Escherichia coli septic arthritis of a lumbar facet joint following urinary tract infection.

Septic arthritis of a lumbar facet joint is a rare condition. We report the case of a 77-year-old diabetic woman who developed fever and back pain 15 days after she had been diagnosed with a genitourinary infection for which she had received ciprofloxacin. Physical examination showed fever (38°C) and pain on pressure over the lower lumbar spinous vertebral apophyses and over the lower left paraspinal musculature. Investigations showed a white cell count of 8.4×10⁹/l, neutrophils 85.3%, erythrocyte sedimentation rate of 125 mm/h, and C-reactive protein of ≥9 mg/dl. Two blood cultures were both positive for Escherichia coli resistant to ciprofloxacin. There was no growth of pathogens from the urine cultures. Scintigraphy with gallium citrate Ga⁶⁷ showed vertical lower lumbar (L4-L5) radionuclide uptake lateralized to the left. Magnetic resonance imaging of the lumbar spine demonstrated signal changes and alteration of the structure at the left interapophyseal L4-L5 joint, an adjacent small collection of 1cm in diameter, and infiltration of the surrounding soft tissues, which extended to the epidural area, left conjunction hole, and paraspinal muscles. The patient was treated with intravenous cefotaxime and gentamicin and bed rest for 21 days, and recovered. This is the first report of interapophyseal arthritis caused by E. coli.