A 50 year-old male had past medical history of type 1 diabetes mellitus complicated with diabetic nephropathy and neuropathy on insulin; and history of simultaneous kidney and pancreas transplant on immunosuppression medications. He presented to the hospital with 4 months history of progressively worsening pain, swelling and darkening of right 2nd toe which started after clipping the toenail. Prior to presentation, he was evaluated by podiatry, plastic surgery and vascular surgery in the clinic. He was offered amputation in the setting of severely decreased perfusion of the right lower extremity as evidenced by ankle brachial index testing, however, he had declined. Pertinent investigations: white cell count 16000 cells/ul, erythrocyte sedimentation rate 56mm/hr and C-reactive protein 9.1 mg/dl. Foot radiograph was not consistent with osteomyelitis. Right lower extremity angiogram revealed severe forefoot arterial occlusive disease. He then underwent amputation of the affected toe. There was no evidence of osteomyelitis on the post-amputation MRI. Tissue culture grew Morganella morganii (MM), sensitive to ertapenem and ciprofloxacin. The patient decided to leave against medical advice and was discharged with a week of oral ciprofloxacin.
He was re-admitted 2 weeks later with worsening right foot pain and swelling. Radiography of the right foot revealed cortical destruction at the second metatarsal head, consistent with osteomyelitis. His white cell count was 13000 cells/ul, sediment rate 130 mm/hr and C-reactive protein was 13.8 mg/dl. Bone biopsy of the right 2nd metatarsal head was performed and cultures grew MM. The blood cultures were negative. He then underwent transmetatarsal amputation of right 2nd toe and was discharged home on 6 weeks of intravenous ertapenem.
MM is a gram-negative, facultative anaerobic, non-lactose fermenting, urease-positive bacillus from Enterobacteriaceae family, normally found in the gastrointestinal system flora. Immunosuppression, long-term urinary catheterization, diabetes, corticosteroid therapy and malignancy are common predisposing factors for MM infection. Clinical infections due to MM often involve the urinary tract, skin and soft tissue and hepatobiliary tract. Urinary tract infections are the most common especially in elderly patients with chronic indwelling urinary catheters. On the other hand, osteoarticular pathologies caused by MM are rarely encountered. Our patient was a transplant patient on immunosuppressant medications, diabetic with peripheral arterial disease posing multiple risk factors for MM osteomyelitis. It is imperative to pursue its diagnosis aggressively, initiating appropriate antibiotics timely and often requires multi-disciplinary approach.
Physicians should consider Morganella morganii as a cause of osteomyelitis in the appropriate clinical setting and approach it aggressively with early initiation of appropriate treatment.