Adaptation of two commercially available DNA probes for the detection of E. coli and Staphylococcus aureus to selected fields of dairy hygiene--an exemplary study.
The application of two commercially available colorimetric DNA hybridization tests (GENE-TRAK E. coli and Staphylococcus aureus) to selected aspects of dairy hygiene was investigated. Bacterial isolates of different origin, naturally contaminated cheese varieties, nonfat dry milk, milk concentrates, artificially contaminated milk and raw milks from udder quarters were examined. Based on the observation that the sensitivity of the E. coli DNA probe was comparable to that of the beta-D-glucuronidase-based fluorescence reaction (with 4-methyl-umbelliferyl-beta-D-glucuronide) of E. coli strains in Fluorocult lauryl sulfate 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 mastitis agent. By using a modified sample preparation, specific diagnosis of this microorganism in milk from udder quarters was enabled within 6 hours. This procedure is recommended to be used in screening tests. Based on the examples presented the potential of these tests in several fields of hygiene was illustrated.
Kneifel
W
W
Institut für Milchforschung und Bakteriologie, Universität für Bodenkulture, Wien.
Manafi
M
M
Breit
A
A
D000818:Animals; D002417:Cattle; D002611:Cheese / Q000382:microbiology; D015169:Colony Count, Microbial; D015342:DNA Probes; D004269:DNA, Bacterial / Q000032:analysis*; D004755:Enterobacteriaceae / Q000254:growth & development / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D005516:Food Microbiology; D008414:Mastitis, Bovine / Q000382:microbiology; D008856:Microscopy, Fluorescence; D008892:Milk / Q000382:microbiology; D009693:Nucleic Acid Hybridization; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*
D015342:DNA Probes; D004269:DNA, Bacterial