09.11.18 Infectious Disease Assays Flashcards
Pathogen that has:
- nucleic acid genome (RNA or DNA) in core
- protein capsid +/- envelope
- not free-living
Virus
Pathogen that has:
- DNA genome, no nucleus, RNA
- cell membrane and wall (G+/-)
- free living
Bacteria
Pathogen that has:
- DNA genome in nucleus, RNA
- cell membrane and wall (chitin)
- free living
Fungi
Pathogen that has:
- DNA genome in nucleus, RNA
- cell membrane only
- free living
Protozoa
the extent to which the test is accurate for those who have the disease in question, avoiding “false negative” errors
Sensitivity
the extent to which the test is accurate for those who do not have the disease in question, avoiding false positive errors
Specificity
The extent to which a positive test indicates presence of disease
Positive predicative value
The extent to which a negative test indicates absence of disease
Negative predicative value
What are pros and cons to using light microscopy?
+ cheap, fat
- low sensitivity, specificity depends
What are pros and cons to culture?
- time/money, not for all bugs (viral difficult)
+ higher sensitivity than microscopy but lower than nucleic acid amplification tests (NAATs)
In an ELISA what do you start with for and what are they indicators for:
A. Antigen detection
B. Antibody Detection
A. Antibody- indicators of current infection
B. Antigen- indicators of past infection
- molecular detection assays for bacteria, viruses and eukaryotic pathogens
- targets are microbial DNA/RNA
- enzymatic amplification of target molecules
- more sensitive than microscopy, culture or antigen detection
- specific for nt seq
- don’t req. live organisms
Nucleic Acid Amplification Tests (NAATs)
What are pros and cons to NAAT?
+ non-invasive in STIs
- test may remain positive for some time after successful treatment
In vitro testing with live organisms grown in the presence of antimicrobial agents
Antimicrobial Susceptibility testing
