|MCLENDON, B - University Of Georgia|
|Cox, Nelson - Nac|
|MONTIEL, E - Merial, Ltd|
|RUSSELL, S - University Of Georgia|
|HOFACRE, C - University Of Georgia|
|WILSON, J - University Of Georgia|
Submitted to: Advanced Food and Nutritional Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2020
Publication Date: 3/17/2020
Citation: Mclendon, B.L., Cox Jr, N.A., Cosby, D.E., Montiel, E.R., Russell, S.M., Hofacre, C.L., Berrang, M.E., Wilson, J.L. 2020. Detection of salmonella in young chicks with cloacal swabs. Advanced Food and Nutritional Sciences. 5:1-6. https://dx.doi.org/10.21065/AdvFoodNutriSci.5.1.
Interpretive Summary: Breeder chicks (broiler and layers) are expensive and valuable to the poultry industry. Industry needs a reliable, non-destructive method to screen these birds for the presences of Salmonella, both for internal use and to sell them to poultry companies in the U.S. and around the world. This study demonstrated that either a shallow or deep cloacal swab is an effective method to detect Salmonella without sacrificing or injuring the chicks. Freezing the swabs for analysis at a later time did not diminish the effectiveness of this method which makes it more useful to the poultry industry.
Technical Abstract: Broiler chicks (n=25) from a commercial hatchery were gavaged with 0.5 mL of a 101 – 105 cells of a marker Salmonella Typhimurium (ST), then placed in isolation units with drinkers, mesh flooring and feeders. At 7 and 14 days, 10 birds per treatment were cloacally swabbed (shallow and deep). Swabs inserted 2 cm (shallow) into the cloaca and 2 cm deep (into the colon). Each swab was immersed in 5.0 mL of 0.05% buffered peptone water (BPW), then streaked onto brilliant green sulfa agar plates with 200 ppm nalidixic acid (BGS w/Nal). Tubes and plates were incubated 24 h at 37 ° C. When negative, the pre-enriched tube was vortexed and plated onto BGS w/Nal plates and incubated. The procedure for the frozen samples was the same except 15% glycerol added to the BPW and then frozen at -20 ° C for 14 days. On d 14 of storage, swab samples were thawed and analyzed as above. After swabbing, chicks were sacrificed, ceca removed, placed into a sterile stomacher bag, macerated with a rubber mallet and the marker strain enumerated. When > 106 CFU/g was present, detection with either method was 47/50 (97%) and when < 106 CFU/g was present, detection with either method fell to 38/60 (63.3%). After 14 d freezing, the shallow method detected 32/64 (50%) and the deep 41/64 (64%). These results indicate freezing does not adversely affect recovery and the deep swab was slightly better than the shallow when frozen, but same day analysis is preferable.