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Background Melioidosis in an infection caused by Burkholderia pseudomallei, an organism endemic to tropical and subtropical regions. Methods This study describes the epidemiology of melioidosis in Townsville, QLD, Australia, as well as clinical features, risk factors associated with the disease, the burden of infection on the Aboriginal and Torres Strait Islander (ATSI) community and patient outcomes over time. Results From 1997 to 2020, 128 patients were admitted to Townsville University Hospital. The total annual incidence of infection was 3.2 cases per 100 000 compared with 15.3 per 100 000 in the ATSI population. The majority of cases (n=82 [64%]) were male. Alcohol excess (55%) and diabetes mellitus (48%) were the most common risk factors. Bacteraemia occurred in 87 (70%) patients and pneumonia was the most common focus of infection in 84 (69%). The case fatality rate was 23%, with no difference for the ATSI population (6/32 [19%]). The presence of malignancy was the risk factor most associated with mortality (relative risk 2.7 [95% confidence interval 1.4–5.1], p=0.005). Conclusions The ATSI community was overrepresented in this study, however, there was no significant difference in adverse outcomes. The case fatality rate was higher than in other regions in Australia. This discrepancy may relate in part to the different risk groups seen in these settings coupled with potential organism variability.

Melioidosis is an infection caused by the bacterium Burkholderia pseudomallei. The most common presentation is bacteremia occurring in 38–73% of all patients, and the mortality rate ranges from 9% to 42%. Although there is abundant data representing risk factors for infection and patient outcomes, there is limited information regarding laboratory investigations associated with bacteremia and mortality. We assessed a range of baseline and diagnostic investigations and their association with patient outcomes in a retrospective cohort study in Townsville, Australia. About 124 patients’ medical and laboratory records were reviewed between January 1, 1997 and December 31, 2020. Twenty-seven patients died and 87 patients were bacteremic. The presence of lymphopenia (< 1.5 × 109 cells/L) was the highest risk for bacteremia (relative risk [RR] 2.2; 95% CI: 1.3–3.7, P < 0.001). Factors associated with mortality included lymphopenia, (RR: 1.4; 95% CI: 1.2–1.6, P = 0.004); uremia (RR: 1.7; 95% CI: 1.1–2.5, P = 0.03); and an elevated international normalized ratio (RR: 1.5; 95% CI: 1.2–2.0, P = 0.006). Median incubation to positive blood culture result was 28 hours with 15/82 (18%) positive in ≤ 24 hours. For serological testing during admission only 53/121 (44%) were indirect hemagglutination assay positive, 67/120 (56%) enzyme immunoassay IgG positive, and 23/89 (26%) IgM positive. Simple baseline investigations at time of presentation may be used to stratify patients at high risk for both bacteremia and mortality. This information can be used as a decision aid for early intensive management.

Background: Townsville is in the dry tropics in Northern Australia and an endemic region for melioidosis. Melioidosis is an infectious disease caused by Burkholderia pseudomallei, a soil dwelling organism. The incidence of melioidosis is associated with high levels of rainfall and has been linked to multiple weather variables in other melioidosis endemic regions such as in Darwin. In contrast to Townsville, Darwin is in the wet-dry tropics in Northern Australia and receives 40% more rainfall. We assessed the relationship between melioidosis incidence and weather conditions in Townsville and compared the patterns to the findings in Darwin and other melioidosis endemic regions. Method: Performing a time series analysis from 1996 to 2020, we applied a negative binomial regression model to evaluate the link between the incidence of melioidosis in Townsville and various weather variables. Akaike's information criterion was used to assess the most parsimonious model with best predictive performance. Fourier terms and lagged deviance residuals were included to control long term seasonal trends and temporal autocorrelation. Results: Humidity is the strongest predictor for melioidosis incidence in Townsville. Furthermore, the incidence of melioidosis showed a three-times rise in the Townsville region when >200 mm of rain fell within the fortnight. Prolonged rainfall had more impact than a heavy downpour on the overall melioidosis incident rate. There was no statistically significant increase in incidence with cloud cover in the multivariable model. Conclusion: Consistent with other reports, melioidosis incidence can be attributed to humidity and rainfall in Townsville. In contrast to Darwin, there was no strong link between melioidosis cases and cloud cover and nor single large rainfall events.

Background: Melioidosis is an infection caused by Burkholderia pseudomallei. Bacteraemia is the most common presentation occurring in 38-73% of patients, with a mortality rate up to 42%. There is limited published data regarding laboratory investigations associated with bacteraemia or mortality. This study assessed standard laboratory investigations and their association with patient outcomes. Methods: Retrospective cohort study in Townsville, Australia. Medical and laboratory records of 124 patients were reviewed from 1 January 1997 -31 December 2020. Results: 87 (70%) patients were bacteraemic and 27 (22%) died. Lymphopenia on admission (<1.5×10 9 cells/L) was the highest risk for bacteraemia [relative risk (RR) 2.2; 95% CI 1.3-3.7, p<0.001). Mortality was associated with lymphopenia, (RR 1.4; 95% CI 1.2-1.6, p= 0.004); uraemia (RR 1.7; 95% CI 1.1 -2.5, p=0.03); and an elevated international normalised ratio (INR) (RR 1.5; 95% CI 1.2-2.0, p=0.006). External validation of the Darwin predictive mortality scoring system demonstrated 85% sensitivity. Conclusion: Simple baseline investigations at time of presentation may be used to stratify patients at high risk for both bacteraemia and mortality. Clinicians may use this information as a decision tool for early intensive management.