Location: Egg and Poultry Production Safety Research Unit
Project Number: 6040-32420-003-001-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jul 1, 2017
End Date: Jul 1, 2022
Objective:
To assess the ability to detect Salmonella spp. at various levels of concentration in single and pooled manure swabs from laying hen production systems. This study will enable a determination of equivalency between single swabs (as cited in 21 CFR 118.8(a) and pooled swabs to be made. The data and equivalency determination will serve as the deliverables from USDA to FDA.
Approach:
Naturally occurring flora from the fecal matter of laying hens will be utilized as the competition for tagged species of Salmonella to determine the ability to detect the organism through traditional cultural microbiological methods. A complex experimental design will allow for multiple comparisons and robust data analysis. The study design will be broken down to aid in reader understanding. Explanation of each component of the design will be presented.
Hen Housing:
Swabs will be collected at the Piedmont Research Station, part of the North Carolina Department of Agriculture and Consumer Service experiment station system. A variety of commercial-style hen housing systems are present at the location. The Piedmont Research Station houses greater than 3,000 hens on site. The farm is certified under the United Egg Producers and has an active Salmonella Enteritidis control plan according to federal requirements (FDA, 2009).
Sample collection times:
The study will be repeated at three distinct hen ages reflecting the required environmental sampling times of U.S. federal law for farms with greater than 3,000 hens on site (FDA, 2009). Sample times will be (in hen age):
1) pullet sampling; 15 wks of age
2) post-peak sampling; 41 or 42 wks of age
3) post-molt sampling; 4-6 wks after molt completed
Swab collection sites:
Two types of swab (manure scraper blades and drag swabs) will be collected throughout the study. Each type of swab will be assessed separately in the experimental design. Swab types will be:
Inoculation treatments:
All organisms to be utilized for inoculation have been trained to be resistant to specific concentrations of antibiotics to ensure appropriate isolation and recovery. The experimental organisms/treatments are:
1) Salmonella Enteritidis
2) Salmonella Typhimurium
3) Salmonella Heidelberg
4) Salmonella Enteritidis + Salmonella Kentucky
5) Positive controls – clean swabs inoculated with each treatment 1-4
6) Negative controls – manure swabs without inoculum introduced
7) Negative controls – clean swabs without inoculum introduced
Inoculation concentrations:
Two concentration levels of each treatment will be utilized. The doses will be:
1) 5-10 cfu/sample
2) 50-100 cfu/sample
Swab pooling:
Three swab pooling treatments will be utilized for each type of swab sample, inoculation treatment, and inoculation concentration. All swabs utilized as inoculated and non-inoculated (with the exception of treatment #5) will be manure scraper blade or manure drag swabs (previously described). The swab pools will be:
1) single inoculated swab
2) single inoculated swab + single non-inoculated swab
3) single inoculated swab + 3 non-inoculated swabs
Salmonella spp. detection:
Traditional Salmonella spp. detection methods will be utilized.
