15. clinical microbiology Flashcards
(33 cards)
What are general requirements to consider when collecting a specimen for microbiological sampling?
- collect from diseased area
- collect enough for all tests
- avoid contamination from other sites
- prompt analysis
- obtain prior to treatment therapy
What are a few direct methods to identify microbes?
- microscopy
- molecular method testing
- bacteriophage typing
- immunologic testing
- culture
Serology and immunofluorescence are what type of microbe identification methods?
- indirect methods
Most bacteria are generally cultured, what are a few exceptions that should undergo stain, immunologic, or PCR for analysis?
- ricketsia
- chlamydiae
- mycoplasmas
Fungi are best identified with what test method?
- sabourad dextrose agar culture
2. tests colony morphology, color and dimorphisms
What types of slides can be made for organisms to be detected with microscopy?
- heat-fixed
- wet-mounted
- chemically fixed
What are the different types of Monoclonal antibodies?
- chimeric
- humanized
- full human
What is a chimeric antibody?
- come from mice that produce antibodies with a human constant region
What is a humanized antibody?
- monoclonal antibody except for the Ag-binding site, which is still mouse derived
What is a full human monoclonal antibody?
- monoclonal antibody that is produced in a mouse from a human genome sequence.
What is the 6 step process for monoclonal Ab production?
- mice injected with Ag, to stimulate Ab production
- spleen is homogenized; B cells are “free”
- B cells are mixed with cancer cells to produce “immortal” hybridomas
- placed in specific medium to only allow growth of hybrid cells
- hybrid cells proliferate
- hybridomas are cultured to increase numbers.
What is the difference between direct and indirect fluorescent antibody detection technique?
- direct: the Ab is fluorescently tagged and binds directly to the Ag ( tests for presence of Ag)
- indirect: the fluorescence comes from an Ab that binds to the Ab that was extracted in the serum of the individual ( tests for presence of the Ab)
What methods can be used to detect the presence/absence of a parasite?
- immunofluorescence
- histological staining
- microscopy
- negative body fluid stain
Ribotyping is a commonly used method of identification that works on what method?
- requires the 16srRNA gene
- amplification of rRNA sequence via PCR
- use to compare sequence of the protein with others in a large database
What are monoclonal antibodies in general?
1.products of hybridoma cells, that allow prolonged lifespan of Ag specific B cells that have been activated
What methods are routinely used to identify parasites?
- blood histology stains
- immunofluorescence
- negative staining of body fluids
What are molecular genetic tests used to identify?
- comparison of proteins
2. detect nucleic acids
What is plasmid fingerprinting?
- characterizing bacteria based on the number of plasmids and their molecular weight
What is sensitivity?
the ability of a test to confirm the presence of a disease
What is specificity?
statistical probability that a person who does not have a disease will show a negative test result
What two features are key to proper immunologic test interpretation?
- test selection and timing of collection
What type of test method uses serum antibodies to detect and identify other molecules?
serotyping
- differentiates microbes that differ in antigen composition structure
Agglutinate
formation of clumps or aggregates of particles in an organized fashion
Widal test
diagnostic test for typhoid fever
