Comparison of AOAC Method and Fluorogenic (MUG) Assay for Enumerating <i>Escherichia coli</i> in Foods

Abstract

ABSTRACT The fluorogenic 4‐methylumbelliferone glucuronide (MUG) test for identifying and enumerating Escherichia coli was compared with the standard most probable number method described in the Official Methods of Analysis of the Association of Official Analytical Chemists. Pecan nutmeats, frozen headless shrimp, and chicken pot pies were seeded with high, medium, and low numbers of viable E. coli organisms ranging from 15 to 500 CFU/g. Twelve replicate units of each food at each seeding level were analyzed by both methods. A statistical evaluation indicated that the MUG method yielded significantly (α= 0.05) higher recovery in three of nine comparisons. The MUG method ranged from 22% lower to 92% higher than the AOAC geometric mean. The MUG method has the potential for reducing analytical time, labor, and media usage.