Prevalence, Risk Factors, and Antimicrobial Resistance Profile of Respiratory Pathogens Isolated From Suckling Beef Calves to Reprocessing at the Feedlot: A Longitudinal Study

Abstract

Here, we investigated the prevalence and risk factors for the presence of Histophilus somni, Mannheimia haemolytica, Mycoplasma bovis, and Pasteurella multocida in the respiratory tract of calves from the spring processing to the reprocessing at feedlots. Additionally, we characterized, phenotypically and genotypically, the antimicrobial resistance (AMR) profile of the four species. Calves from 22 cow–calf operations were enrolled in the study (n = 30 calves per operation) and sampled by deep nasopharyngeal swabs at three time points: spring processing, weaning, or induction into feedlots, and at reprocessing at the feedlot. Isolates were tested for susceptibility using the minimum inhibitory concentration (MIC) test against commonly administered antimicrobials. Additionally, a subset of isolates underwent whole-genome sequencing to infer presence of AMR genes and resistance determinants. Among studied pathogens, P. multocida was the most prevalent species, regardless of time point, followed by M. haemolytica, M. bovis, and H. somni. For M. bovis, a sharp increase in prevalence was detected at the reprocessing sampling, whereas for P. multocida, an increase in prevalence was observed at the weaning/induction sampling. Comingling and co-location of feedlots were not associated with prevalence of any respiratory pathogen. In terms of AMR, resistance against macrolides was prevalent in M. bovis, with most isolates resistant against tildipirosin, tilmicosin, and tylosin. In general, there was limited evidence to support an increase in resistance rates of respiratory bacteria from the spring processing to reprocessing at feedlots, with the exception of florfenicol resistance in M. bovis, which increased at reprocessing. Metaphylactic administration of tetracyclines at feedlot induction was not associated with the MIC of tetracyclines in any respiratory bacteria. Conversely, there were clear associations between the parenteral use of macrolides as metaphylaxis at the feedlot induction, and increased MIC against macrolides in P. multocida, M. haemolytica, and H. somni. Overall, the AMR phenotypes were corroborated by presence of AMR genes. We hypothesize that the administration of macrolides such as tulathromycin at feedlot induction contributes to historical changes in macrolides MIC data of respiratory bacteria of beef cattle.

Comparison of pathogenic bacteria in the upper and lower respiratory tracts of cattle either directly transported to a feedlot or co-mingled at auction markets prior to feedlot placement

“…In a previous longitudinal study (2007–2012) monitoring bacterial resistance, a lack of tulathromycin resistance was observed in cattle sampled at entry and at 60 DOF ( 27 ). However, several studies have now shown widespread macrolide resistance in P. multocida and M. haemolytica ( 28 – 30 ), indicating that rates of resistance are increasing. The dissemination of a single clone from 34 AUC and RANC cattle within 3 weeks of sampling indicates a high horizontal transmission rate of resistant isolates within the feedlot.…”

A Longitudinal Characterization of the Seminal Microbiota and Antibiotic Resistance in Yearling Beef Bulls Subjected to Different Rates of Gain

“…To ensure the viability of the frozen semen samples, the brain heart infusion (BHI) media containing 20% glycerol was used to store the semen samples. This type of cryopreservation method has been commonly used for characterizing culturable bacteria from bovine samples ( 39 – 41 ). However, freeze storage can have an impact on viable bacterial cell recovery, and different bacterial species may have different tolerance to the freezing and protectant used for freezing ( 42 ).…”

Impact of Infectious Diseases on Wild Bovidae Populations in Thailand: Insights from Population Modelling and Disease Dynamics

“…I animals may die from HS at the disease-induced fatality rate ( ρ ) or survive and become recovered ( R ) at infectious rate (1 /γ ). We calculated fatality ranged from 0.53 - 5.84% in the cattle population, using the number of deaths from HS (0.21%; assumed from the percentage of deaths from bovine respiratory disease, [37]) divided by the prevalence of HS (3.59 - 40%, [38, 39]). R animals reenter S when they lose immunity at the immunity loss rate ( ω ).…”