Investigations of representation of certain bacteria strains in lungs of pigs with pneumonia

Abstract

The objective of the investigations described in this paper was to carry out the identification and to establish the incidence of certain strains of bacteria that take part in the etiopathogenesis of pig infections. The investigations covered a total of 237 pathoanatomically altered lungs of expired pigs. Sampling was done during visits to pig farms, most often in situations when it had been necessary to resolve occurring respiratory infections. The samples were examined in a laboratory for the presence of bacterial causes using standard and commercial methods of microbiological diagnostics. For this purpose, the samples were sown on corresponding nutritive bases (blood agar, MacConkey agar, nutritive agar, BHI agar, Baird Parker agar). For the primary isolation of Actinobacillus pleuropneumoniae and Haemophilus parasuis, agar with 5-10% sheep's blood was used and the culture of the strain Staphylococcus aureus which serves as a source of V factor, and for subcultivation of these causes, chocolate agar was used with PolyVitex. In the isolated bacteria, following investigations of morphological and culture characteristics, biochemical identification was performed using the commercial tests BBL Crystal GP ID Kit, E/N ID Kit, Api 20 Strep and Slidex Staph Plus. From the total of 237 examined lung samples, 13 bacteria strains were isolated from 193 samples (81.43%). Among breeding pigs, 112 lung samples were examined and the presence of bacteria was established in 92 (82.14%), while the presence of bacteria was established in 101 samples (80.8%) of 125 examined lung samples from fattening pigs. Two bacteria strains were dominant among the spectrum of lung microorganisms: Pasteurella multocida (32.64%) and Actinobacillus pleuropneumoniae (29.02%), or, these two bacteria strains in total accounted for 61.66% of all strains isolated in pure culture. The participation of the other 11 bacteria strains ranged from 0.52-9.84%. Observed according to production categories, Actinobacillus pleuropneumoniae was most often isolated from lungs of breeding pigs (26 isolates), while Pasteurella multocida was most often isolated from the lungs of fattening pigs (43 isolates). Out of the totally identified 13 bacteria species, only 5 were established in fattening pigs, but these animals were also found to have 4 of the total of 5 detected cases of mixed infection. Infection with mixed bacteria was established in 16 lung samples (8.29%). The presence of Pasteurella multocida and/or Actinobacillus pleuropneumoniae was established in each of the 5 cases of mixed infection.