P1-93 Validation of 3M Molecular Detection System Compared to the Australian Standard Cultural Method for Detection of Salmonella in Water Matrices

Monday, August 1, 2016
America's Center - St. Louis
Scott Egan, 3M Food Safety, North Ryde, Australia
Bruce Reed, ProMicro Pty Ltd, Hillarys, Australia
Introduction: The 3M Molecular Detection System utilizes a combination of isothermal DNA amplification and bioluminescence to detect targeted pathogens following an enrichment step. Previously the system has been shown to provide equivalent results to standard methods when testing food and environmental samples.

Purpose: The project aim was to evaluate the 3M Molecular Detection Assay (MDA) Salmonella for screening water samples and to compare the results obtained to the Australian standard method.

Methods: Water samples analyzed in this study were “as-received” from clients; some of the samples were artificially inoculated with Salmonella to provide positive results. An aliquot of each sample was vacuum filtered and enriched in Buffered Peptone Water for 18-24 h and then tested by two methods: (a) 3M MDA Salmonella as per the manufacturer’s instructions; and (b) Australian Standard cultural method via subculturing into MKTTn and RVS, further selective enrichment incubation for 24 h and 48 h and plating of the selective enrichments onto two different selective agars.

Results: Of the 222 samples tested for Salmonella, 49 were positive by the 3M MDA and Australian standard method while 173 were negative by both methods. This shows 100% agreement between the two methods under the test conditions used.

Significance: The 3M MDA Salmonella provides a presumptive result for the presence of Salmonella in water, within 24 hours, allowing for more timely reporting of results without compromising accuracy.