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ABSTRACT. The Listeria monocytogenes-carrying rates were 100% for listeriosis patients and 1.3% for healthy humans. The L. monocytogenes contamination rates for retail sliced beef (34.2%) and pork (36.4%) were significantly higher (p<0.05) than those for cattle (2.0%) and pigs (0.8%) and for cattle (4.9%) and swine (7.4%) carcasses. The percentages of serotypes 1/2a, 1/2b and 4b which are most dominant in human patients were high in isolates from fresh (90.0%) and processed (100%) fish and shellfish and imported natural cheese (96.7%). -KEY WORDS: Listeria monocytogenes, meat, serotype J. Vet. Med. Sci. 60(12): 1341-1343, 1998 A 1-g portion of stool and intestinal content samples was enriched in 9 ml UVM medium (Difco Laboratories, Detroit, Mich.) or EB medium (Difco). The swabs were each added to 9 ml of an enrichment medium. Samples of natural cheese (25 g) and meat and fresh and processed seafoods (10 g each) were each placed in a stomacher bag containing 225 ml or 90 ml of the enrichment medium, and homogenized for 1 min with a stomacher. The stomacher bags were incubated at 30°C for 48 hr. Two to three loopfuls of the cultured enrichment medium from the stomacher bags were streaked on a plate of Oxford agar medium (Oxoid, Unipath Ltd., Basingstoke, Hampshire, England) or PALCAM agar medium (Merck Co., Inc., Rahway, N.J.) supplemented with amphotericin B (Sigma Chemical Co., St. Louis, Mo.) at a concentration of 6 µg/ml to inhibit the growth of mycetes and the plates were incubated at 30°C for 48 hr. Slightly flat colonies with brownish color in the periphery, which is characteristic of Listeria, were subcultured on Tryptose Agar medium (Difco). The colonies developed on Tryptose Agar medium were observed under a low power microscope with obliquely reflected light and blue greenish colonies were selected [12]. Identification was carried out by Gram staining, catalase and VP tests, observation of umbrella-like growth and motility in semiliquid Brain Heart Infusion Agar medium (Difco), utilization of rhamnose, xylose and mannitol, β-hemolysis on 5% sheep blood Tryptic Soy Agar medium (Difco) and the CAMP test [12] with Staphylococcus aureus JTE 88-221 and Rhodococcus equi JTE 89-387 .The factor sera were prepared by hyperimmunizing rabbits (Japan Laboratory Animals, Inc., Tokyo) with each of 12 reference strains, L. monocytogenes JTE 88-178 to JTE , by the method of Seeliger and Höhne [11]: 11 kinds of somatic (O) antigen factor sera and four kinds of flagellum (H) antigen factor sera were obtained. Serotyping was conducted by O and H agglutination reactions on microplates [1]. Description of the serotypes of the isolates was followed after Seeliger and Höhne [11].As shown in Table 1, the L. monocytogenes-carrying rates

There is a strain of Clostridium perfringens, W5052, which does not produce a known enterotoxin. We herein report that the strain W5052 expressed a homologue of the iota-like toxin components sa and sb of C. spiroforme, named Clostridium perfringens iota-like enterotoxin, CPILE-a and CPILE-b, respectively, based on the results of a genome sequencing analysis and a systematic protein screening. In the nicotinamide glyco-hydrolase (NADase) assay the hydrolysis activity was dose-dependently increased by the concentration of rCPILE-a, as judged by the mass spectrometry analysis. In addition, the actin monomer of the lysates of Vero and L929 cells were radiolabeled in the presence of [32P]NAD and rCPILE-a. These findings indicated that CPILE-a possesses ADP-ribosylation activity. The culture supernatant of W5052 facilitated the rounding and killing of Vero and L929 cells, but the rCPILE-a or a non-proteolyzed rCPILE-b did not. However, a trypsin-treated rCPILE-b did. Moreover, a mixture of rCPILE-a and the trypsin-treated rCPILE-b enhanced the cell rounding and killing activities, compared with that induced by the trypsin-treated rCPILE-b alone. The injection of the mixture of rCPILE-a and the trypsin-treated rCPILE-b into an ileum loop of rabbits evoked the swelling of the loop and accumulation of the fluid dose-dependently, suggesting that CPILE possesses enterotoxic activity. The evidence presented in this communication will facilitate the epidemiological, etiological, and toxicological studies of C. perfringens food poisoning, and also stimulate studies on the transfer of the toxins’ gene(s) among the Genus Clostridium.

Staphylococcal food poisoning (SFP), one of the commonest food-borne diseases, results from the ingestion of one or more staphylococcal enterotoxins (SEs) produced in foods by Staphylococcus aureus. In the present study, 203 S. aureus strains originating from 83 outbreaks that had occurred in Tokyo were examined for their coagulase type and genotype of SEs to analyze their molecular epidemiological characteristics. The representative subsets of the 83 S. aureus isolates were analyzed by multilocus sequence typing (MLST) and S. aureus pathogenicity island (SaPI) scanning. The isolates were integrated into eight specific clonal complexes (CC) s; CC81, CC8, CC6, CC5, CC508, CC59, CC20 and CC30. The profiles of the coagulase type, SE/SEl genotype and the suspected type of enterotoxin-encoding mobile genetic element (MGE) indicated a correlation with each CC. SaPI scanning showed fixed regularity between the distributions of genomic islands, including SaPIs, and the phylogenetic lineage based on MLST. These results indicate that the S. aureus isolates, which classified into eight CCs, have distinguishable properties concerning specific coagulase type, enterotoxin genotype and MGE type. Strains of S. aureus harboring these particular elements possess the potential to cause SFP.

ABSTRACT. Coxiella burnetii is the causative agent of Q fever, and the main route of infection in humans is inhalation of contaminated aerosols. Although oral transmission by contaminated raw milk or dairy products is also a possible route of human infection, there have been few studies investigating the presence of C. burnetii in dairy products. We developed a new method of extracting DNA from cheese and detecting C. burnetii DNA in cheese samples with a nested PCR assay. The limit of detection was 6.0  10 2 C. burnetii particles per gram. We subsequently used this method to examine the presence of C. burnetii in cheese at commercial markets in Tokyo from June 2005 to December 2008. Twenty-eight of 147 cheese samples were found to be positive for C. burnetii DNA. However, when we assessed the viability of C. burnetii by inoculating mice with DNA-positive samples, all of the samples were found to be negative. Thus, the viability of C. burnetii appears to have been lost in these cheese samples.