Enterobacter gergoviae adaptation to preservatives commonly used in cosmetic industry.

The aim of this study was to obtain a better understanding regarding the origin of recurrent contamination by Enterobacter gergoviae in diverse cosmetic formula. We studied 65 isolates collected from various sources (clinical, food, cosmetics). RAPD analysis using AP12H, REP and ERIC-PCR was carried out for epidemiological typing. Evaluation of susceptibility to preservatives currently used in cosmetics for a representative panel of collection strains was measured. Preservative efficacy was evaluated by minimum inhibitory concentrations and minimum bactericidal concentrations (MBCs). Eighty per cent of isolates was unrelated. E. gergoviae showed significant levels of resistance to preservatives. MBC was higher than maximum permitted concentrations imposed by European Commission (EC). Association of preservatives showed in rare case additive effects, and no synergic effects were observed. Most of the cosmetic formulations are contaminated with unrelated E. gergoviae strains. Maximum allowed concentrations for sodium benzoate are inefficient to limit proliferation and control adaptability to this bacterium in cosmetic products. Efflux mechanisms should be involved in methylisothiazolinone-chloromethylisothiazolinone and triclosan adaptation.