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39 Cards in this Set
- Front
- Back
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when a microbiologic test correctly predicts the presence of a pathogen
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true positive
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negative test obtained in the absence of a pathogen
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true negative
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negative in the presence of pathogen
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false negative
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positive when there is no pathogen
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false positive
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sensitivity
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liklihood it will be positive when the pathogen is present
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specificity
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liklihood it will be negative if the pathogen is not present
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screening vs. confirmatory
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screening does not need to be specific, confirmatory must be
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what does the interpretation of a lab test depend on
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technical accuracy is the test used but also the prevalence of the infection int he population to which the patient belongs
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microscopic diagnosis is what for certain infections
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sensitive and specific
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two infections examined by microscope
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helminthic and protozoal
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how is cryptococcus neoformans found
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encapsulated yeast in the CSF
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what bacteria can be seen with a microscope
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syphilis infections
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gram negative diplococci in the leukocytes of urethral pus
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gonococci
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when is a gram stain not useful
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when body fluid or tissue sample is nonsterile
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acid fast bacteria in sputum are assumed to be what
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mycobacterium tuberculosis until proven otherwise
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type of stain for protozoal infections
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giemsa stain
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stain for intestinal helminths
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iodine stain
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systemic fungal pathogens
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silver stains
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method of enhancing accuracy of microscopic and viral pathogens
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use specific antibody test to supplement
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direct fluorescent antibody test
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used for cryptosporidium protozoa, monoclonal antibody conjugated with a fluorescent compound
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what is assumed about microorganisms detected in a culture
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causitive agents (etiologic agent)
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what screening is used for a throat swab plated on blood agar plates
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streptococcus pyogenes, only bacterial agent for udative pharyngitis
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what type of media is needed for nonsterile parts of body
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selective media
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what type of medium is used for gonococci growth
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thayer-martin medium
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what happens to a urine sample that sits for hours
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becomes contaminated from microorganisms present start growing
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subculture
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microorganisms from cultures are transferred to agar plates to permit identification
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what is the lysis centrifugation technique used for
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fungi, mycobacteria and fastidious pathogens
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what properties are for culture identification of bacteria
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phenotypic properties
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what do serologic tests measure
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humoral immune response to infection
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endpoint
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highest dilution of the patients serum that can still exert the measured function, a positive titer
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solid phase assay
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measures the presense of antibodies directly, pathogens attach directly to a solid support
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popular solid phase assay
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ELISA
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what determines the specificity of a serologic test
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character and purity of the antigen used to capture antibodies
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what is one of the most specific seriological methods
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western blot
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what type of infection is serology usually used for
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to see if a specific infection has happened in the past
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what is one method of determining actue vs chronic serology
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taking acute and convalescent titers
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what type of antibodies used for acute infection
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IgM, appear first and dissapear after a few months
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antigen detection test
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antibodies used to capture antigens from a patient sample
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how are captured antigens visualized
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second antibody - enzyme immunoassay
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