2003 年 22 巻 3 号 p. 99-107
Background: This study was designed to assess gut microflora changes in children in Finnish day-care centers (DCCs).Methods: Ninety-four children in four DCCs were randomised to receive a combination ofLactobacillus acidophilusLa 5 andBifidobacterium lactisBb 12 or placebo for six months. Faecal samples were collected monthly and during bouts of diarrhoea. The parents kept a daily record. These groups were similar to infections and antibiotic treatments during the last month before the study. Altogether 14/76 (18%) children developed diarrhoea, and 13 healthy children who did not were studied as controls from the same DCCs at the same time. The gut microflora of altogether 26 children was examined by fluorescent in situ hybridisation at the start of the study, and before and after diarrhoea. Results: Twelve of 26 subjects (46%) had initially an aberrant microflora as determined by high levels of clostridia, the remaining 14 (54%) had balanced microflora. In the group with aberrant microflora, 9/12 (75%) manifested diarrhoea during followup, whereas in the group with balanced microflora, 4/14 (29%) fell ill with diarrhoea (p= 0.04). Diarrhoea reduced the number of all bacteria for at least a month. Antibiotic therapies increased the numbers of bacteria, mostly the number of clostridia. The initial total number of bacteria in the probiotic group decreased significantly in the late follow-up samples;p= 0.0075, this being due to the stabilising effect of probiotics. During treatment with probiotics aberrant microflora tended to approach the pattern in balanced microflora. Conclusions: A smaller and more stable amount of bacteria in the gut microflora was associated with healthy outcome of children during the study. Not only infections and antibiotics caused disruption of the gut microflora; aberrance of the gut microflora itself seems to predispose a child to diarrhoea episodes and other infections. Probiotics reduced the aberrance.