Antimicrobial Susceptibilities of Listeria monocytogenes Isolated from the Imported and the Domestic Foods in Japan

In vitro antimicrobial susceptibility of Listeria monocytogenes isolated from the imported and the domestic foods in Japan was determined by plate dilution method. Eleven isolates from domestic meat, meat products, liver, seafood and environment, and 16 isolates from imported meat and meat products were examined their susceptibilities against ampicillin, chloramphenicol, enrofloxacin, erythromycin, gentamicin, kanamycin, penicillin and tetracycline. All of the isolates except the one isolate from domestic scallop were susceptible to all the antibiotics tested. Only 1 isolate showed resistance to kanamycin and gentamicin. The minimum inhibitory concentration (MIC) for 50% of the strains and the MIC for 90% of the strains were comparable between the imported and the domestic food origins. These results suggest there were less differences of antimicrobial susceptibility between the two origins of Listeria isolates.