Microbiology and Immunology 2500A/B Study Guide - Caseous Necrosis, Alveolar Macrophage, Mycobacterium Bovis
6 Jan 2013
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Mycobacteria- tb and leprosy: tuberculosis- causes tb in humans (humans are only reservoir) Called tb because of tubercle bacilli (form tubercles: bovis- causes tb in cows. Rare in humans- but can thru unpasteurized milk extrapulmonary tb: avium- causes tb-like illness in humans (mainly aids patients, leprae- causes leprosy, tuberculosis. Facts- 2nd largest killer (by infectious disease) 1/3 of pop"n has org in them (2 bill) 1 of 10 of these will develop active tb (10% develop) Obligate human pathogen- only lives in us. Non motile, rod, obligate aerobe (need o2) Long generation time- 15h, takes 4-6 weeks for small colonies in lab. Mycobacteria- high mycolic acid in cell envelope. Resist antibiotics, acid/base, lysis by complement, oxidative stress (can live in macrophage) Impermeable to stains (cant use gram stain) Stain with basic dye (carbolfuschin) with heat to melt wax. 3. counterstain methylene blue acid fast mycobact. are red while the rest are blue.
