Updated: 10/4/2016

Atypical Mycobacterium Infections

Topic
Review Topic
0
0
https://upload.orthobullets.com/topic/6107/images/m. marinum culture.jpg
Introduction
  • Nontuberculous mycobacterial infections
  • Epidemiology
    • demographics
      • often found in marine workers
    • location
      • hand and wrist are involved in 50% of cases
    • risk factors
      • immunocompromised host
  • Pathophysiology
    • incubation
      • average incubation period is two weeks, but can be up to six months
      • average time to diagnosis and appropriate treatment is more than 1 year
    • organisms  
      • widely encountered in the environment, but rarely cause human pathology
        • M. marinum 
          • most common atypical mycobacterium infection
          • more common in stagnant fresh or salt water (aquariums)
        • M kansasii
          • found in soil
        • M terrae
          • found in soil
        • M. avium intracellulare
          • most common in terminal AIDS patients, but can occur in non-HIV patients
  • Prognosis
    • natural history
      • early presentation includes papules, nodules, and ulcers
      • late presentation may have progressed to tenosynovitis, septic arthritis, or osteomyelitis
    • morbidity & mortality
      • mortality rate is 32%
Presentation
  • Symptoms
    • cutaneous rash with discomfort
  • Physical exam
    • papules, ulcers, and nodules are common, especially on the hands
      • many times presents with a single nodule that may ultimately spread to the lymph nodes
      • indistinguishable from tuberculous mycobacterial infection
Studies
  • Histology
    • granulomas may or may not demonstrate acid-fast bacilli on AFB stain
  • Cultures and sensitivities are key to diagnosis
    • Lowenstein-Jensen culture agar
      • M. marinum incubated specifically at 30 to 32° C 
      • M. avium intracellulare incubated at room temperature
Treatment
  • Nonoperative
    • oral antibiotics
      • indications
        • if diagnosed at early stage 
      • medications
        • ethambutol, tetraycline, trimethoprim-sulfamethoxazole, clarithromycin, azithromycin
        • add rifampin if osteomyelitis present
  • Operative
    • surgical debridement + oral antibiotics in combination for 3 to 6 months
      • indications
        • later stage disease
      • use a combination of above medications
 

Please rate topic.

Average 2.6 of 5 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Topic COMMENTS (1)
Private Note