Mycobacterium Flashcards
Mycobacterium description
Aerobic & Acid fast! non spore-forming rods, No flagella or capsules, Gram positive but poor at staining
What does it mean to be acid fast?
Can bind phenol based dyes and resist discoloration
Mycobacterium Major diseases
Tuberculosis - Paratuberculosis - Granulomatous diseases
Mycobacterium Virulence factors
Lipids/glycolipids/peptidoglycolipids - Alkyl hydroperoxidase reductase - Sufolipids, phosphatidyl inosital mannoside, surface mycosides, waxes - Glycolipid Dimycolyl trehalose - Mycobactins & exochelins
Mycobacterium virulence factors that aid in intramacrophage survival & account for acid-fastness
Lipids, glycolipids, peptidoglycolipids
Mycobacterium virulence factors that are responsible for resistance
Alkyl hydroperoxidase reductase
Mycobacterium virulence factor - “cord factor”
Dimycolyl trehalose glycolipid
Mycobacterium virulence factor for iron acquisition
Mycobactins & Exochelins
Tuberculosis - 3 species responsible
Reportable Disease!!!! - M. tuberculosis, M. bovis, M. avium
Tuberculosis - Reservoir species of different Mycobacterium species
Humans (M. tuberculosis) - Cattle & wild mammals (M. bovis) - Birds (M. avium)
Tuberculosis- Transmission
Mainly inhalation & ingestion - Transplacental, transovarian - intrauterine also possible
Tuberculosis Pathogenesis
- Inhalation–> respiratory tract, adjacent lymph nodes & serous cavities - Hematogenous dissemination to liver & kidney - Rare udder infection (zoonotic!!) - Some transplacental to calves (liver & spleen lesions if not aborted)
Tuberculosis Disease patterns
Acute exudative process - Neutrophilic - Large infecting dose favored (inhalation) - High virulence - Predisposition of host - Loose tissue architecture (lungs) - Emaciation - Low grade fever - Enlarged lymph nodes - cough - diarrhea (tissue damage from cytokines, help spread organism)
What Tuberculosis signs arise after effective cell-mediated immune response?
Localized arrested pulmonary lesions
What Tuberculosis signs arise after ineffective cell-mediated immunie response?
Active pulmonary tuberculosis, generalized tuberculosis
Tuberculosis in ruminants - causative species
M. bovis!! sometimes avium/tuberculosis
Tuberculosis in ruminants- Disease pattern
Granulomatous lesions all over lungs, serous cavity surfaces! -
Tuberculosis in horses
M. avium - Rare - GI infection, pharynx & intestine, maybe lungs, spleen & serous membranes
Tuberculosis in pigs
M. bovis & avium - GI, Miliary lesions in liver & spleen
Tuberculosis species in Dogs & Cats
Mainly M. bovis