Enhanced activity of carvacrol against biofilm of Staphylococcus aureus and Staphylococcus epidermidis in an acidic environment

SIFI Pharma SpA, Catania, ItalyNostro A, Cellini L, Zimbalatti V, Blanco AR, Marino A, Pizzimenti F, Di Giulio M, Bisignano G.Enhanced activity of carvacrol against biofilm of Staphylococcus aureus and Staphylococcus epider-midis in an acidic environment. APMIS 2012.Carvacrol is an antimicrobial monoterpenic phenol which occurs in many plant essential oils. Theaim of this study was to investigate its activity at acidic pH on staphylococcal forming and yetestablished biofilms, with particular focus to improve its effectiveness on Staphylococcus epidermidisbiofilm. The results showed that the subinhibitory doses (1/2, 1/4 and 1/8 MIC) of carvacrol deter-mined a higher reduction of S. epidermidis biofilm formation than that observed at neutral pH. Apotentiated inhibitory effect was also observed on established biofilm, carvacrol caused either astrong reduction of biomass (>50%) and bacteria attached to polystyrene (>7 log units). The imagesof scanning electron microscopy and the gas-chromatographic analysis support these results. Thedevelopment of acidic formulations containing carvacrol could be an important tool to control thestaphylococcal biofilm in the medical and food environment.Key words: Carvacrol; biofilm; Staphylococcus aureus; Staphylococcus epidermidis; acidic pH.Antonia Nostro, Pharmaco-Biological Department, Faculty of Pharmacy, University of Messina,Viale S.S. Annunziata, 98168 Messina, Italy. e-mail: anostro@unime.it