Lab assays Flashcards Preview

POM Exam 1 > Lab assays > Flashcards

Flashcards in Lab assays Deck (20)
Loading flashcards...
1
Q

accuracy vs precision?

A

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

2
Q

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

A

sensitivity

3
Q

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

A

specificity

4
Q

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

A

sensitivity

5
Q

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

A

specificity

6
Q

Pros/cons of microscopy?

A

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

7
Q

Culture pros/cons?

A

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
Q

Viral culture issues?

A

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

9
Q

How does a blood culture work?

A
  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
Q

How are antibody detection tests/serology retrospective?

A

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
Q

Antigen detection tests look for what?

A

the presence of the organism in the specimen

12
Q

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

A

antigen detection test

13
Q

Rapid stress tests fall under what category of testing?

A

antigen detection test

14
Q

Particle agglutination tests fall under what category of testing?

A

antigen detection test

15
Q

Explain how NAATs work.

A

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

16
Q

Pros of NAATs?

A

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

17
Q

Exponential amplification refers to?

A

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

18
Q

Potential shortfall of NAATs?

A

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

19
Q

Explain how NAATs can lead to less invasive testing

A

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
Q

Set up needed for antimicrobial susceptibility tests?

A

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