorimetric indicator to identify presumptive Listeria-positive samples. The method permits high throughput screening of the sample population streamlining the number of steps to confirmatory testing. In the original AOAC Research Institute guided performance test method the PDX-LIB selection media was shown to be significantly more sensitive for detection of Listeria spp. on selected surfaces than the USDA method, which utilizes UVM media as its primary selection step. The present study has shown that the PDXLIB selection media permits substantially greater numbers of recoverable Listeria monocytogenes- positive samples in the AOAC surface study protocol than comparable samples enriched with UVM media. The data presented demonstrate that the PDX-LIB method is a more sensitive method than procedures utilizing UVM enrichment media as the primary step particularly with regard to detection of Listeria sp.