The pathogenesis of staphylococcosis in poultry
Abstract
Studies were conducted to investigate the carrier status of Staphylococcus aureus (S. aureus) in healthy chickens, and its effect on the induction of the delayed footpad reaction (DFR) to killed S. aureus antigen. The recoveries of S. aureus from the choanal slit and trachea in healthy chickens were significantly higher than that of the cloaca. Overall, about 49% of the birds tested for S. aureus were positive carriers. Birds presensitized s.c. with killed S. aureus showed a significant delayed footpad reaction (DFR) following intradermal challenge with S. aureus with no difference in the DFR between carrier and non-carrier birds. Using five criteria, the DFR induced by killed S. aureus in chickens was confirmed to be a cell-mediated delayed-type hypersensitivity (DTH) reaction. The five criteria were: (1) the DFR with a peak response at 24 to 48 h postchallenge, (2) inhibition of monocyte/macrophage migration, (3) lymphocyte blastogenic response, (4) mononuclear cell infiltration at the challenge site, and (5) passive transfer of DFR by splenic lymphocytes. The results indicated that the DFR can be used as a delayed reaction model in the study of staphylococcosis in poultry. The DTH reaction can also be induced via multiple intratracheal inoculations of killed S. aureus antigen. Intratracheally sensitized birds showed significant DFR compared to nonsensitized birds, reaching a maximum response at 24 h postchallenge. The histological examination of S. aureus-injected footpads of intratracheally sensitized birds showed typical perivascular infiltration of small lymphocytes. Whether or not prior exposure to S. aureus would facilitate the systemic infiltration of this pathogen following intradermal footpad challenge with live S. aureus was also investigated. Birds injected in the footpads with live S. aureus as compared to PBS had significantly higher S. aureus recoveries in the spleen, liver, and blood; however, the recovery and distribution of S. aureus between S. aureus-sensitized and polyethylene glycol-injected birds were not significantly different.
Degree
Ph.D.
Advisors
Hester, Purdue University.
Subject Area
Animal sciences|Microbiology|Animal Diseases|Physiology
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