Evaluation of intestinal microbiotas of healthy Japanese adults and effect of antibiotics using the 16S ribosomal RNA gene based clone library method.

Intestinal microbiotas of human subjects and effect of antibiotic treatment on them have been reported with cultivation independent methods. However, Japanese fecal microbiotas have not been studied enough. We have constructed a clone library method to obtain results within 3 d. In this study, intestinal microbiotas of 29 healthy Japanese adults, whose fecal samples were collected twice at 5 month intervals from each subject, were analyzed with our clone library method, and using those data as a benchmark effect of antibiotic treatment on intestinal microbiotas was evaluated. The fifty-eight fecal microbiotas were assessed based on percentages at genus level, and the variability was analyzed with a principal component analysis (PCA). PCA showed that the microbiotas divided into three groups depending on the large eigenvectors (genera Ruminococcus, Bacteroides, and Prevotella), and the dual samples from the twenty-two individuals have belonged to the same PCA group. It suggests that almost Japanese adults have own stable intestinal microbiota. The genera Ruminococcus and Bacteroides were present in almost subjects, while the genus Prevotella was found only in nine subjects (approximately 30%) which was preserved with 5 months intervals. Next, the microbiotas before and after antibiotic treatment were evaluated comparing with the 58 healthy adult microbiotas. The results showed that beta-lactams influenced profoundly on intestinal microbiotas and the effect of macrolides depended on the cases. It suggests that our clone library method could show overview of intestinal microbiota and would give us useful information about the effect of antibiotic treatment for daily clinical diagnosis.