Melioidosis: A Diagnostic Dilemma

Abstract

Purpose: Melioidosis is a disease caused by the gram negative bacteria Burkholderia pseudomallei, which is distributed in soil and surface water in tropical regions of Southest Asia and Northern Australia. Findings in chronic melioidosis include cavitating, nodular or streaky infiltrates mimicking tuberculosis. The clinical features (chronic night sweats, weight loss, fatigue) and radiological findings in melioidosis (mediastinal lymphadenopathy) may mimic underlying malignancy. The gold standard for diagnosis of melioidosis is microscopy and culture. The role of cardiothoracic surgery is to provide tissue diagnosis through mediastinal biopsy, to rule out malignancy, and to therapeutically drain abscesses. Methodology: A retrospective study was performed at the Townsville Hospital of patients treated within the last 5 years who underwent drainage of abscess and/or mediastinal biopsy and subsequent diagnosis of melioidosis by culture. Results: Five patients were diagnosed with melioidosis following thoracic surgery and mediastinal biopsy. Four of these patients were to rule out malignancy and the fifth to rule out tuberculosis. All five patients had diabetes. Four out of five were male and three out of 5 patients were Indigenous. Three patients had thoracotomies, one had VATS and one mediastinoscopy. All five patients have subsequently undergone full treatment for melioidosis with 3 to 6 months of ceftazidime, meropenum or bactrim. Conclusion: Melioidosis often presents with lymphadenopathy, and may mimic both tuberculosis and malignancy. Mortality in the setting of systemic disease is very high. Prompt diagnosis via surgical biopsy and treatment through drainage of abscess is crucial for successful management.