Melioidosis

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.

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.

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.

The Burkholderia genus is a highly diverse group of species that are distributed throughout a wide range of environments and habitats. Among this group, which is remarkable for its adaptability to a wider range of environmental conditions including disinfectants and organic solvents, are a subgroup that represents some of the most difficult to treat infections. This subgroup includes Burkholderia pseudomallei, the causative agent of melioidosis; B. mallei, the causative agent of glanders and B. cepacia complex (Bcc) which causes opportunistic infections in people with cystic fibrosis and immunocompromised patients.