Mycobacterium abscessus Otomastoiditis Complicated With Brain Abscess

Significant Statement

Nontuberculous mycobacterium (NTM) are rare pathogens in chronic otomastoiditis, often resistant to many antibiotics. This disease can progress to brain abscess and cause difficulty in treatment. In addition, there is no established principal therapy for NTM otomastoiditis, which requires a combination of antibiotics and surgical intervention. In this article, we present a case of Mycobacterium abscessus otomastoiditis with a concurrent brain abscess. After successful surgical intervention and completing an extended course of antibiotic treatment, the patient recovered well.

Case Report

A 66-year-old woman was diagnosed with left-sided chronic suppurative otitis media, characterized by a yellowish discharge from the left ear that had persisted for 3 months after swimming. Despite receiving antibiotic treatment with a levofloxacin otic solution, she continued to experience recurrent otorrhea, bilateral ear pain, and dizziness, prompting her to seek care at our hospital. Physical examination revealed left conductive hearing loss, with impaired hearing on the left side. Otoscopy revealed a discharged perforation of the left ear, and a tympanogram showed a type C finding, suggesting the possibility of otitis media with effusion. A computed tomography revealed mild hyperattenuating lesions with enhancement in the left middle cranial fossa and the left temporal region. Magnetic resonance imaging (MRI) of brain showed lobulated contours in the left temporal fossa, ear, mastoid, and temporal bone (Figure 1A and 1B).

Figure 1.

(A, B) Initial brain MRI revealed contrast-enhancing tissue with a lobulated contour at the left temporal fossa (arrow) [(A) contrast-enhanced FLAIR, (B) Sagittal T1-weighted 3-dimensional fast spin echo]. (C, D) Histological characteristics of the case, osteochondroid tissue with granulation of ear tissue on H&E staining [(C) 100×, (D) 200×]. (E, F) Follow-up brain MRI indicated residual tuberculous granuloma in the left temporal region (arrow) [(E) Contrast-enhanced FLAIR, (F) sagittal view]. FLAIR, fluid-attenuated inversion recovery; H&E, hematoxylin-eosin; MRI, magnetic resonance imaging.

To identify these lesions, the patient underwent a left modified radical mastoidectomy, tympanoplasty, and a biopsy of the brain mass. Histological findings indicated chronic granulomatous inflammation with fibrosis in the osteochondroid and brain tissue (Figure 1C and 1D). Culture of osteochondroid tissue from the left ear yielded Mycobacterium abscessus. The antibiogram revealed that this M. abscessus is susceptible to clarithromycin, intermediate to amikacin and linezolid, and resistant to doxycycline, moxifloxacin, and imipenem. Given the diagnosis of M. abscessus otomastoiditis complicated with a brain abscess, multidrug therapy with a 3-drug combination based on clarithromycin was initiated. However, the follow-up MRI showed contrast-enhancing lesions in the left temporal region, which had enlarged in size with cerebral vasogenic edema and midline shift. Consequently, a secondary left subtemporal craniotomy was performed. Furthermore, the multidrug regimen was gradually adjusted to azithromycin, rifabutin, and bedaquiline due to adverse drug reactions, including acute pancreatitis, lactic acidosis, and progressive hearing loss after treatment with tigecycline, linezolid, and amikacin, respectively. The patient tolerated the medications well and recovered without any noticeable neurological deficits. The MRI performed 7 months later showed residual brain granulomas in stable condition (Figure 1E and 1F).

Surgical intervention is necessary for the management of ostomastoiditis complicated with brain abscess. Around 20% of cases in previous studies required repeated tympanomastoidectomy. ¹ M. abscessus, a rapidly growing saprophytic nontuberculous mycobacterium (NTM), is highly resistant to several antibiotics. ² M. abscessus otomastoiditis is particularly unique, characterized by refractory otorrhea, insidious mastoiditis, otorrhea, otalgia, osteomyelitis, peripheral facial palsy, hearing loss, and even cerebral infection.^1,3 The pathogen can enter the middle ear directly by perforating the tympanic membrane or a tympanostomy tube, migration through the Eustachian tube, and transmission through surgical instruments. ¹ In addition to surgical interventions, adequate antibiotic treatment is recommended for severe cases.^1,3

A multidrug regimen comprising at least 3 active drugs is recommended for the treatment of infectious diseases caused by this pathogen. ² The Infectious Diseases Society of America (IDSA) guidelines recommend the use of macrolides, such as azithromycin or clarithromycin, combined with at least 2 other antibiotics, including amikacin, imipenem/cilastatin, cefoxitin, tigecycline, linezolid, and clofazimine for NTM pulmonary disease. ² However, recommendations for the treatment of extrapulmonary NTM diseases remain unavailable. Moreover, the high drug resistance of the pathogen and the potential for adverse reactions to antibiotics used to treat it may limit their effectiveness. Bedaquiline, an antibiotic used for multidrug-resistant tuberculosis, has shown promising activity against M. abscessus.^4,5 It has been found to exhibit in vitro effectiveness when used in combination with rifabutin. ⁴

When treating patients with chronic otitis media refractory to standard treatment, physicians should consider the presence of uncommon pathogens such as M. abscessus. The emergence of drug resistance and the need for long-term treatment have made M. abscessus a global health concern. Early diagnosis can help prevent such challenging situations. Surgical intervention, along with a prolonged course of antibiotics, is recommended to treat severe M. abscessus otomastoiditis.^4,5