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24 Cards in this Set
- Front
- Back
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What is the staining characteristic for mycobacterium?
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They are acid fast
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Where do mycobacterium replicate?
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Intracellularly, especially in macrophages for M. tuburculosis
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What are the traditional mycobacterium pathogens? (4)
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M. tuburculosis, M. bovis, M. leprae, and M. ulcerans
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What are the atypical mycobacterium (2)?
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M. avium/intracellulare, and M. kansasii
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What patient population are atypical mycobacterium infections most likely to be found?
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AIDS patients
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Describe the important characteristics of nocardia
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It is an acid fast rod with filaments that branch, intracellular growth within macrophages, and dissemination to the brain forming abcesses
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What sort of patient is infected with nocardia and what are the typical manifestations?
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AIDS, cancer and transplant patients are commonly infected with chronic lung abcesses or granulomas and intracellular growth within macrophages
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What are the three species of bacteria that are acid fast?
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mycobacterium, nocardia, and rhodococcus species
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Both nocardia and rhodococcus are acid fast, so how do you tell them apart?
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Nocardia are long rods and rhodococcus are short rods and cocci
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Describe the morphology of mycobacterium tuburculosis
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They are slender, straight, or curved rods (pleomorphic) that arrange themselves in long cords (serpentine cords); stain poorly with gram stain although considered gram positive
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Describe the growth conditions for m. tuburculosis
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They are obligate aerobes that grow very slowly (weeks on an agar plate) and capable of intracellular growth within macrophages
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Describe the cell wall of mycobacterium tuburculosis
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It contains a cell wall that is analogous to a gram negative wall but contains mycolic acids in the outer membrane; it also contains proteins which are the basis for the PPD skin test
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Describe the transmission of M. tuburculosis
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It is generally by person-to-person contact and inhalation of respiratory droplets; they can survive drying for long periods of time
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Describe the epidemiological significance of M. tuburculosis
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Over one third of the world's population is infected
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Describe the primary infection with mycobacterium tuburculosis
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It is an asymptomatic, non-infectious state with intracellular multiplication in macrophages and a spread to the lymph nodes; bloodstream dissemination is possible
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Describe the formation of a tuburcle
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This is an acquired cell mediated immunity that leads to a granulomatous inflammation with epithelioid cells surrounded by a collar of Th lymphocytes
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Describe the re-infection or secondary infection with TB
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This is the first time symptoms of the disease are seen as well as the first time an agent is infectious
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How does secondary TB become contagious?
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It becomes contagious when the granuloma undergoes caseous necrosis and the contents spill into the bronchus, which are the organisms are then released into the air
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What are the symptoms of a re-activation TB?
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Insidious onset with fever, fatiuge, anorexia, night sweats and wasting
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What is miliary TB?
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When viable bacteria gain rise to lymphatics and the bloodstream and seed in distant organs
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What will the acid fast stain be on a primary TB infection?
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It will not be acid fast
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What is a major problem in the treatment of mycobacterium tuburculosis?
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Multi drug resistant strains and extremely multi drug resistant strains
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What is the BCG vaccine?
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A vaccine of live attenuated strain of m. bovis that can sometimes show a positive PPD
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What sort of abcesses are commonly seen in Nocardia infections?
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Brain abcesses
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