2007 Annual Report
Management of Antibiotic Resistance in Pathogenic Bacteria: The use of antibiotics in the production of livestock and poultry is believed by many to have created a reservoir of antimicrobial-resistant bacteria. One of the problematic issues related to antimicrobial resistance in bacteria is that the organisms can share or transfer antibiotic resistance genetic elements by a process called conjugation; more needs to be known about this phenomenon and its significance in the potential spread of antibiotic-resistant microorganisms. Scientists in the Food and Feed Safety Research Unit at the Southern Plains Agricultural Research Center, College Station, TX, determined the capability of a common poultry feed additive (known as flavophospholipol) to inhibit the spread of genetic information from one E. coli bacterium to another in living poultry. The studies used day-of-hatch chicks inoculated with E. coli, and firmly established that the additive did not prevent the bacteria from sharing genetic information. Although flavophospholipol demonstrated no useful biochemical actions, the work is nonetheless important because it provides solid scientific information on the dynamics of feed additive interactions with poultry gut microorganisms; ongoing work may be successful in identifying practical means to inhibit bacterial conjugation in living animals and thus reduce the threat posed by the antibiotic resistance phenomenon. (NP 108, Component 1.1, Problem Statement 1.1.5)
New Molting Diet for Laying Hens Reduces Stress and Salmonella Levels: Salmonella is a significant food-poisoning bacterium in humans; infections are often acquired by consumption of contaminated poultry products. With laying hens, producers periodically induce hen molting (feather replacement) which results in subsequent increased egg laying by the newly molted birds. However, molting is a stressful process for poultry, and it is known that these stresses can result in the birds becoming very susceptible to Salmonella infections which can result in Salmonella-contaminated eggs. New protocols are needed that will allow molting to be accomplished without the resulting bird stress and egg-contamination potential. Scientists in the Food and Feed Safety Research Unit at the Southern Plains Agricultural Research Center, College Station, TX, in collaboration with scientists at Texas A&M University, developed an alfalfa diet for use during a forced molt that effectively reduces Salmonella levels in the birds during and after the molt and that greatly reduces the likelihood of the birds producing Salmonella-contaminated eggs. This accomplishment is important because implementation of the alfalfa molting diet will enhance the microbiological safety of raw egg products reaching the consumer, and it will provide producers with a much less stressful method for accomplishing a necessary bird management practice. (NP 108, Component 1.1, Problem Statement 1.1.4)
Immune System Modulation to Control Pathogenic Bacteria in Livestock and Poultry: The colonization of livestock and poultry by pathogenic or food-poisoning bacteria is a serious problem in food animal production. One potential way to manage this problem is to exploit the animals’ own immune systems to increase their ability to fight off colonization by the pathogens. Scientists in the Food and Feed Safety Research Unit at the Southern Plains Agricultural Research Center, College Station, TX, defined critical parameters in poultry that are related to the production of nitric oxide which is a major mechanism used by the body’s immune system to defend against bacterial invasion. The work focused on identification of critical components of the nitric oxide pathway in a type of chicken white cell known as a macrophage, and as affected by chemicals that inhibit the production of signals that normally result from macrophage interactions with bacteria or viruses. This accomplishment is important because it demonstrated that the signaling process in birds is very similar to that known to occur in mammals. Thus, the full body of research on the nitric oxide signaling pathway, across higher animal types, can likely be exploited to hasten the success of ongoing efforts to develop effective pathogen management strategies in both livestock and poultry for animal disease control and to enhance human food safety. (NP 108, Component 1.1, Problem Statement 1.1.5)
Byrd II, J.A., Bailey, R.H., Wills, R.W., Nisbet, D.J. 2007. Recovery of Campylobacter from commercial broiler hatchery trayliners. Poultry Science. 86:26-29.
McReynolds, J.L., Byrd II, J.A., Genovese, K.J., Poole, T.L., Duke, S.E., Farnell, M.B., Nisbet, D.J. 2007. Dietary lactose and its effect on the disease condition of necrotic enteritis. Poultry Science. 86:1656-1661.
Poole, T.L., McReynolds, J.L., Edrington, T.S., Byrd II, J.A., Callaway, T.R., Nisbet, D.J. 2006. Effect of flavophospholipol on conjugation frequency between Escherichia coli donor and recipient pairs in vitro and in the chicken gastrointestinal tract. Journal of Antimicrobial Chemotherapy. 58:359-366.
Crippen, T.L., Sheffield, C.L. 2006. External surface disinfection of the lesser mealworm (Coleoptera: Tenebrionidae). Journal of Medical Entomology. 43:916-923.
Sheffield, C.L., Andrews, K., Harvey, R.B., Crippen, T.L., Nisbet, D.J. 2006. Dereplication by automated ribotyping of a competitive exclusion culture bacterial isolate library. Journal of Food Protection. 69:228-232.
Dunkley, K.D., McReynolds, J.L., Hume, M.E., Dunkley, C.S., Callaway, T.R., Kubena, L.F., Nisbet, D.J., Ricke, S.C. 2007. Molting in Salmonella enteritidis-challenged laying hens fed alfalfa crumbles. I. Salmonella enteritidis colonization and virulence gene hilA response. Poultry Science. 86:1633-1639.
Crippen, T.L. 2006. The selective inhibition of nitric oxide production in the avian macrophage cell line HD11. Veterinary Immunology and Immunopathology. 109:127-137.