VMC 311: Systematic Veterinary Bacteriology and Mycology (2+1)

CLASSIFICATION

Classification of Mycobacteria (Tubercle Bacilli)

I. Slowly growing mycobacteria

• Mycobacterium tuberculosis causes human tuberculosis in human and dogs.
• Mycobacterium bovis causes bovine tuberculosis in many animal species and also cause tuberculosis in human
• Mycobacterium africanum causes human tuberculosis.
• The human type (Mycobacterium tuberculosis) is primarily a pathogen for man.
• But can cause disease in cattle, pigs, dogs, monkeys, parrots and other species.
• The bovine type (Mycobacterium bovis) is a common cause of disease in domestic animals particularly cattle, pigs, cat, dogs and horse.
• The avian type (Mycobacterium avium) is primarily a pathogen for birds. But can cause disease in cattle, sheep, goat and pigs.

II. Atypical mycobacteria

• Runyon (1959) grouped the atypical mycobacteria on the basis of pigmentation, colonial morphology and growth rate.
• The photochromogens will produce pigment only if exposed to light. The scotochromogens are those that produce yellowish orange pigments in the dark.
• The slow growing mycobacteria are those that require over 7 days incubation and rapid growers are those requiring less than 7 days.
  • Slowly growing photochromogens
    • Mycobacterium kansasi, Mycobacterium marinum, Mycobacterium simiae
  • Slowly growing scotochromogens
    • Mycobacterium gordonae (tap water scotochromogens)
  • Slowly growing non-chromogens
    • Mycobacterium avium (Avian tuberculosis)
    • Mycobacterium intracellulare
    • Mycobacterium paratuberculosis (Johne’s disease – chronic hypertrophic enteritis in cattle)
    • Mycobacterium lepraemurium (Feline leprosy)
  • Rapid growing mycobacteria
    • Mycobacterium phlei (timothy grass bacillus)
    • Mycobacterium smegmatis

III. Non-cultivable mycobacteriae

• Mycobacterium leprae
  • Addition to this the unspecified acid-fast bacilli such as Mycobacterium senegalense and Mycobacterium farcinogens were isolated from Bovine farcy.