MICROORGANISMS ASSOCIATED WITH PNEUMONIA IN SLAUGHTER WEIGHT SWINE

  • 1 January 1985
    • journal article
    • research article
    • Vol. 49  (2) , 129-137
Abstract
The lungs of 334 pigs were obtained from 2 slaughter plants in Minnesota [USA] and examined in detail. Macroscopic and microscopic evaluation, direct fluorescence for Mycoplasma hyopneumoniae and bacterial culture were done on all of them and a subsample of 50 were selected for virus culture. M. hyopneumoniae, Pasteurella multocida and Haemophilus spp. were detected in 24.0%, 34.1% and 27.0% of the lungs, commonly in conjunction with each other. One isolate of H. pleuropneumoniae serotype 2 was detected and this represents the 1st report of its presence in the United States. No virus was detected in any of the lungs. Lungs with both M. hyopneumoniae and P. multocida had the greatest amount of macroscopic pneumonia (9.8% of the lung). Lungs with M. hyopneumoniae or P. multocida alone had 4.9% and 5.2% of the lung involved with pneumonia, respectively. Lungs with Haemophilus sp. Taxon minor group had 3.8% of the lung involved which was not significantly different from lungs with none of these organisms being detected (1.6%). There was a positive correlation between the extent of M. hyopneumoniae infection, as scored by FAT [fluorescent antibody test] and the amount of macroscopic pneumonia present (r = 0.46; P < 0.001). Likewise, there was a positive correlation between the estimated concentration of P. multocida present, as scored by the relative number of colonies on blood agar and the amount of macroscopic pneumonia present (r = 0.60; P < 0.001). Microscopically, the amount of lymphoreticular proliferation, polymorphonuclear cells and alveolar macrophages were evaluated. Lungs with no isolations had the lowest scores of all 3 components and lungs with M. hyopneumoniae combined with P. multocida had the highest. Haemophilus sp. Taxon minor group was associated with significantly more lymphoreticular proliferation and alveolar macrophages than sections with no isolations.