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.