EN
The aim of the study was the genetic identification and evaluation of properties of field isolates of A. pyogenes. Samples of internal organs as well as pathologically changed joints taken from dead pigs bred in Poland were used for testing. The isolation of bacteria was carried out according to standard microbiological methods. Properties of bacteria were evaluated based on their color, size and shape on the agar plates and in smears stained with the Gram method as well as on results of biochemical tests. Genetic identification of isolates based on results of the elaborated PCR test. Sensitivity to the most commonly used chemotherapeutics was evaluated by the disc diffusion test. Monocultures of transparent, small bacteria of pinhead size, surrounded by large hemolysis zone, Gram positive, fermented with acid production of glucose, fructose, galactose, lactose, cellobrose, trecholose, maltose, melarytose, mannose, glikogen, xylose and starch, of proteolytic activity, were evidenced. Tested A. pyogenes isolates were 100% sensitive to a wide spectrum of beta-lactames, with the exception of penicillin, for which 5% of the strains were resistant. One hundred percent of isolates were sensitive to oxytetracycline, doxycyclin, enrofloxacin, tylosin and florfenicol and 95% of them were sensitive to tetracyklines, cephalosporin and Linco-Spectin. A high percentage (90%) of sensitivity was registered for tiamulin, tulatromycyn, gentamicin and norfloxacin. The highest resistance was evidenced in the case of neomycin (47% resistant strains) and sulphonamides with trimetoprimem (45% of resistant strains). In PCR the presence of genetic material of A. pyogenes was detected in the case of 56 tested strains (98.2%).