Isolation of Listeria monocytogenes from vegetation.

A rural area in Virginia, in which clinical listeriosis of man and animals has been rare, was selected for this study. Vegetatino, which had died and remained in the fields over the winter, was collected and examined for Listeria monocytogenes by Gray's cold-holding procedure. Twelve fields were sampled and cultured, and eight strains of L. monocytogenes were isolated. Only two of the strains were pathogenic for the mouse. Compared with strains of L. monocytogenes isolated from listeric humans and animals in Virginia and the United States as a whole, these represented serotypes of low frequency.