Association of the outer membrane protein Omp33 with fitness and virulence of Acinetobacter baumannii

J Infect Dis. 2013 Nov 15;208(10):1561-70. doi: 10.1093/infdis/jit386. Epub 2013 Aug 1.


Outer membrane protein 33 (Omp33) is an outer membrane porin of Acinetobacter baumannii associated with carbapenem resistance. However, the role of Omp33 in the fitness and virulence of A. baumannii remains unknown. In the present study, we investigated the role of Omp33 in fitness and virulence of A. baumannii by using an isogenic knockout strain deficient in the omp33 gene (JPAB02), derived from the ATCC 17978 wild-type (wt). Both in vitro and in vivo defect in the growth rate was found in the JPAB02 strain in competition with the ATCC 17978 wt, highlighting the effect of Omp33 on the metabolic fitness. A significant reduction was observed both in adherence and invasion of human lung epithelial cells and in cytotoxicity of these cells and macrophages with JPAB02. In a murine peritoneal sepsis model, the JPAB02 strain exhibited lower lethal dose 0 (LD0), LD50, and LD100, and dissemination in mice, with reduced bacterial concentration in spleen and lungs. From these data, we concluded that Omp33 plays an important role for fitness and virulence of A. baumannii.

Keywords: Acinetobacter baumannii; Omp33; fitness; virulence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter Infections / microbiology
  • Acinetobacter Infections / mortality
  • Acinetobacter baumannii / genetics*
  • Acinetobacter baumannii / growth & development
  • Acinetobacter baumannii / pathogenicity*
  • Animals
  • Bacterial Adhesion / genetics
  • Bacterial Outer Membrane Proteins / genetics*
  • Biofilms
  • Cell Death
  • Cell Line
  • Disease Models, Animal
  • Epithelial Cells / metabolism
  • Epithelial Cells / microbiology
  • Gene Knockout Techniques
  • Genetic Fitness*
  • Humans
  • Mice
  • Peritonitis / microbiology
  • Peritonitis / mortality
  • Phenotype
  • Virulence / genetics


  • Bacterial Outer Membrane Proteins