Effects of florfenicol exposure during early life on toxicity, gut microbiota, and fecal metabolome in SD rats

Florfenicol (FLO) is a third-generation veterinary antibiotic with a high residue detection rate in food, which cause the toxicity of FLO even at low doses, receiving notable attention. The impact of FLO exposure during early life on health and gut microbiota is still unclear. Here, the effects of FLO exposure on toxicity, gut microbiota, drug resistance genes, and the fecal metabolome during early life were investigated in suckling Sprague-Dawley (SD) rats. The results showed that FLO exposure during early life significantly increased the body weight, and WBC and LY levels in the blood, induced inflammation in the liver and intestines. FLO had a dose-dependent effect on the alpha and beta diversity of the gut microbiota, increasing the ratio of Firmicutes to Bacteroides and the abundance of some pathogenic bacteria, and changing the abundance of bacteria related to energy metabolism and inflammation, also promoted the enrichment of drug resistance genes. The fecal metabolome also demonstrated the effect of FLO exposure on metabolic pathways related to energy metabolism and inflammation. In conclusion, this research shows that FLO exposure during early life can lead to excessive weight gain, an inflammatory response, gut microbiota imbalance, the enrichment of drug resistance genes, and effects on related metabolic pathways.