Application of PCR fingerprinting techniques for identification and discrimination of Salmonella isolates

Different PCR-based DNA fingerprinting techniques were evaluated for identification and discrimination of bacterial strains. Fifteen strains of Salmonella enterica subspecies enterica serotypes Typhi (10), Paratyphi A (1) and Typhimurium (3) collected over a period of 15 years from stool, blood, and urine samples and river Ganga were tested. All the strains were analysed by restriction analysis of the amplified 16s rDNA (ARDRA), random amplified polymorphic DNA (RAPD) and BOX-PCR methods. In ARDRA, strains belonging to the same species were identified by identical fingerprints; RAPD on the other hand, divided Salmonella into 9 different groups. Two ciprofloxacin (CIP)-resistant strains showed similar PCR fingerprints which were different from the rest of the 12 strains. In BOX-PCR, all the strains of Salmonella showed 6 different groups which showed the presence of a common band. Serotype Typhimurium could be placed in the same group by BOX-PCR. CIP-resistant strains also produced one characteristic extra band by BOX-PCR. It was observed that RAPD had higher discriminatory power than BOX-PCR and was a simple and rapid technique for use in epidemiological studies of isolates belonging to S. enterica.