Abstract
Pigs were inoculated orally with Mycobacterium avium in doses ranging from 15.6 × 102 to 15.6 × 106 viable units daily for 15 days (Table 1). The animals were necropsied 31–32 days after the last inoculation.
Pigs given doses of 15.6 × 106 and 15.6 × 105 viable units showed delayed hypersensitivity to avian tuberculin 24 days after the last inoculation (Table 2). The pig inoculated with 15.6 × 106 viable units showed macro- and/or microscopic lesions of the intestines and the liver, and of the mandibular, mesenteric and hepatic lymph nodes. Cultures showed growth of M. avium from the same tissues and from the spleen and the left tracheobronchial lymph node. The pig inoculated with 15.6 × 105 viable units showed a pronounced granulomatous infiltration in the tonsils and the mesenteric lymph nodes. Growth of M. avium was obtained from the tonsils, the intestinal mucosa (Peyer patch) and the mandibular and mesenteric lymph nodes. Viable unit counts were high in the tonsils and in the mesenteric lymph nodes (Tables 3 and 4).
Lower doses gave rise to a minimal tissue reaction and/or very low viable unit counts, and are not considered to be capable of producing a progressive tuberculosis.
Keywords: Mycobacterium avium, Serotype 2, pathogenicity, oral inoculation, large doses, pigs
Sammendrag
Med det formål at bestemme den mindste dosis af M. avium, der ved peroral podning kunne fremkalde tuberkulose hos svin, blev der podet med doser fra 15,6 × 102 til 15,6 × 106 viable units 5 gange om ugen i 3 uger, ialt 15 podninger (Tabel 1). Grisene blev slagtet 31-32 dage efter sidste podning.
Dyrene podet med doserne 15,6 × 105 og 15,6 × 106 viste følsomhed for aviært PPD tuberkulin (1000 enh. pr. dosis) 24 dage efter sidste podning (Tabel 2). Grisen podet med den højeste dosis (15,6 × 106) havde makro- eller mikroskopiske forandringer i tarmslimhinden (Peyerplet) og lever samt i Inn. mandibulares, mesenterici og hepatici, og ved dyrkning kom vækst af M. avium fra de samme væv samt fra milt og ln. tracheobronchalis sin. Grisen podet med 15,6 × 105 viable units havde udtalt granulomatøs, tuberkuløs infiltration i tonsil og Inn. mesenterici, og der kom vækst af M. avium fra tonsil, tarmslimhinde og Inn. mandibulares og mesenterici. Kimtallene var høje for tonsil og Inn. mesenterici (Tabel 3 og 4).
De mindre doser forårsagede minimal vævsreaktion og/eller meget lav infektion i vævene og menes ikke at være i stand til at fremkalde en progressiv tuberkulose.
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