Mice were treated with antibiotics dissolved in their autoclaved drinking water: gentamicin (2 g l−1; Cellgro, Manassas, VA, USA), metronidazole (1 g l−1; Sigma-Aldrich, St Louis, MO, USA), vancomycin (500 mg l−1; Sigma-Aldrich) (Garrett et al., 2010 (link)).