Ito Y, Moriwaki H, Muto Y, Kato N, Watanabe K, Ueno K
First Department of Internal Medicine, Gifu University School of Medicine, Japan.
J Med Microbiol. 1997 Jan;46(1):80-4. doi: 10.1099/00222615-46-1-80.
Lactulose exerts a beneficial effect on hepatic encephalopathy by decreasing toxic short-chain (iC4-nC6) fatty acid (isobutyrate, butyrate, isovalerate, valerate, isocaproate and caproate) production. However, the precise mechanism by which lactulose exerts this effect remains uncertain. This study investigated the effect of lactulose on faecal flora, particularly Clostridium difficile, which produces mostly iC4-nC6 fatty acids. An in-vitro faecal incubation system was used to estimate how lactulose influences production of short-chain (C2-nC6) fatty acids and lactate. Faecal specimens were collected from patients with liver cirrhosis, who carried C. difficile in the colon. Supplementation of lactulose along with blood in faecal specimens decreased iC4-nC6 fatty acids production and increased acetate and lactate production, resulting in increased faecal acidity. These changes were statistically significant when compared with supplementation by blood alone. Quantitative faecal culture demonstrated that lactulose supplementation suppressed the growth of C. difficile and Bacteroides spp. (B. fragilis group), iC4-nC6 fatty acids-producing organisms. These results suggest that decreased faecal levels of iC4-nC6 fatty acids after lactulose supplementation may be related to suppression of iC4-nC6 fatty acids-producing faecal organisms, especially C. difficile.
乳果糖通过减少有毒短链（iC4 - nC6）脂肪酸（异丁酸、丁酸、异戊酸、戊酸、异己酸和己酸）的产生，对肝性脑病发挥有益作用。然而，乳果糖发挥这种作用的确切机制仍不确定。本研究调查了乳果糖对粪便菌群的影响，特别是对艰难梭菌的影响，艰难梭菌主要产生iC4 - nC6脂肪酸。采用体外粪便培养系统来评估乳果糖如何影响短链（C2 - nC6）脂肪酸和乳酸的产生。从结肠中携带艰难梭菌的肝硬化患者收集粪便标本。在粪便标本中添加乳果糖和血液可减少iC4 - nC6脂肪酸的产生，并增加乙酸盐和乳酸的产生，导致粪便酸度增加。与仅添加血液相比，这些变化具有统计学意义。定量粪便培养表明，添加乳果糖可抑制艰难梭菌和拟杆菌属（脆弱拟杆菌群）（产生iC4 - nC6脂肪酸的微生物）的生长。这些结果表明，补充乳果糖后粪便中iC4 - nC6脂肪酸水平降低可能与抑制产生iC4 - nC6脂肪酸的粪便微生物，特别是艰难梭菌有关。
