- 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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