Kit includes 20 microwell strips in individual foil pouches, 20 bottles of Listeria suspending medium, 1 bottle of red blood cells for haemolysin reaction, holding frame for test microwell strips, result forms and instructions for use. Identification software must be purchased separately.
Testing food and food ingredients for the presence of Listeria species, in particular L. monocytogenes, is one of the main pathogen tests performed in food testing microbiology laboratories. The Listeria ID strip enables laboratories to rapidly identify and confirm from a single colony isolated on selective or non-selective media. In 24 hours or less, Listeria ID will identify and confirm which of the 6 species of Listeria: L. monocytogenes, L. innocua, L. seeligeri, L. welshimeri, L. ivanovii and L. grayi has been isolated.
The Listeria ID system employs 12 standardized microwell biochemical substrates, including an in-well haemolysin test. The substrates are based on classical methods and include: Esculin, Mannitol, Xylose, Arabitol, Ribose, Rhamnose, Trehalose, Tagatose, Glu-1-Phos, Methyl-D-Glucoside, Methyl-D-Mannoside and Hemolysis. The inoculation and incubation of the substrate in each microwell causes a simple color change reaction, yellow is a positive reaction, purple is a negative reaction; there is no guess work involved.
For convenience, an in-well haemolysin test is also included, eliminating the need for additional tests such as CAMP. As the detection of the haemolytic activity is fundamental to the identification of Listeria species (in particular L. monocytogenes and L. ivanovii) and the interpretation of this reaction is sometimes difficult, Microgen Bioproducts has developed a highly sensitive, easily interpreted and stable microwell haemolysin test. The haemolysin test is simply performed by adding 1 drop of the specially stabilized sheep red blood cells (included with kit) to the last well (well 12) of the Microgen Listeria ID test panel. If the organism being identified produces haemolysin, the red blood cells will rapidly be lysed and the cellular contents released into the suspending medium. 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.
Using Listeria ID is simple and requires no set-up. Select a single colony of the isolate to be identified. The colony can be taken from selective or non-selective media, we suggest using BBL™ CHROMagar™ Listeria for presumptive identification. Emulsify colony in the suspending medium provided. Add 3- 4 drops (100µL) suspension to each well of the strip(s). Add 1 drop of red blood cells (provided) to the haemolysin test (well 12). Incubate for 18-24 hours at 35° – 37°C. Read and record results using the software program (sold separately). For a complete explanation of procedure for use, please refer to the Instructions for Use, included with your kit.
AOAC Approval: To establish the performance of the Listeria ID system, in an independent regulatory validation scheme, the product has undergone AOAC Research Institute (RI) Performance Method Tested (PMT) validations against the existing FDA/BAM method. The product was subjected to a range of validation studies including ruggedness, inclusively, exclusivity and performance in direct comparison to the FDA/BAM method. The performance of the product was also assessed using colonies taken from a range of selective, chromogenic and non-selective agars. The outcomes of all of these validation studies were reviewed by independent assessors and the product was granted Performance Method Status by the AOAC research Institute in September 2004. The results achieved in these rigorous validation studies should give confidence to routine food testing laboratories that this miniaturized biochemical identification system for Listeria speciation delivers a rapid method which performs to the highest standards in microbiological testing.
|Listeria ID Technical Information
|The microwell strips are stable in the unopened foil pouches at 2-8°C until the expiry date stated. The Listeria suspending broth and haemolysin reagent should be stored at 2-8°C. The haemolysin reagent should be returned to 2-8°C immediately after use.