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Updated: Jun 28, 2026
Aseptic Laboratory Techniques: Plating Methods
Published on: May 11, 2012
Comparison of Petrifilm Staph Express Count System with the bacteriological analytical manual direct-plating method
Willis M Fedio1, Chitra N Wendakoon, Ruben Zapata
1New Mexico State University, Southwest Center for Animal Health, Food Safety and Bio-Security, Food Safety Laboratory, MSC 3BF, PO Box 30003, Las Cruces, NM 88003-8002, USA. wfedio@nmsu.edu
Abstract:
The 3M Petrifilm Staph Express Count System was compared with the U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM) direct-plate count method for the enumeration of Staphylococcus aureus in 6 types of artificially contaminated hard cheese (Asiago, Cheddar, Gruyère, Parmesan, Romano, and Swiss). Five different samples of each cheese type were inoculated with S. aureus (ATCC 25923) to achieve low, medium, and high inoculum levels. S. aureus was enumerated by the Petrifilm and BAM methods, and the results were compared. Multivariate analysis of variance revealed no significant differences (P<0.05) between the 2 methods. The Petrifilm method compared favorably with the BAM procedure. The rapid method was more convenient to use, considerably faster, and less expensive to perform than the BAM method.
