Effect of injected vs orally administered oxytetracycline on swine microbiomes (gut and respiratory)

The goal of this study was to evaluate route of antibiotic administration (i.e., oral or intramuscular) as a potential way to mitigate the collateral effects of antibiotics, including selection for antibiotic resistance genes. We tested oxytetracycline in pigs, because it is commonly used in pig production and has both an oral and an intramuscular formulation. Our endpoints included 16S rRNA gene sequence analysis of the gut and respiratory microbiomes, isolation and sequence analysis of total fecal plasmids, and amplification and analysis of antibiotic resistance genes from fecal DNA.