Surface changes and polymyxin interactions with a resistant strain of Klebsiella pneumoniae

Tony Velkov, Zakuan Zainy Deris, Johnny X Huang, Mohammad Abul Kalam Azad, Mark Butler, Sivashangarie Sivanesan, Lisa Michelle Kaminskas, Yao Da Charlie Dong, Benjamin James Boyd, Mark A Baker, Matthew A Cooper, Roger Leigh Nation, Jian Li

Research output: Contribution to journalArticleResearchpeer-review

55 Citations (Scopus)

Abstract

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 1H 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.
Original languageEnglish
Pages (from-to)350 - 363
Number of pages14
JournalInnate Immunity
Volume20
Issue number4
DOIs
Publication statusPublished - 2014

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