The first human clinical case of chronic osteomyelitis caused by Clostridium hydrogeniformans

- We describe the first clinical case report attributable to Clostridium hydrogeniformans.
- The organism was proposed as novel species of the genus Clostridium in 2010.
- Conventional methods and MALDI-TOF MS cannot determine this bacterium at present.
- Microbiologist should use gene sequence analysis to identify C. hydrogeniformans.
- Physician needs to consider antibiotics covering anaerobe when treating traumatic patient.

We present the first case report of osteomyelitis due to Clostridium hydrogeniformans in a previously healthy 18-year-old male. He was admitted to our hospital because of an open contaminated fracture of the right arm after being blown into a drain in a motorbike accident. He underwent surgical debridement and treatment course of cefazolin. Although he responded well to these initial treatments, subcutaneous abscess and ulnar osteomyelitis developed 1 month after discharge. Second debridement was performed and specimens were collected from both the abscess and bone tissues. Only anaerobic culture showed a gas-producing Gam-positive rod. Conventional methods and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry could not accurately identify this organism. However, 16S rRNA gene sequence analysis determined the isolate as C. hydrogeniformans with 99.79% homology. The patient recovered after 90 days of antibiotic treatment, and had no evidence of recurrence. Anaerobic bacteria are more common as causative pathogens in osteomyelitis related to traumatic wounds and Clostridium spp. are particularly associated with open fractures, which is consistent with our case. Although the epidemiology and clinical characteristics of C. hydrogeniformans infection is poorly understood because of the limitations of currently available conventional methods of identification, clinicians need to consider this organism as a causative pathogen in a patient with osteomyelitis in traumatic wounds, especially contaminated by sewer water.