3M(™) Petrifilm(™) Rapid Aerobic Count (RAC) Plate Method for the Enumeration of Aerobic Bacteria on Selected Surfaces: AOAC Official Method(SM) 2015.13

BACKGROUND: The 3M(™) Petrifilm(™) Rapid Aerobic Count (RAC) Plate is a sample-ready culture medium system designed to facilitate colony enumeration in 24 h (48 h for dry powders) for selected food and environmental surfaces. OBJECTIVE: The objective of this study is to evaluate the 3M Petrifilm RAC Plate in a matrix extension study for the enumeration of aerobic bacteria on stainless steel, sealed concrete, and rubber surfaces. METHOD: The 3M Petrifilm RAC Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual, Ch. 3 (January 2001): Aerobic Plate Count in a paired matrix study for enumeration of aerobic bacteria on stainless steel, sealed concrete, and rubber environmental surfaces. RESULTS: The 3M Petrifilm RAC Plate showed no statistically significant differences when compared to the reference method for enumeration of aerobic bacteria from stainless steel, sealed concrete, and rubber environmental surfaces. There were no significant statistical differences between the 3M Petrifilm RAC Plate and reference method results for the three matrixes evaluated. CONCLUSIONS: The 3M Petrifilm RAC Plate is an effective plating method for aerobic plate count when analyzing stainless steel, sealed concrete, and rubber surfaces. HIGHLIGHTS: The 3M Petrifilm RAC Plate is robust, quick, and simple to perform, providing enumerable colonies in 22 to 26 h after incubation when compared to the 48 h of the reference method. The small size of the Petrifilm Plate allows for less space to be occupied by plates in the incubators. The visual biochemical and enzymatic indicators make enumeration of colonies a simple task by presenting colonies in either a blue or red color.