Aminoglycosides

Question 1

Name a common amino glycoside antibiotic?

Answer 1

Gentamycin

Question 2

What part of the bacterial cell do aminoglycosides target?

Answer 2

Protein synthesis

Question 3

How do aminoglycosides work?

Answer 3

Irreversibly bind to the 30S subunit of bactrial ribosomes

- This works in the same way as tetracyclines however is BACTERIOCIDAL

Question 4

Are aminoglycosides bactericidal or bacteriostatic

Answer 4

Bactericidal

Question 5

What spectrum do aminoglycosied have?

Answer 5

Gram negative AEROBES

Question 6

Give two common examples of types of bacteria aminoglycosied work against

Answer 6

Staphyloccoci and mycobacterium

Question 7

What types of bacteria do aminoglycosides not work against?

Answer 7

Streptococci and anaerobes

Question 8

Why do aminoglycosides not work against anearobes

Answer 8

Aminoglycosides enter the bacterial cell via an oxygen dependant transport system so aerobic bacteria and streptococci dont have this so are innately resistant

Question 9

How have some bacteria become resistant to aminoglycosides?

Answer 9

Reduced membrane permeability to aminoglycosides and acquisition of enzymes that modify aminoglycosides so they cannot reach the 30s subunit

Question 10

What other antibiotic is commonly prescribed with aminoglycosides?

Answer 10

Penicillins as they weaken the bacterial cell wall therefore enhancing amino glycoside effects

Question 11

What are the common uses for amino glycosides?

Answer 11

1. Severe Sepsis (including of unknown cause often given with penicillin/metranidazole)
2. Acute Pyelonephritis and Complicated UTI (GEntamycin and co-amoxiclav)
3. Biliary and Intrabdomimal sepsis (often given with penicillin/metranidazole)
4. Endocarditis

Question 12

Because of aminoglycosides inability to work against steptocci and anaerobes what else is usually prescibed when the causative organism is unknown?

Answer 12

Penicillins or metronidazole

Question 13

What antibiotics are given in acute pyelonephritis?

Answer 13

Gentamycin and co-amoxclav

OR ciprafloxacin

Question 14

What are the contraindications of using aminoglycosides?

Answer 14

Myasthenia graves (impaires NMJ)

Question 15

When should aminoglycosides be given with caution?

Answer 15

Elderly neonates and those with renal impairment

- Really excreted and are most at risk of vestibulo cochlea damage

Question 16

What are the common interactions with amino glycoside?

Answer 16

1. Loop diuretics - ototoxicity
2. Cephalosporins - nephrotoxicity
3. Ciclosporin - nephrotoxicity
4. Vancomycin - both
5. Platinum chemotherapy - nephrotoxicity

Question 17

What are the common side effects of aminoglycosides and why?

Answer 17

Ototoxicity
Nephrotoxicty
**aminoglycosides accumulate in renal tubular epithelium and cochlea and vestibular hair cells where they cause apoptosis

Question 18

How do nephrotoxicity and ototoxicity present?

Answer 18

Nephrotoxicity: decrease UO and increase in serum creatinine and urea
Ototoxicity: often not noticed until after resolution of infection with hearing loss, tints (cochlea damage) and dizziness (vestibular damage)

Question 19

Are nephrotoxicity and ototoxicity reversible?

Answer 19

Otto: maybe not
Nephro: may be

Question 20

How are aminoglycosided given?

Answer 20

IV

Question 21

How long is the treatment with aminoglycosides?

Answer 21

As short as possible to prevent adverse effects: <7 days ideally

Question 22

How is the dose for aminoglycosides calculated?

Answer 22

Weight and renal function

- Measure renal function