title: Effects of sample storage and delayed secondary enrichment on detection of Salmonella spp in swine feces.
abstract: OBJECTIVE
  To determine effects of fecal sample storage and delayed secondary enrichment (DSE) on detection of Salmonella spp in swine feces. Sample Population-Fecal samples obtained from 84 pigs in a commercial herd.
  
  
  METHODS
  Each fecal sample underwent 3 storage treatments: no storage (ie, processed on the day of collection), storage at 4 C for 6 days, and storage at -15 C for 14 days. After assigned storage treatments, all samples were enriched in Rappaport-Vassiladias (RV) broth (single enrichment) and plated on XLT4 agar. Delayed secondary enrichment was performed, using single enrichment broths that were stored for 4 days at room temperature.
  
  
  RESULTS
  Of 504 cultures, 186 (36.9%) were Salmonella positive. A difference in proportions of samples with positive results was not found between same-day processing and storage at 4 C for 6 days. Compared with use of single enrichment for 24 hours (34% positive), use of DSE resulted in a greater proportion (40%; P < 0.001) of samples with positive results. Estimated relative sensitivities for the storage methods were 0.90, 0.85, and 0.71 for same-day processing, storage at 4 C for 6 days, and storage at -15 C for 14 days, respectively.
  
  
  CONCLUSIONS
  Where practical, processing of fecal samples on the day of collection is recommended, although storage at 4 C for several days does not result in marked loss of sensitivity. Improved detection associated with DSE warrants further investigation and optimization.
authors: Department of Food Animal and Equine Medicine, College of Veterinary Medicine, North Carolina State University, Raleigh 27606, USA.
authors: J M
authors: JM
authors: O'Carroll
authors: P R
authors: PR
authors: Davies
authors: M T
authors: MT
authors: Correa
authors: B D
authors: BD
authors: Slenning
mesh_terms: D000818:Animals; D005243:Feces / Q000382:microbiology*; D005260:Female; D012475:Salmonella / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods / Q000662:veterinary*; D013552:Swine / Q000382:microbiology*