Antibiotics

Question 1

What is selective toxicity

Answer 1

-Antibiotics block or inhibit a metabolic pathway in the micro-organism that is absent or different in mammals

Question 2

Which antibiotics block bacterial cell wall synthesis

Answer 2

• Beta lactase- penicillins, cephalosporins, carbapenems

- Glycopeptides- Vancomycin, teicoplanin

Question 3

What antibiotics inhibit protein synthesis

Answer 3

• Macrolides- erythromycin and clarithromycin
• Fusidic acid- staph infection
• Tetracyclines- Doxycycline
• Aminoglycosides- gentamicin (most powerful)

Question 4

Which antibiotics disrupt bacterial DNA

Answer 4

-Quinolones- ciprofloxacin

Question 5

Which antibiotics block foal metabolism

Answer 5

• Trimethoprim (UTI)

- Sulfonamides

Question 6

what is the difference between antibiotic toxicity and pharmacological toxicity

Answer 6

• Antibiotic toxicity= microbiological upset of natural bacterial flora
• Pharmacological toxicity- allergy (hypersensitivity), renal/ hepatic impairment, drug interactions, neurological toxicity (ciprofloxacin overdose) , bone marrow suppression

Question 7

What is intrinsic antibiotic resistance

Answer 7

• Micro-organism does not have the binding target site needed for the antibiotic to attach
• Micro-organism is impermeable to the antibiotic

Question 8

What is acquired antibiotic resistance

Answer 8

• An adaptive/ evolutionary process
  1) Acquisition of resistance genes
  2) Mutation

Effects

• Decreased permeability to abx -Altered binding site -Vulnerable metabolic step skipped
• Enzyme destruction of abx -Efflux of drug (boots drug out of cell)

Question 9

What is linked resistance

Answer 9

-Over prescribing of drug A can lead to increased resistance in drug B or C as they are genetically linked - can have pieces of DNA with several resistance determinants

Question 10

List some prescribing errors that promote resistance

Answer 10

• Prescribing antibiotics with no infection or viral infection
• Underdosing
• Long courses of therapy
• Excessively broad spectrum agent
• Not discriminating between colonisation and infection