MICROBIOLOGY

• Aerobic Gram-negative rod.
  • B. pseudomallei, member of Burkholderia genus.
  • Two other members, B. thailandensis (SE Asia, Australia), B. oklahomensis (Midwest U.S.), seen in environmental samples, unclear if a cause of disease.
• Cause of melioidosis, most commonly seen in tropical climates of southeast Asia and northern Australia but described elsewhere including South and Central America, Africa.
  • Regions of greatest prevalence: Northern Territory of Australia, northeast Thailand.
• Commonly found in surface waters and muddy soils but the mechanism of transmission remains unclear.
  • Described as colonizing rhizospheres and plant structures.
• Human cases increase significantly during times of heavy rainfall.
  • Regular contact with soil and water are risk factors.
    • Increased risk with diabetes, COPD, alcoholism, chronic renal disease, thalassemia, malignancy, immunosuppression.
  • Acquired by inhalation, traumatic inoculation or ingestion.
  • Transmission to infants through breastfeeding described in mothers suffering from mastitis.
• Culturing methods in laboratories:
  • Ashdown’s media favored for non-sterile specimens such as respiratory.
  • B. cepacia-selective media an alternative