An Archaeal pathogen?

AN ARCHAEAL PATHOGEN? X-ray from a necrotic tooth containing a periapical bone lesion Credit: COURTESY OF MORGANA ELI VIANNA" />AN ARCHAEAL PATHOGEN? X-ray from a necrotic tooth containing a periapical bone lesion Credit: COURTESY OF MORGANA ELI VIANNA 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,

Jeffrey M. Perkel
Jul 1, 2006
<figcaption>AN ARCHAEAL PATHOGEN? X-ray from a necrotic tooth containing a periapical bone lesion Credit: COURTESY OF MORGANA ELI VIANNA</figcaption>
AN ARCHAEAL PATHOGEN? X-ray from a necrotic tooth containing a periapical bone lesion Credit: COURTESY OF MORGANA ELI VIANNA

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 Microbiol, 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...