Comparative study of the antimicrobial activity of bis(Nα-caproyl-L-arginine)-1,3-propanediamine dihydrochloride and chlorhexidine dihydrochloride against Staphylococcus aureus and Escherichia coli

Objectives: The aim of this study is to gain insight into the mechanism of the antimicrobial action of a novel arginine-based surfactant, bis(N-alpha-caproyl-l-arginine)-1,3-propanediamine dihydrochloride [C-3(CA)(2)]. Methods: To this end, we compared its effects against Staphylococcus aureus and Escherichia coli with those caused by the commercial and widely known antiseptic, chlorhexidine dihydrochloride (CHX). Results: Both disrupted the cell membrane of the target bacteria to cause potassium leakage and morphological damage. The effect of C-3(CA)(2) on E. coli was concentration dependent, causing loss of membrane potential and membrane integrity leading to cell death, whereas CHX did not have these effects on E. coli. The effect of C-3(CA)(2) on S. aureus was the formation of mesomes and cytoplasmic clear zones, but the loss of membrane potential and membrane integrity was slightly lower than that with CHX. Conclusions: We propose that C-3(CA)(2) acts preferentially against Gram-negative bacteria through strong initial binding to the surface lipopolysaccharides and subsequently partitioning into the cell membrane to cause membrane damage, followed by cell death.