Distribution of persistent Salmonella typhimurium infection in internal organs of swine.
Experiments were conducted to establish a persistent Salmonella typhimurium infection in convalescent swine, and to determine rate of shedding and distribution of the organism in internal organs. Naturally farrowed Salmonella-free pigs (n = 37) were orally exposed to S typhimurium when 7 to 8 weeks old. Fecal samples, tonsillar scrapings, and rectal swab specimens were examined bacteriologically for S typhimurium at weekly intervals after exposure until necropsy (maximum of 28 weeks after exposure). Necropsies of 1 to 4 randomly selected pigs were conducted at 2, 4, and 7 days and at 2, 4, 6, 8, 12, 16, 20, 24, and 28 weeks after exposure. The following internal organs were examined bacteriologically for S typhimurium: liver, spleen, kidney, gallbladder, heart, lung, and stomach; segments of the intestinal tract with corresponding lymph nodes; lymph nodes from lymphocenters of the head and neck, thoracic and abdominal cavities, pelvic wall, and thoracic and pelvic limbs. Fecal samples were 83 to 100% culture-positive up to postexposure (PE) week 22, then varied from 14 to 67% positive until PE week 28. At least 60% of tonsillar swab specimens and 50% of rectal swab specimens were culture-positive up to PE week 20, after which they varied from 0 to 70% positive until PE week 28. At necropsy, S typhimurium was recovered most frequently from tonsils (93.5% positive), followed by segments of the intestinal tract from caudal portion of jejunum to rectum (71% recovery from cecum), and mandibular (54.8%) and ileocolic (45.2%) lymph nodes.(ABSTRACT TRUNCATED AT 250 WORDS)
Wood
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National Animal Disease Center, US Department of Agriculture, Ames, IA 50010.
Pospischil
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Rose
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D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D004064:Digestive System / Q000382:microbiology*; D005260:Female; D008198:Lymph Nodes / Q000382:microbiology*; D008297:Male; D014066:Palatine Tonsil / Q000382:microbiology*; D012481:Salmonella Infections, Animal / Q000276:immunology / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000254:growth & development / Q000276:immunology / Q000302:isolation & purification*; D013047:Specific Pathogen-Free Organisms; D013552:Swine / Q000382:microbiology; D013553:Swine Diseases / Q000276:immunology / Q000382:microbiology*; D013997:Time Factors
D000907:Antibodies, Bacterial