Micro December 2018

1 Evaluation of the 3M™ Petrifilm™ Rapid E. coli /Coliform Count 2 Plate for the Enumeration of E. coli and Coliform: 3 Collaborative Study 4 5 Patrick Bird, Benjamin Bastin, Nicole Klass, Erin Crowley, James Agin, David Goins 6 Q Laboratories, Inc., 1400 Harrison Ave, Cincinnati, OH 45214 9 3M Food Safety Department, 3MCenter – Bldg. 260-6B-01, St. Paul, MN 55144 10 11 Collaborators: A. Calle, K. Suntharesan, V. Gohil, A. Donkers, R. Smith, D. Wood, S. Diederich, S. 12 Kuchenberg, I. Satoshi, M. Brown, N. Alvarez, S. Corti, M. Hochreuter 13 The 3M™ Petrifilm™ Rapid E. coli /Coliform Count (REC) Plate is a selective and 14 differential sample-ready-culture medium designed for the rapid enumeration of 15 Escherichia coli and coliform in the food and beverage industries. The 3M Petrifilm Rapid 16 E. coli /Coliform Count Plate was compared to the U.S. FDA Bacteriological Analytical 17 Manual (BAM) Chapter 4 Enumeration of Escherichia coli and the Coliform Bacteria , the 18 International Organization of Standards (ISO) 4832:2006 Microbiology of food and animal 19 feeding stuffs – Horizontal method for the enumeration of coliforms—Colony-count 20 technique and ISO 16649-2:2017 Microbiology of food and animal feeding stuffs – Horizontal 21 method for the enumeration of beta-glucuronidase-positive Escherichia coli - - Part 2 Colony- 22 count technique at 44 degrees C using bromo-4-chloro-3-indolyl beta-D-glucuronide methods 23 for the enumeration of E. coli and coliform in dry dog kibble. The candidate method was 24 evaluated using two diluents, Butterfield’s phosphate buffered diluent and peptone salt 25 solution, in a paired study design with each reference method in a multi-laboratory 26 collaborative study following the current AOAC Validation Guidelines. Three (3) target 27 contamination levels (low, 10-100 colony forming unit (CFU)/g; medium, 100-1,000 CFU/g; 28 high 1,000-10,000 CFU/g) and an uninoculated control level (0 CFU/g) were evaluated. No 29 statistical difference was observed between the candidate method and either the BAM or 30 ISO methods for each contamination level. 31 Coliform bacteria are a category of rod-shaped, non-spore forming Gram-negative bacteria. 32 These organisms can be motile or non-motile and can ferment lactose with the production of acid 33 and gas. While coliform bacteria are very common and normally harmless, coliform 34 contamination in food or beverage products does pose a health risk. Since coliforms are 35 commonly found in soil and vegetation, when coliform contamination is found, it usually is 36 caused by the environment. Coliform presence in food products raises the question of pathogen 37 contamination occurring through a similar process. Many coliforms, including E. coli , a 38 subgroup of coliform, can be found in the human digestive tract. While some strains of E. coli 39 are harmless, other strains can cause serious illness. Just like coliform, if E. coli contamination is 40 detected, this poses a greater risk for other pathogens to be present [1]. 41 Traditional screening and confirmation of E. coli or coliform bacteria can require 3 to 7 days 42 are can be very labor intensive for laboratories. The 3M Petrifilm Rapid E. coli /Coliform Count 43 Plate allows for the simple, rapid enumeration and differentiation of coliform and E. coli in food 44 and environmental samples. Test portions are diluted in an appropriate diluent and a sample 45 7 8 Hannah Bakken

1