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United States Department of Agriculture

Agricultural Research Service

Research Project: INVESTIGATING THE IMPACT OF STRESS ON FOODBORNE PATHOGEN COLONIZATION IN TURKEYS Title: Co-infection of Market-age Turkeys with Escherichia coli and Listeria monocytogenes in Two Stress Models

Authors
item Huff, Geraldine
item Dutta, Vikrant - NORTH CAROLINA STATE UNIV
item Huff, William
item Johnson, Michael - UNIV OF ARKANSAS
item Sayler, Ronald - UNIV OF ARKANSAS
item Nannapaneni, Rama - MISS STATE UNIV

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 23, 2009
Publication Date: December 1, 2009
Citation: Huff, G.R., Dutta, V., Huff, W.E., Johnson, M., Sayler, R.J., Nannapaneni, R. 2009. Co-infection of market-age turkeys with escherichia coli and listeria monocytogenes in two stress models. Avian Diseases. 53:495-501.

Interpretive Summary: Stress may result in low-level infection of turkeys with Listeria monocytogenes (Lm) that may be an overlooked source of processing plant contamination. We have shown that infection with Escherichia coli can increase Lm colonization. The objective of this study was to determine the effects of transport stress and a compound known to simulate the effects of stress on the isolation of Lm in turkeys challenged with both E. coli and Lm. Thirteen-wk-old male turkeys housed in floor pens were challenged by environmental exposure to E. coli and Lm using both a coarse spray and feed inclusion. Positive controls were treated with the compound during challenge. At 15 weeks of age a sample of birds was subjected to a 12 hour transport stress protocol and all birds were bled, killed, and examined the following morning. The compound that simulates stress increased mortality and disease incidence. Challenged birds, challenged-transported birds, and all of the birds treated with the compound had lowered body weights compared to controls. The relative liver and heart weights were increased and the relative bursal weights were decreased by treatment with the compound. White blood cell counts and the percentage of heterophils (H), a type of cell that kills bacteria, were increased by the compound, and both stress treatments decreased the percentage of lymphocytes (L) which are another type of white blood cell. The H/L ratio, an indicator of stress in birds, was increased by the compound and in challenged and transported birds. Total red blood cell counts, hematocrit, and hemoglobin were decreased by both stress treatments. The challenge strain of E. coli was consistently isolated from the organs of challenged birds treated with the compound using direct plating on microbiological plates. Listeria monocytogenes was not isolated from significant numbers of birds using direct plating, but was isolated from the knee or hip tissues of a significant percentage of stressed and challenged birds using either pre-enrichment cultural methods or methods detecting bacterial DNA. These data suggest that L. monocytogenes colonization of processing age turkeys can be increased by stress and may be harbored within inapparent infections of turkey knee and hip joints.

Technical Abstract: We have hypothesized that stress-induced subclinical infection of turkeys with Listeria monocytogenes (Lm) may be an overlooked source of processing plant contamination and we have shown that concurrent Escherichia coli challenge can increase Lm colonization. The objective of this study was to determine the effects of dexamethasone (Dex) immunosuppressive treatment and transport stress on the isolation of Lm in an E. coli-Lm challenge model. Thirteen-wk-old male turkeys housed in floor pens were challenged by environmental exposure to E. coli and Lm Scott A using both a coarse spray and feed inclusion. Positive controls were treated with Dex during challenge. At 15 weeks of age a sample of birds was subjected to a 12 hour transport stress protocol and all birds were bled and necropsied the following morning. Dexamethasone treatment increased mortality and disease incidence. Challenged birds, challenged-transported birds, and all Dex-treated birds had lowered body weights compared to controls. The relative liver and heart weights were increased and the relative bursal weights were decreased by Dex treatment. Peripheral blood leukocyte counts and the percentage of heterophils (H) were increased by Dex, and the transport and Dex treatment decreased the percentage of lymphocytes (L). The H/L ratio was increased by Dex and by challenge-transport. Total erythrocyte counts, hematocrit, and hemoglobin were decreased by Dex and Transport. The challenge strain of E. coli was consistently isolated from the organs of Dex-treated, challenged birds using direct plating. Listeria monocytogenes was not isolated from significant numbers of birds using direct plating, but was isolated from the knee or hip synovial tissues of a significant percentage of stressed and challenged birds using either pre-enrichment cultural methods or real time PCR detection. These data suggest that L. monocytogenes colonization of processing age turkeys can be increased by stress and may be harbored within inapparent infections of turkey synovial tissue.

Last Modified: 10/20/2014
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