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32 Cards in this Set
- Front
- Back
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Which areas of the body are sterile?
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Blood, urine, spinal fluid, joint fluid, solid organs, milk, lower respiratory tract (bacteria encountered here should be considered abnormal)
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Name areas of the body which are not sterile.
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hair/fur; skin; saliva, intestines, ears, upper respiratory tract
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Which plates do you use to culture a urine specimen?
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MAC, CNA
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How do mycobacteria stain in the acid-fast stain test?
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They stain as thin red or pin rods against a green or bluish background.
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What are mycobacteria?
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Bacteria that are aerobic and nonmotile containing pathogens that cause leprosy and tuberculosis.
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What does Bile Esculin test for?
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Bile Esculin tests for enterococcal steptococci. + rxn is black.
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What is the catalase test?
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A test where a colony is smeared on a slide and exposed to H2O2. Bubbling indicates + rxn; staphylococcus are catalase positive;steptococcus are negative.
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What is the coagulase test?
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Test staphlococcus w/ rabbit plasma and EDTA; jelly shows + rxn.
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Describe the Gram staining procedure.
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Specimen placed on slide. Air dry and heat fix; stain w/crystal violet, Gram's iodine,decolorizer, safranin. Rinse between stains.
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What signal a positive rxn w/ Gram stain?
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Gram positive bacteria stain purple or dark blue.
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How do Gram negative bacteria stain on the Gram test?
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Gram negative stain pink.
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What is the Kirby-Bauer sensitivity test used for?
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Culture and sensitivity to antibiotics.
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How is an antibiotic assessed on a Kirby-Bauer plate?
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by zones of inhibition - where the bacteria cannot grow due to the antibiotics.
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What are two alternatives to the Kirby-Bauer test?
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test that determines the presence of any enzyme that can inactivate an antimicrobial; broth dilution susceptibility test.
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What is the broth dilution susceptibility test?
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Introduce a std inoculum into a series of tubes w/serial dilution of antimicrobial. Lowest conc that inhibits the growth of the organism is the minimal inhibitory concentration.
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What is the oxidase test?
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place colony on white filter paper; place oxidase reagent on paper; positive test is dark blue for oxidase producing bacteria
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What plates do you use for a fecal culture?
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MAC and SS plates; also GN broth.
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What plates do you use for fungal culture?
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Use slant tubes of DTM and mycosel.
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What are four ways to identify bacteria?
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Immunohistochemical assays, presence of toxins produced by a particular bacterium, DNA testing, PCR
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What is PCR?
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The polymerase chain reaction (PCR) is a technique where a DNA polymerase used to amplify a piece of DNA by in vitro enzymatic replication, generating millions or more copies of the DNA piece.
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What is immunohistochemical assay?
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Immunohistochemistry is a method of analyzing and identifying cell types based on the binding of antibodies to specific components of the cell.
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How is the best sample for bacterial culture collected?
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From a closed, sterile body compartment.
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True/False: Specimens should be collected prior to the administration of antibiotics.
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True
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True/False: A ml of body fluid is a better sample than a swab.
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True.
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What is the minimum amount of body fluid that should be collected for a sample for bacterial isolation?
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1 ml
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What does "falcultative bacteria" mean?
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This is bacteria that can adapt to a new environment - it can grow aerobically or anaerobically.
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What does "obligate bacteria" mean?
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This is bacteria that cannot adapt to a new environment. It can only grow aerobically or anaerobically.
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How should a specimen be kept if it cannot be sent to the laboratory in the same day?
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In the refrigerator.
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What is catalase?
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Catalase is a common enzyme found in nearly all living organisms which are exposed to oxygen, where it functions to catalyze the decomposition of hydrogen peroxide to water and oxygen
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What is coagulase?
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Coagulase is an enzyme produced by Staphylococcus aureus that converts fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates.
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What is the importance of the oxidase test?
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In microbiology, the oxidase test is used for the identification of bacterial strains; it determines whether a given bacterium produces cytochrome oxidases (and therefore utilizes oxygen with an electron transfer chain)
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What bacteria does the coagulase test identify?
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Coagulase-positive staphylococci.
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