Taxonomic and Metabolic Signatures of Gut Microbiota for Assessing the Severity of Depression and Anxiety in Major Depressive Disorder Patients

•Multiple discriminative bacterial taxa were identified among the MDD subgroups.•Fecal Streptococcus was highly correlated with both HAMD and HAMA scores.•Fecal indole-3-carboxyaldehyde proved useful to discriminate depressive symptoms.