Azelaic acid: its uptake and mode of action in Staphylococcus epidermidis NCTC 11047

In vitro tests using Staphylococcus epidermidis as a model have shown that at pH 5.6 the micro-organisms are sensitive to azelaic acid, whilst at pH 6.0 and 7.0 the cells become progressively resistant, especially with nutrients present. In a simple defined medium the growth rate was reduced at 1 mmol/l and growth inhibited at 25 mmol/l. The uptake of azelaic acid was pH dependent, higher transport at lower pH values, and required viable cells. Azelaic acid, 457 mumol/l gave 50% inhibition of protein synthesis and this mechanism could account for the bactericidal and bacteristatic effects. DNA and RNA were affected slightly by 100 mmol/l azelaic acid, and respiration by 500 mmol/l.