• Clinical science

Melioidosis (Burkholderia pseudomallei infection)

Abstract

Melioidosis, also known as Whitmore disease, is an infectious disease caused by the bacterium Burkholderia pseudomallei. It is predominantly seen in tropical climates in Southeast Asia and Northern Australia, where it is transmitted via contact with contaminated water or soil. The clinical course of Melioidosis can vary greatly, ranging from asymptomatic disease to acute or chronic infection. In some cases, there is a latency period after initial infection, followed by reactivation. Symptomatic disease manifests with localized symptoms, pulmonary symptoms, or disseminated systemic symptoms. Antimicrobial therapy is the mainstay of treatment; in severe cases, adjunct therapy is also required. There are no vaccinations available against B. pseudomallei; prevention involves avoiding potentially contaminated sources, wearing protective gear in environments where there is a risk of contracting the pathogen, and observing general contact measures when interacting with infected patients (e.g., gloves, gowns).

Epidemiology

  • Distribution: occurs in tropical climates, mainly in Southeast Asia (e.g., Thailand, Malaysia) and Northern Australia
  • Incidence: ∼ 150,000 case/year worldwide, with most cases occurring in wet seasons

Epidemiological data refers to the US, unless otherwise specified.

Etiology

  • Pathogen: Burkholderia pseudomallei (a facultative intracellular gram-negative bacterium)
  • Transmission
    • Percutaneous inoculation: contact with contaminated soil or water (most common)
    • Inhalation, aspiration, or ingestion of contaminated dust or water
    • Person-to-person transmission is rare

Clinical features

  • Incubation period: 1–21 days (mean ∼ 9 days)
  • Most cases are subclinical or asymptomatic.
  • Symptomatic cases can be acute, chronic (> 2 months), or reactivations of latent infection.
  • Clinical features depend on the infected organ:

Diagnostics

  • Laboratory testing
    • Culture: mainstay of diagnosis
    • Gram stain of sputum or abscess pus
    • Serological testing: not a reliable method of diagnosis; low availability
  • Imaging
    • Chest radiography: may show signs of acute pneumonia
    • CT and MRI imaging: to identify abscess formation in multiple organs

Differential diagnoses

The differential diagnoses listed here are not exhaustive.

Treatment

Prevention

  • In endemic areas, contact with soil and standing water should be avoided (e.g., agricultural workers should wear boots).
  • Health care and laboratory workers should wear masks, gloves, and gowns to prevent infection.
  • No vaccination available