title: Polyethyleneimine is an effective permeabilizer of gram-negative bacteria.
abstract: The effect of the polycation polyethyleneimine (PEI) on the permeability properties of the Gram-negative bacterial outer membrane was investigated using Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium as target organisms. At concentrations of less than 20 micrograms ml-1, PEI increased the bacterial uptake of 1-N-phenylnaphthylamine, which is a hydrophobic probe whose quantum yield is greatly increased in a lipid environment, indicating increased hydrophobic permeation of the outer membrane by PEI. The effect of PEI was comparable to that brought about by the well-known permeabilizer EDTA. Permeabilization by PEI was retarded but not completely inhibited by millimolar concentrations of MgCl2. PEI also increased the susceptibility of the test species to the hydrophobic antibiotics clindamycin, erythromycin, fucidin, novobiocin and rifampicin, without being directly bactericidal. PEI sensitized the bacteria to the lytic action of the detergent SDS in assays where the bacteria were pretreated with PEI. In assays where PEI and SDS were simultaneously present, no sensitization was observed, indicating that PEI and SDS were inactivating each other. In addition, a sensitizing effect to the nonionic detergent Triton X-100 was observed for P. aeruginosa. In conclusion, PEI was shown to be a potent permeabilizer of the outer membrane of Gram-negative bacteria.
authors.affiliation: VTT Biotechnology and Food Research, PO Box 1501, FIN-02044 VTT, Espoo, Finland.
authors.forename: Ilkka M
authors.initials: IM
authors.lastname: Helander
authors.affiliation: VTT Biotechnology and Food Research, PO Box 1501, FIN-02044 VTT, Espoo, Finland.
authors.forename: Hanna-Leena
authors.initials: HL
authors.lastname: Alakomi
authors.affiliation: VTT Biotechnology and Food Research, PO Box 1501, FIN-02044 VTT, Espoo, Finland.
authors.forename: KyÖsti
authors.initials: K
authors.lastname: Latva-Kala
authors.affiliation: Department of Vaccine Development, KTL, Mannerheimintie 166, FIN-00300, Helsinki, Finland.
authors.forename: Pertti
authors.initials: P
authors.lastname: Koski
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D002463:Cell Membrane Permeability / Q000187:drug effects; D003902:Detergents / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004492:Edetic Acid / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D009113:Muramidase / Q000494:pharmacology; D017830:Octoxynol / Q000494:pharmacology; D011094:Polyethyleneimine / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000378:metabolism; D012486:Salmonella typhimurium / Q000187:drug effects / Q000378:metabolism
chemical_list: D003902:Detergents; D005456:Fluorescent Dyes; D008070:Lipopolysaccharides; C005444:N-phenyl-1-naphthylamine; D017830:Octoxynol; D011094:Polyethyleneimine; D015057:1-Naphthylamine; D004492:Edetic Acid; D009113:Muramidase