Background Patients with rheumatic heart disease (RHD) and congestive cardiac failure (CCF) are believed to have an increased risk of melioidosis and are thought to be more likely to die from the infection. This study was performed to confirm these findings in a region with a high incidence of all three conditions. Principal findings Between January 1998 and December 2021 there were 392 cases of melioidosis in Far North Queensland, tropical Australia; 200/392 (51.0%) identified as an Indigenous Australian, and 337/392 (86.0%) had a confirmed predisposing comorbidity that increased risk for the infection. Overall, 46/392 (11.7%) died before hospital discharge; the case fatality rate declining during the study period (p for trend = 0.001). There were only 3/392 (0.8%) with confirmed RHD, all of whom had at least one other risk factor for melioidosis; all 3 survived to hospital discharge. Among the 200 Indigenous Australians in the cohort, 2 had confirmed RHD; not statistically greater than the prevalence of RHD in the local general Indigenous population (1.0% versus 1.2%, p = 1.0). RHD was present in only 1/193 (0.5%) cases of melioidosis diagnosed after October 2016, a period which coincided with prospective data collection. There were 26/392 (6.6%) with confirmed CCF, but all 26 had another traditional risk factor for melioidosis. Patients with CCF were more likely to also have chronic lung disease (OR (95% CI: 4.46 (1.93–10.31), p<0.001) and chronic kidney disease (odds ratio (OR) (95% confidence interval (CI): 2.98 (1.22–7.29), p = 0.01) than those who did not have CCF. Two patients with melioidosis and CCF died before hospital discharge; both were elderly (aged 81 and 91 years) and had significant comorbidity. Conclusions In this region of tropical Australia RHD and CCF do not appear to be independent risk factors for melioidosis and have limited prognostic utility.

Melioidosis is the clinical disease caused by the Gram‐negative bacillus Burkholderia pseudomallei and is endemic to Northern Australia and Southeast Asia. It is commonly referred to as the ‘great mimicker’ because of its wide range of clinical presentations, often making diagnosis challenging. Isolated mediastinal lymphadenopathy as the presenting feature of melioidosis is rare and can be indistinguishable from tuberculosis or malignancy. Endobronchial ultrasound (EBUS) is the preferred technique for evaluating undifferentiated mediastinal lymphadenopathy but its role in the diagnosis of mediastinal melioidosis remains sparsely reported in the literature. In this case series, we present four cases of mediastinal melioidosis, and the role that EBUS guided fine needle aspiration (FNA) played in the diagnosis and management.