Microgen Listeria Identification Kit Gains AOAC RI Approval

The Microgen Bioproducts Listeria Identification Kit, Microgen® Listeria ID (MID 67) has been granted AOAC Research Institute Performance Tested Methods (PTM) Status by the internationally recognized AOAC International.

The achievement of Performance Tested Methods Status is a complex task requiring extensive performance validation including confirming the ability of the kit to accurately identify Listeria spp. from a wide range of sources, the ability of the kit to discriminate clearly between Listeria spp. and non Listeria spp., shelf life validation and the general robustness of the kit under extremes of testing conditions including, inoculum variation, incubation temperature. In addition, compliance with BAM Methods must be confirmed.

The AOAC International has examined the Microgen® Listeria ID (MID 67) kit and has recognized that it is not only does the kit fulfill its intended purpose i.e. identify Listeria spp., but it is able to readily discriminate non Listeria spp. complies with the BAM Method and meets all of the criteria for robustness both in terms of usability and storage required of a kit to meet their stringent requirements for PTM Status.

The Microgen® Listeria ID kit comprises 11 carbohydrate utilization tests and a highly sensitive haemolysis test housed in a microwell format for the identification of Listeria species. The carbohydrate utilization tests employ a simple colour change based on the formation of acid end products from fermentation, whilst the haemolysin test is simply performed by adding 1 drop of the specially stabilized sheep red blood cells comprising the haemolysin reagent to the last well (well 12) of the test panel.

If the organism being identified produces haemolysin (L. monocytogenes), the red blood cells will rapidly be lysed and the cellular contents released into the suspending medium and the contents of the well will appear as a homogeneous red/ brown solution. Alternatively, if the organism being identified does not produce haemolysin, the stabilized red blood cells will remain intact. These cells will settle to the bottom of the microwell forming a distinct red layer with a clear supernatant. The results from the identification panel are then interpreted using the Microgen® Identification Systems Software, an easy to use but sophisticated software package which includes numerous unique features to assist in the interpretation of test results.