[Oligonucleotide probes for the characterization of TEM-1 and TEM-2 beta lactamases in Salmonella strains].
BACKGROUND
The aim of this study was to develop molecular biology techniques as hybridization with oligonucleotide probes to characterize TEM-1 and TEM-2 beta-lactamases in strains of Salmonella spp.


METHODS
Twenty seven strains of Salmonella spp. were selected. Twenty six were resistant to ampicillin due to the production of beta-lactamases enzymes of pl of 5.4 and/or 5.6 corresponding to TEM-type. Initially, they were submitted to colony hybridization with a 420 bp. TEM probe obtained from plasmid pBR322. The strains with positive signal were selected to perform colony hybridization and Southern blot with oligonucleotide probes for TEM-1 (Gln 37) and TEM-2 (Lys 37). Finally, polymerase chain reaction technique (PCR) was developed to obtain DNA.


RESULTS
Only 17 out of the 26 beta-lactamase producing strains gave positive signals with the TEM intragenic probe. Experiments with the oligonucleotide probes in colony hybridization did not allow us discriminate positive from negative signals. Southern blot of DNA obtained from alkaline lysates did not work as we could not obtain any signals in the filters. To resolve these problems and to obtain enough DNA to perform Southern blot we developed PCR. This way it was able discriminate the bla-TEM-1 from the bla-TEM-2 genes.


CONCLUSIONS
PCR technique plus oligonucleotide probes are a good alternative for the specific characterization of TEM-1 and TEM-2 beta-lactamases in Salmonella spp.
Gallego
L
L
Departamento de Microbiología, Facultad de Medicina, Universidad del País Vasco.
Basaras
M
M
Alonso
R
R
Sarria
L
L
Cisterna
R
R
D000668:Ampicillin Resistance; D015342:DNA Probes; D016133:Polymerase Chain Reaction; D012475:Salmonella / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D001618:beta-Lactamases / Q000302:isolation & purification*
D015342:DNA Probes; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1; C056342:beta-lactamase TEM-2
Sondas de oligonucleótidos para la caracterización de betalactamasas TEM-1 y TEM-2 en cepas de Salmonella.