The swine gastrointestinal microbiota is comprised of a diverse and complex microbial population that coexists in a coordinated, complex mucosal ecosystem that contributes to host mucosal health. It is important to understand how common management practices, such as antimicrobial administration, might affect this complex ecosystem. While the antibiotic resistance profiles of pathogens and opportunistic bacteria cultured have been characterized, the Antimicrobial Resistance Genes (ARG) from the whole gut microbiota have received far less attention. The objective of this study was to understand the impact of peri-natal antimicrobials on growth, mortality, fecal microbiota composition and ARG prevalence. Forty-eight litters were blocked to one of six treatments (N=8). Within litter, all pigs received the same treatment. Pigs were weighed and treatments administered at 24 hours of age, after litters have been balanced for size. Treatments were as follows: Control (saline 1cc), Tulathromycin (2.5 mg/kg IM), Ceftiofur Crystalline free acid (5.0 mg /kg IM), Ceftiofur hydrochloride (5 mg/kg IM), Oxytetracycline (22 mg/kg IM) and Procaine Penicillin G (33,000 units/kg IM). Two pigs per litter were individually identified and deep fecal swabs were collected at days 0 (prior to treatment), 5, 10, 15 and 20. High throughput, next generation sequencing was used to assess microbial diversity and the presence of ARGs (Tet O, Tet W, Tet C, Sul 1, Sul 11, bla ctx and erm B). Preliminary analysis shows that, while antimicrobial treatment had no effect on individual weight gain, or mortality, it was associated with significant changes in the abundance of ARGs, and the composition and progression of the fecal microbiota. Interestingly, the duration and extent of the observed changes were contingent on the class of antimicrobial administered. The data also indicates that perinatal antimicrobial administration increases the prevalence of antibiotic-resistant bacteria and ARG. In combination, these results raise important questions regarding the practice of perinatal antimicrobial administration and on the design of antimicrobial stewardship programs in the swine industry. |
