Michael Melia, M.D., John G. Bartlett, M.D.


  • Gram-positive branching, beaded, filamentous rod.
    • Partially acid fast with modified Kinyoun stain.
    • Can be difficult to recover; notify lab if high index of suspicion.
    • Grow on non-selective media in 2-14 days.
      • Selective media (Thayer-Martin, paraffin agar, charcoal-buffered yeast extract media) may be needed to enhance growth and minimize contaminants.
  • More than 50 species known. Found worldwide, considered a soil pathogen. May also be seen in human oral flora.
    • Many of the isolates initially identified as N. asteroides are now known by modern techniques to have been misclassified.
  • Classified by some according to drug-susceptibility patterns + other organisms/groups:
    • Type I: N. abscessus
    • Type II: N. brevicatena/paucivorans complex
    • Type III: N. nova complex (including N. nova, N. veterana, N. africana)
    • Type IV: N. transvalensis complex
    • Type V: N. farcinica
      • Most common cause of disseminated/extrapulmonary disease
    • Type VI: N. cyriacigeorgica
    • N. brasiliensis
      • Cause of primary cutaneous infection in immunocompetent hosts
    • N. pseudobrasiliensis 
    • N. otitidiscaviarum 

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Last updated: July 30, 2017