Direct Automatic Bacterial Analysis of Rat Stool Samples; The Effects of Diet and Medical Treatment Studied by Computerised Gas-liquid Chromatography of Bacterial Fatty Acids

Abstract

Gas-liquid chromatography (GLC) of bacterial cellular fatty acids was used to produce fatty acid profiles of the stool samples of six different groups of rats, three with different medications, two with experimental diets and a control group with ordinary laboratory food. Such a profile represents all the bacterial cellular fatty acids in the sample and thus reflects its microflora. The profiles were then compared to each other in order to test the applicability of the GLC method for simple and rapid detection, clustering and measurement of faecal bacterial changes. The analysis of the profiles was performed automatically by using coniputerised fatty acid profile correlation analysis combined with a cluster analysis. The results showed the method able to detect identical samples and quantify the differences between the groups. The experimental diets, fish-powder and all-meat, and the anltibiotics, ciprofloxacin and clindamycin, markedly altered the intestinal flora, whereas a non-steroidal anti-inflammatory analgesic, diclofenac, did not. The results indicate that the GLC of stool samples combined with computerised fatty acid profile analysis is a fast and useful method to detect and quantify changes in faecal floras induced by various environmental factors. Keywords: Faecal flora; Diet; Antimicrobe effect; Computer analysis; Gas chromatography; Fatty acids.