Mycobacterium
species
BY HABTAMU BIAZIN

Mycobacterium species
• Mycobacterium is a genus within the order of
actinomycetal.
• It compromises a large number of well characterized
species.
• Several of which are associated with human and
animal diseases such as TB and leprosy.
• The genus Mycobacterium contains three groups.

Mycobacterium species …
• Obligate parasites: this includes
• 1. Mycobacterium Tuberculosis Complex(MTC):
• M. tuberculosis, M. bovis, M.africanum, M. canetti, M.microti,
M.caprae, M. pinnipeddi
• 2. Mycobacterium leprae
• Opportunistic pathogens
• These are the nontuberculosis Mycobacterium (NTM)
• they are categorized as
• Photochromogens

Mycobacterium species …
• Scotochromogen, Non-chromogens AND Rapid Growers
This is the traditional Runyon classification
1. tuberculosis
complex
M. tuberculosis M. bovis M.africanum
M. leprae
2. Photochromogens M. kansassi , M. marinum
3. Scotochromogen M. scrofulaceum, M. gordonae, M. szulgai
4. Non-chromogens M. avium-intracellulare, M. xenopi, M. terrae
5. Rapid growers M. fortuitum, M. abscessus, M. chelonae, M. Smegmatis

Mycobacterium species
• Saprophytes:
• are isolated from may sources
• These includes: M. phlei (grass) and M. Smegmatis
(smegma)

GENERAL PROPERTIES
• Mycobacteria are Slender Rods
• They sometimes show branching, filamentous forms resembling
with fungi mycelium.
• They are aerobic, non motile, non capsulated and non spore
forming
• usually having slow growth
• They are acid fast bacilli (AFB)
• Cell wall- rich in lipids

Mycobacterium Tuberculosis
• The bacterium that causes Tuberculosis.
• TB also caused by M.bovis
• M.tuberculosis was discovered in 1882 by Robert Koch
• Morphology
• In tissue
• Mtb is a thin, straight or slightly curved rod(0.4× 3 µm) where as
M.bovis is straight rod and short (0.3×3 µm).

Morphology…
• On artificial media:
• Filamentous forms are seen with variable morphology from one
species to the an other.
• They occur singly, in pairs or as a small clumps.
Mtb on LJ medium

Morphology …
• They are obligate aerobic, non motile, non capsulated and non spore
forming.
• They are alcohol and acid fast.
• Slow growing ( doubling time 18hrs)
• cell wall: rigid, rich in lipids, hydrophobic, resistant to many
disinfectants, detergents, stains, antibiotics and host immune
responses.

Property… Resistance
• Relatively resistance acid and alkali
• 5% phenol, 15% H2 SO4, 3% nitric acid, 4% NaOH
• Resistance to dehydration:
• can survive
• expectorated sputum for 20-30 hrs and
• in droplet nuclei for 8-10 days.
• which is important for transmission by aerosols.

Property… Resistance
• Destroyed by 80% ethanol for 2 minutes and 5
minutes iodine solution.
• Sensitive to formaldehyde, glutaraldehyde
• Killed at 60℃ 𝑓𝑜𝑟 10 − 15 𝑚𝑖𝑛𝑢𝑡𝑒𝑠
• Culture may be killed by direct sunlight for 2hrs.

• Thank you for your attention!!!!