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Part III: Guidelines for selected antimicrobial use

3.5 Colistin/colomycin

  1. Colistin belongs to the polypeptide antibiotic class polymyxin.
  2. Mainly used in infections caused by multidrug-resistant Gram-negative bacteria like CRE, pandrug-resistant Acinetobacter baumannii, and Pseudomonas aeruginosa.
  3. All Gram-positive bacteria, Moraxella catarrhalis, Morganella morganii, Proteus spp., Providencia spp. and Serratia marcescens are intrinsically resistant to colistin.
  4. Poor lung penetration after intravenous administration. For pneumonia cases, use high I.V. dose with possible addition of nebulised colistin (156).
  5. Dosing and administration
    • Despite being available for more than 50 years, colistin use is still not optimised. This is due to confusion in dosing due to different conventions, outdated and diverse product information and uncertainties about susceptibility testing and breakpoints (157).
    • Colistin strength is expressed in colistin base activity (mg CBA), milligrams (mg) or international units (IU) in different parts of the world.
    • Consider 30 mg CBA approximately equal to 1 million IU colistin (158).
  6. Please consult clinical microbiologist or infectious disease physician for the use of colistin.