Melioidosis is a bacterial infection caused by Burkholderia pseudomallei, a gram-negative saprophytic bacillus. Melioidosis is a potentially fatal infectious disease caused by the environmental anaerobic Gram-negative bacillus Burkholderia pseudomallei. Melioidosis is endemic to areas of northern Australia and Southeast Asia. With increasing international travel and migration, imported cases of melioidosis are being reported regularly. Melioidosis is of public health importance in endemic areas, particularly in tropical and sub-tropical areas
Isolation of B. pseudomallei from clinical specimens has been improved with the use of selective media. However, even with positive cultures, identification of B. pseudomallei can be difficult in clinical microbiology laboratories, especially in non-endemic areas where clinical suspicion is low. Commercial identification systems may fail to distinguish between B. pseudomallei and closely related species such as Burkholderia thailandensis.
As melioidosis was not suspected initially, bacterial culture was not done but electron microscopy showed morphologically viable and dividing bacilli in the lesion. Moreover, the surgical wound became infected with B. pseudomallei several days post-surgery. After treatment with ceftazidime and trimethoprim/sulfamethoxazole, the wound infection cleared. We believe this could be a unique case of asymptomatic latentmelioidosis in the spleen. In endemic countries, chronic granulomas should be investigated for B. pseudomallei infection, and if available, ISH may be helpful for diagnosis.Melioidosis should be in the differential diagnosis of bone and joint infections in residents or returning travelers from the endemic area.
Melioidosis diagnosis is missed in many parts of the world due to the lack of awareness of this infection and limited laboratory training and diagnostic techniques. It also mimics other diseases such as tuberculosis. Delay in the diagnosis, or the initiation of appropriate and effective treatment against melioidosis, could worsen the outcome. Initial therapy with ceftazidime, or carbapenem with or without cotrimoxazole is recommended, followed by the oral eradicationtherapy (based on the antimicrobial susceptibility) with amoxicillin/clavulanic acid or cotrimoxazole. Surgical intervention remains important.
Melioidosis in travelers was acquired mostly in Thailand (46% of cases). The mean duration of stay in the endemic area was 36 days (range 7-330 days). Symptoms usually started at 23 days (range 1-360 days) after leaving the endemic area. The clinical presentation was varied, sepsis being the most common (34%) followed by pneumonia (29%) and abscess formation (25%). Melioidosis in travelers was less often associated with predisposing risk factors (37.5%), diabetes mellitus being the most common (21%), and had lower mortality (17%) than had the infection in autochthonous cases in Southeast Asia.