A PCR-based strategy for simple and rapid identification of rough presumptive Salmonella isolates

The purpose of the present study was to investigate the application of read y-to-go Salmonella PCR tests, based on dry chemistry, for final identificat ion of rough presumptive Salmonella isolates. The results were compared wit h two different biotyping methods performed at two different laboratories. The sensitivity of the BAX Salmonella PCR test was assessed by testing a to tal of 80 Salmonella isolates, covering most serogroups, which correctly id entified all the Salmonella strains by resulting in one 800-bp band in the sample tubes. The specificity of the PCR was assessed using 20 non-Salmonel la strains, which did not result in any DNA band. A total of 32 out of the 36 rough presumptive isolates were positive in the PCR. All but one isolate were also identified as Salmonella by the two biochemical methods. All 80 Salmonella strains were also tested in the two multiplex serogroup tests ba sed on PCR beads. All strains belonging to the serogroups B, C-1, C-2-C-3, and D were grouped correctly. Among the 32 rough presumptive isolates ident ified, 19 isolates resulted in a band of 882 bp (serogroup B), 11 isolates resulted in a band of 471 bp (serogroup C-1), and two isolates showed a ban d of 720 bp (serogroup D). In conclusion, rough presumptive Salmonella isol ates can be conveniently confirmed to the serogroup-revel, using the pre-mi xed PCR tests. The system can be easily implemented in accredited laborator ies with limited experience in molecular biology. (C) 1999 Elsevier Science B.V. All rights reserved.