THE INCIDENCE OF ESCHERICHIA-COLI ON BEEF CARCASSES AND ITS ASSOCIATION WITH AEROBIC MESOPHILIC PLATE-COUNT CATEGORIES DURING THE SLAUGHTERPROCESS

An analysis of 535 prefabricated beef carcass samples taken in three p rocessing plants demonstrated an association between the mesophilic ae robic plate count (APC) class and the incidence of obtaining an Escher ichia coli-positive ample. Beef carcasses were sampled from three sepa rate plants; one was a fed-beef processing plant and the other two wer e cow/bull plants. Samples were obtained by sponging and were analyzed for APC and E. coli. When samples were classified into four APC level s or classes(class 1: <2, class 2: greater than or equal to 2 and <3, class 3: greater than or equal to 3 and <4, and class 4: greater than or equal to 4 log CFU/cm(2)), a trend indicating that samples from hig her APC classes were more likely to be positive for E. coli biotype I was observed. Of the APC class 4 samples (greater than or equal to 4 l og CFU/cm2), 88% were positive for the presence of E. coli, as opposed to 21% in APC class 1 (<2 log CFU/cm2). Univariate chi-square analysi s of the resulting contingency tables from reclassified data (class 1: <2, class 2: greater than or equal to 2 and <3, and class 3: greater than or equal to 3 log CFU/cm(2)) indicated a strong association betwe en APC class and the incidence (presence or absence) of an E. coli-pos itive sample. Using multivariate analysis to account for influences of plant and within plant processing site, the data indicated a strong p ositive Linear trend between the presence of E. coli and the APC class .