Biology 216 - Lect 27 
Mycobacterium General
Order: General, atypicals, TB, leprosy
I. Mycobacterium in general (fungal bacterium)
	Gm+ rods, stain poorly, non-motile, non-sporeforming, 
		acid fast (mycolic acid - C90)
	Ubiquitous in soil, animals 
		(except M. tuberculosis and M. leprae)
	Fungal-like: crusty, slow growing
II. Atypical mycobacteria - 
	MOTTs - Mycobacterium other than TB; (NTM) - 
		Non-TB Mycobacterium
	Used to be considered saprophyte, however, 
		now recognized cause of TB in comprom
	Confusing to learn each (read for own interest):
		M. marinum (fish tank granuloma)
	Know: M. avium-intracellulare complex (MAC) - 
		difficult to speciate and treat.
	A. Classification Groups- based on Runyon scheme
		1. Speed of growth - most take greater than 10 days.
		2. Scotochromogenic - pigment in the dark
		3. Photochromogenic - pigment 
			after 1 hour light exposure.
		4. Niacin accumulation - M. tuberculosis makes 
			and stores; colorimetric assay.
		5. Other biochemicals to speciate within the group: 
			tween hydrolysis, sugars...
	B. Pathogenesis - same for all species (chronic disease).
		1. Reservoir - MOTTS not person to person (water, soil,.....)
		2. Transmission - inhalation, break in skin, ...
		3. Compromised host (immunological or lung) 
				and high numbers required.
			Middle age smokers, previous lung disease, AIDS, 
				autoimmune (rheumatoid arthritis-Portland)
		4. CMI is protective, humoral occurs, but insignificant.
		5. Lesion - granuloma (tubercle) - Macs, 
			giant cell, fibroblasts, fibrin, Ca++
			Dynamic equilibrium - must rebuild to maintain wall.
	C. Isolation and ID - hood and special containment
		1. MOTT - require repeat isolation, closed lesion, 
			history of compromised, + x-ray
		2. Butte Co - solubilize  (N-acetyl-L-cys); decontaminate; 
			pellet; Lowenstein-Jensen/7H11, 
			set up tests to group, send to state to speciate.
		3. DNA probe by state - 125I-DNA probe to rRNA 
			for TB (very sensitive and specific)
	D. Treatment - long term combination antibiotics 
		(INH, Sm, Rif, Ethambutol)
		Isoniazid (nitrogen/ring, simple) - block mycolic acid synthesis
		Ethambutol (similar structure to INH) - block CHO metabolism
		High rate resistance to these INDIVIDUALLY, 
			so combination for long time (6 - 12 months)
		MDR - evolved from not taking all pills 
			-  Nausea discourages completion of drugs.
			- Outpatient treatment
			- 10 % compliance when many pills
			- Food and clothing vouchers to encourage
		Now combinations available in one pill
		50 % fatality with MDR Mycobacteria (surgical removal as last resort)
		New fluoroquinolones effective, but resistance is developing.
		Must penetrate lesion and bacteria - extended therapy 1 - 2 years.
		Sensitivity testing (2 more weeks) 
		MAC - No effective cure - 4 - 6 antibiotics