1. What are the general characteristics of mycobacterium
    • aerobic
    • non spore
    • non motile
    • rods
    • difficult to grow in culture
    • arrangement may be in cords: mediated by cord factor
    • slow growing
  2. what is significant in the DNA of mycobacterium
    high G+C content in DNA making it more thermostable
  3. what type of specialized medium does mycobacterium tuberculosis grow in
    • lowenstein jensen (green) medium
    • contains inhibitory malachite green dye
  4. mycobacterium cell wall is rich in and typically seen in what kind of stain
    • lipid rich: full of mycolic acids
    • "weak gram (+)"
    • strong acid fast
  5. what is the significance of the lipid rich mycolic acid cell wall of mycobacteria?
    resistant to; antibiotics, disinfectants, detergents, host immune response
  6. How are proteins in mycobacterium used as a diagnostic tool
    antigens on cell wall can be extracted and purified as purified protein derivatives (PPDs) to measure exposure to M. Tuberculosis
  7. what is cord factor in mycobacterium
    • modified mycolic acid found in the surface of mycobacteria
    • a virulence factor that prevents phagosome lysosome function
    • causes "cord" arrangement of cells
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  9. what are the 4 mycobacterium classified as mycobacterium tuberculosis complex (strictly pathogenic)
    • M. tuberculosis
    • M. leprae
    • M. Africanum
    • M. Bovis
  10. what are the 4 mycobacteria classified as slow growing non tuberculous and are usually pathogenic
    • M. avium complex
    • M Kansasii
    • some strains are yellow
  11. what are the 5 bacteria classified as rapidly growing nontuberculous mycobacteria
    • M. abcessus
    • M. fortuitum
    • M. Chelonae
    • M. Smegmatis
    • M. Gordonae
  12. what are the characteristics of M. Tuberculosis that makes it pathogenic
    • lipid rich cell wall: resistant to antibiotics
    • slow growth
    • life long infection can be dormant/active
    • intracellular pathogen and cord factor: makes bacteria avoid being phagocytized
  13. what structure is formed from M. Tuberculosis infected cells as an inflammatory response
    • granuloma: organized collection of tightly clustered macrophages- including immune cells and collagen that is walled off from bacteria.
    • may be necrotic
    • bacteria may survive inside granulomas and reemerge if the immune system becomes compromised
  14. what are the type of granulomas
    • caseous
    • necrotizing: associated with M. Tuberculosis
  15. what is the size of granulomas when there are few M. Tuberculosis cells
    • granuloma is small
    • infection can be cleared with minimal tissue damage
  16. what is the size of the granuloma when there are a lot of M. Tuberculosis cells
    • large (caseous) granulomas
    • encased in firbin/collagen that protect bacteria from macrophage killing
    • bacteria may be dormant when not cleared, then will turn active if immune function decreases
  17. describe the cycle of how M. Tuberculosis can be latent and reactivate
    • M. tuberculosis bacteria becomes encased in granulomas that protects the bacteria from macrophage. This attributes to dormant stage, consisting of 90-95% of infections.
    • once bacteria reactivates due to decreased immune function, bacteria can spread and tissue damage occurs. Patients are contagious at this stage
  18. what are the reservoir of M. Tuberculosis
    • disease is spread through person to person by respiratory droplets
    • 1/3 of world's population is infected
  19. what are the populations at greatest risk for disease
    • immunocompromised patients
    • drug/ alcohol abusers
    • prisoners
    • homeless
    • people exposed to diseased patients
  20. what are the 2 resistant M. tuberculosis strains
    • MDR TB: multi-drug resistant M. Tuberculosis
    • XDR TB: extensively drug resistant to at least one second line drug. Potentially untreatable
  21. What is tuberculosis
    • restricted to lungs in immunocompromised patients
    • can involve any organ if bacteria disseminates
    • nonspecific symptoms: malaise, weight loss, cough, night sweats
    • primary disease: cavitation (holes) in alveoli.
  22. what are the laboratory techniques used to diagnose TB
    • specimen: sputum
    • radiographic evidence of lung infection
    • positive skin test
    • microscopic/ culture based evidence
  23. how is M. Tuberculosis treated?
    prolonged treatment with combination of INH, ethambutol for 2 months followed by INH, rifampin for 4-6 months
  24. what are the disease symptoms of mycobacterium leprae
    • leprosy
    • tuberculoid (paucibacillary) leprosy
    • lepromatous (multibacillary leprosy)
  25. how is leprosy transmitted
    • person to person contact
    • inhalation
    • skin contact
    • incubation may be as long as 20 years after infection
  26. what is tuberculoid leprosy
    • induces strong immune reaction: cytokine production, phagocytosis
    • hypopigmented skin macules
    • peripheral nerve damage at site of skin lesion
    • low infectivity
  27. what is lepromatous (multibacillary) leprosy
    • serious skin disease with skin lesions, nodules, plaques, thickened dermis
    • highly infectious
  28. how is lepramotous leprosy treated
    rifampicin, dapsone, for at least 12 months
  29. how is tuberculoid leprosy treated
    rifampicin and dapsone for 6 months
  30. leprosy is endemic in what areas
    • not as widespread
    • in india, brazil, madagascar
  31. what are the two species of mycobacterium avium complex (MAC)
    • M. avium
    • M. intracellulare
  32. how is MAC (mycobacterium avium complex) acquired
    • injestion 
    • inhalation
  33. who are the patients at greatest risk for M. Avium complex
    • AIDs
    • those with long standing pulmonary disease
  34. what is the clinical disease associated with M. Avium complex for immunocompetent patients
    • chronic localized pulmonary disease
    • "lady windermere syndrome"
    • slowly evolving cavitary disease
    • solitary pulmonary nodule
  35. what are the clinical diseases with associated with M. Avium complex for immunocompromised patients
    disseminated disease, affecting all organs and impairing normal organ function
  36. what does IFN-y do
    activates macrophages, thus increases intracellular killing of M. Tuberculosis cells
  37. what does TNF-a do
    stimulates production of nitric oxide, which increases intracellular killing of bacterial cells
  38. what are the cytokines released by macrophages and T cell in response to M. Tuberculosis infection
    • macrophage: IL-12, tumor necrosis factor alpha (TNF-a)
    • T cell: IFN-y (gamma)
  39. what are the tests for mycobacterium to diagnose?
    • mycobacterial antigen skin test (PPD)
    • Measuring IFN-gamma by T cells in whole blood
    • acid fast bacteria
    • truant fluorochrome method: most sensitive
    • Mycobacterial cultures: ex] MODs, special egg based agar, antimycobacterial
    • PCR: used when culture is not available or microscopy is inaccurate
Card Set
clinical diseases, diagnostic for mycobacterium genus