Preliminary investigation of the use of dietary supplementation with probiotic Bacillus subtilis strain QST713 shows that it attenuates antimicrobial-induced dysbiosis in weaned piglets.

Growth performance of pigs has been associated with healthy gut microbiota. To improve production, pigs are usually treated with antimicrobials. Nonetheless, while antimicrobials harm the gut-indigenous microbiota, probiotic supplementation seems to help keep it healthy. Here, using antimicrobials, we artificially induced dysbiosis in pigs and evaluated a possible preventive effect of probiotic supplementation. Three 6-week-old piglets were given a basal feed, and 3 more the feed supplemented with 2.0 × 106  CFU of Bacillus subtilis QST713/g of feed. After 14 days, antimicrobial enrofloxacin (5 mg/kg B.W.) was injected intramuscularly to all pigs on days 14-16. Feces were collected on days 14, 17, 19, 21, and 23. Total bacteria count was unaffected by enrofloxacin or QST713. However, Lactobacillus spp. and, in particular, Escherichia coli were affected by enrofloxacin, the latter not being observed in the feces on days 17 and 19. Interestingly, a reciprocal increase in E. coli was observed in control pigs on days 21 and 23, although in QST713-supplemented piglets, this increase was attenuated. While the gut microbiota composition did not return to initial levels in antimicrobial-administered piglets, it did in QST713-supplemented piglets. QST713 supplementation was likely crucial to keep the microbiota of piglets healthy.