Updated: 1/5/2019

Mycobacterium Other Than Tuberculosis (MOTTS)

Review Topic
  • A 4-year-old boy presents to the pediatrician by his mother due to noting a lump under his mandible. She first noticed the lump approximately 2 weeks ago and it has progressively increased in size. On physical exam, the patient does not appear to be in any acute distress. There is a 2-3 cm, nontender mass with parchment-like skin overlying the mass. The mass is drained and cultures and a polymerase chain reaction are sent of the mass. (Superficial lymphadenitis likely caused by MAC)
  • Definition
    • infectious mycobacterium that is not tuberculosis, which can cause 4 clinical syndromes
      • pulmonary disease
        • caused by Mycobacterium avium complex (MAC)
      • superficial lymphadenitis
        • caused by 
          • MAC (more common in children)
          • M. scrofulaceum
          • M. malmoense
      • disseminated disease in immunocompromised patients (e.g., AIDS)
        • most commonly caused by MAC
      • skin and soft tissue infection
        • most commonly caused by M. marinum
          • typically due to direct inoculation of the organism
  • Epidemiology
    • incidence
      • the most common nontuberculous species that cause disease in humans in the United States are
        • MAC
        • M. kansasii
Nontuberculous Mycobacterium
Clinical Presentation
Making the Diagnosis
Pulmonary disease
  • Symptoms are typically non-specific and depend if the patient has underlying pulmonary disease
    • patients with underlying pulmonary disease typically present similar to tuberculosis (e.g., cough, weight loss, upper lobe infiltrates, and cavities)
  • Symptoms include
    • cough (dry or productive)
    • fatigue
    • malaise
    • dyspnea
    • weakness
  • Based and clinical and radiographic findings (e.g., nodular or cavitary opacities or multifocal bronchiectasis)
  • Sputum acid-fast bacilli and culture
  • Lung biopsy with mycobacterial histopathologic features (granulomatous inflammation or acid fact bacillus), if needed
Superficial lymphadenitis
  • Enlarged lymph nodes
    • most commonly the cervicofacial node in children
    • nontender and unilateral
    • enlarges over the course of weeks
  • Culture or polymerase chain reaction (PCR) of the fistula drainage, tissue, or caseous material
  • Most commonly affects children < 5 years of age
Disseminated disease
  • Fever
  • Fatigue
  • Malaise
  • Anorexia
  • Sequelae of organ involvement
    • bone marrow (neutropenia and anemia)
    • hepatosplenomegaly
  • Blood cultures of the mycobacterium
  • Risk factors include
    • advanced HIV infection
    • hematologic malignancy
    • tumor necrosis alpha inhibitors or other immunosuppressive agents
Skin and soft tissue infection
  • Skin lesion
    • erythematous or bluish papule or nodule at the site of abrasion
      • lymphadenopathy may be present
  • Culture or PCR of the lesion
  • Fisherman or people who work at aquariums are at risk of developing M. marinum infection

  • Medical
    • macrolide, rifamycin, and ethambutol
      • indication
        • initial empiric treatment option for MAC
      • comments
        • in cases of macrolide-resistance, the regimen is changed to rifamycin, ethambutol, clofazimine, and an intravenous aminoglycoside
        • note, the appropriate treatment for M. marinum has not been identified
  • Dissemination of the nontuberculous mycobacterium can occur in severely immunocompromised patients

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