Investigation of Isolates, Drug Susceptibility and Prognosis of Cattle with Refractory Pneumonia in the Towada area, Aomori Prefecture, Japan

We isolated the causative organisms from bronchoalveolar lavage fluid (BALF) in the cattles with refractory pneumonia that had not been cured by primary care, and investigated the drug susceptibility and the prognosis of the cases. The major isolates were Mycoplasma bovis (41.7%), Trueperella pyogenes (29.2%), Pasteurella multocida (26.4%), and Mannheimia haemolytica (8.3%). 62.5% of the cattle were cured by antimicrobial therapy based on the drug susceptibility of BALF-derived bacteria. On the other hand, a high proportion of multidrug-resistant and highly drug-resistant M. bovis was isolated from the BALF of cattle with a poor prognosis, and the choice of susceptible antimicrobial agents was very limited. Other isolates were also susceptible in the good prognosis group but were resistant to most antimicrobial agents in the poor prognosis group, making treatment very difficult. This study revealed that the increase in the number of resistant bacteria is decreasing the cure rate of pneumonia.