Antimicrobials

Question 1

Define antimicrobial resistance and why it is such a major problem (3)

Answer 1

• The number of infections due to antibiotic resistant bacteria is growing
• A number of initiatives aimed at reducing AB prescribing in the 1990s were associated with a fall in AB prescribing in the late 1990s to 2000. However, antimicrobial prescribing seems to be on the increase again, particularly in primary care.
• Antimicrobial resistance is considered to be a global health crisis

Question 2

What are the top 10 tips for effective antibiotic prescribing (RCP)

Answer 2

• Start AB tx immediately in pts with life threatening infections
• Prescribe in accordance with local policies and guidelines, avoiding broad spectrum agents.
• Document in clinical notes (rational)
• Use antimicrobial susceptibility data to de escalate/substitute/add agents/switch from IV to PO
• Prescribe the shortest course likely to be effective
  Always select agents to minimise collateral damage
• Monitor AB drug levels (when appropriate)
• Use single use antibiotic prophylaxis wherever possible
• Consult local infection experts

Question 3

What are the 4 Rs of antibiotic prescribing?

Answer 3

• Right diagnosis - consider delaying, is it clinically indicated
• Right antibiotic - check for sensitivity and use narrow agent if possible
• Right dose - follow local guidelines
• Right length of treatment / follow local guidelines

Question 4

Bacteria can be categorised into gram +ve and gram -ve bacteria. Explain the differences….

Answer 4

Gram +ve
* Takes up blue stain on dye due to its thick wall
* not as dangerous
* has an enzyme layer

Gram -ve
* Takes up red/pink stain on dye as the wall is not as thick
* Has an outer wall
* Has an enzyme layer
* More complex so harder to treat

Question 5

Antibiotics can be categorised as…..

Answer 5

• Bactericidal - kills bacteria
• Bacteriostatic - holts the production of new bacteria

Question 6

Antibiotic resistance can develop through….

Answer 6

• Human factors (human to human transfer)
• Genetic mechanisms
• Biochemical mechanisms

Question 7

Genetic mechanisms:

Answer 7

• Transformation - resistant DNA gets taken up by neighbouring cells
• Conjugation - sexual reproduction of bacteria. They fuse and swap genetic material
• Transduction - The use of a virus to transport resistant DNA from a donor bacteria to the recipient bacteria

Question 8

Biochemical mechanisms…

Answer 8

• Enzymes break down the chemical structure of antibiotics using beta lactase changing the configuration of the binding site.
• Pumps the antibiotic back out - efflux pumps