RESUMEN
BACKGROUND: We investigated 'rare' bile acids (BA) as potential markers in septic neonates. METHODS: 'Rare' (C-6 hydroxylated BA) and 'classical' BA were determined in 102 neonates using high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS). Four groups according to maturity (full term, FT vs. preterm, PT) and septic status (early-onset neonatal sepsis, EOS vs. CTR; non-septic controls) were formed: FT-CTR; (n = 47), PT-CTR (n = 22), FT-EOS (n = 20), PT-EOS (n = 13). RESULTS: Firstly, FT-CTR had a significant higher amount of 'rare' BA than PT (FT-CTR: 0.5 µmol/L, IQR: 0.3-1.3 vs. PT-CTR: 0.01 µmol/L, IQR 0.01-0.2; p < 0.01). The most common 'rare' BA in FT-CTR were tauro-γ- (TGMCA) and tauro-α-muricholic acid (TAMCA). Secondly, in EOS, absolute 'rare' BA levels were comparable in both gestational age groups (FT-EOS: 0.6 µmol/L, IQR: 0.1-1.6 and PT-EOS: 0.6 µmol/L, IQR: 0.2-1.5). Therefore, EOS had significantly higher median 'rare' BA values than non-septic PT neonates (p < 0.01). In PT and term neonates, the relative amount of tauro-ω-muricholic acid (TOMCA) within the 'rare' BA pool was significantly higher in EOS than in controls (FT-CTR vs. "FT-EOS and PT-CTR vs. PT-EOS; p < 0.01). It was hence the predominant 'rare' BA in EOS. CONCLUSION: TOMCA is an independent factor associated with EOS. It has diagnostic potential.