Antimicrobial effects of azelaic acid

Azelaic acid has been shown to be an effective topical acne therapy. Cream containing 20% azelaic acid significantly reduces the skin surface and follicular propionibacteria and staphylococci by at least 96% after 8 weeks of treatment. In vitro, azelaic acid reduces the growth rate of, and inhibits and kills Propionibacterium acnes and Staphylococcus epidermidis. The effect is dependent on the concentration of azelaic acid and the pH of the environment. Azelaic acid is more effective at low pH values. Azelaic acid is actively transported into P. acnes and S. epidermidis and its mode of action is directed to protein synthesis with 50% inhibition at 313 and 457 μM respectively. Follicular concentrations of azelaic acid reached those sufficient to inhibit both P. acnes and S. epidermidis after one application to the skin. No mutants resistant to azelaic acid appeared in P. acnes or S. epidermidis when they were grown for 9.8 × 1013 and 5.5 × 1013 cell generations, respectively, in its presence.