Volume 58 (2008) Issue: 2008 No#5-6

Isolation and identification of Actinobacillus pleuropneumoniae in pig's lungs at farms and their sensitivitty to antibiotics

Author(s): Žutić M, Ašanin Ružica, Milić N, Ivetić V, Vidić Branka, Žutić Jadranka, Ašanin Jelena

Keywords:Actinobacillus pleuropneumoniae, pigs, antimicrobial agents, sensitivity

The presence of Actinobacillus pleuropneumoniae has been established in all suspected cases of pleuropneumonia at several farms that have been included in the research. Equal incidence of pleuropneumonia has been found both among piglets for breeding and for fattening. The health monitoring of herds is extremely important, firstly because of the need for the adequate strategy to be chosen for controlling the Actinobacillus-caused pleuropneumonia and, at the same time, in order to prevent enormous economic losses that this disease may cause. The morphological, physiological and biochemical characteristics of isolated strains of Actinobacillus pleuropneumoniae were completely identical to those of referent strains. It has been found that Actinobacillus pleuropneumoniae grows most abundantly on chocolate agar when PolyVitex (bioMerieux) is used as the substrate. Out of 237 samples of altered parts of swine lungs, 13 bacterial species have been found in 193 (81%), and the incidence of Actinobacillus pleuropneumoniae within this percentage was 33%. Of all bacterial species isolated in pure culture from all investigated specimen the most dominant species were Pasteurella multocida with the incidence of 32.64% and Actinobacillus pleuropneumoniae with 29.01%. Their common incidence in all positive findings was 61.65%. If one adds to this their participation in mixed infections (2.59%), this percentage is higher (64.24%). The high percentage of these two bacterial species shows that they are at the same time the most common bacterial pathogens causing pneumonia in pigs. The incidence of other species of bacteria isolated from the lungs of diseased pigs ranged from 0.51 to 10.88%. The sensitivity of isolated strains of Actinobacillus pleuropneumoniae to the selected range of antibiotics used in clinical veterinary medicine (penicillin, ampicillin, amoxicillin, cephalosporin (III gen.) gentamycin, streptomycin, neomycin, thylosine, enrofloxacin, linkomycin-spectinomycin, tetracycline, florphenycol, trimethoprimsulphomethoxazol and tulatromycin) was tested by the disc-diffusion method, with the implementation of antibiogram tabletes (Torlak) and antibiogram discs (Oxoid), on chocolate agar and on Chaemophilus test medium (HTM, Biomedics). All tested strains of Actinobacillus pleuropneumoniae were sensitive to thulatromycin, while resistance of same strains was the highest to tetracycline (53%) and trimethoprim/sulphomethoxazole (56%).