The investigators totally collected 26 fecal samples from 18 infants diagnosed with SBS during parenteral nutrition administration, and these samples were divided into three groups according to complications of enrolled patients at sampling time: asymptomatic group, central catheter-related blood stream infections group and liver injury group. 7 healthy infants with supplementary food were enrolled as control. Fecal microbiota, sIgA and calprotectin, bile acids and short chain fatty acids were also detected by 16S ribosomal ribonucleic acid (rRNA) gene sequencing, enzyme-linked immunosorbent assay and liquid/gas chromatography.