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a | Typical colony morphology of B. pseudomallei on Ashdown's agar after incubation at 37°C in air for 3 days. b,c | Colony variation is commonly seen during culture of clinical isolates on Ashdown's agar. (c) shows the variable colony morphology that can be seen from a single sample; genotyping of these colonies showed that one clonal type was present. Colony variation can also be seen within a single colony, as shown in (b) in which the parental colony (pink) has given rise to a second morphotype. 
Pictures courtesy of Mrs Vanaporn Wuthiekanun and Mrs Narisara Chantratita, Wellcome Trust, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.

cutaneous melioidosis 
probably B. thailandensis 



photo Erasmus MMIZ

Burkholderia pseudomallei

  • General information

    • the following information is not yet verified
      Several Burkholderia species have been isolated from human clinical samples, but only Burkholderia cepacia complex, B. gladiola, B. mallei, B. pseudomallei are generally recognized as human pathogens.

      Taxonomy
      Family: Burkholderiaceae

      Natural habitat
      They are found in soil and surface water primarily in tropical and subtropical areas.
      They have been isolated in the rice-growing regions of northeast Thailand, western Cambodia, Laos, and southern and central Vietnam. Also in northern Australia, Madagascar and Mauritius.

      They can survive deep in the ground and to be rinsed during the rainy season to the surface.

      Transmission
      There is no person to person transmission

      B. pseudomallei is acquired from the environment by inoculation through cut or abraded skin, inhalation, or ingestion.

      Clinical significance
      B. pseudomallei is the causative agent of the human and animal disease melioidosis.

      Melioidosis
      is an especially important potential travel related illness for those with CF, and persistent colonization of airways with B. pseudomallei can occur in CF despite prolonged therapy.

      Infection with this organism should be considered in the differential diagnosis of any individual with a fever of unknown origin or a tuberculosis-like illness who has a history of travel to a region where B. pseudomallei infection is endemic.

  • Gram stain

    • the following information is not yet verified
      Small Gram negative rods,

      0.3 to 1-3 µm,

      with bipolar staining, making the cells resemble safety pins.

  • Culture characteristics

    • the following information is not yet verified

      Obligate aerobic

      Colonies are typically small, smooth, and gray to pale yellow or creamy in the first 48 hours.
      On further incubation, this appearance changes to give dry, wrinkled colonies.
      (like Pseudomonas stutzeri)

      Colony variation occurs in the same culture.

      McConkey growth
      Colorless or pink colonies

      Colony variation occurs in the same culture

      BBAØ no growth

      Asdown’s agar (selective agar)
      B. pseudomallei colonies on this agar showing the characteristic cornflower head morphology

      Smell
      musty or earthy odor (don’t sniff on open plates)

  • Characteristics

  • References


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