Clinical Diagnostic

Question 1

Obligate pathogens

Answer 1

•any time in body will cause an infection/illness

Question 2

Opportunistic pathogen

Answer 2

•when on body usually harmless
•unless compromised in some way

Question 3

What does sensitivity mean in terms of pathogen testing

Answer 3

•probability the test will be positive in he presence of pathogen
*no false negatives

Question 4

What does specificity mean in terms of pathogen testing

Answer 4

•probability the test will be negative if pathogen not present
*no false positives

Question 5

What parameter tests the probability there will be no false negatives

Answer 5

•sensitivity

Question 6

What parameter tests the probability there will be no false positives

Answer 6

•specificity

Question 7

Description of culture tests

Answer 7

•microbes grown in culture
•samples taken from specific areas of patient

Question 8

Negatives of culture tests

Answer 8

•slow
•labour intensive
•some organisms can’t be cultured

Question 9

Positives of culture tests

Answer 9

•test effect of antibiotic (will it be useful)
•antibiotic resistance?
•can grow whatever is there (don’t need to know what looking for)

Question 10

Negatives of non culture testing

Answer 10

•may not reveal antibiotic patterns
•can only find what u are looking for (need to know what to look for beforehand)

Question 11

Positives of non culture testing

Answer 11

•rapid
•organisms don’t need to be viable

Question 12

Non culture testing methods

Answer 12

•microscopy
•host antibody response (ELSIA, PCR)
•detection of microbial products

Question 13

Gram positive cocci examples

Answer 13

•staphylococcus (bunches)
•streptococcus (varying chains)

Question 14

What arrangement and shape is streptococcus pneumoniae

Answer 14

•diplococci

Question 15

Gram negative cocci examples

Answer 15

•Niesseria

Question 16

Gram negative rods examples

Answer 16

•E.Coli
•salmonella
•campylobacter

Question 17

Describe necrotizing fasciitis

Answer 17

•infections of subcutaneous tissue
•spreads through fascial planes
•due to release of enzymes, endo and exotoxins by Group A streptococcus

Question 18

What shape and arrangement is shown by neisseria

Answer 18

•diplococci

Question 19

What are some characteristics of Niesseria meningitis

Answer 19

•septic shock
•rash (destruction of blood vessels)
•extreme cases = disseminated intravascular coagulation

Question 20

How does N meningitis cause blood rashes and septics shock

Answer 20

•lipo oligo saccharide in outer membrane
•acts as endotoxin

Question 21

How can N meningitis cause disseminated intravascular coagulation

Answer 21

•outer membrane as endotoxin

Question 22

Bacterial identification from culture methods

Answer 22

•biochemical tests
•MALDI-TOF

Question 23

Mechanism of MOLDI-TOF

Answer 23

•organism samples fixed in matrix
•this captures the organisms released proteins
•sample is lazered
•protein molecules vaporised and ionized
•these fly into vacuum
•flight time determines molecular mass

Question 24

What type of test is MOLDI-TOF

Answer 24

Mass spectrometry

Question 25

What weight molecules will arrive first out of the vacuum during MOLDI-TOF

Answer 25

•lighter ones then heavier ones

Question 26

Example of biochemical tests

Answer 26

•Biomerieux API system

Question 27

Mechanism of Biomerieux API system

Answer 27

•standardised test strips to identify microorganisms •how it reacts to many different chemicals and substances •compare results to database to identify