Chapter 17 Flashcards
what are the 3 methods of diagnosis to prepare for the survey of microbial disease?
Phenotypic
Genotypic
Immunologic
Phenotypic
Microscopic and macroscopic morphology
Physiological and biochemical characteristics
Chemical composition
Genotypic
Genetic composition
Immunologic
Exploits the host’s antibody reaction to microbial antigens for purposes of diagnosis
Genetic composition uses which method of diagnosis?
genotypic
Chemical composition uses which method of diagnosis?
phenotypic
physiological and biochemical characteristics use which method of diagnosis?
phenotypic
Reviewing the microscopic and macroscopic morphology refers to which method of diagnosis?
phenotypic
Exploiting the host’s antibody reaction to microbial antigens for purposes of diagnosis refers to which method of diagnosis?
immunologic
What is the common point that guides the health care decision of every member of a clinical team?
specimen collection
What is the most vital concern with specimen collection?
Aseptic techniques must be used
In order for identification and treatment to be successful what 3 things are important when concerning specimens?
How the specimen is collected, handled, and stored.
What is the phenotypic method for testing the specimen?
immediate direct examination of the specimen
What test/method is used to detect syphilis?
Phenotypic method - Direct fluorescent antibody test (DFA)
Two examples of phenotypic method of testing?
DFA (Direct fluorescent antibody) test for syphilis
Direct antigen testing
DNA analysis using genetic probes refers to which method of diagnosis?
genotypic method
Hybridization is which method?
genotypic method
What is one example of genotypic method of diagnosis?
PCR and rRNA identification
The branch of immunology that deals with in vitro diagnostic testing of serum
serology
What do serological (immunological) tests involve?
Most are in vitro assessments for the detection, identification, and quantification of Antigen - Antibody from a variety of body fluids
Visible results can be obtained from
- Agglutination
- precipitation
- immunodiffusion
- complement fixation
- fluorescent antibodies
- immunoassay techniques (ELISA)
What is used to read a titer?
Ag - Ab reaction
How are Ag - Ab reactions used to read a titer?
A sample is diluted in tubes or a multiple welled microtiter plate and mixed with antigen. Titer is expressed as the highest dilution of serum gives a visible reaction with an Ag. The higher the titer, the more antigen present in the serum. Knowing the relative quantity of antibody permits different samples to be standardized and compared.
How can reading a titer be useful?
Reading a titer allows us to figure out how much antibody is present in a sample. Then samples can be standardized and compared.
In regards to agglutination antigens are ______.
whole cells (RBC, bacteria with determinant groups on surface)
In agglutination antibodies are called _________ which cross link the Ag ___________ to form to form _________.
agglutinins
agglutinogens
3D visible clumps
Agglutination determines ____ and ____ blood types.
ABO and Rh (Rhesus)
Explain how agglutination works?
Antisera containing Ab against the blood group antigens on RBC are mixed with a small sample of blood and read for the presence or absence of clumping. This will detect the specific antibodies and also gives the serum titer.
What technique is used for salmonellosis and undulant fever?
Widal Test
The Weil-Felix reaction is used for?
rickettsial infections
What technique is used for detection of the pregnancy hormone in urine?
Latex agglutination
What technique tests for staphylococci, streptococci, and gonococci?
latex agglutination
Viral hemagglutination is the technique used to test for….?
some viral Ag
Name 4 agglutination techniques?
Viral hemagglutination
latex agglutination
Weil-Felix reaction
WIdal test
In precipitation antigens are ________ called ____________.
soluble molecules, precipitinogen
In precipitation antibodies are called
precipitins
Precipitinogens are _____ by precipitins.
precipitated
Precipitates are easily disrupted in __________
liquid media
Most precipitation reactions are carried out in ________.
Agar gels
Why are agar gels used for precipitation?
Substrates are soft enough to allow (Ag/Ab) to freely diffuse, yet firm enough to hold the Ag-Ab precipitate in place.
Name 5 precipitation techniques
- Double diffusion (Ouchterlony)
- Immunoelectrophoresis
- Western Blot
- Complement fixation
- Fluorescent antibodies (immunofluorescence)
Outerlony refers to?
Double diffusion - precipitation technique
What happens in both agglutination and precipitation when Ag and Ab are optimally combined so neither is in excess?
One Ag is interlinked by several Abs to form insoluble 3D clumps so large that cannot remain suspended.
Define Complement fixation (CF) - lysin or cytolysin
An Ab that “fixes” complement to complete the lysis of its Ag target cell
What happens when the lysins act with the C-system on RBC
the cells hemolyze
Define hemolyze
lyse and release hemoglobin
The CF test is used to detect _____.
hemolysis
If hemolysis is detected, then the unfixed complement lysed ________.
Sheep RBC
Name 3 diseases Verification of CF is needed for.
Scarlet fever
Rheumatic fever
several streptococcal syndromes
Western Blot is used to verify ____ in the ELISA test.
Ab+ for HIV
Western Blot has significant applications for detecting _______ in specimens.
microbes and their Ag
Explain Western Blot
Precipitation technique:
Specific and sensitive for the identification of protein Ab or Ag electrophoresed in a gel which separates out particular bands.
Gel is transferred to a special blotter that binds reactants in place.
Blot is incubated with solution with Ab or Ag labeled with radioactive, fluorescent, or luminescent labels.
Sites of specific bindings appear
Patterns of bands are compared with known positive or negative samples.
Numerous applications in diagnostic immunology
Fluorescent antibodies and immunofluorescence testing
Antibodies are labeled with fluorescent dye
Fluorescent antibodies and immunofluorescence testing
Need fluorescent microscopy (UV light lamp)
Fluorescent antibodies and immunofluorescence testing
Name two techniques for Fluorescent antibodies and immunofluorescence testing
Direct testing and indirect testing
Define direct testing in regards to Fluorescent antibodies and immunofluorescence testing
valuable for identifying and locating antigens on the surface of cells or in tissues
Fluorescent antibodies can be ________.
anti-isotypic
Anti-isotypic means _________.
made to react with the fluorescent region of another Ab (remember that Ab can be antigenic)
What does ELISA stand for?
Enzyme-Linked Immunosorbent Assay
ELISA is also called _______.
Enzyme Immunoassay (EIA)
Name 2 enzymes used in ELISA
Horse-radish peroxidase
Alkaline phosphatase
Both enzymes release a dye called _____ when exposed to their substrate?
chromogen
ELISA relies on a solid support such as _____ that adsorb (attract on surface) the reactants
plastic microtiter plate
ELISA screens for *name 5
HIV Helicobacter rickettsias Salmonella Vibria
In ELISA the enzymes affixed to the Ag will ____ the substrate and release a _____
hydrolyze, colored dye
ELISA contains an enzyme-Ab complex that can be used as a _______
color tracer for Ag-Ab reactions
Two techniques for ELISA
direct and indirect
Type of In vivo testing
tuberculin testing
Tuberculin Test
uses small amounts of purified protein (PPD) from Mycobacterium tuberculosis injected in the skin.
The aim of in vivo testing is to
detect presence of neutralizing antibodies and elicit a visible Ag-Ab response after an Ag has been introduced into the host
Name 5 diagnostic skin sensitivity tests for
Coccidiodin Histoplasmin Allergens Schick for diptheria Dick for scarlet fever
How is a tuberculin test deemed positive
Raised lesion on the skin indicates previous exposure to tuberculosis.