ACTION OF A QUATERNARY AMMONIUM DISINFECTANT ON CELL-MEMBRANE OF STAPHYLOCOCCUS-AUREUS

Treatment of Staphylococcus aureus cells with a quaternary ammonium di sinfectant, didecyldimethyl ammonium chloride (DDAC), induced increase in turbidity of the cell suspension and inhibited the cell respiratio n. Addition of DDAC also increased turbidity of the suspension of prot oplasts, the membrane and cytoplasm fraction, and even the liposome pr epared from the cell phospholipid and soybean lecithin. In addition, i t enhanced membrane fluidity of the liposome prepared from the cell ph ospholipid. It is proposed from findings in this and previous papers t hat the cationic surfactant first causes damage to the structure of th e cell membrane which results in irreversible inactivation of all memb rane functions.