Klebsiella pneumoniae Type VI Secretion System Contributes to Bacterial Competition, Cell Invasion, Type-1 Fimbriae Expression, and in Vivo Colonization

Pei Fang Hsieh, Yi Rou Lu, Tzu Lung Lin, Li Yin Lai, Jin Town Wang*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

60 Scopus citations

Abstract

Background We previously isolated a Klebsiella pneumoniae strain, NTUH-K2044, from a community-acquired pyogenic liver abscess (PLA) patient. Analysis of the NTUH-K2044 genome revealed that this strain harbors 2 putative type VI secretion system (T6SS)-encoding gene clusters. Methods The distribution of T6SS genes in the PLA and intestinal-colonizing K pneumoniae clinical isolates was examined. icmF1-, icmF2-, icmF1/icmF2-, and hcp-deficient K pneumoniae strains were constructed using an unmarked deletion method. The roles of T6SSs in antibacterial activity, type-1 fimbriae expression, cell adhesion, and invasion and intestinal colonization were determined. Results The prevalence of T6SSs is higher in the PLA strains than in the intestinal-colonizing strains (37 of 42 vs 54 of 130). Deletion of icmF1/icmF2 and hcp genes significantly reduced interbacterial and intrabacterial killing. Strain deleted for icmF1 and icmF2 exhibited decreased transcriptional expression of type-1 fimbriae and reduced adherence to and invasion of human colorectal epithelial cells and was attenuated for in vivo competition to enable colonization of the host gut. Finally, Hcp expression in K pneumoniae was silenced by the histone-like nucleoid structuring protein via direct binding. Conclusions These results provide new insights into T6SS-mediated bacterial competition and attachment in K pneumoniae and could facilitate the prevention of K pneumoniae infection.

Original languageEnglish
Pages (from-to)637-647
Number of pages11
JournalJournal of Infectious Diseases
Volume219
Issue number4
DOIs
StatePublished - 29 01 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© The Author(s) 2018. Published by Oxford University Press for the Infectious Diseases Society of America.

Keywords

  • H-NS protein
  • Klebsiella pneumoniae
  • intestinal colonization
  • type VI secretion system (T6SS)
  • type-1 fimbriae

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