Antibiotics, AMR and diagnostics

Question 1

What are antibiotics?

Answer 1

Naturally produced drugs

From penicillin mould

Question 2

BActeria can be bacteriocidial or bacteriostatic. What do these terms mean?

Answer 2

Kill bacteria

Prevent bacterial replication

Question 3

Antibiotics can be narrow spectrum or broad spectrum.What are narrow spectrum antibiotics?

Answer 3

Affect few bacteria - too big to penetrate gram negative outer membrane
Organism is identified and targeted

Question 4

What are broad spectrum antibiotics?

Answer 4

Target a group of microorganisms e.g. gram positive or negative, anaerobes
For unidentified organisms

Question 5

How do antibiotics work?

Answer 5

Prevent growth and survival of organism without damaging host- try target prokaryotic features
Target enzymes, inhibit DNA synthesis, inhibit protein synthesis, inhibit folic acid synthesis, cell wall synthesis

Question 6

What is prophylaxis and metaphylaxis?

Answer 6

Pro - treatment given to prevent a disease

Met - mass medication given to group to try eliminate disease

Question 7

What is minimal inhibitory concentration?

Answer 7

Minimum concentration of a drug given that inhibits bacteria growth

Question 8

Does resistance develop in a pathogen during treatment?

Answer 8

NO

Except fluoroquinolones and rif

Question 9

Resistance can be inherent or acquired. Define these terms

Answer 9

Inherent - natural trait

Acquired - developed by mutation or horizontal gene transfer

Question 10

Plasmids can cause multi drug resistance and co selection. What is co selection?

Answer 10

Resistance to multiple classes of drug

Question 11

PCR can be used to identify AMR genes, however what is an issue with this?

Answer 11

Does not show whether gene is being expressed

Question 12

How do pathogens become AMR?

Answer 12

Outer membrane permeability decreases so drug cannot enter
Efflux of drug - drug is pumped out to decrease intracellular concentration
Target is altered so drug can no longer bind
Enzymes produced to breakdown drug (inactivation)

Question 13

What is antibiotic stewardship?

Answer 13

Improving the use of antibiotics by decreasing use where possible
To prevent AMR

Question 14

What is aetiology?

Answer 14

The cause of a disease/condition

Question 15

What are the 3 types of methods to identify microorganisms?

Answer 15

Phenotypic - morphology
Immunological - serology, ELISA
Molecular - Genetics, DNA, PCR

Question 16

What are the dis/advantages of using microscopes to identify a microorganism?

Answer 16

Not for viruses
Immediate
Shows number
Allows presumed identification
Shows host cellular response?

Question 17

What is a pure culture?

Answer 17

A single species of organism

Question 18

What test is used for the presence of metabolic enzymes?

Answer 18

Oxidase test

Question 19

Why can some mycoses be seen under UV light by phenotypic identification

Answer 19

Produce fluorescent metabolites

Question 20

What is a direct smear examination

Answer 20

Sample of faeces under a microscope to identify pathogen

Question 21

How do you collect a specimen?

Answer 21

Collect sufficient amount from aseptic site before antimicrobial therapy
Freeze at -80 if storing
Record patient history site, sample type etc

Question 22

WHat is an example of an antibiotic susceptibility testing method?

Answer 22

Disc diffusion
qualitative - does not show MIC
Quantitative when using dilutions of 1 antimicrobial

Question 23

Viruses are obligate parasites. What does this mean?

Answer 23

They must grow on living cells