Chapt 26 Mycobacteria Flashcards
(30 cards)
Photochromogenic
Characteristic appearance of Mycobacterium spp. in which exposure to light stimulates pigment production
Acid-fastness
Ability of bacteria, such as the Mycobacterium spp., to retain dye when treated with mineral acid or an acid-alcohol solution
Scotochromogenic
Mycobacterium spp., produces pigment in either light or dark growth requirements
Nonphotochromogen
Mycobacterium spp., such as M. tuberculosis, that don’t produce pigmentation
Purified Protein Derivative (PPD)
Diagnostic skin test for tuberculosis
Endogenous
Originating from within an organism
Leprosy
Infection of the skin, mucous membranes, & peripheral nerves caused by Mycobacterium leprae
Lowenstein-Jenson agar
Non-selective media for the isolation of Mycobacteria
Nutrients: eggs, potato, flour, glycerol
Inhibitors: malachite green
Middlebrook agar
Non-selective media for the isolation of Mycobacteria
Nutrients: Oleic acid, albumin
Inhibitors: Malachite green
Kinyon stain
Procedure often used for acid-fast staining, like Ziehl-Neelson stain, a carbol-fuchsin method; thought does not involve heat application
Mycobacterium genus
Branching, filamentous, straight-curved rods, aerobic, DON’T stain w/ Gram stain, Acid Fast Bacilli (AFB), cell walls have high lipid content, needs Acid Fast Stain, ubiquitous (present in soil & water); normal flora, opportunistic, and true pathogens
Mycobacteria cultures
Airborne pathogens require BSL3 processing & testing, special enriched/selective media in sealed screw top tubes, separate incubators with lights, and prolonged incubation, generally incubated for 8 wks
Slow growers
Visible colonies in >7 days
Rapid growers
Visible colonies in <7 days
Special growers
Will not grow in vitro
Acid Fast Stain
1-Primary Stain 2-Decolorizer 3-Counter Stain
MOTT
Mycobacteria Other Than Tuberculosis
Mycobacterium tuberculosis
TB…consumption…Koch’s bacillus, slow groweres 3-6 wks for visible colonies, complex nutritional & increased CO2 requirements, dry-buff tan colored colonies, very prolonged chronic, ultimately fatal respiratory infections, weight loss, night sweats, fatigue, bloody sputum, acquired from aerosols & possible dissemination, PMNs+Monocytes phagocytize organism, forming characteristic exudate lesions (tubercles)
M. tuberculosis biochemical tests?
Niacin (+) Nitrate (+)
M. tuberculosis treatment?
An initial 2-mos phase of four drugs: Isoniazid, Rifampin, Pyrazinamide, & Ethambutol, followed by a 4-mos continuation phase of Isoniazid & Rifampin
Strict adherance to treatment is critical, antibiotic resistance is increasing, MDR-TB (Multi-drug resistant TB)
PPD of >5mm
(+) for high risk patients (HIV)
PPD of >10mm?
(+) for high risk of progression (healthcare)
PPD of >15mm?
(+) for patients with no known risk
Mycobacteria leprae
Causative agent of leprosy (Hansen’s Disease), 150 US cases per yr (most acquired over seas), weak pathogen…95% human immune, stains as parallel bundles of organisms of AFB stains, infects skin, mucous membranes, & cartilaginous tissue, effective antibiotic treatment, Armadillo (15%) is the only animal, besides humans that is known to carry leprosy, will not grow in vitro, armadillo food pads used for in vivo cultures
