Purpose: To validate the Atlas Salmonella SEN Detection Assay for the analyses of individual or 5 sample wet composited environmental sponge samples enriched in BPW or Lactose broth.
Methods: Sixty, 4”×4” stainless steel coupons were utilized for surface inoculation. Ten replicates were non-inoculated, 40 were inoculated at a low-level and 10 at a high level to approach POD=1. Samples were inoculated with Salmonella Derby (ATCC #6960) and 10X Citrobacter freundii(ATCC #6879) and allowed to dry overnight. Surfaces were sampled with sponge swabs pre-hydrated with D/E neutralizing broth. Half of the test samples were enriched with 190mL BPW for 20 hours at 42°C and half with 225mL Lactose broth for 24 hours at 35°C. Post enrichment, 1ml of each sample was combined with 4mL of non-inoculated sample enrichment to form a 5 sample wet composite. Both individual and pooled samples were assayed by the SEN method in duplicate using 12 and 400µL analytical volumes as well as by FDA BAM 5 cultural analysis.
Results: For individual and wet pooled samples in BPW, SEN detected 9 and 5 presumptive positives from the low and high level replicates, respectively, and for the 12µL and 400µL analytical volumes. For individual and wet pooled samples in Lactose broth, SEN detected 8 and 5 presumptive positives across the study parameters. All presumptive results correlated 100% with FDA BAM 5 reference culture results.
Significance: These data support the application of the SEN assay for the accurate analyses of individual or 5 sample wet composited environmental samples enriched in BPW or Lactose broth.