JAC Advance Access originally published online on February 8, 2006
Journal of Antimicrobial Chemotherapy 2006 57(4):691-698; doi:10.1093/jac/dkl012
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Comparative study of the antimicrobial activity of bis(N
-caproyl-L-arginine)-1,3-propanediamine dihydrochloride and chlorhexidine dihydrochloride against Staphylococcus aureus and Escherichia coli
1 Institute for Chemistry and Environmental Research, CSIC, c/Jordi Girona 18-26, 08034 Barcelona, Spain; 2 Serveis Científico-Tècnics, Universitat de Barcelona, c/Josep Samitier 1-5, 08028 Barcelona, Spain; 3 Laboratori de Microbiologia, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
Received 6 June 2005; returned 20 September 2005; revised 20 October 2005; accepted 5 January 2006
* Corresponding author. Tel: +34-934024496; Fax: +34-934024498; E-mail: amanresa{at}ub.edu
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
-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.
Keywords: antimicrobial activity , flow cytometry , viability reduction , transmission electron microscopy , potassium leakage , cationic surfactants