EC Microbiology

Orthopaedic infections are associated with a substantial risk of recurrence due to the difficult penetration of antibiotics in bone tissue. Though most often the causative agent is Gram positive bacteria, in some cases, unusual pathogens can cause bone infections due to underlying clinical conditions.

A 56-year-old woman affected by an autoimmune hepatitis treated with mycophenolic acid (1g per day) and steroids (prednisone 12.5 mg per day) since 2004, was evaluated because of a haematoma in the right-side gluteus secondary to a fall. A CT scan of the pelvis showed an abscess of the right gluteus (41 x 68 mm x 7.5 cm) and an exophytic part of the bone close to a minor bleeding arteriole. The biopsy showed emphysematous chronic osteomyelitis; the microbiological examination of the bone and the drainage performed before antibiotic treatment were positive for Corynebacterium amycolatum, in absence of other pathogens. C. amycolatum infections are usually described in immune-compromised individuals. Most commonly it was reported in paediatric patients who underwent peritoneal dialysis and developed peritonitis, other reported the pathogen in corneal ulcers or even endocarditis. Usually, C. amycolatum is isolated as part of a mixed flora.

This is the first single-pathogen bone infection due to C. amycolatum; the isolation of this bacteria indicates that even alone, it could cause invasive infections alone in immunocompromised patients.

Keywords: Corynebacterium amycolatum; Osteomyelitis; Immunosuppressed

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