AN ABATTOIR SURVEY OF PNEUMONIA AND PLEURITIS IN SLAUGHTER WEIGHT SWINE FROM 9 SELECTED HERDS .4. BACTERIOLOGICAL FINDINGS IN CHRONIC PNEUMONIC LESIONS

A total of 855 pig lungs were collected at slaughter and evaluated mac roscopically. Bacteriological examinations were carried out on tissue samples from chronic pleuropneumonic lesions (n = 196) and from chroni c bronchopneumonic lesions with suppuration (n = 14). Samples from nor mal lung tissue (n = 22) were also included. Pasteurella multocida was isolated from 54%, Actinobacillus (Haemophilus) pleuropneumoniae from 11%, and Streptococcus spp. from 14% of the pneumonic lesions, respec tively. From normal lung tissue P. multocida was isolated from 3 (14%) of the samples, A. pleuropneumoniae was not recovered and streptococc i were isolated from only 1 (5%) of these samples. The above mentioned bacterial species were recovered either in pure cultures or mixed wit h various other microbes. A total of 109 P. multocida strains were fur ther characterized by capsular serotyping and testing for production o f dermonecrotic toxin. Ninety-nine (91%) of the strains were capsular type A 10 (9%) were type D. Out of the type A and the type D strains 9 4% and 90% were toxigenic, respectively. Most of the A. pleuropneumoni ae strains were serotype 2. Strains of serotypes 1 and 7 were also ide ntified. The majority of the streptococci were identified as either St reptococcus suis or Streptococcus dysgalactiae. Actinomyces pyogenes w as isolated from 14% of the lesions and anaerobic bacteria from 18%, r espectively. The significance of the various bacterial species in rela tion to the development of chronic pneumonic lesions is discussed. Spe cial attention is paid to P. multocida, and it is concluded that this bacterial species is probably of importance for the development of bot h types of chronic pneumonias.