title: Surface changes and polymyxin interactions with a resistant strain of Klebsiella pneumoniae.
abstract: This study examines the interaction of polymyxin B and colistin with the surface and outer membrane components of a susceptible and resistant strain of Klebsiella pneumoniae. The interaction between polymyxins and bacterial membrane and isolated LPS from paired wild type and polymyxin-resistant strains of K. pneumoniae were examined with N-phenyl-1-naphthylamine (NPN) uptake, fluorometric binding and thermal shift assays, lysozyme and deoxycholate sensitivity assays, and by (1)H NMR. LPS from the polymyxin-resistant strain displayed a reduced binding affinity for polymyxins B and colistin in comparison with the wild type LPS. The outer membrane NPN permeability of the resistant strain was greater compared with the susceptible strain. Polymyxin exposure enhanced the permeability of the outer membrane of the wild type strain to lysozyme and deoxycholate, whereas polymyxin concentrations up to 32 mg/ml failed to permeabilize the outer membrane of the resistant strain. Zeta potential measurements revealed that mid-logarithmic phase wild type cells exhibited a greater negative charge than the mid-logarithmic phase-resistant cells. Taken together, our findings suggest that the resistant derivative of K. pneumoniae can block the electrostatically driven first stage of polymyxin action, which thereby renders the hydrophobically driven second tier of polymyxin action on the outer membrane inconsequential.
authors.affiliation: 1Drug Development and Innovation, Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
authors.forename: Tony
authors.initials: T
authors.lastname: Velkov
authors.forename: Zakuan Z
authors.initials: ZZ
authors.lastname: Deris
authors.forename: Johnny X
authors.initials: JX
authors.lastname: Huang
authors.forename: Mohammad A K
authors.initials: MA
authors.lastname: Azad
authors.forename: Mark
authors.initials: M
authors.lastname: Butler
authors.forename: Sivashangarie
authors.initials: S
authors.lastname: Sivanesan
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Kaminskas
authors.forename: Yao-Da
authors.initials: YD
authors.lastname: Dong
authors.forename: Ben
authors.initials: B
authors.lastname: Boyd
authors.forename: Mark A
authors.initials: MA
authors.lastname: Baker
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Cooper
authors.forename: Roger L
authors.initials: RL
authors.lastname: Nation
authors.forename: Jian
authors.initials: J
authors.lastname: Li
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000187:drug effects*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D003091:Colistin / Q000378:metabolism; D003840:Deoxycholic Acid / Q000378:metabolism; D004347:Drug Interactions; D004351:Drug Resistance; D057927:Hydrophobic and Hydrophilic Interactions; D007710:Klebsiella Infections / Q000188:drug therapy* / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000502:physiology*; D008070:Lipopolysaccharides / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D009113:Muramidase / Q000378:metabolism; D011112:Polymyxin B / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D013045:Species Specificity; D055672:Static Electricity
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D008070:Lipopolysaccharides; D003840:Deoxycholic Acid; C005444:N-phenyl-1-naphthylamine; D015057:1-Naphthylamine; D009113:Muramidase; D011112:Polymyxin B; D003091:Colistin
keywords: Klebsiella pneumoniae; Polymyxin; colistin; lipopolysaccharide; surface