| Autor: |
Ossa-Trujillo C; Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA., Taylor EA; Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences Texas A&M University, College Station, TX 77843, USA., Sarwar F; Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences Texas A&M University, College Station, TX 77843, USA., Vinasco J; Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences Texas A&M University, College Station, TX 77843, USA., Jordan ER; Department of Animal Science, Texas A&M University, Dallas, TX 75252, USA., Buitrago JAG; Department of Extension Animal Sciences and Natural Resources, New Mexico State University, Clovis, NM 88101, USA., Hagevoort GR; Department of Extension Animal Sciences and Natural Resources, New Mexico State University, Clovis, NM 88101, USA., Lawhon SD; Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences Texas A&M University, College Station, TX 77843, USA., Piñeiro JM; Department of Animal Science, Texas A&M University, Amarillo, TX 79106, USA., Galloway-Peña J; Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences Texas A&M University, College Station, TX 77843, USA., Norman KN; Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA., Scott HM; Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences Texas A&M University, College Station, TX 77843, USA. |
| Abstrakt: |
Antimicrobial resistance is a significant concern worldwide; meanwhile, the impact of 3rd generation cephalosporin (3GC) antibiotics on the microbial communities of cattle and resistance within these communities is largely unknown. The objectives of this study were to determine the effects of two-dose ceftiofur crystalline-free acid (2-CCFA) treatment on the fecal microbiota and on the quantities of second-and third-generation cephalosporin, fluoroquinolone, and macrolide resistance genes in Holstein-Friesian dairy cows in the southwestern United States. Across three dairy farms, 124 matched pairs of cows were enrolled in a longitudinal study. Following the product label regimen, CCFA was administered on days 0 and 3 to cows diagnosed with postpartum metritis. Healthy cows were pair-matched based on lactation number and calving date. Fecal samples were collected on days 0, 6, and 16 and pooled in groups of 4 ( n = 192) by farm, day, and treatment group for community DNA extraction. The characterization of community DNA included real-time PCR (qPCR) to quantify the following antibiotic resistance genes: bla CMY-2 , bla CTX-M , mphA , qnrB19, and the highly conserved 16S rRNA back-calculated to gene copies per gram of feces. Additionally, 16S rRNA amplicon sequencing and metagenomics analyses were used to determine differences in bacterial community composition by treatment, day, and farm. Overall, bla CMY-2 gene copies per gram of feces increased significantly ( p ≤ 0.05) in the treated group compared to the untreated group on day 6 and remained elevated on day 16. However, bla CTX-M , mphA, and qnrB19 gene quantities did not differ significantly ( p ≥ 0.05) between treatment groups, days, or farms, suggesting a cephamycinase-specific enhancement in cows on these farms. Perhaps unexpectedly, 16S rRNA amplicon metagenomic analyses showed that the fecal bacterial communities from treated animals on day 6 had significantly greater ( p ≤ 0.05) alpha and beta diversity than the untreated group. Two-dose ceftiofur treatment in dairy cows with metritis elevates cephamycinase gene quantities among all fecal bacteria while paradoxically increasing microbial diversity. |
