Spearman’s correlation analysis of microbiota and NMR spectra of the control and ciprofloxacin groups (A, C) or the vancomycin-imipenem group (B, D) after 14 days of antibiotic treatment and 9 days after cessation of antibiotics, respectively. Spearman’s correlation analysis of microbiota and NMR spectra of the control and ciprofloxacin groups (A, C) or the vancomycin-imipenem group (B, D) after 14 days of antibiotic treatment and 9 days after cessation of antibiotics, respectively. Bacterial taxa and metabolites in the correlation matrix were sorted based on the Euclidean distance and Ward’s method of hierarchical clustering. Significant microbiota-metabolite correlations were determined based on an r of less than −0.75 or more than 0.75 and an FDR adjusted P value of less than 0.01. Jocelyn M. Choo et al. mSphere 2017; doi:10.1128/mSphere.00005-17