Intestinal Colonization Leading to Fecal Urobilinoid Excretion May Play a Role in the Pathogenesis of Neonatal Jaundice

Abstract

Urobilinoids can be detected in stools of 57% of newborns at day 5 after delivery. However, the urobilinoid production during the first week of life is quantitatively insufficient to contribute significantly to the removal of bilirubin. Enhancement of the microbial conversion of bilirubin could decrease the intestinal concentration of bilirubin and may decrease the degree or enhance the removal of neonatal hyperbilirubinemia.

Comparison of Serum Zinc Level Between Neonates With Jaundice and Healthy Neonates

“…Enhanced enterohepatic circulation of bilirubin (EHC) that can occur with resection or bypass in adults or ileal inflammation leads to hypersecretion of bilirubin into the bile with increased formation of black pigment gall stones (3,4). Since active transport for non-conjugated bilirubin is not proved in the intestine, bilirubin may cycle only via passive diffusion under certain conditions (3)(4)(5). Interestingly, two thirds of bilirubin enter the systemic circulation; the remainder reabsorbed from the intestine is removed from blood by the liver (3-7).…”

Identification of bilirubin reduction products formed by Clostridium perfringens isolated from human neonatal fecal flora

“…Microbial catabolism of bilirubin in the gut lumen contributes importantly to serum bilirubin homeostasis [1]. In the absence of bilirubin-reducing microflora, such as in the early newborn period, or in patients treated with systemic antibiotics, unconjugated bilirubin (UCB) may undergo substantial enterohepatic and enterosystemic circulation.…”

“…It is generally believed that negligible amounts of fecal urobilinoids are present in the intestinal lumen of infants during the first months of their life, due to undeveloped intestinal microflora capable of reducing bilirubin [1,[2][3][4]. This presumably contributes importantly to the pathogenesis of neonatal jaundice [1].…”

“…This presumably contributes importantly to the pathogenesis of neonatal jaundice [1]. In adults, the urobilinoid production is highly efficient.…”

“…Under normal conditions only small amounts of bilirubin can be found in stools of adults (5-20 mg/day) while urobilinoids are predominant bile pigments (50-250 mg/day) [2]. Nevertheless, only few bacterial strains have been isolated, that are unequivocally capable of reduction of bilirubin to urobilinogens: Clostridium ramosum [5], Clostridium perfringens and Clostridium difficile [1] and Bacteroides fragilis [6]. Previously, such catalytic activity had been already suggested to be an attribute of the Clostridium genus [7][8][9].…”