A Rare Case of Emphysematous Osteomyelitis With Concurrent Septic Arthritis.

A rare and possibly fatal infection of the bone called emphysematous osteomyelitis (EO) is caused by the presence of intraosseous gas due to gas-forming organisms. Common gas-producing organisms are in the Enterobacteriaceae family or are anaerobes. This gas within bones is most frequently detected using computed tomography (CT) imaging, and prompt diagnosis is important due to the high mortality rate. We present a 76-year-old male who complained of altered mental status, right upper and lower extremity weakness, and lower back pain. The MRI of the lumbar spine showed moderate edema in L3 and L4, with fluid in L3-L4 and L4-L5 concerning discitis/osteomyelitis. A CT-guided biopsy of L3/L4 was then performed by interventional radiology, revealing air present in the L3 and L4 vertebral bodies. Bone cultures from the L3 and L4 vertebra were later positive for E. coli that was susceptible to all tested antibiotics, and this was consistent with a diagnosis of vertebral EO. The infectious disease team recommended a six-week course of intravenous ceftriaxone. During the patient's hospital stay, he also developed a septic right knee joint positive for E. coli, alongwith the concurrent vertebral EO.