Purpose: Compare traditional serotyping to three molecular typing strategies: riboprinting, pulsed field gel electrophoresis (PFGE), and Luminex xMAP Salmonella Serotyping Assay (SSA) to characterize S. enterica.
Methods: A diverse panel of food, outbreak, and environmental S. enterica isolates (n >150) were evaluated by Riboprinting using EcoRI and PvuII restriction enzymes, by PFGE using XbaI and BlnI, and by SSA. The results were compared to traditional serotyping.
Results: Strong agreement of serotyping results were observed for food- and outbreak-related S. enterica isolates when comparing molecular typing strategies to traditional serotyping. Riboprinting and PFGE were in strong agreement with outbreak isolates of S. Enteritidis and S. Typhimurium. Molecular serotyping outperformed traditional serotyping in several instances. For example, traditional serotyping identified one food-related isolate as S. Senftenberg, but both riboprinting and SSA independently identified the isolate as S. Johannesburg or Urbana. Characterization of environmental isolates proved more problematic, with frequent discrepancies between molecular serotyping methods. Results from two of the three typing strategies were frequently identical for a particular isolate, and by combining the outputs of the different typing strategies, extremely accurate serotyping was possible.
Significance: The majority of S. enterica serotypes can be effectively typed using molecular serotyping methods, and combining methods improves typing efficacy for environmental isolates, which may be difficult to characterize using traditional serotyping. Among the molecular methods evaluated, PFGE offers the advantage of lower cost, SSA enables high throughput analyses, and riboprinting is easier to perform and more rapid.