Q fever is a worldwide zoonosis caused by Coxiella burnetii. The clinical manifestations of
Q fever include
endocarditis,
pneumonitis and
hepatitis. Disease awareness and evolving diagnostic tests have enabled the recognition of unusual manifestations of
Q fever. We report a case of
Q fever osteomyelitis. A 51-year-old patient was admitted to hospital because of
fever, leg weakness, and
asthenia. His past medical history included surgery and a bone graft for the treatment of a
giant cell tumor on the distal part of the femur. Blood and bone biopsy cultures were negative. Bone histological examination was consistent with a sub-acute or chronic inflammatory reaction that involved foci of epithelioid and gigantocellular infiltrates and
necrosis. Serology testing revealed high antibody titers to C. burnetii
antigens (phase I:
IgG 3200;
IgA 200; phase II:
IgG 6400;
IgA 400), which is indicative of
chronic Q fever. The specific Polymerase Chain Reaction (PCR) of the
abscess sample from the femoral region was positive for C. burnetii. The patient was treated for
chronic Q fever with
doxycycline and
hydroxychloroquine for 18 months and recovered gradually without recurrence of
pain or functional impairment.
Q fever osteomyelitis is a rare and most likely underestimated disease. Epithelioid and gigantocellular granulomatous
osteomyelitis in the context of culture-negative bone specimens should raise suspicion of
Q fever. Serological tests, specific PCR and cell culture can provide evidence of a C. burnetii
infection. Although bone diffusion may be a concern, the currently recommended treatment for
Q fever was effective in this case.