Other atypical mycobacteria


  • M. celatum: slow growing (3-8 wks to culture), non-photochromogenic.
    • It may cause false-positive M. tuberculosis direct (MTD) test or ribosomal RNA test.
    • Found widely in the environment (soil, water, dust).
  • M. genavense: very slow grower (42d average); difficult to grow; alert lab if M. genavense suspected.
    • Consider if AFB is growing poorly and Mtb, MAI probe negative.
    • Found in bird populations and ferrets.
    • Antimicrobial testing is often problematic due to poor culture growth.
  • M. haemophilum: slow growing; alert lab if suspected since it requires hemin or iron to grow in culture and grows best at 28-30°C.
  • M. malmoense: slow growing; most clinical isolates/reports are from northern Europe.
  • M. mucogenicum: rapid grower (< 7 days in culture); sporadic contaminant in respiratory samples; water is the environmental reservoir.
    • Previously known as M. chelonae-like organism.
  • M. simiae: growth may take 4-6 weeks on LJ slants.
  • M. szulgai: scotochromogen at 37ºC and a photochromogen at 25ºC.

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Last updated: April 16, 2023