Mycobacterium abscessus is a topic covered in the Johns Hopkins ABX Guide.

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MICROBIOLOGY

  • Human pathogen, occasional environmental contaminant. Present in water, sewerage, vegetation.
  • Considered among the most pathogenic and chemotherapy-resistant of rapid-growing mycobacteria.
    • Organism produces clavulanate-insensitive broad-spectrum β-lactamase that limits the in vivo efficacy of β-lactams[6].
  • Formerly part of "M. chelonae-complex", but important to distinguish from M. echelon as antimycobacterial therapy more difficult with M. abscessus senso strictu.
    • Three human subspecies have been proposed: rpoB gene-based typing necessary to distinguish; usual biochemical/phenotypic methods fail. Speciation is difficult and there is not uniformity in recognition, so confusion in not infrequent when applying labels to M. abscessus isolates.
      • M. abscessus subsp. abscessus
        • Seen more commonly in North America
        • Many isolates have the erm gene, which confers macrolide, often inducible, resistance.
        • Resistance often seen after 3-14d employment of macrolide. Testing of isolates for inducible macrolide resistance suggested.
      • M. abscessus subsp. massiliense
        • Lacks inducible macrolide resistance or erm gene[9].
        • More frequently seen in Korea.
      • M. abscessus subsp. bolletii
      • First two represent most human infections.
  • Occasionally confused with Corynebacterium spp. (described as diphtheroid growing in broth systems).
  • In vitro resistance rates (most studies from Asia):

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Last updated: May 30, 2016