Molecular typing of Salmonella enterica serovar Sofia in Australia by pulsed-field gel electrophoresis and repetitive element PCR typing

Classification of Salmonella enterica serotypes from Australian poultry using repetitive sequence-based PCR

AIMS

To evaluate a semi-automated repetitive extragenic palindromic sequence-based PCR (rep-PCR) system for the classification of Salmonella serotypes from Australian poultry.

METHODS AND RESULTS

Using a DNA fingerprint library within the DiversiLab(®) System, four separate databases were constructed (serogroup B, C, E and Other). These databases contained 483 serologically confirmed (reference laboratory) Salmonella isolates. A blinded set of Salmonella cultures (n = 155) were typed by rep-PCR, matched against the internal library and compared with traditional serotyping. The predicted (Kullback-Leibler) serotype of 143 (92·3%) isolates matched traditional typing (P < 0·05). Of the 12 (7·7%) remaining isolates, ten (6·5%) resulted in 'No Match', one (0·65%) was incorrectly matched to the library (Salm. subsp 1 ser 4,12:-:-), and the other (0·65%) was referenced as Salm. ser. Sofia, whereas rep-PCR and in-house serotyping concurred as Salmonella serovar Typhimurium. Financial analysis showed higher material cost (215%) and a lower labour component (47·5%) for rep-PCR compared with serotyping.

CONCLUSION

The DiversiLab(®) System, with serogroup databases, was successfully implemented as an adjunct for reference serotyping of Salmonella enterica.

SIGNIFICANCE AND IMPACT OF THE STUDY

The DiversiLab(®) System platform is a cost-effective and easy-to-use system, which can putatively determine Salmonella enterica serotypes within a few hours.