Listeria Confirmation/Speciation

Method References

ISO 11290: Microbiology of food and animal feeding stuffs - Horizontal method for the detection and enumeration of Listeria monocytogenes

Sample Size

Listeria confirmation/speciation testing is typically requested and completed directly from a presumptive product or presumptive environmental enrichment samples.
Customers may also submit Listeria enrichments or agar plates with isolated Listeria growth for confirmation or speciation.

Estimated Turn Around Time

Confirmation 48-72 hours
Speciation 5 days
Turnaround time may vary if additional time is needed for regrowth and isolation.

Reporting Unit

Listeria confirmation testing will be reported as either Positive or Negative.
Listeria speciation testing will be reported as genus and species, e.g. Listeria monocytogenes.

Method Description

Listeria confirmations are struck to selective and differential agar types. If typical colonies are present then the confirmation is positive. If there is no growth or only atypical growth present, the confirmation is negative.
Listeria speciations can be requested independently or they can be carried on from a positive Listeria confirmation by customer request. Listeria speciations start by being struck to the same selective and differential agar types. Typical colonies are carried on for additional confirmatory testing and resulting in a bacterial identification which will provide the species of Listeria.

Additional Information

Listeria confirmations and speciations are important tools to utilize when dealing with contamination in either product or your production environment.
It is important to know that if you have Listeria monocytogenes present in your environment, you will want to take action to prevent the pathogen from potentially contaminating your product.

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