Micro December 2018

Evaluation of the 3M™ Petrifilm™ Rapid E. coli /Coliform Count Plate Method 1

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AOAC® Performance Tested Method SM 051801

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Abstract

6 The 3M™ Petrifilm™ Rapid E. coli/ Coliform (REC) Count Plate is a selective and differential 7

sample-ready-culture-medium system used for the rapid enumeration of Escherichia coli and 8

coliforms from a broad range of foods and select environmental surfaces. The method was 9

evaluated for AOAC® Performance Tested Method SM certification in accordance with AOAC 10

guidelines. Results from the inclusivity and exclusivity evaluation showed that the test method 11

can distinguish E. coli from all non- E. coli organisms. For non- E. coli coliform strains, the 3M 12

Petrifilm Rapid E. coli /Coliform Count Plate can differentiate coliforms from non-coliform 13

strains. In the matrix study, the performance of the 3M Petrifilm Rapid E. coli /Coliform Count 14

Plate was compared to the U.S. Food and Drug Administration reference method for 31 foods 15

and two environmental surfaces, and to the ISO reference methods for 12 of the 31 foods and 16

both surfaces. Mean differences calculated between the 3M Petrifilm Rapid E. coli /Coliform 17

Count Plate and each reference method were <0.5 log 10 for each level of each matrix. In 18

robustness testing, small deviations to sample volume and incubation time did not affect test 19

results. The 3M Petrifilm Rapid E. coli /Coliform Count Plate demonstrated reliability as a rapid 20

and accurate alternative to the reference methods for the enumeration of E . coli and coliforms 21

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for all foods and environmental surfaces tested in this study.

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