Microbial alcohol-conferred haemolysis (MACH) occurring in Staphylococcus aureus biofilms

Recently, the phenomenon called microbial alcohol-conferred haemolysis (MACH) was described for Staphylococcus aureus. It is characterized by increments in haemolysis when colonies are exposed to ethanol vapors. However, the confirmation of MACH by biofilms of S. aureus grown in presence of ethanol has been no reported. Methods: To respond such question, MACH phenomenon was evaluated in aerobic and anaerobic biofilms of S. aureus ATCC®25923™ grown in the presence of 0.5 mg mL-1 and 1 mg mL-1 ethanol and followed up for 24 and 48 h. Biomasses and haemolytic activities were measured. Results: Increments in the haemolytic activity for aerobic biofilms occurred in a time-dependent manner. Anaerobic biofilms did not show any increment in such parameters when ethanol was present at any concentration. Conclusions: These observations may be important for clinicians that treat chronic drinkers