Characteristics and prognosis of intractable otomastoiditis caused by nontuberculous mycobacteria

To clarify the clinical characteristics, management, and prognosis of nontuberculous mycobacteria (NTM) otomastoiditis, a rare and intractable disease with high relapse risk. This study presents the largest case series to date, analyzing 30 patients with NTM otomastoiditis.

This retrospective case series was conducted at a single tertiary referral center. Clinical data including causative pathogens, imaging findings, antibiotic regimens, surgical interventions, complications, and audiometric outcomes were reviewed and analyzed.

Among the 30 patients (14 males; mean age 55 ± 20 years), Mycobacterium abscessus was identified in 26 (87 %) cases. Skull base osteomyelitis or intracranial involvement was present in 7 (23 %) patients. All patients received anti-NTM antibiotics, with macrolides being the most frequently prescribed. The median antibiotic duration was 13 months. Twenty-three (77 %) patients underwent surgery, and 12 (40 %) had additional operations. Among 23 patients with complete audiometric data, mean air-conduction hearing thresholds improved from 64.1 to 55.6 dB HL (p = 0.04); however, irreversible total deafness developed in 3 patients.

Nontuberculous mycobacterial otomastoiditis requires early recognition and comprehensive management. Combined surgical debridement and prolonged antibiotic therapy are often necessary, and all patients can achieve disease control. Hearing outcomes vary, but functional preservation is possible in appropriately managed cases.