Tuesday, July 18, 2006
The rogue's gallery of human pathogens is filled with members of the Bacteria and Eukaryota domains of life. Notably absent is the third domain: Archaea. According to a recent report in the Journal of Clinical Microbiology, however, that may no longer be the case.
When Hans-Peter Horz, an assistant professor at the University Hospital in Aachen, Germany, and colleagues used real-time quantitative PCR to survey the microbial ecology of 20 infected dental root canals, they found that five contained archaeal sequences, representing up to 2.5% of the total microbial load in these samples (J Clin Microbiology, 44:1274-82, April 2006). The predominant archaeal species was Methanobrevibacter oralis.
Healthy root canals are sterile environments, Horz says. 'Microbes that are able to penetrate into this area must have some pathogenic features: They must be able to invade into the system and they must be able to evade host immune mechanisms,' he says.