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18 Cards in this Set
- Front
- Back
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Purpose of the streak plate technique?
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-dilute the number of visual organisms in order to visualize single colonies
-single colonies are considered pure |
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purpose of the gram stain?
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-determine gram + or gram -
-gram + has more peptidoglycan (blue) and will retain more crystal violet -gram negative will stain with the counter stain safarin and turn pink |
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purpose of acid fast stain?
which bugs? |
-stain bacteria with high lipid containing cell walls
-mycobacterium, nocardia, microsporidium - |
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three methods for acid fast?
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ZN method: carbolfuchsin + heat
Kinyoun method: conc. carbolfuchsin Auramine or Rhodamine: fluorescent stain seen with UV microscope |
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Puropse of spore stain?
which bugs? |
-Malachite green plus HEAT
-detect the spores in spore forming bugs -bacillus and clostridium species |
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Capsule stains
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-congo red or india ink
-negative staining technique Streptococcus pneumoniae, Klebsiella pneumoniae, H. influenzae Pseudomonas aeruginosa Neisseria meningitidis Cryptococcus neoformans |
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Motility Assay
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-dispersion from the agar in solution means it is motile with a flagellum
-E. coli, pseudomonase |
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MacKonkey Agar
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-selects gram - by inhibiting gram -
-differentiates lactose fermenting by forming red colonies with a low pH -Enterobacteria: E. coli or Klebsiella |
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Purpose of blood agar?
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detect hemolytic activity
-those that produce exotoxins lead to hemolysis of RBC's |
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Purpose of Tellurite Agar?
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-colonies turn black as certain bacteria reduce tellurite
-cornybacterium diptheria |
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Catalase test
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-converts H2O2 to O2 and you get bubbles
-staph is positive, strep is negative |
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Coagulase test
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S. Aureus
-clots plasma |
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Novobiocin test
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-grow on agar with novobiocin to differentiate staph species
-S. epidermis is sensitive to it -S. saprophyticus is not |
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Beta hemolytic
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strep agalactiae and pyogenes
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Alpha hemolytic
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strep viridans and pneumoniae
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Bacitracin Sensitivity
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Strep pyogenes is sensitive
agalactae and enterococcus (gamma hemolytic) is not |
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Optochin Sensitivity
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Strep Pneumonia is sensitive
strep viridans is not |
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Oxidase test
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cytochrome oxidase
-neisseria and pseudomonas |
