Mycobacterium xenopiによる感染性脊椎炎の1例

Vertebral Osteomyelitis Due to Mycobacterium xenopi : A Case Report

　非常に稀な非結核性抗酸菌脊椎炎の1例を経験した．症例：62歳　男性．皮膚筋炎でステロイド治療中であった．2008年4月から腰痛，右下肢痛により歩行困難となり入院した．単純X線像およびMRIでL3/4椎体終板の骨破壊像を認め，感染性脊椎炎を疑い経皮的髄核摘出術法により生検を行った．培養でMycobacterium xenopiが検出されethambutol，rifampin，isoniazid，clarithromicinの4剤による化学療法を行った．Mycobacterium xenopi感染症はわれわれの渉猟しえた限り本邦では20例で，自験例は初めての脊椎病変であった．

　Infectious spondylitis caused by non-tuberculous mycobacteria is an uncommon disorder.　We experienced a very rare case of infectious spondylitis due to Mycobacterium xenopi.　Till date, only 8 such cases have been reported in the world.　A 62-year-old man receiving prednisolone therapy for the treatment of dermatomyositis since 10 years presented with severe low back pain of 12-months duration.　Lumbar spine radiographs showed a collapsed disc space and destruction of the endplates at the L3-4 level.　Magnetic resonance imaging showed abnormal signals in both vertebral bodies and discs, and a rim-enhancing mass was observed in the iliopsoas muscle.　Percutaneous disc biopsy was performed using Hijikata instruments, and atypical mycobacterial growth was observed 7 weeks after the biopsy.　The organism was found to be M. xenopi by DNA-DNA hybridization.　Antituberculosis therapy (isoniazid, rifampin, clarithromicin, and ethambutol) was started.　There was a gradual decrease in low back pain, and the patient was discharged 16 weeks after starting antituberculosis therapy.　To the best of our knowledge, this is the first case report of an extrapulmonary infection by M. xenopi in Japan.