Reactivation of Q fever: case report of osteoarticular infection developing at the site of a soft tissue injury.

Coxiella burnetii , the causative agent of Q fever, is known to cause acute and persistent infection, but reactivation of infection is rarely reported. This case demonstrates reactivation of a distant, untreated Q fever infection after a relatively innocuous soft tissue injury in an adjacent joint without pre-existing pathology. A 52-year-old male abbatoir worker sustained an adductor muscle tear in a workplace injury. He was unable to walk thereafter, and developed a chronic, progressive, destructive septic arthritis of the adjacent hip with surrounding osteomyelitis of the femur and acetabulum. He had evidence of prior Q fever infection, with a positive skin test and serology 15 years beforehand. He was diagnosed with chronic osteoarticular Q fever on the basis of markedly elevated phase I antibodies, and symptomatic and serological response to prolonged antibiotic treatment with doxycycline and hydroxychloroquine. He required a two-stage hip arthroplasty. This case illustrates reactivation of latent C. burnetii infection at the site of a soft tissue injury. Clinicians need to be aware of this possibility in patients with previous Q fever infection, and in the setting of undiagnosed osteoarticular pathology following soft tissue injury.