Evaluation of the 3M™ Petrifilm™ Rapid E. coli/Coliform Count Plate for the Enumeration of E. coli and Coliforms: Collaborative Study, First Action: 2018.13.

Abstract

The 3M™ Petrifilm™ Rapid E. coli/Coliform Count Plate is a selective and differential sample-ready-culture medium designed for the rapid enumeration of Escherichia coli (E. coli) and coliforms in the food and beverage industries. The 3M Petrifilm Rapid E. coli/Coliform Count Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM) Chapter 4 Enumeration of Escherichia coli and the Coliform Bacteria, the International Organization of Standards (ISO) 4832:2006 Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of coliforms-Colony-count technique, and ISO 16649-2:2017 Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of beta-glucuronidase-positive Escherichia coli-Part 2 Colony-count technique at 44 degrees C using bromo-4-chloro-3- indolyl beta-D-glucuronide methods for the enumeration of E. coli and coliforms in dry dog kibble. The candidate method was evaluated using two diluents, Butterfield's phosphate buffered diluent and peptone salt solution, in a paired study design with each reference method in a multi-laboratory collaborative study following the current AOAC Validation Guidelines. Three target contamination levels and an uninoculated control level were evaluated. The candidate and reference methods were not statistically different at each contamination level. Reproducibility values obtained during the collaborative study were similar between the candidate and reference methods. These results demonstrate that the candidate method is equivalent to the reference methods. 3M Petrifilm Rapid E. coli/Coliform Count Plate was recommended for Official First Action status for enumeration of E. coli and coliforms in a broad range of foods and environmental surfaces.