Diagnosis

Question 1

What is needed to diagnose a pathogen?

Answer 1

Species, basic information, how to take a sample and how to report the result. Also which method to analyse

Question 2

What is a sterile site?

Answer 2

Somewhere where bacteria shouldnt be; we can use a sensitive but not specific detection method since the only bacteria likely to be there are the pathogen. Blood, brain and joints are good examples.

Question 3

What is an unsterile site?

Answer 3

Somewhere a lot of bacteria lives (i.e skin or stomach); need a very specific method to pick up the right pathogen

Question 4

What does sensitivity mean and how is it calculated?

Answer 4

True positive / (true positive + false neg.). Its how good the test is at generating a positive test result in a sick individual. Needs to be high to not generate false negatives.

Question 5

What does specificity mean and how is it calculated?

Answer 5

True negative / (true negative + false positive). Specificity refers to how well the test identifies people who do not have the pathogen. Need to be high not to generate false positives.

Question 6

What are the pros and cons with microscopy as a diagnostic tool?

Answer 6

Pros:
Quick, easy to use.
Immediate results

Cons:
Not specific
Need knowledge to know what youre seeing

Question 7

What are some ways to improve microscopy?

Answer 7

Use a fluorescence dye to make it easier to spot and increase sensitivity. Use a stain such as gram or acid fast.

Question 8

What are the pros and cons with culturing as a diagnostic tool?

Answer 8

Pros:
Can confirm specific organism
Is reproducable
Can test for Ab resistance

Cons:
Slow
Requires viable organism
Some just dont grow on plates

Question 9

What are immunodiagnostics?

Answer 9

You look at the antibodies instead of at the organism. Ex. ELISA or serology

Question 10

What are the pros and cons with molecular diagnostics as a diagnostic tool?

Answer 10

Pros:
High sensitivity and specificity
Detects pathogen directly
Quick
Cost effective

Cons:
Easily contaminated
Only see what you’re looking for
Can be too sensitive and pick up infectious diseases in asymptomatic carriers (unsterile sites)

Question 11

What are some ways to improve molecular diagnostics?

Answer 11

Look at several regions

Question 12

What is MALDI-TOF?

Answer 12

Do mass-spectrometry on colony from plate and generate a profile of expressed proteins, which you can compare to other profiles on database