Binding of some polyhexamethylene biguanides to the cell envelope of Escherichia coli ATCC 8739

Abstract

Absorption and antibacterial action of some polyhexamethylene biguanides upon Escherichia coli has been investigated. An amine-ended-dimer (AED) (n = 2), a polydisperse mixture sold by ICI Limited as the active ingredient of vantocil IB (PHMB) (n = 5.5), and a high molecular weight fraction of PHMB (HMW, n greater than or equal to 10) were used. Bactericidal activity was determined over a range of pH (5-9). Similarly, adsorption of drug to the cell surface, indicated by changes in electrophoretic mobility, and overall drug absorption by the cells were determined. Maximal activity occurred at pH 6 for PHMB and HMW and at pH 5 for AED. This corresponded to minimal surface adsorption and maximal distribution of drug to the underlying cytoplasm and cytoplasmic membrane. Uptake of drug corresponded to high affinity isotherms and indicated a rapid transfer of biocide into the cells following their initial interaction at the surface.