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Piecing together the puzzle: current knowledge and open questions about the Klebsiella pneumoniae type VI secretion

Leticia Miranda Santos Lery1, Paulo Ricardo Batista2

  • 1Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Microbiologia Celular, Rio de Janeiro, RJ, Brasil.

Memorias Do Instituto Oswaldo Cruz
|July 22, 2026
PubMed

Insights

Klebsiella pneumoniae infections are a major threat due to multidrug resistance (MDR). The type VI secretion system (T6SS) in K. pneumoniae is crucial for its virulence and competitiveness, requiring further study for therapeutic development.

Area of Science:

  • Microbiology
  • Genomics
  • Molecular Biology

Background:

  • Klebsiella pneumoniae (Kp) poses a significant global health threat due to multidrug-resistant (MDR) infections.
  • The co-occurrence of hypervirulence and MDR in Kp exacerbates this public health crisis.
  • K. pneumoniae exhibits substantial genomic diversity, influencing its resistance and virulence capabilities.

Purpose of the Study:

  • To provide a comprehensive review of the Klebsiella pneumoniae type VI secretion system (Kp-T6SS).
  • To explore the mechanisms, regulation, and effector functions of the Kp-T6SS.
  • To highlight the clinical relevance and genomic surveillance of Kp-T6SS.

Main Methods:

  • Chronological review of published literature on Kp-T6SS.
  • Analysis of genomic data for T6SS presence and variability.
  • Characterization of Kp-T6SS effector proteins (e.g., Tle1, Pld1, VgrG4).

Main Results:

  • The type VI secretion system (T6SS) is present in most Kp genomes and is vital for pathogenesis and interbacterial competition.
  • Various effector proteins, including Tle1, Pld1, and VgrG4, are associated with Kp-T6SS function.
  • Kp-T6SS is found on mobile genetic elements and in clinical isolates, underscoring its epidemiological importance.

Conclusions:

  • Understanding Kp-T6SS mechanisms and effectors is critical for developing novel therapeutic strategies against MDR Kp.
  • Genomic vigilance and routine detection of Kp-T6SS in high-risk clinical settings are essential.
  • Further research is needed to fully elucidate Kp-T6SS regulation and its role in virulence.

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