ADAPTION OF 2 COMMERCIALLY AVAILABLE DNA PROBES FOR THE DETECTION OF ESCHERICHIA-COLI AND STAPHYLOCOCCUS-AUREUS TO SELECTED FIELDS OF DAIRYHYGIENE - AN EXEMPLARY STUDY

The application of two commercially available colorimetric DNA hybridi zation tests (GENE-TRAK(R) E. coli and Staphylococcus aureus) to selec ted aspects of dairy hygiene was investigated. Bacterial isolates of d ifferent origin, naturally contaminated cheese varieties, nonfact dry milk, milk concentrates, artificially contaminated milk and raw milks from udder quarters were examined. Based on the observation that the s ensitivity of the E. coli DNA probe was comparable to that of the beta -D-glucuronidase-based fluorescence reaction (with 4-methyl-umbellifer yl-beta-D-glucuronide) of E. coli strains in Fluorocult(R) lauryl sulf ate broth, a Most Probable Number technique for enumerating E. coli in cheese using the DNA probe was developed. Another specific DNA probe was applied for the detection of S. aureus as a mastititis agent. By u sing a modified sample preparation, specific diagnosis of this microor ganism in milk from udder quarters was enabled within 6 hours. This pr ocedure is recommended to be used in screening tests. Based on the exa mples presented the potential of these tests in several fields of hygi ene was illustrated.