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Supplement to the Method MFLP-74
April 2004
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(PDF Version - 69.60 K)1. Application
The following information is offered as a supplement to the method, MFLP-74, dated April 2002, and should be used with this method. The purpose of the attached is to provide additional information (such as: source(s) of materials, critical steps, confirmation steps, or helpful hints etc.).
6.5 Interpretation
Changes to the Interpretation are in bold.
6.5.1 1:10 dilution
If more than two colonies in total from any set of two plates (e.g., two LPM, two Oxford) are confirmed as L. monocytogenes, report the result as positive; i.e., >100 CFU/g. Otherwise report as ≤ 100 CFU/g.
6.5.2 1:5 dilution
If one or more colonies in total from a set of 3 plates (e.g., three LPM, three Oxford), are confirmed as L. monocytogenes , report the result as positive; i.e., >5 CFU/g. Otherwise report as ≤ 5 CFU/g.
6.5.3 Record the results separately for each of the two selective agars. However, for simplicity and convenience, only the highest result should be reported. If any one of the five sample units is positive, the lot should be reported as positive, i.e., >5 CFU/g or >100 CFU/g.
