Macrolides

• cheap

• not teratogenic

Examples

• erythromycin

• azithromycin

  • reduced activity Gram-positive

  • enhanced activity against Gram-negative (inc. H. Influenzae)

• clarithromycin

Properties

• bacteriostatic

• broad spectrum

Activity / Use

• Gram-positive (when penicillin allergy)

• pulmonary infections

  • Mycoplasma,

  • Legionella,

  • Chlamydia

• Campylobacter

• Mycobacterium avium (azithromycin, clarithromycin)

• Neisseria gonorrhoeae

• Syphilis

Mechanism of action

• reversible binding to 50S ribosome

Resistance

• methylation of 23S ribosomal RNA prevents binding

• destruction of lactone ring by erythromycin esterase

• active efflux

Side Effects

• nausea

• vomiting

• abdominal discomfort

• diarrhoea

  • antibiotic-associated colitis

• allergy

  • urticaria

  • rashes

• reversible hearing loss

• cholestatic jaundice

• cardiac effects

  • chest pain

  • arrythmias