Analysis of Diversity and Distribution of Antibiotic Resistance Genes in Holstein Friesian Dairy Cattle Feces by Shotgun Metagenomic Approach

Antibiotic resistance is a significant public health issue, and animals have a vital role in the development and preservation of antibiotic-resistant bacteria. This work employed shotgun metagenomics to examine antibiotic resistance genes (ARGs) present in the feces of dairy cattle. The presence of resistance genes in the feces indicates that certain microorganisms carry several resistance genes, which are often found in close proximity and originate from various species. Our findings indicates that the gastrointestinal system of dairy cows harbors a repertoire of 216 antimicrobial resistance genes, which are presumed to confer resistance to 23 distinct antibiotics. The identified ARGs were associated with tetracyclines, macrolides, bacitracin, quinolones, β-lactams, and aminoglycosides, which correspond to antibiotics often administered to both animals and humans. An important discovery in this study is the recognition of Enterobacteriaceae as the predominant family in the phylum Proteobacteria, together with enterococcus species from the phylum Firmicutes, which possess numerous antibiotic resistance genes associated with health risks. The presence of antibiotic-resistant Gram-negative and Gram-positive bacteria underscores the significance of using suitable antibiotic therapy to minimize the dissemination of resistance in both animals and humans.