Combination Therapy with Azithromycin and Clostridium butyricum Retains Anti-Diarrheal Efficacy but Partially...

Most probiotics require separate administration from antibiotics due to sensitivity issues. Clostridium butyricum, however, exhibits intrinsic resistance, making it a promising candidate for combined therapy against diarrhea. In this study, a diarrhea model was established in mice induced by Escherichia coli, followed by treatment with azithromycin (AZM), C. butyricum (RH₂), or their combination (COM) to assess therapeutic efficacy. The results demonstrated that mice in RH₂ and COM groups achieved full body weight recovery and significant alleviation of diarrhea, accompanied by normalized fecal E. coli loads, preserved tissue integrity, reduced pro-inflammatory cytokines (IL-1β, IL-6, TNF-α), and elevated anti-inflammatory IL-10. In contrast, AZM treatment led to sex-specific disparities in weight recovery and E. coli loads, and both sexes experienced relapse-prone diarrhea. Furthermore, the AZM group displayed shortened colons, sustained inflammatory infiltration, epithelial damage, and elevated IL-1β and male-specific IL-6. Gut microbiota analysis revealed that the COM group retained beneficial genera (e.g., Parabacteroides, Blautia) from the AZM group while uniquely enriching Lachnospiraceae taxa (e.g., NK4A136_group, FCS020_group). Untargeted metabolomics demonstrated the COM group activated GABA/arginine pathways, enhancing anti-inflammatory and barrier functions, whereas azithromycin disrupted butyrate synthesis and steroid metabolism. These findings highlight the advantage of combining C. butyricum with azithromycin for intestinal protection.