Constitutive Phenotypic Modification of Lipid A in Clinical Acinetobacter baumannii Isolates

Su Hyun Kim, Sohyeon Yun, Woojun Park

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The degree of polymyxin B (PMB) resistance was measured in 40 clinical Acinetobacter baumannii isolates obtained from health care facilities. All of the tested isolates possessed a multidrug-resistant (MDR) phenotype against four classes of antibiotics (meropenem, doxycycline, gentamicin, and erythromycin), except for PMB. The blaOXA-23 gene was detected throughout the genetic analysis and experimental assay, indicating that all of the MDR strains were carbapenem-resistant A. baumannii strains. Multilocus sequence typing-based genotyping revealed that nine selected strains belonged to the international clone II lineage. When matrix-assisted laser desorption ionization–time of flight mass spectrometry was performed, intrinsic lipid A modification by phosphoethanolamine (PEtN) incorporation was noticeable only in the PMB-resistant (PMBR) strains. However, the presence of hexa- and penta-acylated lipid A due to the loss of the laurate (C12) acyl chain was noted in all PMB-susceptible strains but not in the PMBR strains. The reduction of negative surface charges in the PMBR strains was assessed by zeta potential analysis. Fluorescence imaging using dansyl-PMB revealed that, in the PMBR strains, PMB was less likely to bind to the cell surface.

Original languageEnglish
JournalMicrobiology spectrum
Volume10
Issue number4
DOIs
Publication statusPublished - 2022 Aug

Bibliographical note

Funding Information:
We thank the Samsung Medical Center, Sungkyunkwan University, for providing 5 clinical isolates (F-1025 to F-1629) and the NCCP for providing the other 35 clinical isolates (NCCP 12276 to NCCP 16011). This work was supported by the National Research Foundation of Korea (NRF) (grant NRF-2020M3A9H5104237). S.-H.K. and W.P. designed the study and wrote the manuscript. S.-H.K. conducted the experiments and analyzed the data. S.Y. performed zeta potential measurements and took CLSM images. W.P. supervised and acquired funding for this study.We report no potential conflicts of interest.

Funding Information:
We thank the Samsung Medical Center, Sungkyunkwan University, for providing 5 clinical isolates (F-1025 to F-1629) and the NCCP for providing the other 35 clinical isolates (NCCP 12276 to NCCP 16011). This work was supported by the National Research Foundation of Korea (NRF) (grant NRF-2020M3A9H5104237). S.-H.K. and W.P. designed the study and wrote the manuscript. S.-H.K. conducted the experiments and analyzed the data. S.Y. performed zeta potential measurements and took CLSM images. W.P. supervised and acquired funding for this study. We report no potential conflicts of interest.

Publisher Copyright:
© 2022 Kim et al.

Keywords

  • Gram-negative bacteria
  • carbapenem-resistance
  • lipopolysaccharide
  • phosphoethanolamine
  • pmrC
  • polymyxin

ASJC Scopus subject areas

  • Physiology
  • Ecology
  • General Immunology and Microbiology
  • Genetics
  • Microbiology (medical)
  • Cell Biology
  • Infectious Diseases

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