Week 8 Y

Question 1

Sensitivity

Answer 1

Ability to detect a true positive

Question 2

Specificity

Answer 2

The ability to test for a true negative

Question 2

Name types of culture methods

Answer 2

General purpose, selective, differential, chromogenic

Question 2

Microscopy advantages and disadvantages

Answer 2

Fast, cheap specificity possible

Poor sensitivity, can’t recover organisms

Question 3

Advantages + dis of culture

Answer 3

Cheap, shows antigen well, pathogen can be analysed further

Slow, difficult to culture some pathogens

Question 4

Immunodiagnostics tests

Answer 4

Agglunitation
ELISA

Question 5

Antibiotics

Answer 5

Inhibits the growth of micoorganisms

Question 6

Bacterialcidal

Answer 6

Kills bacteria

Question 7

Bacteriostatic

Answer 7

Stops growth, doesn’t kill bacteria, can grow back again

Question 8

Minimum inhibitory concentration

Answer 8

lowest concentration of the antibiotic that results in
inhibition of visible growth under standard conditions.

Question 9

Selective toxicity

Answer 9

More damage to bacterium than host

Question 9

Synergy

Answer 9

If two antibiotics used in
combination has an antibacterial effect much
greater than either drug alone

Question 9

How the inactivation of a drug works

Answer 9

Enzymes are produced by microbes which degrade the drug, neutralising it, e.g beta-lactamase

Question 9

How drug targets are duplicated

Answer 9

The microbe produces additional copies of the drug target, diluting the drug’s effect as it binds to only a subset of the targets.

Question 9

How drug permeability is reduced

Answer 9

The microbial cell reduces the uptake of the drug by altering membrane permeability or reducing the number of drug-specific porins, e.g gram negative bacteria

Question 9

How modification of drug target works

Answer 9

Microbes alter the structure of the drug’s target site, reducing or eliminating the drug’s binding affinity

Question 9

Transformation

Answer 9

Bacteria take up free DNA from their environment, often from lysed (broken) cells, incorporated into dna

Question 9

Absence of drug target

Answer 9

The microbe naturally lacks the specific structure or pathway targeted by the drug, making it inherently resistant.

Question 9

The importance of the environment in ARGs

Answer 9

Site of Antibiotic resistance

Promotes evolution of ARGs and can create drug-resistant organisms

Question 9

Advantages of cultivation as a diagnostic tool

Answer 9

Direct observation, only living organisms, low cost, can find the CFU

Question 10

Disadvantages of cultivation as a diagnostic tool

Answer 10

Time consuming, not suitable for all organisms, labour-intensive

Question 11

What is the goal of biochemical testing

Answer 11

Identifies colonies growing, ensures it’s the right one as colonies have overlapping features e.g lactose fermenter with E.coli

Question 12

What is the goal of immunological testing with an example

Answer 12

Identifies and confirms an organism by using an antigen and antibody e.g Staphylococcus aureus on Mannitol Salt Agar

Question 13

maldi-tof stands for

Answer 13

matrix assisted laser desorption ionization-time of flight mass spectrometry

Question 14

RT-PCR

Answer 14

Stands for Reverse transcriptase Polymerase Chain reaction

Quantifies RNA using PCR

to study genes and identify viruses and pathogens

Isolate RNA, use RT enzyme to produce cDNA from RNA template, amplify to extend, identify products using gel

High sens + spec but can’t identify RNA without qRT-PCR

Question 16

Therapeutic index

Answer 16

The ratio of dose toxic to host to the therapeutic dose

Question 17

MIC - Minimum inhibitory concentration

Answer 17

Lowest conc of AB that results in inhibition of growth under standard conditions

Question 18

MBC - Minimum bactericidal concentration

Answer 18

Lowest conc of the AB that kills 99.9% of the inoculum in the given time

Question 19

Synergy

Answer 19

Combining 2 AB to create a greater antibacterial affect

Trimethoprim and sulphonamides

Question 20

Antagonism

Answer 20

When 2 drugs in combination have activity less than the better of the two