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Updated: Aug 7, 2026

Intradermal Inoculation of Mycobacterium avium in the Mouse Ear
Published on: July 3, 2025
[Disseminated Mycobacterium avium infection in an immunocompetent aged patient]
Tadasuke Shimokawaji1, Hideo Kobayashi, Soichiro Kanoh
1Third Department of Internal Medicine, National Defense Medical College.
Abstract:
We reported an immunocompetent elderly patient with disseminated Mycobacterium avium infection exhibiting bronchial, pulmonary, nodal, otitic and osteitic lesions. An 82-year-old man was initially hospitalized with cervical and mediastinal lymphadenopathy. M. avium was demonstrated in gastric juice and a lymph node. An endobronchial polypoid lesion was formed by perforation of mediastinal mycobacterial lymphadenitis into the right main bronchus. Combined treatment by CAM, RFP, EB, and SM caused the lesions to diminish and the treatment was continued for 18 months. One year after completion of treatment the patient was re-admitted with complaints of left ear pain, and a subcutaneous abscess on his back. M. avium was again demonstrated from external ear exudate and aspirated subcutaneous pus. Re-treatment with combined chemotherapy induced prompt resolution of the ear and bone lesions. It is unusual that immunocompetent patients suffer disseminated non-tuberculous mycobacterial infection, but chest physicians should pay attention to M. avium infection because of its worldwide dissemination.
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