[Comparative study with digoxigenin and biotin markers for the DNA probe identification of genes coding for type TEM...

We have tested two non-isotopic labels: digoxigenin--11-dUTP and biotin-7-dATP for the detection of TEM-1 beta-lactamase gene with a TEM-1 probe by DNA:DNA hybridisation (using spot technique). The use of radioactive labels is inconvenient and not available to all the clinical bacteriological laboratories. The strains tested were: 16 on file (14 carriers of different types of beta-lactamase) and 19 clinical isolated strains. Previously, the plasmid beta-lactamase of these strains had been identified by analytical isoelectric focusing. Using the probe labeled with digoxigenin-11-dUTP, the correlation between results obtained by DNA:DNA hybridisation and those by analytical isoelectric focusing was excellent, with no false positives; with the biotin--7-dATP labeled probe, reading was difficult and some false positives were observed.