FluorescentIn Situ Hybridization (FISH) as a Tool in Intestinal Bacteriology

Abstract

Fluorescentin situhybridization (FISH) with 16S rRNA targeted oligonucleotides was used in combination with automated microscopy to determine the quantitative composition of the bacterial microflora in faeces of human volunteers. The percentage bifidobacteria andBacteroideswas determined in faecal samples of different age groups (12-20 d breast-fed, 1-3 yr, 18-52 yr, > 75 yr). The percentage bifidobacteria was 72.8, 10.0, 4.0 and 9.2%, respectively. The percentageBacteroideswas 1.3, 24.9, 20.6 and 5.9%, respectively. There are large individual differences especially in adults and even more in elderly. Comparison of the adult age groups in China and the Netherlands shows no significant differences in the percentage bifidobacteria andBacteroides. However the percentage bacteria belonging to the Clostridium coccoides-Eubacterium rectale group was significantly higher in samples from China (31.4%) than in those from the Netherlands (19.9%). Individual differences were large. The effect of oral treatment with metronidazole on the bacterial composition in faecal samples of one volunteer was investigated with several probes. There is a 3-fold decrease in the total number of bacteria and the results show that there is a large increase of lactobacilli-enterococci and an increase of bifidobacteria.Bacteroidesremains unaffected. The results show that automated FISH is an excellent tool to study intestinal bacteriology in response to modulation.