Ch 26 – Mycobacterium tuberculosis and nontuberculous mycobacteria

MYCOBACTERIUM TUBERCULOSIS

● Robert Koch’s Bacillus (1882)

● Obligate anaerobe

● Gram-positive or gram ghost/neutral

● Slightly curved rod measuring 0.2-0.6 micron in diameter and 1-4 micra in length (Bailey’s); 0.2-0.6 um x 1-10 um in size (Mahon)

● Requires CO2 for growth

● Virulence: Cord Factor and Sulfatides, Lipids (Mycolic Acids, Phospholipids

Mycobacterium tuberculosis
Mycobacterium leprae

Most familiar spp, causative agents of tuberculosis and Hansen disease (leprosy). Answer respectively

Mycobacterium leprae

Causative agent of leprosy

Nontuberculus mycobacteria

sometimes referred to as atypical mycobacteria other than tubercule bacillus (MOTT).

• M. tuberculosis & M. leprae inhabits environment & makes disease resembling TB in humans

Mycobacteria

• slender, slightly curved or straight, rod-shaped

• nonmotile, non-endospore former
•strictly aerobic

• 0.2–0.6 μm x 1-10 μm

• cell wall has high lipid content (mycolic acid); creates a hydrophobic permeability

• Resists decolorization with acid alcohol
• Slow growers (required 2-6 weeks of incubation for growth)

2-6 weeks

Mycobacteria associated with disease require _(range of how long) of incubation on complex media at specific optimal temperatures

2-3 days
20-40C

Rapidly growing spp. generally grow on simple media in _(how long) at what temperature range?

M. leprae

What mycobacteria pathogenic to humans fail to grow in vitro?