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Flashcards in Lab assays Deck (20):
1

accuracy vs precision?

accurate tests get close on average to the right answer, precise tests have consistently reproducible results (may not necessarily be "correct" though)

2

Which test property most influences test performance with...low organism burden?

sensitivity

3

Which test property most influences test performance with...potential detection of closely related organisms?

specificity

4

Which test property most influences test performance with...too little specimen?

sensitivity

5

Which test property most influences test performance with...low prevalence population?

specificity

6

Pros/cons of microscopy?

Pros: low cost, rapid results
Cons: what you see is what you get

7

Culture pros/cons?

Pros: recovery of live organisms, higher specificity than microscopy
Cons: requires specialized media, incubator etc, lower specificity than NAATs, and some bugs can't be cultivated in vivo

8

Viral culture issues?

requires host cells, $$$, special labor, equipment, and training

9

How does a blood culture work?

1. blood drawn and split into 2 bottles (1 set)
2. 2 sets overall taken from 2 different body sites to confirm there is no contamination
3. when results from both sets are the same, source is organism in patient's blood

10

How are antibody detection tests/serology retrospective?

Because we form antibodies in response to infection. If you're detecting antibodies to a certain organism/pathogen, that infection happened in the past.

11

Antigen detection tests look for what?

the presence of the organism in the specimen

12

Direct fluorescence microscopy assays are an example of what kind of testing?

antigen detection test

13

Rapid stress tests fall under what category of testing?

antigen detection test

14

Particle agglutination tests fall under what category of testing?

antigen detection test

15

Explain how NAATs work.

enzymatically amplify target viral DNA/RNA molecules (i.e. by PCR, rtPCR, or other techniques)

16

Pros of NAATs?

highly sensitive (compared to microscopy, cultures, or antigen detection) and more specific for nucleotide sequences, doesn't require live organisms

17

Exponential amplification refers to?

millions of copies of a template molecule that can be amplified quickly using NAATs

18

Potential shortfall of NAATs?

high sensitivity can pick up dead organisms - may lead you to believe there's an ongoing infection when abx have actually killed organisms

19

Explain how NAATs can lead to less invasive testing

Example of STDs - sensitivity of NAATs is so high that you can take use a urine sample instead of an invasive/uncomfortable endocervical or urethral swab

20

Set up needed for antimicrobial susceptibility tests?

in vitro test with live organisms grown in presence of antimicrobial agents; may find genetic basis of resistance