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Burkholderia pseudomallei virulence: definition, stability and association with clonality

G C Ulett1, B J Currie, T W Clair

  • 1Department of Microbiology and Immunology, James Cook University, 4814, Townsville, Queensland, Australia. glen.ulett@jcu.edu.au

Microbes and Infection
|July 11, 2001
PubMed

Insights

The virulence of Burkholderia pseudomallei, the cause of melioidosis, varies significantly between isolates. Factors like iron availability influence virulence, impacting disease severity in mice and potentially humans.

Area of Science:

  • Microbiology
  • Pathogenesis
  • Infectious Diseases

Background:

  • Melioidosis, caused by Burkholderia pseudomallei, presents with diverse clinical manifestations.
  • The underlying mechanisms driving these varied disease forms are not well understood.
  • Bacterial virulence is a key factor in melioidosis pathogenesis, particularly in murine models.

Purpose of the Study:

  • To assess the virulence of a collection of clinical and environmental Burkholderia pseudomallei isolates in susceptible BALB/c mice.
  • To investigate the stability of bacterial virulence through in vivo and in vitro manipulations.
  • To explore correlations between isolate characteristics, virulence, and clinical presentation.

Main Methods:

  • Determined the lethal dose 50 (LD50) for 42 non-arabinose-assimilating (ara(-)) Burkholderia pseudomallei isolates.
  • Investigated virulence stability via serial in vivo passage in mice and repetitive in vitro subculture.
  • Utilized pulsed-field gel electrophoresis and randomly amplified polymorphic DNA typing to assess isolate relatedness.

Main Results:

  • Significant variation in LD50 values (10 to >10^6 CFU) was observed among ara(-) isolates.
  • Virulence did not consistently correlate with isolate origin (clinical vs. environmental) or arabinose assimilation.
  • In vitro subculture on iron-rich media attenuated virulence, linked to colony morphology changes, while in vivo passage showed minimal impact on virulence stability.

Conclusions:

  • Burkholderia pseudomallei isolate virulence is variable and influenced by environmental factors like iron bioavailability.
  • Despite observed virulence changes, no consistent molecular alterations were detected in isolates.
  • Inoculum size and host risk factors remain critical in determining melioidosis clinical severity.

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