There are about thirty known Burkholderia species. They are saprophytes.
Burkholderia pseudomallei (B. pseudomallei), Burkholderia mallei (B. mallei) and Burkholderia cepacian (B. cepacian) are the important human and animal pathogens.
Burkholderia pseudomallei causes melioidosis (pneumoenteritis) in human and animals.
It is a life-threatening infection. Mainly this disease can be seen in Malaysia, Vietnam, Thailand, Myanmar, Guam, Sri Lanka, northern Australia, and the Philippines.
This disease can be seen in rice-growing areas, especially in wet season.
In endemic areas Burkholderia pseudomallei found in soil and water. Mainly in still water containing paddy fields.
During rainy season isolation rates are high. Mainly transmission happens via the soil contaminated organisms.
They enter to the body through open wounds and skin aberrations.
They can also be entered to the body by inhalation.
B. pseudomallei is known as a highly infectious pathogen belong to hazard category 3. In acute disease high fever and bloody purulent sputum can be seen.
If untreated it may turn into sepsis and death. In chronic disease pneumonia or lung abscess can be seen and it resemble tuberculosis.
According to the site of infection sample collection can be done for culture. In pulmonary disease sputum can be cultured.
In systemic disease blood is collected for culture. Moreover, pus can be collected from abscesses.
Microscopy
It is a small motile organism. B. pseudomallei is a Gram-negative bacillus which show bipolar staining.
When stained with methylene blue or Giemsa stain bipolar staining can be seen well. They appear as safety pins.
Culture
B.pseudomallei is an aerobic organism. It grows at 35 ºC – 37 ºC. It also grows at 42ºC
Blood agar
Produce small, nonhemolytic, dry, ringed and striated colonies after overnight incubation.
Characteristic earthy odour and metallic appearance can be seen.  After several days’ colonies become wrinkled.
MacConkey agar
They grow on MacConkey agar and produce acid by oxidation. Produce corrugated and rough colonies.
In cultures B. pseudomallei produce orange-brown pigment. However, the organism does not produce pyocyanin or fluorescein. The cultures produce a characteristic ammoniacal smell (earthy odour).
On broth cultures pellicle formation can be seen.
Ashdown’s agar
Produce characteristic cornflower head morphology colonies. This medium is useful for selective identification of B. pseudomallei
Biochemical Identification
Oxidase positive
Produce acid by the oxidation of glucose, lactose, maltose and mannitol
They can grow at 42ºC.
Serological confirmation can be done ate reference laboratories. Moreover, gas liquid chromatography and 16S rDNA sequencing are used for the formal identification. (ELISA) Enzyme-linked immunosorbent assays is used for the diagnosis specific antibodies in the evaluation of pyrexia of unknown origin.
Treatment
For the successful management of the disease early and accurate identification is necessary. Intra venous ceftazidime or meropenem are used for the treatment.
Oral co- trimoxazole or Amoxicillin clavulanic acid (Co- amoxiclav) are useful for the treatment. To avoid relapse prolonged treatment is necessary.
Prevention
No vaccine is available to prevent this organism.
However, persons with open skin wounds, diabetes or chronic renal failures should avoid contact with soil and still water.
When performing agricultural works, it is necessary to use boots to prevent infection through feet and lower leg.
Taking care when treating patients with the disease and following standard precautions when handling samples and patients, can prevent unnecessary infections.
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