บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Foodborne pathogens in poultry production and post-harvest control

Nayak, Rajesh R

Ph.D., West Virginia University, 2000, 180 pages; AAT 3003343

2000

บทคัดย่อ

Foodborne pathogens in poultry production and post-harvest control

A comprehensive ecological survey was conducted from April 1997 to June 1999 o­n four turkey flocks (F5-F8) to identify the preharvest sources of Salmonella colonization. Generic E. coli and total coliforms were enumerated as indicators of fecal contamination in F7 and F8. Turkey cecal and crop contents, litter, drinkers, air, feed, feeder contents, and environmental swabs were sampled and tested for Salmonella and E. coli. Salmonella was isolated from 13% of litter, 11% of turkey ceca, 10% of drinkers, and 5% of swabs. Escherichia coli and total coliforms were detected in 45 and 53% of samples, respectively. Salmonella heidelbergwas the major serotype isolated from the sampled flocks. About 25% of the Salmonella isolates were resistant to antibiotic(s). Identifying preharvest sources of Salmonella and E. coli colonization would assist integrators and producers in designing hazard analysis and critical control point (HACCP) Protocols. o­n-farm reduction of these pathogens will assist processors in reducing positive carcasses at the plant.

A skin attachment model was used to examine the ability of ZnCl 2 to reverse or inhibit Salmonella attachment to broiler skin. In reversal experiments, skin samples were first treated with 1 mL of S. typhimurium culture (10 8 CFU/mL) for 30 min, followed by the addition of 1 mL of 25 or 50 mM ZnCl 2 for 5 or 15 min. For inhibition experiments, this order was reversed. "Firmly" and "loosely" attached salmonellae were enumerated o­n the skin. Treated skin samples were observed under a scanning electron microscope. In reversal experiments, 25 and 50 mM ZnCl 2 reduced (p < 0.01) "firmly" attached cells by 77 and 89%, respectively, when compared to the control (water). At 25 and 50 mM concentration, ZnCl 2 reduced (p < 0.0001) cells in the "discard" by 99.4 and 99.9%, respectively. Micrographs indicated that 25 and 50 mM ZnCl 2 reduced (p < 0.1) Salmonella attachment by 69 and 99.9%, respectively, in the reversal experiments. In the inhibition experiments, 25 and 50 mM ZnCl 2 reduced (p < 0.01) "firmly" attached cells by 82 and 91%, respectively. Reduction of Salmonella may be attributed, in part, to the bactericidal activity of ZnCl 2 in addition to detachment of the bacterial cells o­n skin.