Aims: This paper reports on a new putative enterotoxin SEU encoded by the enterotoxin gene cluster egc from Staphylococcus aureus and on a real-time polymerase chain reaction (PCR) assay for detecting the seu gene. Methods and Results: PCR and sequencing revealed a new putative enterotoxin SEU encoded by some egc clusters. The seu gene resulted from sequence divergence in the w ent1 and w ent2 pseudogenes previously described in the egc cluster (Jarraud et al. [2001] Journal of Immunology 166, 669). The presence of the seu gene was investigated in a collection of S. aureus strains by conventional PCR and by a specific 5¢-nuclease PCR assay. Among the 24 strains harbouring the egc cluster, four tested positive for the seu gene. Conclusions: The existence of the seu gene adds to the number of newly described se genes and underlines the need for a better understanding of their role in the pathogenesis of S. aureus. Significance and Impact of the Study: A thorough study of the seu gene should provide further insight into the phylogenetics of the staphylococcal enterotoxins.

No abstract

No abstract

No abstract

To evaluate a 16s rRNA gene probe for the identification of staphylococcal species and subspecies, we have augmented previous studies involving 12 staphylococcal species by analysing the remaining 16 species currently classified in the genus Staphylococcus. HindIII-and EcoRI-restricted DNA of isolates from validly described species of Staphylococcus was probed with radiolabelled plasmid pBA2 containing 16s rDNA from Bacillus subtilis. The Dice coefficient was used to assess similarity between the 74 HindIII-and the 81 EcoRI-hybridization patterns obtained from a total of 271 isolates belonging to 31 staphylococcal taxa (28 species, of which three include two subspecies). The use of HimlIII yielded a better discrimination of the stagbylococci than the use of EcoRI. All of the isolates belonging to the same species or subspecies, except S. hyicus isolates, were recovered as homogeneous clusters using their Hind111 hybridization patterns. The phenotypically close taxa were clearly distinguished. Thus, the method presented in this study constitutes a powerful tool for the identification of taxa within the genus StaphyfococcuA

Aims: This paper provides information on a PCR-ELISA method for detecting Shiga toxinproducing Escherichia coli (STEC), and on their prevalence in dairy products. Methods and Results: The sensitivity and speci®city of the test was evaluated using pure cultures, spiked and naturally-contaminated samples. A comparative study with vero cytotoxicity testing was conducted, and STEC isolated from naturally-contaminated 1 samples were characterized. The PCR-ELISA test was highly speci®c and sensitive, and detected 14% more positive samples than the vero cell assay. The prevalence of STEC in raw milk and unpasteurized cheese was 21á5% and 30á5%, respectively, while samples from the`dairy environment' and from pasteurized cheese were less contaminated. The 34 strains of STEC isolated from natural samples showed that some of them carried virulence genes. Conclusions: No conclusion can be drawn at the moment concerning the potential risk to consumers. Signi®cance and Impact of the Study: These data show the necessity of valuable screening methods to appreciate the virulence of STEC.

No abstract

The prevalence of Clostridium botulinum types A, B, E, and F was determined in 214 fresh fish and environmental samples collected in Northern France. A newly developed PCR-enzyme-linked immunosorbent assay (ELISA) used in this survey detected more than 80% of samples inoculated with fewer than 10 C. botulinum spores per 25 g and 100% of samples inoculated with more than 30 C. botulinum spores per 25 g. The percent agreement between PCR-ELISA and mouse bioassay was 88.9%, and PCR-ELISA detected more positive samples than the mouse bioassay did. The prevalence of C. botulinum in seawater fish and sediment was 16.6 and 4%, respectively, corresponding to 3.5 to 7 and 1 to 2 C. botulinum most-probable-number counts, respectively, and is in the low range of C. botulinum contamination reported elsewhere. The toxin type identification of the 31 naturally contaminated samples was 71% type B, 22.5% type A, and 9.6% type E. Type F was not detected. The high prevalence of C. botulinum type B in fish samples is relatively unusual compared with the high prevalence of C. botulinum type E reported in many worldwide and northern European surveys. However, fish processing and fish preparation in France have not been identified as a significant hazard for human type B botulism.