Quiz 6 (CH 17, 18, 19A) Flashcards
(64 cards)
Methods of identifying unknown microbes
Phenotypic: micro, macro, physiological
Genotypic: PCR, FISH, gel electrophoresis, Ribosomal RNA sequencing
Immunologic: serology
What do you look for in micro and macro scopic morphology
Micro: size, shape, structures (fimbria, glycocalyx, flagella, cilia, endospores, appendages)
Macro: colony appearances, texture, size, shape (margin, color, elevation)
What are the different stains used in phenotypic methods
Gram stain, acid-fast stain (used for TB), direct immunofluorescent antibody, and direct antigen testing
What are the two phenotypic methods for the cultivation of specimen
Isolation media: enrichment, selective or differential
Biochemical testing API: physiological rxn to nutrients and other substrates
What are the miscellaneous phenotypic tests
Phage typing: plaque formation will be present if you identified the bacteria
Antimicrobial sensitivity: used to determine treatment drugs
Explain FISH
with a blood culture do a gram stain, there is a genetic probe that will bind the nucleotides to their targets on the sample. If they bind they will stay bound and be able to see the fluorescent stage.
The probe has pre-set nucleotides on it to bind to the sample
Explain Pulse-field gel electrophoresis
With the ladder examine the samples and see which matches more closely to the ladder.
Cut DNA at specific positions to look for DNA matches to ID it
Explain Polymerase chain rxn (PCR)
amplification of DNA, or a forced DNA replication over and over
sensitive and specific, detect HIV, Lyme disease, HPV, TB, and hepatitis
Explain Ribosomal RNA sequencing
There are more differences in ribosomal DNA, it is used to study the phylogeny and taxonomy of samples.
What are the serological methods
In vivo testing, testing patient serum, test culture colony with known antibodies, card test, and streak plate
Describe in vivo testing and give an example
Antigens are introduced into the body to determine the +/- of antibodies
allergy and tuberculin skin test
Describe what happens in the patient serum and prepared antigen test
when the antigen and antibody come together there is a visible change or clumping when positive, if negative there is no rxn
Describe what happens in the patient serum and prepared antigen test
when the antigen and antibody come together there is a visible change or clumping when positive, if negative there is no rxn
Describe what happens in the culture colony with known antibodies
once the patient sample is cultured, it is placed on a slide with antiserum with antibodies to a pathogen. If it contains the antigen it will clump and will be positive, if neg there is no rxn
Describe the card and streak plate
Serum card: different known antigens are on the card along with control if an rxn there is clumping
Streak plate: colonies mixed with Neisseria meningitides antiserum (+ rxn will have clumping)
all is visualized
Describe Agglutination tests
The antibody cross-links whole-cell antigens, from visible insoluble clumps
if binding occurs see the large precipitate on the bottom of the tube, if not bound they will stay throughout the tube
has a threshold of when it turns from + agglutinated cells to - unagglutinated cells
as you go through the tubes the more diluted the patient sample becomes
Describe the precipitation tests
the soluble antigen is made insoluble by an antibody
Ouchterlony double diffusion: samples are in wells and if a precipitation band is seen it is a + result (the antibodies are present)
VDRL: when bind together they will form a specific precipitated
Describe the Western Blot test
Electrophoretic separation of proteins, followed by an immunoassay to detect
uses to look at something over time, looking for the formation of antibodies against infection (from the same bands as control) Bands intensifying over days show the patient is showing stronger and stronger response to the infection (bad since has to fight harder against infection)
Describe the Complement fixation test
Lysins red blood cells not bound to antibodies - result (where there is a rxn there is no antibody, hemolysis happens)
lysins fail to lyse in the + rxn and can bind to antibodies and hemolysis doesn’t happen
Describe Direct immunofluorescent testing (add more if you would like)
an unknown antigen is fixed and exposed to a fluorescent known antibody solution.
the antibody is binding directly onto the bacterial cell which is casing the rxn
and identifies antigens on the surfaces of cells/tissues
ex. syphilis, gonorrhea, chlamydiosis, whooping cough
Describe indirect immunofluorescent testing (add more if you would like)
the antibody binds onto the cell, but to see that it has bound a second fluorescently labeled antibody binds to the first antibody and shows the tag
used to diagnose syphilis and various viral infections
What is radioimmunoassay (RIA)
antigens or antibodies labeled with radioactive isotopes
Describe indirect ELSA
Start with the antigen bound to the well, add the patient sample serum which may or may not contain antibodies, if it does those antibodies will bind to the antigen, rinse out the well only the antibodies bound to the antigen will stay. Add another antibody (like a tag) to the sample and if the original antibody is bound then the second antibody will bind, rinse again. order should be antigen, antibody, antibody. Add a substrate which if both antibodies are present will cause a rxn and change the well color to yellow. If no antibodies present no color change
describe capture or sandwich ELSA
the antibody is bound to the well, the solution potentially containing the antigen is added to the well (if present will bind to the antibody). Then the enzyme-linked antibody is added if the antigen is present it will bind to the antigen, and rinse well. Then the enzyme substrate is added and if the enzyme is present the color will change. Antibody, antigen, enzyme
