Septic arthritis of a lumbar facet joint due to pyonex.

We present a case of septic arthritis of a lumbar facet joint with an associated epidural abscess. A 13-year-old boy was hospitalized with acute severe back pain and fever after pyonex was done. The infection was precisely localized with magnetic resonance imaging, bone and gallium scintigraphy. He responded to antibiotic therapy. We suppose that the infection was caused by pyonex because the blood cultures were negative, and the patient had an abrupt onset of severe pain and fever 24 h after the acupuncture.