Where There's Smoke, There's Fire?

Not always.

In their provocative paper, “The Microbiome of Osteoarthritic Hip and Knee Joints: A Prospective Multicenter Investigation,” Goswami et al. report on the presence of microbial DNA in osteoarthritic knees and hips. In an environment that has been assumed to be sterile, 468 out of 549 samples yielded positive next generation sequencing (NGS) results indicative of microbial DNA.

DNA does not equal infection

The presence of microbial DNA in joints, in the absence of other findings of infection, is not diagnostic of infection. This is an important reminder in the era of increasing popularity of molecular diagnosis of periprosthetic joint infections.

Where does this leave us?

It is likely that microbial nucleic acids are present in arthritic joints, but it is unclear from where they originated. Next steps will confirm whether the DNA source is from living bacterial colonies within the arthritic joint or if it is transient. There is potential for development in optimizing molecular tests to avoid overreacting to subclinical amounts of bacterial DNA.