Diagnostic Testing 1 Flashcards
(50 cards)
Types of samples taken from patients
Blood
Sputum
Urine
Stool
Pus
CSF
Mucus drainage
Antigens include
Generally includes bacteria, viruses, and other foreign invaders
An antigen is _____
any substance capable, under appropriate conditions, of inducing a specific immune response in the body and reacting with the products of that response
Antibody
An immunoglobulin molecule having a specific amino acid sequence that gives each antibody the ability to adhere to and interact with the antigen that induced its synthesis.
Such as antibodies made targeting Hepatitis B.
What are serologic tests focused on?
these tests focus on the immune component of the serum, looking at antigens or antibodies
Types of serologic tests (sometimes called Immunologic Tests):
- Agglutination Tests: Latex type
- Enzyme Immunoassays
- Western Blot Test
- Rapid Antigen Tests: Rapid Strep, Flu tests, Rapid Covid-19
How does latex agglutination testing work?
the sample (saliva, urine, serum, CSF) is mixed with a prepared solution that contains latex beads that are coated with antibodies specific to the target antigen.
If the antigen is present in the sample, clumping (AKA agglutination) will be visible to the eye (a positive test)
Limitations of latex agglutination
This test is only semi quantifiable (serial dilutions possible)
If there is a low quantity of the antigen, then little if any lattice formation occurs and no clumping is seen
_____ uses an antibody specific to the target protein that is tagged with an enzyme marker that facilitates easy detection
Enzyme-Linked Immunosorbent Assay (ELISA or EIA)
Which serologic test produces a color change, fluoresce under light, or simply emit light when antigen is present?
ELISA
Because of high ____, ELISA is a great screening tool for some conditions.
sensitivity
Commonly used for many conditions, the ELISA may be most well known for being a screening tests for ___ and ____
HIV and Lyme
_____ is a laboratory method that uses electrophoresis with gel and a membrane in order to detect specific protein antigens.
Western Blot Testing
Which tests are highly specific, making good confirmatory tests?
Western blot
IgM and IgG antibodies
IgM - Generally the first or early antibody made in the fight against the infection (appears early, fades)
IgG - The type that appears later, but generally persists
Rapid antigen tests are considered _____, producing visual results that are qualitative (pos vs neg).
immunochromatographic assays
Common examples of rapid antigen tests
Rapid strep
Rapid influenza
Rapid malaria
Rapid Covid-19
Benefits of Rapid Antigen testing
ability to perform the test in clinic and getting results very quickly
Limitations of rapid antigen testing
Less sensitive early on
Lots of opportunity for user error
Sample problems
How do NAAT tests work?
- This type of testing specifically detects pieces of the microorganism’s genetic material (DNA or RNA), establishing its presence.
- Genetic material testing in ID attempts to shorten the time of detection, detecting organisms before the antibodies can form.
Because genetic material of microbes is not present in large amounts, one of the first steps of NAAT is to______
amplify the DNA or RNA, replicating them many times in order to make the chance of detection higher.
Limitations of NAAT testing
- Considered quite expensive
- Does not replace culture for susceptibility/sensitivity
In some situations, we test for skin-level sensitivity to certain pathogens, such as Purified Protein Derivative (PPD) through _____
Skin testing for sensitivity
Whether the bacteria is gram positive or gram negative can direct your choice of ____
antibiotic
