Clinical

Question 1

What does the reliability of any test depend on?

Answer 1

its specoificity and sensitivity

Question 2

What does specificity mean?

Answer 2

The ability to recognise the target pathogen - minimizing false postives

Question 3

What does sensitivity mean?

Answer 3

The minimum amount of pathogen needed for the test to detect it - minimizing false negs

Question 4

What selective media can be used for primary isolation of Neisseria gonorrhoeae?

Answer 4

^Modified Thayer Martin agar

Question 5

Purpose of general-purpose media

Answer 5

support growth of most aerobic and facultatively aerobic organism - blood agar

Question 6

Purpose of enriched media

Answer 6

contain specoific growth factors that enhance growth of certain fastidious pathogens

Question 7

What does selective media do

Answer 7

Allow some to grow and inhibit others

Question 8

What does differential media do

Answer 8

allow identification of organisms based on their growth and appearance on the medium

Question 9

Only way of immediately isolating and identifying septicemia

Answer 9

Blood culture
2 bottles - one cultured aerobically and one anaerobically

Question 10

What are disease causing agents of UTIs usually and how are they cultured?

Answer 10

-Uusually normal flora
-cultured using general-purpose media (blood agar), selective media (MacConkey agar, eosin-methylene blue agar) or additional differential media may be used

Question 11

What is used to culture MRSA

Answer 11

Chromogenic agar media - MRSA produces distinctly coloured colonies

Question 12

What are serology and titers

Answer 12

The study of antigen-antibody reactions in vitro

Question 13

What are monoclonal antibodies?

Answer 13

Produced by isolating single clones of B cells that are fused with cancer cells to make immortalized celllines that produce a sinle type of antibody

Question 14

What are EIAs or ELISAs and what do they to?

Answer 14

Enzyme (linked) immunoassay (immunosorbent assay)
-Very sensitivce
-widely used in clinical diagnostics and research applications
-EIAs employ covalently bonded enzymes attached to antibody molecules
-Rapid tetss are similar
-Both allow detection of antigen-antibody complexes

Question 15

What are the 4 diff EIA methods used

Answer 15

-direct EIA - detection of antigen
-indirect EIA - detection of antibody
-sandwich EIA - detection of antibody
-combination EIA - combination of direct EIA and sandwich EIA

Question 16

How do rapid tests work?

Answer 16

Body fluid is applied to support the matrix
-matrix contains a soluble antigen conjugated to a colored molecule (chromophore)
-matrix also contains a line of fixed antigen
-antibodies bind to antigens
-colour forms when conc of chromophore is high enough

Question 17

How does reverse transcriptase PCR work? (RT-PCR)

Answer 17

Uses pathogen-specific RNA to make cDNA

Question 18

How does quantitative real-time PCR (qPCR) work?

Answer 18

Uses fluorescently labelled PCR products
Almost immediate results