Microarray Detection of Bacteria in Chronic Endodontic Infection

Objectives: Bacteria such as Peptostreptococcus micros , P. gingivalis , P. intermedia, P. endodontalis and Tannerella forsythia are involved in the etiology and perpetuation of endodontic infections. Microarray is a new develop technique for bacterial detection. The aim of this study was to evaluate the prevalence of these species in chronic endodontic infections by using microarray techniques. Methods: Samples of 100 patients with root canals displaying chronic endodontic infections were obtained by sterilized paper points. Bacterial identification was performed by using 16S rDNA microarray technique. DNA isolated from clinical samples were amplified by PCR with universal bacterial primers based on 16S rRNA genes, the products of PCR hybridized with the microarray in which the specific oligonucleotide probes were added. The results of hybridization were screened by confocal laser scanner. Results: By this 16S rDNA microarray 58% of the samples harbored Peptostreptococcus micros (42%), P. gingivalis (24%), P. intermedia (28%), P. endodontalis (33%), and Tannerella forsythia(30%). The presence of these bacteria alone or in association in chronic endodontic infections seems to be frequent. Conclusions: Microarray is a very sensitive technique for detecting DNA from bacterial cells. Especially it can identify bacterial species from a clinical endodontic sample including many kinds of bacteria only at a same reaction.It will be developed into a kind of clinical bacterial detective system through adding probe quantity of oral bacteria in the panel. This reseach was supported by National Natural Science Foundation of China No. 30271413 and Research Fund of Shanghai Education Commission No. 06BZ017.