Laboratory Methods Flashcards
Types of Lab Methods 4
Direct visualization of the agent
Growth in culture
Immunological tests
Nucleic acid tests
Direct visualization of the agent
stain and look at the shape (morphology)
Growth in culture
putting specimen in growth medium, colony forms if its the proper growth medium
Immunological tests
based on the antigen/antibody binding
Nucleic acid tests
test for genetic material of the infectious agent in host tissue/fluids . can see if person is infected, by how much and the type
Possible indicators of recent infection (3)
Detection of IgM
Symptoms and IgG
4 fold increase in IgG from acute and convalescent serum (at onset and 4 weeks later)
Normal flora
Microorganisms that normally reside at a given human body site that, under normal circumstances, to not cause disease
two types of body sites
Normally sterile
Not normally sterile
Normally sterile
bacteria found in sites that are sterile
ex. blood, cerebrospinal, bone, lymph nodes, certain organs
Not normally sterile
ex. skin, respiratory tract, vagina, GI tract
Validity has to have what 2 components to measure what we think it measures
sensitivity and specificity
sensitivity?
The ability of the test to correctly identify those who do have the disease
Specificity?
The ability of the test to correctly identify those who do not have the disease.
Gold standard
an external source of truth about the disease status of the population
Possible gold standards
-Another test that is in use
-A more invasive or expensive test
WHY to we use laboratory method for in infectious disease epidemiology?
to confirm or deny the disease
