Mycobacteria Flashcards
Mycobacterium tuberculosis complex - species examples
(7)
- Mycobacterium bovis
- Mycobacterium tuberculosis
- Mycobacterium africanum
- Mycobacterium microti
- Mycobacterium canetti
- Mycobacterium caprae
- Mycobacterium pinnipedi
Mycobacterium avium complex - examples of species (4)
- Mycobacterium avium subspecies avium
- Mycobacterium hominissuis
- Mycobacterium intracellulare
- Mycobacterium avium subspecies paratuberculosis
Examples of mycobacteria other than tuberculosis (15)
- Mycobacterium flavescens
- Mycobacterium scrofulaceum
- Mycobacterium gordonae
- Mycobacterium kansasii
- Mycobacterium malmoense
- Mycobacterium terrae
- Mycobacterium leprae
- Mycobacterium marinum
- Mycobacterium xenopi
- Mycobacterium smegmatis
- Mycobacterium phlei
- Mycobacterium fortuitum
- Mycobacterium vaccae
- Mycobacterium chelonae
- Mycobacterium ulcerans
Basic background info on mycobacteria - taxonomy, characteristics, staining (4)
Mycobacteria membrne structure (3)
What diseases are caused by mycobacteria? (2)
- Tuberculosis
- Mycobacteriosis
Which mycobacteria species cause tuberculosis (2)
- M. bovis
- M. tuberculosis
Which mycobacteria species cause mycobacteriosis? (4)
What are non-tuberculous species? (3)
- Usually affect immunocompromised hosts
- Lymphadenitis, lung lesions resembling tuberculosis
- Skin lesions from infection of wounds
What is M. avium?
Most commonly causes mycobacteriosis in birds, but sometimes cattle, pigs, horses, sheep, primates
What is M. tuberculosis?
Mostly seen in humans but sometimes pigs, primates, dogs, cats, cattle, psittacine birds
What is M. bovis?
Persists in soil, can remain infective for weeks (hardy) - high doses needed for oral transmission so environmental contamination is not an important means of transmission - badgers + cattle
What is the pathogenesis of mycobacteria? (3)
- Early infection - bacteria are phagocytosed by macrophages and may be eliminated
- If not, infected macrophages persist at the site of infection for a long time before the disease progresses
- Release TNF-α, IL-12, and cytokines to recruit other macrophages and lymphocytes
- IL-12 drives a type I immune response (cell-mediated)
- Lymphocytes activate the macrophages, which become epithelioid or form MNGCs (multinucleated giant cells)
- Helps overcome the blockage of phagolysosome fusion
- Promotes formation of reactive oxygen and nitrogen species
- Promotes lysosomal enzyme production
- Cell-mediated immunity is detectable via skin test at 14-28 days post-infection
Epithelioid macrophages - lots of cytoplasm + indistinct borders (pathogenesis)
Multinucleated giant cell - usually Langhans type (nuclei ar periphery) = horse-shoe shape (pathogenesis)
What is a tuberculoid granuloma? (4)
What are tubercles? - Gross morphology of tuberculoid granuloma (5)
What are the differential diagnoses for tuberculoid granulomas? (6)
- Cestodes
- Fungi
- Bacterial
- Foreign body pyogranuloma
- Abscesses
- Neoplasia
Tuberculoid granuloma
Mycobacterium bovis hosts (4)
- Cattle
- Humans
- Deer
- Pigs
Mycobacterium bovis reservoir hosts (8)
Mycobacterium bovis - dead-end hosts and how they are infected (6)
Mycobacterium - geography (3)
Mycobacterium bovis - clinical presentation (2)
Mycobacterium bovis - lesions (5)
Respiratory lesions of mycobacterium bovis (4)
Mycobacterium bovis - generalised lesions (3)
Mycobacterium bovis - lesions of cervids (4)
Mycobacterium bovis - lesions of carnivores (5)
Mycobacterium bovis - lesions of camelids (3)
Mycobacterium bovis - lesions of horses (2)
- Usually alimentary, lesions in retropharyngeal and mesenteric LNs, intestine (GIT)
- Tubercles can look more solid and resemble sarcomas
Mycobacterium bovis - lesions of small ruminants
Uncommon, often form cavitary lesions with lots of bacilli
Mycobacterium bovis - lesions of pigs (2)
- Often systemic, M. bovis looks similar to cattle
- M. avium looks more like proliferative lesions of TB in horses
Mycobacterium bovis - diagnosis (2)
Mycobacterium bovis - active and passive management (5)
What type of hypersensitivity reaction is produced by mycobacteria?
Type IV - T-cells, macrophages
What are purified protein derivatives? (6)
Mycobacterium bovis - UK management (3)
