title: Longitudinal Monitoring of Successive Commercial Layer Flocks for Salmonella enterica Serovar Enteritidis.
abstract: The Pennsylvania Egg Quality Assurance Program (EQAP) provided the framework for Salmonella Enteritidis (SE) control programs, including the Food and Drug Administration (FDA) mandated Final Egg Rule, for commercial layer facilities throughout the United States. Although flocks with ≥3000 birds must comply with the FDA Final Egg Rule, smaller flocks are exempted from the rule. As a result, eggs produced by small layer flocks may pose a greater public health risk than those from larger flocks. It is also unknown if the EQAPs developed with large flocks in mind are suitable for small- and medium-sized flocks. Therefore, a study was performed to evaluate the effectiveness of best management practices included in EQAPs in reducing SE contamination of small- and medium-sized flocks by longitudinal monitoring of their environment and eggs. A total of 59 medium-sized (3000 to 50,000 birds) and small-sized (<3000 birds) flocks from two major layer production states of the United States were enrolled and monitored for SE by culturing different types of environmental samples and shell eggs for two consecutive flock cycles. Isolated SE was characterized by phage typing, pulsed-field gel electrophoresis (PFGE), and clustered regularly interspaced short palindromic repeats-multi-virulence-locus sequence typing (CRISPR-MVLST). Fifty-four Salmonella isolates belonging to 17 serovars, 22 of which were SE, were isolated from multiple sample types. Typing revealed that SE isolates belonged to three phage types (PTs), three PFGE fingerprint patterns, and three CRISPR-MVLST SE Sequence Types (ESTs). The PT8 and JEGX01.0004 PFGE pattern, the most predominant SE types associated with foodborne illness in the United States, were represented by a majority (91%) of SE. Of the three ESTs observed, 85% SE were typed as EST4. The proportion of SE-positive hen house environment during flock cycle 2 was significantly less than the flock cycle 1, demonstrating that current EQAP practices were effective in reducing SE contamination of medium and small layer flocks.
authors: 1 Department of Veterinary and Biomedical Sciences, The Pennsylvania State University , University Park, Pennsylvania.
authors: Thomas N
authors: TN
authors: Denagamage
authors: 2 Department of Animal Science, The Pennsylvania State University , University Park, Pennsylvania.
authors: Paul
authors: P
authors: Patterson
authors: 1 Department of Veterinary and Biomedical Sciences, The Pennsylvania State University , University Park, Pennsylvania.
authors: Eva
authors: E
authors: Wallner-Pendleton
authors: 3 Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University , Ames, Iowa.
authors: Darrell
authors: D
authors: Trampel
authors: 4 Department of Food Science, The Pennsylvania State University , University Park, Pennsylvania.|5 Department of Biology, Gettysburg College , Gettysburg, Pennsylvania.
authors: Nikki
authors: N
authors: Shariat
authors: 4 Department of Food Science, The Pennsylvania State University , University Park, Pennsylvania.
authors: Edward G
authors: EG
authors: Dudley
authors: 1 Department of Veterinary and Biomedical Sciences, The Pennsylvania State University , University Park, Pennsylvania.
authors: Bhushan M
authors: BM
authors: Jayarao
authors: 1 Department of Veterinary and Biomedical Sciences, The Pennsylvania State University , University Park, Pennsylvania.
authors: Subhashinie
authors: S
authors: Kariyawasam
mesh_terms: D000822:Animal Husbandry / Q000295:instrumentation / Q000331:legislation & jurisprudence / Q000592:standards; D000818:Animals; D002645:Chickens / Q000254:growth & development / Q000382:microbiology*; D004196:Disease Outbreaks / Q000517:prevention & control; D004531:Eggs / Q000009:adverse effects / Q000382:microbiology* / Q000592:standards; D004866:Equipment Contamination / Q000517:prevention & control*; D005260:Female; D005506:Food Contamination / Q000517:prevention & control*; D005513:Food Inspection; D063427:Food Quality; D005759:Gastroenteritis / Q000453:epidemiology / Q000209:etiology / Q000382:microbiology; D006801:Humans; D007484:Iowa / Q000453:epidemiology; D007881:Legislation, Food; D051379:Mice; D058889:Molecular Typing / Q000662:veterinary; D010414:Pennsylvania / Q000453:epidemiology; D011786:Quality Control; D012375:Rodent Control / Q000331:legislation & jurisprudence / Q000592:standards; D012478:Salmonella Food Poisoning / Q000453:epidemiology / Q000209:etiology / Q000382:microbiology; D012477:Salmonella enteritidis / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification*; D062211:Spatio-Temporal Analysis; D014481:United States / Q000453:epidemiology
keywords: CRISPR-MVLST; PFGE; Salmonella Enteritidis; layers; phage typing; poultry