Mycobacterium scrofulaceum

Paul Auwaerter, M.D.

MICROBIOLOGY

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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