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Title: Comparison of the TEMPO® System, Petrifilm® , and Cultural MPN Procedure for Enumeration of E. coli, Coliforms and Total Aerobic Plate Counts

item Cosby, Douglas
item Bailey, Joseph

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 2/23/2007
Publication Date: 7/8/2007
Citation: Cosby, D.E., Bailey, J.S. 2007. Comparison of the TEMPO® System, Petrifilm® , and Cultural MPN Procedure for Enumeration of E. coli, Coliforms and Total Aerobic Plate Counts. International Association for Food Protection. P2-58:161.

Interpretive Summary:

Technical Abstract: Introduction: Recent innovations in microbiological methods for analysis of food products have been in methods for detection of bacterial pathogens. Petrifilm dehydrated plates are the only significant addition to cultural procedures for indicator organisms in the last 20 years. An automated most probable number (MPN) has been developed utilizing liquid media to enumerate indicator organisms. Purpose: The purpose of this study was to compare the TEMPO automated procedure with cultural MPN procedures and Petrifilm assays for enumeration of E. coli, coliforms, and total aerobic plate counts (TAPC) from chicken samples. Methods: Post-chill chicken carcasses (n=360) were rinse sampled in sterile water and ground chicken (n=250) were stomached in sterile water. The rinsed and stomached samples were serially diluted on the appropriate Petrifilm plate for E. coli, coliforms, and TAPC and tested with the bioMerieux TEMPO system, according to instructions. Results: The correlation between cultural MPN and TEMPO was 0.82 for E. coli and 0.81 for coliforms from post-chill chicken rinse samples. When TEMPO was compared to Petrifilm, the correlation for E. coli, coliforms, and TAPC was 0.78, 0.58, and 0.90 respectively for chicken rinse samples and 0.54, 0.09, and 0.91 for ground chicken samples. There was good correlation between TEMPO and Petrifilm for TAPC. The lack of correlation with Petrifilm coliform and E. coli counts was due to the inability of Petrifilm to distinguish low levels from background microflora. Significance: The data suggests the TEMPO and Petrifilm procedures give comparable counts for TAPC. The low correlation for E. coli and coliforms is explained because of the inability of Petrifilm to enumerate some E. coli and coliforms, particularly when there is a high ratio of competing organisms. TEMPO is an automated system requiring little technician time after the initial processing and provides automated reading, calculation of counts and storage of data.