A simple colony-blot method for identification of Listeria in food samples.

A method for identification of Listeria in food samples was developed. It consisted of cultivating of suspected specimen on standard agar medium, direct absorption of grown colonies onto nitrocellulose membrane and processing of the latter with rabbit serum raised against purified cell wall protein Lm79/39 of L. monocytogenes. Analysis using anti-rabbit peroxidase conjugate and 4-chloro-1-naphthol and H2O2 solutions allowed direct detection of Listeria colonies which remained readily available for subsequent isolation.