The use of DNA probes for confirming enterotoxin production by Staphylococcus aureus and micrococci

Development of a single-reaction multiplex PCR toxin typing assay for Staphylococcus aureus strains

We describe here the development of a single-reaction multiplex PCR assay for the enterotoxin genes from Staphylococcus aureus that utilizes a universal toxin gene primer in combination with toxin-specific primers to amplify characteristic toxin gene products. In combination with a new DNA purification method, the assay can detect enterotoxin genes A to E from a pure culture within 3 to 4 h. The test was used to characterize a diverse set of environmental S. aureus isolates, and a 99% correlation with toxin typing using standard immunological tests was found. The design of the assay allows it to be extended to include both newly characterized and as-yet-unknown toxin genes.

Probes and polymerase chain reaction for detection of food-borne bacterial pathogens

DNA-hybridization and the polymerase chain reaction (PCR) are techniques commonly used to detect pathogenic bacteria. In this paper, the use of these techniques for detection of Salmonella, E. coli, V. cholerae, non-O1 Vibrio, Yersinia enterocolitica, Campylobacter, Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, and C. botulinum is reviewed with emphasis on application in food microbiology. In food control, DNA-techniques have most often been used in a 'culture confirmation' fashion, i.e. bacteria are enriched and sometimes even purified by traditional culture procedures and thereafter identified by the use of DNA-based methods. The most desirable approach is, however, to detect organisms directly in the food, but major problems remain to be solved before this can be routinely performed.

Feasibility of a reference material for staphylococcal enterotoxin A

A reference material for staphylococcal enterotoxin A (SEA), was produced by spray-drying the toxin in milk. With this procedure the SEA was distributed homogeneously in the material. For ease of handling the reference material was encased in gelatin capsules, each containing 405 ng of SEA. Simply dissolving the milk powder in distilled water resulted in a 100% recovery of the SEA present. The reference material would appear suitable for testing laboratory performance, comparison of detection methods and to validation of extraction procedures.