Comparison among the effectiveness of ozone, nisin and benzalkonium chloride for the elimination of planktonic cells and biofilms of Staphylococcus aureus CECT4459 on polypropylene

In search for alternative disinfection methods to prevent the development of bacterial resistances, the effectiveness of benzalkonium chloride (BAC), nisin and ozone against planktonic cells and biofilms of Staphylococcus aureus CECT 4459 was compared. Maximum effect of each compound was determined by comparing the times of exposure at which maximum mortality was reached. A dose–response study was carried out at such exposure times and LD90 values (doses causing 90% of mortality) were determined. BAC and ozone were more effective against biofilms than against planktonic cells, presumably due to a higher accessibility of biofilm cells. Concerning the control of biofilms, BAC was highly effective, but the application of 250 IU/ml of nisin or 1 μg/g of ozonized water allowed to reach 99% inactivation in only 2 min. It is concluded that nisin and ozone could be good alternative disinfectants to prevent the development of bacterial resistances, but factors such as applicability, price and risk to employers and food should also be taken into account.