Proteus species bloodstream infections: Comparative epidemiology of three species.

BACKGROUND: Although Proteus species are occasional causes of serious infections, their epidemiology has not been well defined. The objective was to describe the overall and species-specific occurrence and determinants of Proteus species bloodstream infection (BSI) in a large Australian population. METHODS: All Queensland residents with Proteus species BSI identified within the publicly funded healthcare system between 2000 and 2019 were included. RESULTS: A total of 2,143 incident episodes of Proteus species BSI were identified among 2,079 Queensland residents. The prevalence of comorbid illness differed with higher Charlson comorbidity scores observed with P. penneri and P. vulgaris, and higher prevalence of liver disease with P. penneri, higher comorbid cancer with P. vulgaris, and lower diabetes and renal disease prevalence with P. mirabilis BSIs. CONCLUSION: This study provides novel information on the epidemiology of Proteus species BSI.

Pseudomonas stutzeri bloodstream infection is a prevailing community-onset disease with important mortality rates: results from a retrospective observational study in Australia.

BACKGROUND: The recognition of Pseudomonas stutzeri as a cause of infections in humans has been increasing. However, only case reports and small series of P. stutzeri bloodstream infections have been published. Epidemiological data on these infections are extremely scarce. Our objective was to describe the incidence, epidemiology, antimicrobial resistance rates, and outcomes of P. stutzeri bloodstream infections in a large population-based cohort in Australia. METHODS: Retrospective, laboratory-based surveillance study conducted in Queensland, Australia (population ≈ 5 million) during 2000-2019. Clinical information was obtained from public hospital admissions and vital statistics databases. RESULTS: In total, 228 episodes of P. stutzeri bloodstream infections were identified. Increased incidence was observed in the later years, especially in older men, and was higher during the rainy months of the year and in the warmest and more humid regions of the state. The majority of bloodstream infections were community-onset with 120 (52.6%) community-associated and 59 (25.9%) ambulatory healthcare-associated episodes. Only 49 cases (21.5%) were nosocomial. The most common foci of infection were skin and soft tissue, lower respiratory tract, and intra-abdominal. No isolate showed antimicrobial resistance. Thirty-one patients (13.6%) died. The mortality rate in patients with a respiratory infectious source was higher (21%). CONCLUSIONS: P. stutzeri bloodstream infection was predominantly a community-onset condition including ambulatory healthcare related cases, with increasing incidence, especially in older males. No antimicrobial resistance was observed. Mortality was high in patients with respiratory infectious source. This new observational data have implications when considering the epidemiology of these infections and for patient management.

Time to positivity is a risk factor for death among patients with bloodstream infections: a population-based cohort.

OBJECTIVES: Studies examining time to positivity (TTP) of blood cultures as a risk factor for death have shown conflicting results. The study objective was to examine the effect of TTP on all-cause-30-day case-fatality among a population-based cohort of patients with bloodstream infections (BSI). METHODS: A retrospective cohort study including all residents of Queensland, Australia with incident monomicrobial BSI managed in the publicly funded healthcare system from 2000 to 2019 was performed. Clinical, TTP and all-cause 30-day case-fatality information was obtained from state-wide sources. RESULTS: A cohort of 88 314 patients was assembled. The median TTP was 14 hours, with 5th, 25th, 75th, and 95th percentiles of 4, 10, 20, and 53 hours, respectively. The TTP varied significantly by BSI aetiology. The 30-day all-cause case-fatality rate was 2606/17 879 (14.6%), 2834/24 272 (11.7%), 2378/20 359 (11.7%), and 2752/22 431 (12.3%) within the first, second, third, and fourth TTP quartiles, respectively (p < 0.0001). After adjustment for age, sex, onset, comorbidity, and focus of infection, TTP within 10 hours (first quartile) was associated with a significantly increased risk for death (odds ratio 1.43; 95% CI, 1.35-1.50; p < 0.001). After adjustment for confounding variables (odds ratio; 95% CI), TTP within the first quartile for Staphylococcus aureus (1.56; 1.41-1.73), Streptococcus pneumoniae (1.91; 1.49-2.46), ß-hemolytic streptococci (1.23; 1.00-1.50), Pseudomonas species (2.23; 1.85-2.69), Escherichia coli (1.37; 1.23-1.53), Enterobacterales (1.38; 1.16-1.63), other Gram-negatives (1.68; 1.36-2.06), and anaerobes (1.58; 1.28-1.94) increased the risk for case-fatality. DISCUSSION: This population-based analysis provides evidence that TTP is an important determinant of mortality among patients with BSI.

Mortality, hospital length of stay, and recurrent bloodstream infections associated with extended-spectrum beta-lactamase-producing Escherichia coli in a low prevalence region: A 20-year population-based large cohort study.

OBJECTIVES: This population-based study aimed to investigate the risk factors and effect of extended-spectrum beta-lactamase (ESBL) production on clinical outcomes in Escherichia coli bloodstream infection (BSI) patients. METHODS: The study population was defined as patients aged ≥15 years with E. coli BSI in Queensland, Australia, from 2000 to 2019. Outcomes were defined as 30-day case fatality, hospital length of stay (LOS), and recurrent E. coli BSI. RESULTS: A total of 27,796 E. coli BSIs were identified, of which 1112 (4.0%) were ESBL-producers. Patients with ESBL-Ec BSI were more frequently older, male, with comorbidity, recurrent E. coli BSI, and less likely with community-associated community-onset infections as compared to non-ESBL-Ec BSI patients. The standardized mortality rate of ESBL-Ec BSI increased 8-fold from 2000 to 2019 (1 to 8 per million residents) and case fatality was 12.8% (n = 142) at 30 days from positive blood culture. Patients with ESBL-Ec BSI were not at higher risk of 30-day case fatality (adjusted hazard ratio [HR] = 0.98, 95% CI: 0.83-1.17), but had higher risk of recurring episodes (adjusted subdistribution HR = 1.58, 95% CI: 1.29-1.92) and observed 14% longer LOS (adjusted incidence rate ratio = 1.14, 95% CI: 1.10-1.18) than non-ESBL-Ec BSI patients. CONCLUSION: In this large patient cohort, ESBL-Ec BSI did not increase case fatality risk but observed higher hospital LOS and recurrent E. coli BSI than non-ESBL-Ec BSI. Clinical resources are warranted to account for the higher morbidity risk associated with ESBL production and incidence.

Vibrio species bloodstream infections in Queensland, Australia.

BACKGROUND: Vibrio species bloodstream infections have been associated with significant mortality and morbidity. Limited information is available regarding the epidemiology of bloodstream infections because of Vibrio species in the Australian context. AIMS: The objective of this study was to define the incidence and risk factors for developing Vibrio species bloodstream infections and compare differences between different species. METHODS: All patients with Vibrio spp. isolated from positive blood cultures between 1 January 2000 and 31 December 2019 were identified by the state-wide Pathology Queensland laboratory. Demographics, clinical foci of infections and comorbid conditions were collected in addition to antimicrobial susceptibility results. RESULTS: About 100 cases were identified between 2000 and 2019 with an incidence of 1.2 cases/1 million person-years. Seasonal and geographical variation occurred with the highest incidence in the summer months and in the tropical north. Increasing age, male sex and multiple comorbidities were identified as risk factors. Vibrio vulnificus was isolated most frequently and associated with the most severe disease. Overall case fatality was 19%. CONCLUSIONS: There is potential for increasing cases of Vibrio species infections globally with ageing populations and climate change. Ongoing clinical awareness is required to ensure optimal patient outcomes.

Bloodstream infections in neutropenic and non-neutropenic patients with haematological malignancies: epidemiological trends and clinical outcomes in Queensland, Australia over the last 20 years.

Knowledge of the epidemiology of bloodstream infection (BSI) in haematology patients is essential to guide patient management. We investigated the epidemiology of BSI in patients with haematological malignancies in Queensland over the last 20 years (2000-2019), including all episodes diagnosed by the state-wide microbiology service. We identified 7749 BSI in 5159 patients, 58% associated with neutropenia. Gram-negatives were the main causative pathogens (58.3%), more frequent in neutropenic than non-neutropenic patients (3308/5309, 62.3% vs 1932/3678, 52.5%, p < 0.001). Amongst 8987 isolates the most common were E. coli (15.4%) and Pseudomonas spp. (14.2%). Pseudomonas spp. (16.6% vs 10.7%, p < 0.001), Klebsiella spp. (11.6% vs 6.8%, p < 0.001), viridans-group streptococci (4.4% vs 1.2%, p < 0.001) and E. faecium (2.4% vs 0.9%, p < 0.001) were more common in neutropenic than non-neutropenic patients, while S. aureus was less common (5.9% vs 15.6%, p < 0.001). Several antimicrobial resistance rates increased over time and had higher prevalence in neutropenic than non-neutropenic patients, including ciprofloxacin-resistant E. coli (94/758, 12.4% vs 42/506, 8.3%, p = 0.021), trimethoprim-sulfamethoxazole-resistant E. coli (366/764, 47.9% vs 191/517, 36.9%, p < 0.001), penicillin-resistant streptococci (51/236, 21.6% vs 28/260, 10.8%, p < 0.001) and vancomycin-resistant enterococci (46/250, 18.4% vs 9/144, 6.3%, p < 0.001). Carbapenem-resistant Pseudomonas spp. (OR 7.32, 95%CI 2.78-19.32) and fungi, including yeasts and moulds (OR 3.33, 95%CI 2.02-5.48) were associated to the highest odds of 30-day case-fatality at a multivariable logistic regression analysis. Neutropenia was associated with survival (OR 0.66, 95%CI 0.55-0.78). Differences were observed in the BSI epidemiology according to neutropenic status, with an overall increase of resistance over time associated to adverse outcome.

Scedosporium species and Lomentospora prolificans fungaemia is uniformly fatal in patients with haematological malignancy.

Scedosporium and Lomentospora species are environmental moulds that are virulent in immunocompromised hosts and rarely cause bloodstream infection (BSI). Patients with Scedosporium and Lomentospora species BSI were identified by the state public laboratory service in Queensland, Australia, over a 20-year period. Twenty-two incident episodes occurred among 21 residents; one patient had a second episode 321 days following the first. Of these, 18 were Lomentospora prolificans, three were Scedosporium apiospermum complex and one was a nonspeciated Scedosporium species. Seventeen (81%) patients died during their index admission, and all-cause mortality at 30, 90 and 365 days was 73%, 82% and 91% respectively. All 20 patients with haematological malignancy died within 365 days of follow-up with a median time to death of 9 days (interquartile range, 6-20 days) following diagnoses of BSI.

Global hotspots of traded phylogenetic and functional diversity.

Wildlife trade is a multibillion-dollar industry1 targeting a hyperdiversity of species2 and can contribute to major declines in abundance3. A key question is understanding the global hotspots of wildlife trade for phylogenetic (PD) and functional (FD) diversity, which underpin the conservation of evolutionary history4, ecological functions5 and ecosystem services benefiting humankind6. Using a global dataset of traded bird and mammal species, we identify that the highest levels of traded PD and FD are from tropical regions, where high numbers of evolutionary distinct and globally endangered species in trade occur. The standardized effect size (ses) of traded PD and FD also shows strong tropical epicentres, with additional hotspots of mammalian ses.PD in the eastern United States and ses.FD in Europe. Large-bodied, frugivorous and canopy-dwelling birds and large-bodied mammals are more likely to be traded whereas insectivorous birds and diurnally foraging mammals are less likely. Where trade drives localized extinctions3, our results suggest substantial losses of unique evolutionary lineages and functional traits, with possible cascading effects for communities and ecosystems5,7. Avoiding unsustainable exploitation and lost community integrity requires targeted conservation efforts, especially in hotspots of traded phylogenetic and functional diversity.

Bloodstream Infection and Colorectal Cancer Risk in Queensland Australia, 2000-2019.

BACKGROUND: Bloodstream infections may occur as a complication of colorectal cancer or be a marker for its occult presence. The objectives of this study were to quantify the overall and etiology-specific risks for incident colorectal cancer-associated bloodstream infection. METHODS: Population-based surveillance for community-onset bloodstream infection was conducted among adults aged 20 years and older in Queensland, Australia between 2000 and 2019. Statewide databases were used to identify patients with incident colorectal cancer and collect clinical and outcome information. RESULTS: After exclusion of 1794 patients with prior colorectal cancer, a cohort of 84,754 patients was assembled, of which 1030 had colorectal cancer-associated bloodstream infection and 83,724 had no colorectal cancer. Bloodstream infection was associated with a 16-fold annualized increased risk for diagnosis of colorectal cancer (incidence rate ratio 16.1; 95% confidence interval [CI], 15.1-17.1) in the adult population. Patients who had colorectal cancer-associated bloodstream infection were more likely to be older and male, have hospital-onset and polymicrobial infections, and have fewer non-cancer-related comorbidities. The organisms associated with highest risk for colorectal cancer included Clostridium species (relative risk [RR] 6.1; 95% CI, 4.7-7.9); especially C. septicum (RR 25.0; 95% CI, 16.9-35.7), Bacteroides species (RR 4.7; 95% CI, 3.8-5.8); especially B. ovatus (RR 11.8; 95% CI, 2.4-34.5), Gemella species (RR 6.5; 95% CI, 3.0-12.5), Streptococcus bovis group (RR 4.4; 95% CI, 2.7-6.8); especially S. infantarius subsp. coli (RR 10.6; 95% CI, 2.9-27.3), Streptococcus anginosus group (RR 1.9; 95% CI, 1.3-2.7), and Enterococcus species (RR 1.4; 95% CI, 1.1-1.8). CONCLUSION: Although much attention has been afforded to S. bovis group over the past decades, there are many other isolates associated with higher risk for colorectal cancer-associated bloodstream infections.

Caffeine consumption and withdrawal among patients in the intensive care unit.

BACKGROUND: There is a lack of data surrounding the use of therapeutic caffeine among adults admitted to intensive care units (ICUs). OBJECTIVES: The objective of this study was to determine reported caffeine use and withdrawal symptoms among patients admitted to the ICU to inform future prospective interventional trials. METHODS: This study used a cross-sectional survey design, where a survey was conducted by a registered dietitian among 100 adult patients admitted to an ICU in Brisbane, Australia. RESULTS: The median age of patients was 59.8 y (interquartile range: 44.0-70.0), and 68% were male. Ninety-nine percent of patients had daily consumption of caffeine with a median 338 mg (interquartile range: 162-504). Caffeine consumption was self-reported in 89% of patients and was uncovered by detailed identification in 10%. Almost one-third (29%) reported caffeine withdrawal symptoms while admitted to intensive care. Common withdrawal symptoms reported were headaches, irritability, fatigue, anxiety, and constipation. Eighty-eight percent of patients reported willingness to participate in future studies of therapeutic caffeine if they were admitted to the ICU. Preferred methods of parenteral and enteral routes of administration varied by patient and illness characteristics. CONCLUSIONS: Patients admitted to this ICU were ubiquitous consumers of caffeine before admission, and one-tenth were unaware. Patients viewed trials of therapeutic caffeine as highly acceptable. The results provide important baseline information for future prospective studies.

Population-Based Incidence and Characteristics of Adult Escherichia coli Bloodstream Infection in Queensland, Australia, From 2000 to 2019.

Background: There is increasing morbidity and mortality attributed to escalating incidence of Escherichia coli bloodstream infection (BSI). The epidemiology of E. coli BSI is dynamic and differs across populations. This study aimed to describe this epidemiology in Queensland, Australia. Methods: Incident E. coli BSIs (new or recurring ≥30 days from previous BSI) in adult (≥15 years) Queenslanders were identified from 2000 to 2019 using Queensland Health databases. Incidence rates, crude and standardized by age and gender, were calculated. Negative binomial regressions were performed to determine predictors of E. coli BSI incidence. Results: From 2000 to 2019, 30 350 E. coli BSIs in 27 793 patients were detected; the standardized incidence rate almost doubled from 34.1 to 65.9 cases per 100 000 residents. Predictors of higher incidence rate were older age (≥65 years), comorbidity, and community-onset infection. Despite holding these factors constant, the incidence rate was estimated to increase 4% (adjusted incidence rate ratio [IRR], 1.04; 95% CI, 1.03-1.04) annually over the study period. Approximately 4.2% of E. coli isolates produced extended-spectrum beta-lactamase (ESBL-Ec), with most (95%) detected after 2010. The incidence rate of ESBL-Ec increased 25% (IRR, 1.25%; 95% CI, 1.2-1.3) annually, significantly faster than that of non-producers. Amikacin and carbapenems remain effective in vitro against ESBL-Ec BSI in Queensland. Conclusions: The rise in E. coli BSIs is driven both by a higher infection rate and shifting epidemiology toward community-onset infections. These are likely attributed to an aging Australian population with increasing chronic comorbidity. The rapid expansion of ESBL-Ec in recent years is concerning and should be acknowledged for its implication in the community.

Significant clinical differences but not outcomes between Klebsiella aerogenes and Enterobacter cloacae bloodstream infections: a comparative cohort study.

PURPOSE: Although Klebsiella aerogenes (formerly Enterobacter aerogenes) and Enterobacter cloacae share many phenotypic characteristics, controversy exists as to whether they cause clinically distinguishable infections. The objective of this study was to determine the comparative incidence, determinants, and outcomes of K. aerogenes and E. cloacae bloodstream infections (BSI). METHODS: Population-based surveillance was conducted among residents aged ≥ 15 years of Queensland, Australia during 2000-2019. RESULTS: Overall 695 and 2879 incident K. aerogenes and E. cloacae BSIs were identified for incidence rates of 1.1 and 4.4 per 100,000 population, respectively. There was a marked increase in incidence associated with older age and with males with both species. Patients with K. aerogenes BSIs were older, were more likely male, to have community-associated disease, and to have a genitourinary source of infection. In contrast, E. cloacae were more likely to have co-morbid diagnoses of liver disease and malignancy and be associated with antimicrobial resistance. Enterobacter cloacae were significantly more likely to have repeat episodes of BSI as compared to K. aerogenes. However, no differences in length of stay or all cause 30-day case-fatality were observed. CONCLUSION: Although significant demographic and clinical differences exist between K. aerogenes and E. cloacae BSI, they share similar outcomes.

Evolving insights into the epidemiology of Moraxella species bloodstream infection from two decades of surveillance in Queensland, Australia.

The epidemiology of Moraxella species bloodstream infection (BSI) is poorly defined due to their rarity. We sought to determine the incidence, risk factors, and outcomes of Moraxella species BSI in a large Australian population. All Moraxella species BSIs in patients admitted to Queensland (population estimate 5 million) public health facilities between 2000 and 2019 and submitted to Queensland pathology laboratory-based surveillance were included. Clinical and hospitalisation data were matched with laboratory-based surveillance data. Incidence rate ratios (IRR) with 95% confidence intervals (CI) were calculated. In total, 375 incident Moraxella species BSI occurred during 86 million person-years of surveillance, with an annualised age and sex standardised incidence of 4.3 per million residents. Isolates were most commonly identified as M. catarrhalis (n = 128; 34%) and community-associated (n = 225; 60%). Incidence was highest in infants, with increasing age associated with lower incidence rate. Males were at higher risk (incidence 2.9 vs. 2.0 per million, IRR1.4; 95% CI, 1.2-1.8), this was most pronounced at age extremes. Two-thirds of adults and 43% of children with Moraxella BSI had at least one comorbid illness. When compared to infections in adults, children were more likely to have community-associated disease, and a head and neck source focus of infection. The all-cause 30-day case-fatality rate was 4% (15/375) and this was significantly higher among adults (14/191; 7% vs 1/183; 1%; p < 0.001). Our findings demonstrate the low burden of Moraxella species BSI in a state-wide cohort, for which young children have the highest risk.

Institution-free days after critical illness: A multicenter retrospective study.

BACKGROUND: Patient-centered outcomes beyond mortality such as institution-free days (IFD) are becoming increasingly relevant in critical care trials. METHODS: We calculated IFD using three definitions which differed in the way death and censoring of after-hospital deaths were handled analysing data from adult patient databases admitted to four ICUs of North Brisbane, Australia. Differences in distribution of IFD using different definitions were explored with descriptive statistics and histograms. Six pre-specified variables (age, illness severity, comorbidities index, elective status, surgical/medical admission and treatment limitations) were assessed and reported as determinants of IFDs for the proposed definitions. RESULTS: Data from 25,371 ICU admissions was analysed. The density distribution of IFD was bimodal with a peak at 0 days and a variable right-sided peak depending on the definition used. The mean IFD varied from 253 (standard deviation(SD) 151.3) to 295 (SD 116.2) depending on definition used. Multivariable zero-inflated negative binomial regression modelling showed that the six pre-specified variables had significant associations with IFD and their magnitude of effect varied with the definition used. CONCLUSIONS: IFD is a simple, easily measurable patient-centered outcome that varies depending on the definition used. Patient input should be sought to define the optimum definition and clinical use of IFD.

High sensitivity of tropical forest birds to deforestation at lower altitudes.

Habitat conversion is a major driver of tropical biodiversity loss, but its effects are poorly understood in montane environments. While community-level responses to habitat loss display strong elevational dependencies, it is unclear whether these arise via elevational turnover in community composition and interspecific differences in sensitivity or elevational variation in environmental conditions and proximity to thermal thresholds. Here we assess the relative importance of inter- and intraspecific variation across the elevational gradient by quantifying how 243 forest-dependent bird species vary in sensitivity to landscape-scale forest loss across a 3000-m elevational gradient in the Colombian Andes. We find that species that live at lower elevations are strongly affected by loss of forest in the nearby landscape, while those at higher elevations appear relatively unperturbed, an effect that is independent of phylogeny. Conversely, we find limited evidence of intraspecific elevational gradients in sensitivity, with populations displaying similar sensitivities to forest loss, regardless of where they exist in a species' elevational range. Gradients in biodiversity response to habitat loss thus appear to arise via interspecific gradients in sensitivity rather than proximity to climatically limiting conditions.

Excess burden of critical illness related to inflammatory bowel disease.

BACKGROUND: Although inflammatory bowel disease (IBD) is associated with major morbidity and mortality, few studies have evaluated its associated burden of critical illness. AIMS: To examine the epidemiology and outcome of intensive care unit (ICU) admission among patients with IBD in North Brisbane, Australia. METHODS: A population-based cohort design was used. All admissions to ICU serving the Metro North Hospital and Health Service among adult residents during 2017-2019 were included. Data were obtained from ICU clinical information systems with linkages to statewide admissions and death registries. RESULTS: Among 9011 ICU admissions, 101 (1.1%) were among patients with IBD, of which 57 (0.6%) and 44 (0.5%) had ulcerative colitis (UC) and Crohn disease (CD) respectively. The incidence of ICU admission was 379, 1336, 1514 and 1429 per 100 000 annually among those without IBD, CD, UC and IBD respectively. Patients with IBD were at excess risk for admission across all age groups, with women aged <50 years at highest risk and men thereafter. The all-cause 90-day case-fatality rates following ICU admission were not significantly different among patient groups and were 18%, 12%, 15% and 12% for CD, UC, IBD and non-IBD respectively. However, as compared with non-IBD patients, those with CD (151.8 vs 39.4 per 100 000; relative risk (RR) 3.85; 95% confidence interval (CI) 1.25-9.02; P = 0.013), UC (159.4 vs 39.4 per 100 000; RR 4.05; 95% CI 1.48-8.84; P = 0.005) and IBD (155.6 vs 39.4 per 100 000; RR 3.95; 95% CI 1.96-7.10; P = 0.002) were at significantly higher risk for mortality. CONCLUSIONS: Patients with IBD suffer a major burden of critical illness.

90-day Case-Fatality in Critically ill Patients with Chronic Liver Disease Influenced by Presence of Portal Hypertension, Results from a Multicentre Retrospective Cohort Study.

BACKGROUND: Critical illness in patients with chronic liver disease (CLD) is increasing in occurrence, and by virtue of its adverse effect on prognosis, its presence may influence the decision to offer admission to intensive care units (ICU). Our objective was to examine the determinants and outcome of patients with CLD admitted to ICU. METHODS: A retrospective cohort of patients admitted to four adult ICUs in Queensland, Australia from 2017 to 2019. Patients with mild or moderate-severe CLD were defined by the absence and presence of portal hypertension, respectively, and were was determined using granular ICU and state-wide administrative databases. The primary outcome was 90-day all cause case-fatality. RESULTS: We included 3836 patients in the analysis, of which, 60 (2%) had mild liver disease and 132 (3%) had moderate-severe liver disease . Patients with CLD had higher incidence of other co-morbidities with the median adjusted-Charlson co-morbidity index (CCI) was 1 (interquartile range; IQR 0-3) for no CLD, 2 (IQR 1.5-4) for mild CLD, and 3 (IQR 2-5) for moderate-severe CLD. Case-fatality rates at 90 days was 17% for no CLD, 25% for mild CLD, and 41% for moderate-severe CLD. Among those with mild and moderate-severe CLD, an increased co-morbidity burden as measured by an adjusted CCI score of low (0-3), medium (4-5), high (6-7) and very high (>7) resulted in increasing case-fatality rates of 24-40%, 11-28.5%, 33-62%, and 50% respectively. Moderate-severe CLD, but not mild CLD, was independently associated with increased case-fatality at 90 days (Odds Ratio 1.58; 95% confidence interval 1.01-2.48; p = 0.004) after adjusting for medical co-morbidities and severity of illness using logistic regression analysis. CONCLUSIONS: Although patients with moderate-severe CLD have an increased risk for 90-day case-fatality, patients with mild CLD are not at higher risk for death following ICU admission.

Determinants and outcomes of bloodstream infections related to obesity.

Although obesity is a major healthcare problem that is increasing in many populations worldwide, there are limited studies that have examined its contribution to infectious diseases morbidity and mortality. The aim of this study was to examine the clinical determinants and outcomes of bloodstream infections among patients with obesity. All adults within the publicly funded healthcare system in Queensland, Australia, identified with a BSI during 2017-2019 were included and the presence of obesity was based on discharge International Classification of Diseases (ICD-10) codes. Clinical features, microbiology, and outcomes were compared among obese and non-obese subjects. A total of 24,602 incident BSI were identified among 21,613 Queensland residents; of which 4,579 (21.2%) and 17,034 (78.8%) were classified as obese or non-obese, respectively. Obese patients were less likely to have community associated infections and were more likely to be younger, female, have higher comorbidity scores, and have bone and joint or soft tissue infections as compared to non-obese subjects. Obese patients had a lower proportion of Escherichia coli BSI and higher proportions of b-haemolytic streptococci. Although obese patients had longer hospital admissions and more repeat incident BSI within 1 year, they had lower overall case fatality. In a logistic regression model, obesity was associated with a lower risk for 30-day case fatality (adjusted odds ratio 0.51, 95% confidence interval 0.45-0.58). Obesity is associated with significant differences in the determinants and outcome of BSI. Increasing rates of obesity is likely to influence the epidemiology of BSI in populations.

Culture-based determinants and outcome of Staphylococcus aureus bloodstream infections.

BACKGROUND: The objective of this study was to examine the occurrence, determinants, and outcome of S. aureus bloodstream infections (BSI) diagnosed based on single versus multiple positive initial cultures. METHODS: All adults with first episodes of mono-microbial S. aureus BSI in Queensland during 2000-2019 were included. RESULTS: 10,855 (67%) and 5,421 (33%) were diagnosed based on one and multiple positive initial cultures, respectively. Patients with multiple positive initial cultures were significantly younger, more likely to have community-associated disease, have a shorter time to culture positivity, less likely to have methicillin-resistant S. aureus BSI, and have a different distribution of comorbid medical illnesses and clinical foci. The 30-day all-cause case-fatality rate was 18% and single positive initial culture was an independent risk factor for death. CONCLUSIONS: Among patients with S. aureus BSI, those diagnosed by single positive initial blood cultures have different clinical features and a higher risk for death.

Achromobacter Species: An Emerging Cause of Community-Onset Bloodstream Infections.

BACKGROUND: Case reports and small series indicate that Achromobacter species bloodstream infection (BSI) is most commonly a complication of hospitalization among patients with chronic lung disease. The aim of the present study was to determine the incidence, risk factors, and outcomes of Achromobacter sp. BSI in an Australian population. METHODS: Retrospective, laboratory-based surveillance was conducted in Queensland, Australia (population ≈ 5 million) during 2000-2019. Clinical and outcome data were obtained by linkage to state hospital admissions and vital statistics databases. BSI diagnosed within the community or within the first two calendar days of stay in hospital were classified as community-onset. Community-onset BSIs were grouped into community-associated and healthcare-associated. RESULTS: During more than 86 million person-years of surveillance, 210 incidents of Achromobacter sp. BSI occurred among 195 individuals for an overall age-and sex-standardized annual incidence of 2.6 per million residents. Older individuals and males were at highest risk (2.9 vs. 2.0 per million, IRR for males 1.5; 95% CI, 1.1-1.9; p = 0.008). Most (153; 73%) cases were of community-onset of which 100 (48%) and 53 (25%) were healthcare- and community-associated, respectively. An increasing proportion of community-onset cases were observed during twenty years of surveillance. Underlying medical illnesses were common with median (interquartile range) Charlson Comorbidity Index (CCI) scores of 3 (1-5). CCI scores of 0, 1, 2, and 3+ were observed in 37 (18%), 27 (13%), 40 (19%), and 105 (50%) of cases, respectively. All but one of the cases were admitted to hospital for a median (interquartile range) length of stay of 12 (5-34) days. All-cause case-fatality rates in hospital by day 30 and by day 90 were 30 (14%), 28 (13%), and 42 (20%), respectively. The 90-day case-fatality rate increased with increasing comorbidity and was 3% (1/37), 11% (3/27), 25% (10/40), and 27% (28/105) among those with Charlson Comorbidity Indices of 0, 1, 2, and 3+, respectively (p = 0.004). CONCLUSIONS: Although comorbidity is an important determinant of risk, most Achromobacter sp. BSI are of community-onset and one-fifth of cases occur in patients without significant underlying chronic co-morbidities. This study highlights the value of population-based methodologies to define the epidemiology of an infectious disease.