Endocarditis

Question 1

Aminoglycosides (gentamicin)

Common indications

Answer 1

1. Severe sepsis- including where the source if unidentified
2. Pyelonephritis and complicated UTI
3. Biliary and intra-abdominal sepsis
4. Endocarditis

• NB- aminoglycosides lack activity against step and anaerobes so must combine with metronidazole or penicillin if sensitivity is not known

Question 2

Aminoglycosides (gentamicin)

MOA

Answer 2

• Aminoglycosides bind irreversibly to bacterial ribosomes (30s sub-unit) and inhibit protein synthesis.
• They are bacteriocidal, this may be due to unknown MOA
• Spectrum they cover: G-ve, Aerobes, staph, and mycobacteria
• Aminoglycoside enter into the cell by O2-dependent transport system- mechanism of resistance
• Another common mechanism of resistance is an enzyme which modifies the compound making it ineffective

Question 3

Aminoglycosides (gentamicin)

Important adverse effects

Answer 3

• Nephrotoxicity
• Ototoxicity

Question 4

Aminoglycosides (gentamicin)

Warnings

Answer 4

• Monitoring of plasma concentrations is very important particularly in neonates and the elderly who are more susceptible to renal impairment (AKI + CKD)
• Aminoglycosides can impair neuromusclar transmission so should not be given to people with myasthenia gravis

Question 5

Aminoglycosides (gentamicin)

Important interactions

Answer 5

• Ototoxicity- this is especially prevalent when co-prescribed with other drugs that do the same
  
  • Diuretics- particularly furosemide
  • Vancomycin
• Nephrotoxicity (same as ototoxicity)
  
  • Ciclosporin
  • Cisplatin
  • Cephalosporins
  • Vancomycin

Question 6

Aminoglycosides (gentamicin)

Communication

Answer 6

• Must monitor plasma concentration
• Look out for ringing in the ears or a change in hearing
• Renal function

Question 7

Vancomycin

Common indications

Answer 7

1. Treatment of G+ve infections e.g. endocarditis, where infection is severe and or penicillins cannot be used due to resistance
2. Antibiotic-associated colitis- caused by C.diff infection (usually second-line where metronidazole is ineffective or not tolerated

Question 8

Vancomycin

MOA

Answer 8

• Vancomycin inhibts growth and cross-linking of peptidoglycan chains, inhibiting synthesis of the cell wall of G+ bacteria
• Resistance is being increasingly reported- with one mechanism changing the cell wall structure to prevent vancomycin from binding

Question 9

Vancomycin

Important adverse effects

Answer 9

• Thrombophlebitis
• Red man syndrome- anaphylactoid reactions- erythema, hypotension and bronchospasm
• Anaphylaxis
• Nephrotoxicity
• Ototoxicity
• Blood discaries- Neutropenia and thrombocytopenia

Question 10

Vancomycin

Warnings

Answer 10

• Vancomycin treatment requires careful monitoring of plasma drug concentrations and dose adjustment to avoid toxicity
• Particular care should be taken for people with renal impairment and the elderly (hearing impairment)

Question 11

Vancomycin

Interactions

Answer 11

• Ototoxicity- co-prescribing with gent, ciclosporin and loop diuretics