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

Abstract

Objectives: The aim of this study is to gain insight into the mechanism of the antimicrobial action of a novel arginine-based surfactant, bis(Nα-caproyl-l-arginine)-1,3-propanediamine dihydrochloride [C3(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 C3(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 C3(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 C3(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. © 2006 Oxford University Press.