A retrospective study was performed on culture-positive patients (n = 57) with melioidosis presenting to the Townsville Hospital to define the epidemiology of the disease in Queensland, Australia. Mortality was 25% (n = 14) with a 9% (n = 5) relapse rate. At presentation, primary organs involved included the lungs (58%; n = 33), genitourinary system (11%; n = 6), skin and soft tissue (9%; n = 5), bone and joints (4%; n = 2), central nervous system (4%; n = 2), mycotic aneurysm (2%; n = 1) and peritonitis (2%; n = 1). No focus of infection could be identified in 12% of cases (n = 7). There was no significant difference in the clinical presentation of melioidosis in Queensland compared with the Northern Territory. Regional trends in the clinical presentation of melioidosis in Australia compared with Southeast Asia were confirmed. Risk factors for disease included diabetes (42%), excess alcohol consumption (42%), chronic lung disease (26%), immunosuppressive drug use (12%), renal disease (11%), malignancy (7%) and autoimmune disease (5%). No risk factors were identifiable in 18% of cases. The presence of multiple risk factors for melioidosis was not significantly associated with increased mortality (P > 0.05).

Cancer immunotherapy with checkpoint blockade has become standard of care treatment for numerous cancer types. Despite this, robust predictive biomarkers are lacking. There is increasing evidence that the host microbiome is a predictor of immunotherapy response, although the optimal host microbiome has not been defined. Metabolomics is a new area of medicine that aims to analyze the metabolic profile of a biological system. The microbiome-derived metabolome (fecal and serum) represents the end products of microbial metabolism and these may be functionally more important than the distinct bacterial species that comprise a favorable microbiome. Short-chain fatty acids (SCFA) are metabolites produced by gut microbiota and have a role in T cell homeostasis, including differentiation of regulatory T cells. Recent studies have confirmed differential expression of SCFA for immunotherapy responders compared with non-responders. We propose that the microbiome metabolome, with a focus on SCFA may be a novel predictive biomarker for immunotherapy efficacy.

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