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P1-41 Rapid Serotyping Method to Characterize Salmonella enterica subsp. enterica Isolates

Monday, August 4, 2014
Exhibit Hall D (Indiana Convention Center)
Christina Ferrato, Provincial Laboratory for Public Health - Alberta, Calgary and Edmonton, Canada
Linda Chui, Provincial Laboratory for Public Health - Alberta, Calgary and Edmonton, Canada
Marie Louie, Provincial Laboratory for Public Health - Alberta, Calgary and Edmonton, Canada
Introduction: Salmonella is one of the most common enteric pathogens linked to foodborne illness. ProvLab Alberta uses serological methods and follows the White-Kauffmann-Le Minor scheme for serotyping Salmonella isolated from food samples during foodborne illness investigations. Phenotypic serovar determination is often incomplete and confirmation may be required at the National Microbiology Laboratory (NML). The Check&Trace Salmonella (CTS) platform (Check-Points, The Netherlands), a commercial DNA microarray system which can fully genetically determine the serotype designation of a known Salmonella isolate.

Purpose: We evaluated the CTS platform for genetic characterization of Salmonella isolates in parallel to conventional serotyping.

Methods: Salmonella subsp. enterica identified by conventional methods using commercial (Statens Serum Institute) or in-house antisera were tested on CTS. Isolates were assigned a ‘genovar’ number based on the microarray result and matched to known serovars in a database.

Results: A total of 471 Salmonella enterica subsp. enterica isolates were serotyped by conventional methods; 406 isolates had a complete antigenic formula and serovar determined.  Of these, CTS found a concordant serovar result to 349 (86.0%), discordant result to 4 (<1%), and a genovar only to 53 (13.1%) isolates. All but seven of the isolates in the “genovar only” category represent serovars rarely found in the top 20 S. enterica subsp. enterica in ProvLab. Of the remaining 65/471 isolates for which the serovar could not be determined through conventional methods (due to incomplete antigenic formula), CTS was able to determine the majority (54/65, 83.1%) of serovars. These serovars were: 4,[5],12:i:- (29); Enteritidis (2); Heidelberg (2); Javiana (5); Paratyphi B var Java (3); Stanley (5); Typhimurium (3); and others (5).

Significance: CTS is an effective, rapid and easy to use platform and can generate Salmonella serovar results within eight hours. Using this molecular typing method can shorten the turn-around-time required during foodborne illness investigations.

Back to: Poster Session - Applied Laboratory Methods, Produce, Low-water Activity, Beverages and Water
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