Tuesday, July 30, 2013
Exhibit Hall (Charlotte Convention Center)
Srinivas Ramaswamy, Pathogenetix, Woburn, MA
Ekaterina Protozanova, Pathogenetix, Woburn, MA
Mohan Manoj Kumar, Pathogenetix, Woburn, MA
Maura Faggart, Pathogenetix, Woburn, MA
Mikhail Safranovitch, Pathogenetix, Woburn, MA
Gene Malkin, Pathogenetix, Woburn, MA
Shilpi Vyas, Pathogenetix, Woburn, MA
Katarzyna Crissy, Pathogenetix, Woburn, MA
Jimmy Symonds, Pathogenetix, Woburn, MA
Rudolf Gilmanshin, Pathogenetix, Woburn, MA
Introduction: Safe production, distribution and storage of foods are a difficult responsibility of the food industry that requires rapid and accurate detection of foodborne pathogens. Pathogenetix has developed an automated instrument to type bacterial pathogens based on Genome Sequence Scanning (GSS) technology. GSS system automatically prepares long restriction DNA fragments (> 90 kb), which are fluorescently labeled with sequence-specific probes and a nonspecific intercalator. These DNA molecules are then stretched in a microfluidic device and passed through light spots that excite fluorescence of the probes. These optical patterns are defined by the underlying DNA sequence and are compared to a database for strain identification.
Purpose: The purpose of this study is to demonstrate typing of Salmonella in different food matrices following enrichment for a standard screening assay.
Methods: We spiked 25 g samples of ground beef or fresh spinach with < 5 CFU of one of the following Salmonella strains: 3 each of Enteritidis and Typhimurium and 1 each of Newport, Javiana, Montevideo, and Heidelberg. One set of experiments also included 10-fold excess of spiked microbes from cow feces as competing background flora. All samples were tested six times by enriching in BPW with Salmonella supplement (Biomerieux) for 18 h at 42°C and analyzed by GSS. Total aerobic counts and Salmonella were measured on TSA and XLD agars, respectively, for enrichment control.
Results: Of the 240 samples spiked with Salmonella, 235 were confirmed to be positive for the presence of the correct serovar by GSS analysis. Salmonella was not detected in five samples (4 in spinach, 1 in ground beef) due to poor enrichment. No false positives were detected from any of the 24 unspiked samples.
Significance: The data shows that GSS performed sub-typing Salmonella serovars in two different matrices using a commercial broth even in the presence of other bacteria.
