Antimicrobial susceptibility of Pasteurella multocida and Haemophilus parasuis isolates associated with porcine pneumonia

Pasteurella multocida and Haemophilus parasuis pig isolates obtained in the Czech Republic were tested for their susceptibility against selected antimicrobial agents by broth microdilution method between 2008 and 2011. A low degree of resistance was observed for ampicillin, amoxicillin/clavulanic acid, ceftiofur, tulathromycin, tilmicosin, florfenicol and enrolloxacin in 20 (6.0%), 15 (4.5 %), 2 (0.6%), 8 (2.4%), 13 (3.9%), 5 (1.5%) and 5 (1.5%) P multocida isolates as well as for tiamulin, gentamicin, tulathromycin, tilmicosin and ampicillin in 2 (2.4%), 2 (2.4%), 3 (3.6%), 3 (3.6%) and 6 (7.2%) H. parasuis isolates. In addition, moderate level of resistance to tiamulin was found in 60 (18.1%) P multocida isolates and high level of resistance for tetracycline was detected in 107 (32.2 %) P multocida isolates and in 23 (27.7%) H. parasuis isolates. Differences between resistance rates of P. multocida and H. parasuis were significant (P <= 0.5) only for tiamulin. These data confirmed that antimicrobial resistance is not very widespread among current porcine P multocida and H. parasuis isolates in the Czech Republic.