Microbiology and Immunology 3820A Lecture Notes - Lecture 3: Mantoux Test, Dapsone, Tuberculosis
8 Dec 2016
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Waxy, greasy cell envelope and wall structure. Slow growth, poor staining and acid fastness (i. e. once stained, resistant to decolorization by acid and alcohol) gram positive by structure but does not gram stain. Cell walls that are 60% lipid, including unique long chain fatty acids called mycolic acids. Mycobacterium leprae (causal agent of leprosy: m. tuberculosis complex. Mycobacterium bovis cattle, greater problem 100 years ago, vets paid attention to herds, some problems with wild bison out west. If the sputum stains negative for afb patient is noninfectious. Incidence of tb is low in north america except in first nations, inuit, refugees, aids and the homeless. Can have latent positive test but cannot transmit. Curve of descending return great loss of opportunity to eliminate. The hallmark of tb is the tubercle, which is a caseating granuloma (inner most part disintegrates into cheese like substance) reactive granulating tissue due to infection. Pulmonary tb is asymptomatic at first, with insidious onset of cough.
