ATCC 43256 (from Mexican-style cheese) and ATCC 49594 (derived from L. monocytogenes strain Scott A) (American Type Culture Collection, Manassas, Va.), and JCM 7676 (from roast beef), JCM 7672 (from salami sausage), and JCM 7671 (from lax ham) (Japan Collection of Microorganisms) were used in this study. Strains were provided by the Laboratory of Zoonosis