Submitted to: Food Safety Consortium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/12/2003
Publication Date: 10/12/2003
Citation: Huff, G.R., Huff, W.E., Johnson, M.J., Nannapaneni, R., Hargis, B.M. 2003. Stress-induced chronic infections of turkeys with listeria monocytogenes and implications for product and processing plant contamination. In: Proceedings of the Food Safety Consortium. October 12-14, 2003, Fayetteville, Arkansas. 2003 CDROM. Interpretive Summary: Male turkey poults were treated with a compound that mimics stress and then were challenged Listeria monocytogenes (Lm). At one week after challenge 6 birds from each treatment were necropsied. At two weeks all remaining birds were necropsied. There were no differences in disease due to Lm challenge, however the relative weight of a major immunel organ, the bursa of Fabricius, was lower in birds challenged with Lm. The percent of birds having Lm in blood cultures was significantly higher only birds that were treated with the compound and a certain strain of Lm called Scott A. At 1 week PI, Lm was isolated from the knees of only those same birds. A thick yellow film was clearly visible without magnification in test tubes containing material from these knees. This material was grown in cell culture and a test using antibodies showed that Lm was present.
Technical Abstract: Turkey osteomyelitis complex (TOC) is a stress related disease of processing age turkeys in which opportunistic bacteria produce abscesses, synovitis, arthritis, and osteomyelitis in otherwise normal-appearing carcasses. In Experiment 1, 220 male turkey poults were immunosuppressed with dexamethasone (DEX) at five weeks of age followed by either respiratory or oral inoculation with either the V7 (serotype ½a) or Scott A (serotype 4b) strains of Listeria monocytogenes (Lm). At one week post infection (PI), six birds/group were bled and necropsied. At two weeks PI all remaining birds were necropsied. Both respiratory and TOC lesions were scored and these as well as the left knee of every bird were cultured for Lm using transport swabs. All culture negative swabs from the left knee were stored at 4 degrees cellcius for 2 months after which they were cultured in 1 ml of PBS-trypsin for 24 h followed by the addition of 1ml 2X Listeria enrichment medium. These tubes were incubated at 30 degrees cellcius for 3 weeks, then at 4 degrees cellcius for 6 more weeks. All tubes were scored blind to treatment by two individuals for the extent of biofilm formation using a stereo microscope after 3 and 9 weeks of incubation. The biofilm coating the tubes was stained using both direct and indirect fluorescence microscopy specific for Lm as well as Staphylococcus aureus and Streptococcus. There were no differences in morbidity or mortality due to Lm challenge; however the relative weight of a major immunological organ, the bursa of Fabricius, was lower (P=0.007) in all birds challenged with Lm. The percent of Lm positive blood cultures at 1 week PI was significantly higher only in DEX-treated birds receiving a respiratory challenge with Lm Scott A when compared with the unchallenged control. At 1 week PI, Lm was isolated from the knees of only those birds challenged with both DEX and Lm Scott A. A thick yellow biofilm was clearly visible without magnification at the 1 mL interface of some tubes after the 30 degrees cellcius incubation. Mean biofilm scores from culture-negative knee joints were significantly increased in all challenged groups as compared to negative controls, however, the presence of a characteristic yellow pigmented biofilm was significantly increased by DEX immunosuppression, respiratory challenge, and the Scott A strain. Biofilms were positive for Lm using fluorescent antibody microscopy of infected macrophages.