Upon incubation at 37°C in the absence of Ca2" ions, pathogenic yersiniae release large amounts of pYV plasmid-encoded proteins (PuID) or in the assembly of ifiamentous bacteriophages (gene IV product). At least the putative products of yscD, yscJ, and yscL were shown to be required for the export of Yops. YscJ turned out to be YlpB, a lipoprotein that we had detected previously. The yscM gene shares homology with yopH, the adjacent gene on the pYV plasmid. Its product does not appear to be necessary for the production of Yops. Transcription of the virC operon was subjected to the same regulation as the yop genes.

No abstract

The intron-encoded endonuclease I-CeuI from Chlamydomonas eugametos was shown to cleave the circular chromosomes of all Clostridium perfringens strains examined at single sites in the rRNA operons, thereby generating ten fragments suitable for the rapid mapping of virulence genes by pulsed-field gel electrophoresis (PFGE). This method easily distinguishes between plasmid and chromosomal localisations, as I-CeuI only cuts chromosomal DNA. Using this approach, the genes for three of the four typing toxins, beta, epsilon, and tau, in addition to the enterotoxin and lambda-toxin genes, were shown to be plasmid-borne. In a minority of strains, associated with food poisoning, where the enterotoxin toxin gene was located on the chromosome, genes for two of the minor toxins, theta and mu, were missing.

Several bacterial indicators are used to evaluate hygiene during the meat slaughtering process. The objectives of this study were to assess the Belgian baseline data on hygienic indicators and the relationship between the indicators and zoonotic agents to establish hygiene indicator criteria for cattle, pig, and chicken carcasses and meat. The study used the results from the official Belgian surveillance plan from 2000 to 2003, which included the monitoring of Escherichia coli counts (ECC), Enterobacteriaceae counts (EC), aerobic colony counts (ACC), and Pseudomonas counts (PC). The sampling method was the wet and dry swabbing technique for cattle and pig carcasses and neck skin excision for broiler and layer chicken carcasses. The 75th and 95th percentiles of ECC were -0.20 and 0.95 log CFU/cm2 for cattle carcasses, 1.20 and 2.32 log CFU/cm2 for pig carcasses, and 4.05 and 5.24 log CFU/g for chicken carcasses. The ACC were 2.1- to 4.5-log higher than the ECC for cattle, pigs, and chickens. For cattle and pig carcasses, a significant correlation between ECC, EC, and ACC was found. ECC for pork and beef samples and EC in pig carcasses were significantly higher in samples contaminated with Salmonella. In poultry samples, ECC were in general higher for samples containing Salmonella or Campylobacter. Thus, E. coli may be considered as a good indicator for enteric zoonotic agents such as Salmonella for beef, pork, and poultry samples and for Campylobacter in poultry samples.