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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., (© 2023 Royal Australasian College of Physicians.)

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., Competing Interests: Declarations of competing interest DLP has received research grants from Merck, Pfizer, bioMerieux, and Shionogi outside of the submitted work. He has also received personal fees from AMR Action Fund, Merck, Pfizer, Shionogi, Spero, Lysovant, The Medicines Company, Entasis, VenatoRx, QPex, bioMerieux, and Accelerate, and is conducting a study on E. coli vaccination sponsored by Janssen. PNAH has received research grants from Merck, Sharpe, and Dohme (MSD), Sandoz, and Shionogi Ltd, outside of the submitted work, and has served on advisory boards for OpGen, Merck, and Sandoz and received speakers fees from Pfizer, OpGen, and Sandoz paid to the University of Queensland. The remaining authors have no competing interests to declare., (Copyright © 2023. Published by Elsevier Ltd.)

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., (© 2023. The Author(s).)

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., (© 2023. The Author(s).)

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., (Copyright © 2023 Elsevier Inc. All rights reserved.)

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., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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., (© 2022. The Author(s).)

Although recent reports of extensively antibiotic-resistant strains have highlighted the importance of Morganella morganii as an emerging pathogen, the epidemiology of serious infections due to this organism is not well defined. The objective of this study was to determine the incidence, determinants, and outcomes of Morganella morganii bloodstream infections (BSIs). Retrospective, population-based surveillance for Morganella morganii BSIs was conducted in Queensland, Australia, in 2000 to 2019; 709 cases were identified, for an annual incidence of 9.2 cases per million population. Most cases were of community onset, with 280 (39.5%) community-associated cases and 226 (31.9%) health care-associated cases. Morganella morganii BSIs were rare in children and young adults, and the incidence increased markedly with advancing age. The most common foci of infection were skin and soft tissue (131 cases [18.5%]), genitourinary (97 cases [13.7%]), and intraabdominal (90 cases [12.7%]). Most patients (580 cases [81.8%]) had at least one comorbid medical illness, with diabetes mellitus (250 cases [35.3%]), renal disease (208 cases [29.3%]), and congestive heart failure (167 cases [23.6%]) being most prevalent. Resistance to one or more of quinolones, co-trimoxazole, aminoglycosides, or carbapenems was observed in 67 cases (9.5%), and this did not change significantly over the study. The 30-day all-cause case fatality rate was 21.2%, and increasing age, nonfocal infection, heart failure, dementia, and cancer were independently associated with increased risk of death. Morganella morganii BSIs are increasing in our population, and elderly male subjects and individuals with comorbidities are at highest risk. Although antibiotic resistance is not a major contributor to the current burden in Queensland, ongoing surveillance is warranted. IMPORTANCE Recent reports of extensively antibiotic-resistant strains have highlighted the importance of Morganella morganii as an emerging pathogen. Despite its present and evolving importance as an agent of human disease, there is a limited body of literature detailing the epidemiology of serious infections due to Morganella morganii. Therefore, the objectives of this study were to examine the incidence and determinants of Morganella morganii BSIs and to examine risk factors for death in a large Australian population in 2000 to 2019.

Background: Small case series and reports suggest that Sphingomonas paucimobilis is predominantly a cause of nosocomial bloodstream infections (BSI) with very low associated mortality. Our objective was to describe the epidemiology and outcome of Sphingomonas species BSI in a large Australian population., Methods: We included all residents of Queensland, Australia, with BSI because of Sphingomonas species identified within the publicly funded system from 2000 to 2019., Results: A total of 282 incident episodes of Sphingomonas species BSI were identified for an age- and sex-adjusted incidence of 3.2 per million population annually. Incidence rates were highest in the tropical regions of the state. Most (94%) of the isolates were confirmed as Sphingomonas paucimobilis. In addition, 77% of the infections were community-onset, of which 48% were community-associated, and 30% were healthcare-associated. The very young, the old, and male patients were at the highest risk. Patients with community-associated disease were, on average, younger, had fewer co-morbidities, and were less likely to have polymicrobial infections. At least 1 co-morbidity was identified in 62% of patients, with malignancy, diabetes, and lung disease most prevalent. The overall all-cause 30-day case-fatality rate was 6%., Conclusion: Sphingomonas paucimobilis BSI is a predominantly community-onset disease associated with a significant risk of death., Competing Interests: Conflict of interest The authors declare they have no conflicts of interest., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Pasteurella species are infrequent but potentially severe causes of bloodstream infection (BSI). The objective of this study was to determine the incidence, risk factors, and outcomes of Pasteurella species BSI in a large Australian population. Retrospective, laboratory-based surveillance was conducted in Queensland, Australia (population ≈ 5 million) during 2000-2019, and clinical and outcome information was established by linkage to state hospital admissions and vital statistics databases. During more than 86 million person-years of surveillance, 272 incident Pasteurella species BSI occurred for an overall age- and sex-standardized annual incidence of 3.3 per million residents. The incidence of Pasteurella species BSI was highest in recent years and older individuals were at greatest risk. The median (interquartile range) Charlson Comorbidity Index was 2 (0-4) with scores of zero, 1, 2, and 3 + observed in 81 (30%), 37 (14%), 44 (16%), and 110 (40%) of cases. The 30-day all-cause case fatality was 9% (24/272) and patients who died had more comorbidities and were less likely to have community-associated disease. Although Pasteurella species are infrequent causes of BSI, older individuals and those with comorbidities are at highest risk. The burden of this disease may be expected to increase with an aging and more comorbid population., (© 2022. The Author(s).)

The epidemiology of bloodstream infections caused by Shewanella spp. is not well defined. Our objective was to define the incidence and determinants of Shewanella spp. bloodstream infections by using population-based surveillance in Queensland, Australia during 2000‒2019. The incidence was 1.0 cases/1 million persons annually and was highest during summer and in the tropical Torres and Cape region. Older persons and male patients were at highest risk. At least 1 concurrent condition was documented in 75% of case-patients, and 30-day all cause case-fatality rate was 15%. Aging populations in warm climates might expect an increasing burden of these infections.

Blood cultures obtained with a lysis-centrifugation (L-C) system and a conventional two-bottle broth system were compared for the recovery of bacteria and yeasts from 7,000 cultures. The L-C system recovered significantly more total organisms, Escherichia coli, and Candida spp. and detected more patients with bacteremia and fungemia due to members of the family Enterobacteriaceae and yeasts. The broth system recovered significantly more streptococci and detected significantly more low-level Pseudomonas bacteremias. Polymicrobic bacteremia and fungemia were detected equally well by either culture system. Aerobic organisms grew equally well on blood, chocolate, or brain heart infusion agar plates used for L-C inoculation. A total of 82% of colony counts measured no more than 10 CFU/ml of blood, and it was at these low levels that enhanced detection of organisms by either system was observed. The L-C system isolated organisms and detected yeasts more rapidly than did the broth system. Contaminants occurred in 8.2% of L-C cultures and 1.9% of broth cultures. Low colony counts on L-C plates occurred for both Staphylococcus epidermidis contamination and septicemia.

Serial quantitative blood cultures were performed before and during treatment in four patients with the acquired immune deficiency syndrome (AIDS) and Mycobacterium avium-intracellulare bacteremia. Initial colony counts were 350 to 28,000 cfu/ml, the counts declined substantially with treatment in two patients, and they declined modestly with treatment but rose when it was stopped in the other two. In one patient who was studied in detail, most of the circulating organisms were within the leukocytes, colony counts in blood subjected to lytic agents were 1.9- to 5.2-fold higher than in unlysed blood, and there were 10(5) to 10(6) times more organisms per gram in several tissue specimens obtained at autopsy than per milliliter of blood. It is concluded that continuous high-grade bacteremia is common in patients with AIDS and severe M. avium-intracellulare infections and that serial quantitative blood cultures provide a potential means for studying treatment in these patients.