The Applicability of Commonly Used Severity of Illness Scores to Tropical Infections in Australia

The Epidemiological, Clinical, and Microbiological Features of Patients with Burkholderia pseudomallei Bacteraemia-Implications for Clinical Management

Patients with melioidosis are commonly bacteraemic. However, the epidemiological characteristics, the microbiological findings, and the clinical associations of Burkholderia pseudomallei bacteraemia are incompletely defined. All cases of culture-confirmed melioidosis at Cairns Hospital in tropical Australia between January 1998 and June 2023 were reviewed. The presence of bacteraemia was determined and correlated with patient characteristics and outcomes; 332/477 (70%) individuals in the cohort were bacteraemic. In multivariable analysis, immunosuppression (odds ratio (OR) (95% confidence interval (CI)): (2.76 (1.21-6.27), p = 0.02), a wet season presentation (2.27 (1.44-3.59), p < 0.0001) and male sex (1.69 (1.08-2.63), p = 0.02), increased the likelihood of bacteraemia. Patients with a skin or soft tissue infection (0.32 (0.19-0.57), p < 0.0001) or without predisposing factors for melioidosis (0.53 (0.30-0.93), p = 0.03) were less likely to be bacteraemic. Bacteraemia was associated with intensive care unit admission (OR (95%CI): 4.27 (2.35-7.76), p < 0.0001), and death (2.12 (1.04-4.33), p = 0.04). The median (interquartile range) time to blood culture positivity was 31 (26-39) hours. Patients with positive blood cultures within 24 h were more likely to die than patients whose blood culture flagged positive after this time (OR (95%CI): 11.05 (3.96-30.83), p < 0.0001). Bacteraemia portends a worse outcome in patients with melioidosis. Its presence or absence might be used to help predict outcomes in cases of melioidosis and to inform optimal clinical management.

The Incidence of Infection Complicating Snakebites in Tropical Australia: Implications for Clinical Management and Antimicrobial Prophylaxis

Objective

To define the incidence of infection following snakebite in tropical Australia and the resulting implications for the routine prescription of prophylactic antibiotics.

Methods

A retrospective study of all individuals presenting to Cairns Hospital, a tertiary referral hospital in tropical Australia, after a snakebite between December 2013 and October 2020.

Results

There were 732 hospitalisations, 720 (98.4%) patients presented within 8 hours of the snakebite, and 29/732 (4.0%) were envenomated. Envenomated patients were more likely to receive empirical antibiotics than nonenvenomated patients (8/29 (27.6%) versus 14/703 (2.0%), p < 0.001), although this was frequently as a bundle of care for critically ill individuals. Superficial skin infection was diagnosed by clinicians in 6/732 (0.8%) patients during their hospitalisation; infection was diagnosed more commonly in envenomated than in nonenvenomated patients (3/29 (10.3%) versus 3/703 (0.4%), p = 0.001). All 3 envenomated individuals diagnosed with infection were believed to have taipan (genus Oxyuranus) bites. Five (83%) of the six patients diagnosed with infection had received empirical antibiotics at presentation; only 1/710 (0.1%) patients who received no antibiotics developed a (superficial) infection.

Conclusion

Infection is a very uncommon complication of snakebite in tropical Australia. Individuals bitten by snakes in tropical Australia should not routinely receive antibiotic prophylaxis.

Interpretations of the Role of Plasma Albumin in Prognostic Indices: A Literature Review

This review assesses how publications interpret factors that influence the serum or plasma albumin (PA) level in prognostic indices, focusing on inflammation and nutrition. On PubMed, a search for "albumin AND prognosis" yielded 23,919 results. From these records, prognostic indices were retrieved, and their names were used as search strings on PubMed. Indices found in 10 or more original research articles were included. The same search strings, restricted to "Review" or "Systematic review", retrieved yielded on the indices. The data comprised the 10 latest original research articles and up to 10 of the latest reviews. Thirty indices had 294 original research articles (6 covering two indices) and 131 reviews, most of which were from recent years. A total of 106 articles related the PA level to inflammation, and 136 related the PA level to nutrition. For the reviews, the equivalent numbers were 54 and 65. In conclusion, more publications mention the PA level as a marker of nutrition rather than inflammation. This is in contrast to several general reviews on albumin and nutritional guidelines, which state that the PA level is a marker of inflammation but not nutrition. Hypoalbuminemia should prompt clinicians to focus on the inflammatory aspects in their patients.

The aetiology and clinical characteristics of cryptococcal infections in Far North Queensland, tropical Australia

Cryptococcal infections are an important cause of morbidity and mortality in tropical Australia. This retrospective audit was conducted to characterise the aetiology, temporospatial epidemiology, and clinical course of 49 cryptococcal infections in Far North Queensland between 1 January 1999 and 31 December 2019. Cryptococcus gattii was identified in 15/32 (47%) in whom it was possible to speciate the organism. Among these 15 patients, 13 (87%) had a rural residential address, 10 (67%) were Indigenous Australians and 11 (73%) presented during the May-November dry season. When compared to the 17 patients with Cryptococcus neoformans infection, patients with C. gattii were less likely to be immunocompromised (0/15 versus 8/17 (47%), p = 0.003). Neurosurgery was necessary in 5/15 C. gattii cases and 3/17 (18%) C. neoformans cases (p = 0.42). Outcomes were generally good with 42/49 (86%) cases—and 14/15 (93%) with C. gattii infection—surviving to hospital discharge. These positive outcomes are likely to be explained by the development of standardised treatment guidelines during the study period, low rates of comorbidity in the patients with C. gattii infection and access to liposomal amphotericin and neurosurgical support in the well-resourced Australian healthcare system.

The seasonality of infections in tropical Far North Queensland, Australia: A 21-year retrospective evaluation of the seasonal patterns of six endemic pathogens

An understanding of the seasonality of infections informs public health strategies and assists clinicians in their management of patients with undifferentiated illness. The seasonality of infections is driven by a variety of environmental and human factors; however, the role of individual climatic factors has garnered much attention. This study utilises Poisson regression models to assess the seasonality of six important infections in tropical Australia and their association with climatic factors and severe weather events over a 21-year period. Melioidosis and leptospirosis showed marked wet season predominance, while more cases of rickettsial disease and cryptococcosis were seen in cooler, drier months. Staphylococcus aureus infections were not seasonal, while influenza demonstrated inter-seasonality. The climate did not significantly change during the 21 years of the study period, but the incidence of melioidosis and rickettsial disease increased considerably, highlighting the primacy of other factors-including societal inequality, and the impact of urban expansion-in the incidence of these infections. While anthropogenic climate change poses a threat to the region-and may influence the burden of these infections in the future-this study highlights the fact that, even for seasonal diseases, other factors presently have a greater effect on disease incidence. Public health strategies must also target these broader drivers of infection if they are to be effective.