ERP Micro December 2019

bioMérieux GENE-UP® Listeria species 2 (LIS 2) AOAC ® Certification Number 121803

DISCUSSION OF THE MODIFICATION APPROVED May 2016 (4) The GENE-UP Listeria species Assay successfully detected Listeria species from all of the food matrices and the environmental surfaces analyzed. Using POD analysis, no statistically significant differences were observed between the number of positive samples detected by the candidate method and the reference methods for all matrices and environmental surface tested. During the independent laboratory evaluation, two false positive results were obtained, one for deli ham and one for stainless steel. Each sample was reanalyzed due to possible target cross contamination based on the CP and TM values provided by the software. The negative GENE UP result from the stainless steel reanalysis of the retained primary enrichment eliminated the discrepant presumptive positive result. For deli ham the retained lysate indicated a positive for the target analyte; however, the primary enrichment broth was not available for conclusive reanalysis. After careful analysis of the amplification and melting peak curves, the method developers deduce that both initial false positive results (deli ham and stainless steel) from the independent laboratory evaluation were the result of a contamination event during enrichment transfer into the lysis tubes. The GENE-UP Listeria species method is quick and simple to perform, providing results in less than 1.5 hours post incubation of the selective enrichment for 30 sample replicates. The GENE-UP software is user friendly with the ability to track lot information and sample identification quickly and with ease. The GENE-UP software and instrument also offer the ability to utilize an open platform and set up unique runs before a run is completed. The software also provides the user to analyze each individual CT curve and melting curve as well to help aid in problem solving any issues within an individual reaction. The small footprint is also desirable when working in laboratories with a limited amount of space, or a small PCR amplification room.

Table 1. GENE-UP Listeria species Inclusivity Results (4) Reference a Strains

Origin

Assay

Result

1402273

Listeria monocytogenes 1/2a

Beacon

LIS

Positive

1402272

Listeria monocytogenes 1/2a

Ham

LIS

Positive

904046

Listeria monocytogenes 1/2a

Cheese (Pasteurized)

LIS

Positive

1402270

Listeria monocytogenes 1/2a

Smoked Salmon

LIS

Positive

1402283

Listeria monocytogenes 1/2a

Kidney (Pork)

LIS

Positive

1402282

Listeria monocytogenes 1/2a

Environmental Sample

LIS

Positive

906247

Listeria monocytogenes 1/2b

Raw Milk Cheese

LIS

Positive

1402274

Listeria monocytogenes 1/2b

Cheese (Pasteurized)

LIS

Positive

904041

Listeria monocytogenes 1/2c

Raw Milk Cheese

LIS

Positive

904043

Listeria monocytogenes 1/2c

Raw Milk Cheese

LIS

Positive

904045

Listeria monocytogenes 1/2c

Raw Milk Cheese

LIS

Positive

904049

Listeria monocytogenes 1/2c

Fish Fillet

LIS

Positive

1402256

Listeria monocytogenes 1/2c

Environmental Sample

LIS

Positive

904062

Listeria monocytogenes 3a

Collection (ATCC 51782)

LIS

Positive

1402266

Listeria monocytogenes 3b

Sausage

LIS

Positive

1402255

Listeria monocytogenes 3c

Liver (veal)

LIS

Positive

1402254

Listeria monocytogenes 4a

Fish Fillet

LIS

Positive

904042

Listeria monocytogenes 4b

Raw Milk Cheese

LIS

Positive

1402251

Listeria monocytogenes 4b

Shelfish

LIS

Positive

9409081

Listeria monocytogenes 4d

Collection (ATCC 19117)

LIS

Positive

904067

Listeria monocytogenes 4e

Collection (ATCC 19118)

LIS

Positive

8309033

Listeria monocytogenes 4e

Salt meat

LIS

Positive

9408051

Listeria monocytogenes

Smoked salmon

LIS

Positive

9501016

Listeria monocytogenes

Raw Milk

LIS

Positive