Abstract
Optimization of antimicrobial use in swine management systems requires full understanding of antimicrobial-induced changes on the developmental dynamics of gut microbiota and the prevalence of antimicrobial resistance genes (ARGs). The purpose of this study was to evaluate the impacts of early life antimicrobial intervention on fecal microbiota development, and prevalence of selected ARGs (ermB, tetO, tetW, tetC, sulI, sulII, and blaCTX–M) in neonatal piglets. A total of 48 litters were randomly allocated into one of six treatment groups soon after birth. Treatments were as follows: control (CONT), ceftiofur crystalline free acid (CCFA), ceftiofur hydrochloride (CHC), oxytetracycline (OTC), procaine penicillin G (PPG), and tulathromycin (TUL). Fecal swabs were collected from piglets at days 0 (prior to treatment), 5, 10, 15, and 20 post treatment. Sequencing analysis of the V3-V4 hypervariable region of the 16S rRNA gene and selected ARGs were performed using the Illumina Miseq platform. Our results showed that, while early life antimicrobial prophylaxis had no effect on individual weight gain, or mortality, it was associated with minor shifts in the composition of fecal microbiota and noticeable changes in the abundance of selected ARGs. Unifrac distance metrics revealed that the microbial communities of the piglets that received different treatments (CCFA, CHC, OTC, PPG, and TUL) did not cluster distinctly from CONT piglets. Compared to CONT group, PPG-treated piglets exhibited a significant increase in the relative abundance of ermB and tetW at day 20 of life. Tulathromycin treatment also resulted in a significant increase in the abundance of tetW at days 10 and 20, and ermB at day 20. Collectively, these results demonstrate that the shifts in fecal microbiota structure caused by perinatal antimicrobial intervention are modest and limited to particular groups of microbial taxa. However, early life PPG and TUL intervention could promote the selection of ARGs in herds. While additional investigations are required to explore the consistency of these findings across larger populations, these results could open the door to new perspectives on the utility of early life antimicrobial administration to healthy neonates in swine management systems.
Highlights
The widespread use of injectable antimicrobials in the treatment and prevention of human and animal diseases continues to rise globally (MacKie et al, 2006)
The extensive use of antimicrobials has led to emergence of antimicrobial-resistant bacteria and ARGs in the environment, which is thought to pose an imminent threat to animal and human health (Berendonk et al, 2015)
Our analysis focused on short-term impacts of antimicrobial administration on the fecal microbiota
Summary
The widespread use of injectable antimicrobials in the treatment and prevention of human and animal diseases continues to rise globally (MacKie et al, 2006). Antimicrobial resistance develops when the administered antimicrobial eliminates susceptible microorganisms but leaves behind resistant strains that continue to grow and multiply (Wegener, 2003). The majority of studies evaluating the effect of antimicrobial administration on emergence of antibiotic resistant bacteria and ARGs have focused on pathogenic organisms using culture-based methods (Thanner et al, 2016). While this approach has enhanced our understanding of the nature of antimicrobial resistance in a single class of organisms, it is limited in its ecosystem-level application. Advancements in culture independent techniques such as generation sequencing have allowed for the determination of microbial diversity in several animal biogeographic niches and have helped in the assessment of antimicrobial resistance determinants at the microbial ecosystem-level (Zhao et al, 2017; Zeineldin et al, 2019b)
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