Antibiotics

Question 1

What antibiotics are penicillins and how do they work?

Answer 1

Penicillin

Question 2

What antibiotics are aminoglycosides and how do

they work?

Answer 2

Gentamycin
Streptomycin
Neomycin
Tobramycin etc.

Question 3

What antibiotics are glycopeptides and how do they work?

Answer 3

Vancomycin
Teicoplanin etc.

Aerobic and anaerobic G+ve bacteria

Vanc. used for MRSA

Question 4

What antibiotics are macrolides and how do they work?

Answer 4

Azithromycin
Clarithromycin
Erythromycin

Question 5

.

Answer 5

.

Question 6

How do you administer gentomycin?

Answer 6

IV:
Dilute in Glucose 5% or Sodium Chloride 0.9%
Give over 30 minutes

Question 7

What are some side effects of aminoglycosides?

Answer 7

Tinnitus = most significant

Question 8

What are cautions and contraindications to aminoglycosides?

Answer 8

Cautions - 
All (by injection):
Auditory disorders 
Vestibular disorders 
Muscular weakness disorders 
Dehydration (correct before starting)
Renal failure  

Contraindications -
All (by injection):
Myasthenia gravis - may impair neuromuscular transmission
Pregnancy - CN8 damage to foetus if given in 2nd/3rd trimester (greatest risk with streptomycin)

Gentamycin (used by ear):
Patent grommet
Perforated tympanic membrane

Question 9

How do you titrate aminoglycoside antibiotics to avoid ototoxicty and renal damage?

Answer 9

Should obtain peak serum concentrations post dose - if outside the reference range:

• Extend the dose interval
• Decrease the dose

This will drop the peak concentration and mitigate damage

Question 10

What monitoring is required for aminoglycosides?

Answer 10

Renal function:

• Before and during treatment
• Multiple daily dose regimen: one hour (‘peak’) serum concentration should be 5–10 mg/litre ; pre-dose (‘trough’) concentration should be less than 2 mg/litre.

Serum-Abx concentration: - To prevent toxicity and ensure efficacy

Auditory + vestibular functioning:
- During treatment, to identify signs of toxicity

Question 11

How should you deliver vancomycin?

Answer 11

Not PO for systemic infections as not absorbed significantly

Avoid rapid infection as risk of anaphylactoid reactions

Caution in teicoplanin sensitivity (as cross reaction possible)

Rotate infusion sites

IV: give intermittently in Glucose 5% or Sodium chloride 0.9%; reconstitute each 500 mg with 10 mL water for injections and dilute with infusion fluid to a concentration of up to 5 mg/mL (10 mg/mL in fluid restriction but increased risk of infusion-related effects); give over at least 60 minutes (rate not to exceed 10 mg/minute for doses over 500 mg)

Question 12

What monitoring is required for vancomycin?

Answer 12

Initial doses based on body weight then adjustment based on plasma concentrations on day 2 of treatment and immediately before next dose if renal function intact

Periodic auditory/vestibular testing

Blood counts, urinalysis, hepatic and renal function periodically

Leucocyte count regularly in long term users or if given concurrently with other drugs that cause neutropenia or agranulocytosis

Avoid concurrent use of ototoxic drugs -
Elderly are particularly vulnerable to damage