title: Association between indoor environmental contamination by Salmonella enterica and contamination of eggs on layer farms.
abstract: This study involves longitudinal and point-in-time surveys of Salmonella carriage and environmental contamination on two commercial cage layer farms positive for Salmonella enterica subsp. enterica serovar Typhimurium (flock A age, 32 weeks; flock B age, 34 weeks). Salmonella-positive fecal, egg belt, and dust samples were all unconditionally associated with eggshells testing positive for Salmonella. The odds of an eggshell testing positive for Salmonella were 91.8, 61.5, and 18.2 times higher when fecal, egg belt, and dust samples, respectively, tested positive for Salmonella. The agreement between the culture-based methods and real-time PCR on preenriched broths for detecting Salmonella was almost perfect for eggshell (observed agreement, 99.19%; kappa coefficient, 0.94) and egg belt samples (observed agreement, 95%; kappa coefficient, 0.88), and it was substantial for fecal (observed agreement, 87.14%; kappa coefficient, 0.47) and floor dust samples (observed agreement, 80.61%; kappa coefficient, 0.58). A 1-log increase in the load of Salmonella detected in the fecal, egg belt, and floor dust samples resulted in 35%, 43%, and 45% increases, respectively (P < 0.001), in the odds of an eggshell testing positive for Salmonella. The multilocus variable-number tandem-repeat analysis (MLVA) patterns of the S. Typhimurium strains isolated from flock A were distinct from those of flock B. S. Typhimurium strains detected from human food poisoning cases exhibited an MLVA pattern similar to those of the strains isolated from flocks A and B.
authors: School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia.
authors: Vaibhav C
authors: VC
authors: Gole
authors: South Australian Research and Development Institute, Adelaide, South Australia, Australia.
authors: Valeria
authors: V
authors: Torok
authors: Primary Industries and Regions SA, Adelaide, South Australia, Australia.
authors: Margaret
authors: M
authors: Sexton
authors: School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia.
authors: Charles G B
authors: CG
authors: Caraguel
authors: School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia kapil.chousalkar@adelaide.edu.au.
authors: Kapil K
authors: KK
authors: Chousalkar
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D001431:Bacteriological Techniques; D002645:Chickens / Q000382:microbiology*; D003430:Cross-Sectional Studies; D004531:Eggs / Q000382:microbiology*; D004783:Environmental Microbiology; D005243:Feces / Q000382:microbiology; D006801:Humans; D008137:Longitudinal Studies; D018598:Minisatellite Repeats; D017720:Molecular Epidemiology; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D012486:Salmonella typhimurium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*