Objectives:

Studies of the intestinal microbial ecosystem by classical culture techniques suggest that only 30% of the microflora can be cultured. PCR procedures based on 16S rRNA gene specific for bacteria were developed to detect bacterial populations in hamster faeces.

Methods:

A total of 30 populations of bacteria were characterised by their genomic DNA sequences and targeted by PCR probes: Actinomyces group, Bacteroides distasonis, Bacteroides fragilis, Bifidobacterium group, B. adolescentis, B. angulatum, B. catenulatum, B. infantis, B. longum, Clostridium group, C. clostridiiforme, C. coccoides, C. difficile, C. leptum, C. perfringens, Fusobacterium prausnitzii, Lactobacillus group, Peptosteptococcus productus, Propionibacterium group, Pseudomonas aeruginosa, Ruminococcus obeum, Citrobacter group, C. freundii, Escherichia group, Enterobacteria group, Enterobacter cloacae, Morganella morganii, Proteus mirabilis, Staphylococcus group, Salmonella group.

Results:

Sensitivity was measured by extraction of total genomic DNA and PCR amplification and a significant detection level of 10³ bacteria/faecal sample was obtained. Qualitative variations of bacteria population were observed during the first 2 weeks of acclimatisation, suggesting a stabilisation period for hamster microflora in new environmental conditions. After oral antibio-therapy, with one dose of 30 mg/kg amoxicillin-clavulanic acid, some groups were eradicated from hamster faeces: Propionibacterium, Staphylococcus and C. leptum, C. clostridiiforme. As reported in the literature, no antibiotic effect was observed on levels of dominant faecal groups: Bifidobacterium, Peptostreptococcus. Antibiotic-associated perturbations are linked with the disruption of the normal intestinal flora leading to a colonisation of pathogen bacteria species. In order to understand the role of Saccharomyces boulardii (S.b.) in prevention of antibiotic-associated diarrhoea, 4 × 10¹⁰ CFU/kg/day of S.b. were administered to hamsters during oral antibiotic treatment. The results showed that populations that were eradicated by antibiotic administration remained expressed and stabilised with concomitant S.b. treatment, suggesting an effective protection by S.b. on the intestinal flora.

Conclusions:

These PCR results should be used to quantify the intestinal microflora by DNA microarray analysis.