Prevalence of multi drug antimicrobial resistance in Mannheimia haemolytica isolated from high-risk stocker cattle at arrival and two weeks after processing1

Abstract

Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in North American beef cattle. () is the bacterial pathogen most frequently isolated from cattle with BRD and the prevalence of antimicrobial resistance in this pathogen has been increasing. Administration of antimicrobials to prevent BRD is commonplace in stocker cattle, but the impact of this practice on emergence of resistance in is unknown. High risk, sale barn origin bull and steer calves ( = 169) were transported to a stocker facility in central Georgia and sampled via deep nasopharyngeal swab (NPS) at arrival processing. All calves received the macrolide antimicrobial tulathromycin (2.5 mg/kg subcutaneously) at arrival processing. A second NPS was collected from each calf 10 to 14 d after arrival. The occasional calves diagnosed and treated for BRD prior to 10 to 14 d were swabbed and cultured prior to treatment. Swabs were submitted for culture and antimicrobial susceptibility testing using the Kirby-Bauer disk diffusion method. Of the 169 cattle enrolled, 27 (16.0%) were culture positive for at arrival processing and of these, a multi-drug resistant (MDR) strain of was detected in 1 (3.7%). In contrast, 123 (72.8%) cattle were culture positive for at second sampling and of these, a MDR strain of was detected in 122 (99.2%). The proportions of cattle culture positive for and positive for MDR at arrival processing and at second sampling were significantly different ( < 0.001). At the level of the individual bacterial isolate, 366 individual isolates were collected from the calves at the time of the second sampling. Of these isolates, 361 (98.6%) were intermediate or resistant to all macrolides tested (tilmicosin, gamithromycin, tulathromycin) and the fluoroquinolone enrofloxacin. In addition, 254 isolates (69.4%) were intermediate or resistant to florfenicol and 4 (1.1%) were intermediate or resistant to ceftiofur. There was a significant difference in the proportion of isolates resistant to all of the drug classes except cephalosporins at arrival processing versus second sampling ( < 0.001). Our results show that there was an increase in the proportion of calves positive for from arrival processing to second sampling, and that there was an increase in the proportion of calves that had MDR strains of detected from arrival processing to second sampling. More research is needed to understand the role of metaphylaxis on MDR in and the impact of MDR on morbidity and mortality in stocker cattle.

Integrative and Conjugative Elements (ICEs) in Pasteurellaceae Species and Their Detection by Multiplex PCR

“…The overall picture suggests that some of the M. haemolytica ICE sequences are of older origin and were acquired before those found in P. multocida . In the case of the strains isolated from cattle, this is consistent with M. haemolytica being a primary etiologic agent associated with BRD (Klima et al, 2016 ; Snyder et al, 2017 ).…”

Antimicrobial Susceptibility of Bacteria That Cause Bovine Respiratory Disease Complex in Alberta, Canada

“…In North America, there is a trend toward increasing frequencies of MDR in pathogens involved in high mortality BRD cases ( 6 , 8 , 24 , 25 ). Recent reports examining the molecular basis for AMR in Pasteurellaceae strains from BRD mortalities indicate that large mobile elements, linking arrays of resistance genes together, are present in both American and Canadian fed cattle populations ( 10 , 26 ).…”

Essential oils inhibit the bovine respiratory pathogensMannheimia haemolytica,Pasteurella multocidaandHistophilus somniand have limited effects on commensal bacteria and turbinate cellsin vitro

“…) and the US (Snyder et al . ) showed significantly high levels of resistance (≥50%) in M. haemolytica , P. multocida and H. somni isolated from the respiratory tract of feedlot cattle, with some bacteria resistant against multiple classes of antibiotics. Therefore, novel strategies are needed to reduce antimicrobial use and to mitigate antimicrobial‐resistant respiratory pathogens in beef cattle.…”

“…However, multidrug resistance in bacterial respiratory pathogens isolated from feedlots has increased in the last decade (Portis et al 2012), including the emergence of bacterial pathogens that are resistant to several classes of antibiotics used for both the control and treatment of BRD (Noyes et al 2015). Recent studies conducted in commercial feedlots in Canada (Anholt et al 2016;Timsit et al 2017) and the US (Snyder et al 2017) showed significantly high levels of resistance (≥50%) in M. haemolytica, P. multocida and H. somni isolated from the respiratory tract of feedlot cattle, with some bacteria resistant against multiple classes of antibiotics. Therefore, novel strategies are needed to reduce antimicrobial use and to mitigate antimicrobial-resistant respiratory pathogens in beef cattle.…”