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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

INTRODUCTION: Bacterial bronchopneumonia (BP) has been associated with purchasing cattle through auction markets. However, whether auction markets are a source of BP-associated bacterial pathogens is unknown. This study evaluated prevalence, antimicrobial susceptibility, and genetic relatedness (usi...

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Detalles Bibliográficos
Autores principales: Hirsch, Christina, Timsit, Edouard, Uddin, Muhammed Salah, Guan, Le Luo, Alexander, Trevor W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9902877/
https://www.ncbi.nlm.nih.gov/pubmed/36761402
http://dx.doi.org/10.3389/fvets.2022.1026470
Descripción
Sumario:INTRODUCTION: Bacterial bronchopneumonia (BP) has been associated with purchasing cattle through auction markets. However, whether auction markets are a source of BP-associated bacterial pathogens is unknown. This study evaluated prevalence, antimicrobial susceptibility, and genetic relatedness (using pulsed-field gel electrophoresis, PFGE) of Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni isolated from cattle either transported to an auction market prior to feedlot placement (AUC), or directly to a feedlot from a farm (RANC). METHODS: Two groups of cattle were enrolled (N = 30 per group) from two separate farms with 15 animals from an individual farm designated as AUC or RANC. Deep nasal swab (DNS) and trans-tracheal aspirates (TTA) were collected on day 0 at weaning (T0) and on day 2 at on-arrival processing at the feedlot (T1). The DNS were also collected on day 9 (T2) and day 30 (T3) after arrival at the feedlot. RESULTS AND DISCUSSION: In both TTA and DNS, prevalence of bacteria did not differ between AUC and RANC groups (P > 0.05). None of the bacteria isolated at T0 were resistant to antimicrobials and diversity of all bacteria was greatest at T0 and T1. In Group 1 cattle, 100% of P. multocida isolated at T2 and T3 were multi-drug resistant. These isolates were highly related (>90%) according to PFGE, with most being clones. Though limited in size, results for animals evaluated in this study suggested that auction markets were not a major source of resistant BP pathogens, however, horizontal transmission of a multi-resistant strain of P. multocida occurred in a feedlot. Spread of resistant P. multocida was likely due to the selective pressures imposed by feedlot antimicrobial use and encoded resistance by the bacteria.