Prevalence and temporal trends in antimicrobial resistance of bovine respiratory disease pathogen isolates submitted to the Wisconsin Veterinary Diagnostic Laboratory: 2008–2017

摘要

The objective of this study was to describe the prevalenceand trends in antimicrobial resistance for bacterialpathogens associated with bovine respiratory disease(BRD) isolated from samples submitted to the WisconsinVeterinary Diagnostic Laboratory (WVDL). Datawere retrospectively collected from bovine respiratoryisolates including Pasteurella multocida, Mannheimiahaemolytica, Histophilus somni, and Bibersteinia trehalosiidentified at the WVDL between January 2008and December 2017. Antimicrobial susceptibility testingdata were queried from antimicrobial resistancedatabases at the WVDL. A total of 4,261 isolates wereidentified. Pasteurella multocida was most frequentlyidentified, accounting for 2,094 isolates (49% of total)over the study period. Mannheimia haemolytica wasthe second most frequently isolated bacterial respiratorypathogen (n = 1,267, 30%) followed by H. somni(n = 749, 18%) and B. trehalosi (n = 151, 4%). Overthe 10-yr period, B. trehalosi had the highest medianpercentage of isolates that were resistant to at least oneantibiotic at 33% (interquartile range: 24, 47) followedby M. haemolytica (13%; 8, 23). For P. multocida, 10%(4, 26) of isolates were classified as resistant to at leastone antibiotic, whereas H. somni had the fewest resistantisolates (9%; 3, 15). When comparing 2013–2017 to2008–2012, the overall percentage of resistant isolatesfor P. multocida and B. trehalosi decreased, whereasthe percentage of resistant isolates for M. haemolyticaand H. somni increased. Increased resistance againstflorfenicol, fluoroquinolones, gentamicin, tilmicosin,and tulathromycin was observed for M. haemolytica.These data show that antimicrobial susceptibility forBRD bacterial pathogens has changed in the populationserved by the WVDL over this 10-yr period. ForP. multocida, resistance is relatively low and has eitherimproved or at least remained constant for the majorityof drugs labeled for treatment of respiratory diseasein dairy cattle. Veterinarians and producers should beaware of the bacterial pathogens most commonly associatedwith BRD and work toward early disease detection,proper antibiotic administration, and monitoringlung lesions to ensure that their treatment protocolsimprove lung health.