What infection does Pseudomonas pseudomallei cause? How would it manifest clinically? Discuss its epidemiology, laboratory diagnosis and management.

Outline:
•	Prevalence: Southeast Asia
•	Disease: melioidosis

Suggested Answer:

	Pseudomonas pseudomallii (now under the Burkholderia spp.) is an oxidase-positive Gram-negative non-fermenter that produces dry, wrinkled colonies on blood agar for several days. It is found in soil and stagnant water and is the cause of melioidosis, a potentially fatal granulomatous disease that principally affects the lungs and soft tissues.

	Melioidosis or Whitmore’s disease is endemic in Southeast Asia and Northern Australia. It is transmitted to humans through contact with the bacteria by contaminated soil or dust. It most commonly involves the lungs where the infection can form a cavity of pus. The bacteria can also spread from the skin through the bloodstream to the brain, eyes, heart, liver, kidneys and joints. The common symptoms of melioidosis are not specific. They include headaches, fever, chills, cough, chest pain, and loss of appetite. Meliodosis can also cause encephalitis with seizures.

	The diagnosis is by a microscopic evaluation of a sputum sample in the laboratory. A blood test may detect early acute cases of melioidosis. The treatment of meliodosis involves antibiotics and depends on the location of the disease. The organism is usually susceptible to ceftazidime, co-trimoxadole, doxycycline and chloramphenicol. Intravenous chloramphenicol is used in severe illness with persistent blood infection. If sputum cultures remain positive for 6 months, surgical removal of lung abscesses with lobectomy is considered. Melioidosis can remain latent for years and emerge when a person’s resistance is lowered.