Frequency and antibiotic susceptibility of Pasteurella multocida and Mannheimia haemolytica isolates from nasal cavities of cattle

The aim of the present study was to determine the frequency of Pasteurella multocida and Mannheimia haemolytica from nasal cavities of cattle, and to find antibiotic susceptibility profiles of the isolates. Bilateral nasal swab samples were collected from 47 clinically healthy Holstein cattle, with no history of antimicrobial treatment prior to sampling. Respectively, 5 and 27 isolates were identified as M. haemolytica and P. multocida. Seventeen samples from cattle of 1 year or younger were found to have P. multocida. On the other hand, from 29 samples from cattle of 2 years or older, 10 P. multocida and 5 M. haemolytica strains were isolated. Each isolate was tested for susceptibility against florfenicol, sulfamethoxazole/trimethoprim, enrofloxacin, ampicillin, and erythromycin. All P. multocida and M. haemolytica isolates were found susceptible against florfenicol, and 27 P. multocida and 5 M. haemolytica isolates showed susceptibility against enrofloxacin, sulfamethoxazole/trimethoprim, erythromycin, and ampicillin at the rates of 85.1% and 80%; 92.6% and 80%; 44.5% and 60%; 100% and 80%, respectively.