Broad-Spectrum Antibiotic Treatment in Mice

Broad-spectrum antibiotic treatment was performed according to previous publications.^{35 (link),36 (link)} Mice were fed by way of gavage with 0.2 ml broad-spectrum antibiotics at a concentration of 10 mg/mice/day including ampicillin (Solarbio), neomycin (Solarbio), metronidazole (Solarbio) and vancomycin (Lilly, Inc.) for 5 days to ensure equal doses taken by each mouse, then the antibiotics administered in drinking water (ampicillin, neomycin, and metronidazole: 1 g/L; vancomycin: 500 mg/L) until the end of the experiment to avoid too much stress which would have been induced by long-term gavage. Drinking water was exchanged twice a week. For the control group, saline was administrated in the same way as the antibiotics.