Listeria Species in Commercially Broken Raw Liquid Whole Egg

Abstract

Commercially broken raw liquid whole egg (LWE) was obtained from 11 processing establishments across the United States on 3 or 4 occasions over an eight-month period. The samples were evaluated for the presence of Listeria species by the FDA, USDA, and cold enrichment procedures. Forty-five Listeria isolates were obtained from 15 of 42 (36%) egg samples. Both the USDA and FDA methods were useful for isolation of Listeria species, resulting in 12 and 8 positive samples, respectively. Six samples were positive by both procedures. Listeria was isolated from one sample by cold enrichment. The most frequently isolated species was L. innocua, which was found in all (15) of the listeriae-positive samples. L. monocytogenes was the only other species isolated and was obtained from 5% (2) of the egg samples. The USDA and FDA procedures each yielded one L. monocytogenes-positive sample. The two L. monocytogenes-positive samples contained estimated populations of 1 and 8 CFU L. monocytogenes/ml and were obtained from the same plant during the spring and early summer sampling times. Twelve (80%) of the 15 Listeria-positive samples were solids-adjusted LWE. Thus, Listeria species, including the psychrotrophic pathogen L. monocytogenes, are present in commercially broken raw LWE.