The bacteriophagous nematode Caenorhabditis elegans has been recognized as a surrogate host for human pathogens. The aim of this study was to examine whether food-borne pathogens are pathogenic in nematodes. Young adult worms were allocated onto peptone-free medium covered with a bacterial suspension of each pathogen. The plates were incubated and as the number of live and dead worms scored at least every 24 h. Twelve of the 14 pathogenic strains, namely Aeromonas sobria, the diarrheagenic Escherichia coli strains (enteroaggregative E. coli, enterohemorrhagic E. coli, enteropathogenic E. coli, enterotoxigenic E. coli, enteroaggregative E. coli heat-stable enterotoxin 1 gene-possessing E. coli, and di#usely adherent E. coli), Listeria monocytogenes, Salmonella Enteritidis, Staphylococcus aureus, Vibrio parahaemolyticus, and Yersinia enterocolitica reduced the survival rate of worms to varying degrees. The remaining 2 strains, Bacillus cereus and enteroinvasive E. coli, did not. Thus, food-borne pathogens can infect and proliferate within bacteriophagous nematodes on peptone-free medium to the same extent as reported with conventional peptone-containing medium. However, the non-enteropathogenic E. coli strain HS and deletion mutants of L. monocytogenes, which have lost their virulence in the murine model, were also still nematocidal. Although this nematode could be an alternative host for these pathogens, the nematocidal activity of these pathogens may not necessarily reflect enteropathogenicity in humans. Pathogens and the virulence genes to be analyzed must be carefully selected before using this alternative host.Key words: C. elegans, Enteric pathogen, Virulence, Screening, Infection model Introduction A variety of experimental models have been developed to study microbial virulence or the pathogenicity of protein toxins. However, due to increasing ethical considerations as well as economic reasons, the use of mammalian hosts is decreasing in popularity, and the establishment of e#ective alternative non-mammalian systems is urgently required.There has recently been increasing interest in the soil nematode Caenorhabditis elegans as a possible host of human pathogenic bacteria, since it was reported by Ausubel et al. in 1999 that Pseudomonas aeruginosa caused fatal infection of C. elegans 31) . C. elegans has also been reported as a successful model for the investigation of virulence-associated factors of human pathogens such as Burkholderia pseudomallei 10) , Cryptococcus neoformans 19) , Enterococcus faecalis 27) , enteropathogenic Escherichia coli 2, 16) , Listeria monocytogenes 34) , P. aeruginosa 32) , Serratia marcescens 14) , Shigella flexneri 6) , Staphylococcus aureus 11,28) , and Vibrio vulnificus 9) .We recognized nematodes as a potential new surrogate host, and the degree of similarity between this nematode, C. elegans, and humans is greater than expected 17) . In the above-cited reports, the human pathogens and associated ῍ Ί̮ ῌ558ῌ8585 ̮ῒ ̮ῐῑ̮Ὶ 3ῌ3ῌ138 ῖῚ̮Ῐῗ̮Ῑ῏῎ΐ Jpn.