Danofloxacin Treatment Alters the Diversity and Resistome Profile of Gut Microbiota in Calves

Beyi, Ashenafi Feyisa
Brito-Goulart, Debora
Hawbecker, Tyler
Slagel, Clare
Ruddell, Brandon
Hassall, Alan
Dewell, Renee
Dewell, Grant
Sahin, Orhan
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Veterinary Microbiology and Preventive MedicineVeterinary Diagnostic and Production Animal MedicineCenter for Food Security and Public Health
Fluoroquinolones, such as danofloxacin, are used to control bovine respiratory disease complex in beef cattle; however, little is known about their effects on gut microbiota and resistome. The objectives were to evaluate the effect of subcutaneously administered danofloxacin on gut microbiota and resistome, and the composition of Campylobacter in calves. Twenty calves were injected with a single dose of danofloxacin, and ten calves were kept as a control. The effects of danofloxacin on microbiota and the resistome were assessed using 16S rRNA sequencing, quantitative real-time PCR, and metagenomic Hi-C ProxiMeta. Alpha and beta diversities were significantly different (p < 0.05) between pre-and post-treatment samples, and the compositions of several bacterial taxa shifted. The patterns of association between the compositions of Campylobacter and other genera were affected by danofloxacin. Antimicrobial resistance genes (ARGs) conferring resistance to five antibiotics were identified with their respective reservoirs. Following the treatment, some ARGs (e.g., ant9, tet40, tetW) increased in frequencies and host ranges, suggesting initiation of horizontal gene transfer, and new ARGs (aac6, ermF, tetL, tetX) were detected in the post-treatment samples. In conclusion, danofloxacin induced alterations of gut microbiota and selection and enrichment of resistance genes even against antibiotics that are unrelated to danofloxacin.
This article is published as Beyi, Ashenafi Feyisa, Debora Brito-Goulart, Tyler Hawbecker, Clare Slagel, Brandon Ruddell, Alan Hassall, Renee Dewell et al. "Danofloxacin Treatment Alters the Diversity and Resistome Profile of Gut Microbiota in Calves." Microorganisms 9, no. 10 (2021): 2023. DOI: 10.3390/microorganisms9102023. Copyright: © 2021 by the authors. Creative Commons Attribution (CC BY) license. Posted with permission.
antimicrobial resistance genes (ARGs), bovine calves, bovine respiratory disease, Campylobacter, danofloxacin/fluoroquinolones, fecal microbiota, resistome