Volcano plot analysis of fecal metabolites altered in the ciprofloxacin or vancomycin-imipenem groups at the end of treatment (A) or 9 days after cessation of antibiotics (B). Volcano plot analysis of fecal metabolites altered in the ciprofloxacin or vancomycin-imipenem groups at the end of treatment (A) or 9 days after cessation of antibiotics (B). The x and y axes of the volcano plot represent the log2-fold changes (against the control group) and the corresponding log FDR-adjusted P value of all metabolites, respectively. The vertical and horizontal lines separate metabolites that had a 2-fold change and an FDR-adjusted P value at 0.05. AABA, α-aminobutyric acid; GABA, γ-aminobutyric acid. Jocelyn M. Choo et al. mSphere 2017; doi:10.1128/mSphere.00005-17