Mycobacterium scrofulaceum


  • Slow-growing acid fast bacilli (AFB), nontubercular Mycobacterium (NTM).
    • Runyon classification Group 2: scotochromogen (meaning develops yellow-orange pigment in either the light or the dark; other members include M. szulgai, M. gordonae).
  • Worldwide distribution; the reservoir is soil and water.
  • AFB smear appearance is thicker and longer than M. tuberculosis, but definitive identification depends on culture.
    • Differentiation from other NTM may be difficult.
    • DNA probes or 16s ribosomal sequencing are helpful.
  • Newly described M. parascrofulaceum may account for many clinical isolates. Difficult to distinguish in the lab from M. scrofulaceum.
    • Most closely related to M. simiae.

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Last updated: January 23, 2023