Antimicrobial susceptibility and serotype distribution were investigated in 480 Mannheimia haemolytica isolates obtained between 1991 and 2010 from cattle with bovine respiratory disease. Of these isolates, 358 (66.9%) were resistant to at least one of 16 antimicrobial agents, and the resistance rates ranged from 0.2 to 39.0%. Resistance to dihydrostreptomycin was the most prevalent (39.0%), followed by resistance to nalidixic acid (37.9%), ampicillin, oxytetracycline, thiamphenicol, doxycycline, kanamycin, chloramphenicol, amoxicillin, enrofloxacin, and danofloxacin. Almost 90% of the isolates belonged to three serotypes (A1, A2, or A6), and the relative prevalence of serotype A6 has increased significantly during the last decade. Compared with bacteria belonging to other serotypes, those in serotype A6 exhibited a significantly higher dissociative ratio of antimicrobial resistance (χ2 test, p < 0.05). The results of this investigation provide useful information for the prevention of pneumonic pasteurellosis.
(Tohoku Research Station, Viral Disease and Epidemiology Research Division)
References:
- Katsuda K. et al (2008) Vet. J. 178(1):146-148
- Katsuda K. (2011) Soc. Farm Anim. Infect. Dis. 6(2):39-41
