Melioidosis

Melioidosis is the name used to describe any infection of humans and a wide range of other animals caused by the saprophytic environmental bacterium Burkholderia pseudomallei. The disease is increasingly recognized as an important indigenous infection in many tropical and sub-tropical regions, but is probably greatly under-diagnosed. This increasing recognition, including travel-associated cases, along with its potential as a biological weapon, has seen a surge of interest in the disease in recent years. Diagnosis usually requires isolation of the causative organism from clinical samples: available serology and molecular diagnostic tools lack sensitivity and specificity. Clinical manifestations are highly variable, but melioidosis is most frequently associated with community-acquired sepsis and pneumonia, with abscess formation, especially in lungs, liver, spleen, prostate and parotid, being common. It is an opportunist pathogen, particularly strongly associated with diabetes mellitus, chronic renal and lung disease, but not HIV infection, although up to 20% of cases may have no known underlying predisposition. The diagnosis should be considered in anyone with compatible symptoms, particularly those with a predisposing condition, who has ever visited an endemic area because of the potential for long periods of latency. Treatment requires long courses of antibiotics, initially an intensive parenteral phase with either ceftazidime or a carbapenem, followed by an oral eradication phase with cotrimoxazole or coamoxiclav, although both relapses and reinfection may occur. There is currently no available vaccine, so prevention depends on minimizing contact with environmental organisms: fortunately person-to-person spread is very rare.