Characterization of pasteurella multocida isolates from bovine respiratory diseases in terms of vaccine strain potential

Bovine respiratory system diseases have an important place in cattle breeding and Pasteurella multocida is frequently isolated from cattle with clinical findings. In this study, it was aimed to isolate and characterize P. multocida from lung samples taken from cattle at slaughter stage in slaughterhouses and to evaluate their potential to become a vaccine strain. Within the scope of the study, lung samples were taken from 410 cattle for the isolation of P. multocida. For the selective isolation of P. multocida, bacteriological cultivation was performed from lung samples. Genotypic identifications of bacteria considered as suspicious for P. multocida were performed by PCR. Typing of P. multocida strains according to capsular antigens and genes related to virulence factors that play a role in pathogenesis were investigated by PCR. Biofilm formation status of P. multocida isolates was determined in vitro by Congo Red Agar method. Antibiotic susceptibilities of isolates were investigated by Kirby Bauer Disk Diffusion Method. P. multocida isolates were genotyped by RAPD-PCR. A lilac-colored bacterial colony was determined in Pasteurella selective medium from 92 of the lung samples. As a result of PCR, 92 isolates were identified as P. multocida. By capsular typing, 19 isolates were determined as serogroup A, 4 isolates as serogroup B, 5 isolates as serogroup D, 19 isolates as serogroup E and 1 isolate as serogroup F. 56, 72, 33, 65, 40, 45, 22, 28, 45, 47, 31, 0 and 7 of the 92 isolates examined were positive for fur, sodA, pmHAS, plpB, fimA, sodC, ompH, ompA, tonB, nanH, nanB, toxA, and oma87, respectively. 52 of the examined isolates were evaluated as positive in terms of biofilm forming. 22, 33, 10, 33, 17 and 70 of the isolates were resistant to danofloxacin, tilmicosin, florfenicol, cefquinom, gentamicin, and tetracycline, respectively. It was determined that the isolates included in serogroups A, B, D and E showed similarity of 65-97%, 54-91%, 41-91% and 41-92%, respectively by RAPD-PCR. As a result of the study, P. multocida isolates numbered 48, 29, 25, 52 and 69 - determined for serogroup A-F, respectively- were selected as potential vaccine strains. It was concluded that the selected vaccine strains are suitable for use in in vivo vaccine trials as mono- and/or multivalent.