Effects of iron on the growth, biofilm formation and virulence of Klebsiella pneumoniae causing liver abscess

Abstract

Background: Klebsiella pneumoniae is considered the most clinically relevant species of Enterobacteriaceae, known to cause severe infections including liver abscesses. To the best of our knowledge, a large proportion of iron in the human body is accumulated and stored in the liver. We hypothesize that increased iron availability is an important factor driving liver abscess formation and we therefore aim to understand the effects of iron on K. pneumoniae causing liver abscesses. Results: All tested K. pneumoniae clinical isolates, including those isolated from liver abscesses and other abdominal invasive infection sites, grew optimally when cultured in LB broth supplemented with 50 μM iron and exhibited the strongest biofilm formation ability under those conditions. Decreased growth and biofilm formation ability were observed in all tested strains when cultured with an iron chelator (P < 0.05). The infection model of G. mellonella larvae indicated the virulence of liver abscess-causing K. pneumoniae (2/3) cultured in LB broth with additional iron was significantly higher than those under iron-restricted conditions (P < 0.05). The relative expression levels of the four siderophore genes (iucB, iroB, irp1, entB) in K. pneumoniae strains isolated from liver abscesses cultured with additional iron were lower than those under iron-restricted conditions (P < 0.05).Conclusions: It is suggested by our research that iron in the environment can promote growth, biofilm formation and enhance virulence of K. pneumoniae causing liver abscesses. A lower expression of siderophore genes correlates with increased virulence of liver abscess-causing K. pneumoniae. Further deeper evaluation of these phenomena is warranted.

Evaluation of a novel, multi-functional inhibitor compound for prevention of biofilm formation on carbon steel in marine environments

“…FeII + and FeIII + could have promoted selective attachment based on an ability for chemolithotrophic metabolism, a well-established phenomenon in Shewanella strains 18 . In Klebsiella and Pseudomonas , research has demonstrated that addition of iron to cultures results in faster replication and formation of more robust biofilms 56 , 57 .…”

Biofilm Produced In Vitro by Piscirickettsia salmonis Generates Differential Cytotoxicity Levels and Expression Patterns of Immune Genes in the Atlantic Salmon Cell Line SHK-1

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Developing Rapid Antimicrobial Susceptibility Testing for Motile/Non-Motile Bacteria Treated with Antibiotics Covering Five Bactericidal Mechanisms on the Basis of Bead-Based Optical Diffusometry

“…Notably, the diffusive patterns for the morphological changes showed a monotonically declining slope in phase II when bacteria expressed obvious resistance to the antibiotics. Considering the four bacteria usually reproduce themselves every 20 min to 2 h [ 47 , 48 ], the morphological changes in the bacteria, i.e., elongation/rupture/lysis, were detected within the 2-h measurement. Overall, we observed that fast-reproducing bacteria (<2 h) were more likely to result in a similar diffusivity trend in the phase II region.…”