P1-12 Comparison of 3M™ Molecular Detection Assay (MDA) Listeria monocytogenes with ISO Standard Method for Rapid Detection of L. monocytogenes Artificially Inoculated on Food Contact Surfaces with or without Organic Load

Sunday, July 26, 2015
Exhibit Hall (Oregon Convention Center)
Hazel Sin Yue Lim , National University of Singapore , Singapore , Singapore
Qianwang Zheng , National University of Singapore , Singapore , Singapore
Marta Mikš-Krajnik , National University of Singapore , Singapore , Singapore
Matthew Turner , 3M Asia Pacific , Singapore , Singapore
Hyun-Gyun Yuk , National University of Singapore , Singapore , Singapore
Introduction: Food contact surfaces contaminated with L. monocytogenes is an important issue for Ready-to-Eat food manufacturers, since surfaces could be a major source of reoccurrence of Listeriosis. It is crucial to implement rapid detection methods at the factory to control such Listeriosis. A commercial rapid detection system based on loop-mediated isothermal amplification coupled with bioluminescence has been developed, and requires broader validation with food contact surfaces in detecting L. monocytogenes.

Purpose: This study aims to evaluate the performance of 3M Molecular Detection System (MDS) in comparison with ISO method for detection of L. monocytogenes on stainless steel and polyethylene surfaces artificially inoculated at low levels with or without organic load.

Methods: The 3-strain cocktail of L. monocytogenes was inoculated on stainless steel and polyethylene surfaces (10 x 10 cm) to achieve 100, 101 and 102 CFU/100 cm2. To prepare the surface with organic load, fresh raw salmon was homogenized with peptone water and the suspension was spread evenly across the surface prior to inoculation. A total of 120 samples were subjected to both MDS and ISO methods. 

Results: The MDS method performed equally effectively compared with ISO method at inoculum levels of 100 and 102/100 cm2, on both surfaces. Reported sensitivity and specificity for inoculum at 101 CFU/100 cm2 were more than 80%, except for stainless steel surfaces without organic load that had a reported sensitivity and specificity of 75% and 92%, respectively.

Significance: This study demonstrates that MDS can provide cost effective, rapid and accurate detection of L. monocytogenes at low inoculum levels on stainless steel and polyethylene surfaces in 26 - 30 hours with a single enrichment.