Bloodstream infection due to β-hemolytic streptococci: a population-based comparative analysis

Purpose: Although the burden of illness due to Streptococcus pyogenes is widely recognized, other β-hemolytic streptococci are also important causes of invasive infections. The objective of this study was to compare the population-based epidemiology of groups A, B, and C/G β-hemolytic streptococcal bloodstream infection (BSI). Methods: Population-based surveillance was conducted in the western interior of British Columbia, Canada, 2011–2018. Results: A total of 210 episodes were identified for an incidence of 14.4 per 100,000; the incidences of groups A, B and C/G streptococcal BSI were 4.2, 4.7, and 5.5 per 100,000, respectively. There was an increasing annual incidence of β-hemolytic streptococcal BSI from 2011 through to a peak incidence in 2016 that decreased thereafter. Fifty-two percent (110) of BSIs were community associated, 43% (91) were healthcare associated, and 4% (9) were hospital onset. Patients with group A were younger, more likely to be female, and have fewer co-morbidities than patients with groups B and C/G streptococcal BSI. The most common focus of infection was soft tissue (109/52%), followed by primary (33; 16%), and bone and joint (20; 10%) and these varied by streptococcal species (p Conclusion: Although the determinants vary, the overall burden of disease related to BSI is similar amongst groups A, B and C/G β-hemolytic streptococci.</p

Population-based study of Morganella-Proteus-Providencia group bloodstream infections

BACKGROUND: There is a paucity of studies investigating the population-based epidemiology of Morganella-Proteus-Providencia (MPP) group infections. Our objective was to determine the incidence, risk factors, and outcome of MPP group bloodstream infections (BSI), and explore species-specific differences. METHODS: Population-based surveillance was conducted in the western interior of British Columbia, Canada, between April 1, 2010 and March 30, 2020. RESULTS: Sixty-two incident MPP group BSI occurred for an annual incidence of 3.4 per 100,000 residents; rates for Morganella morganii, Proteus mirabilis, and Providencia species were 0.5, 2.6, and 0.3 per 100,000 population, respectively. The median year of age was 72.5 and was different (p = 0.03) among the groups. Most (92%) MPP group BSIs were of community-onset. Significant differences were observed in the distribution of clinical focus of infection, with most notably 81% of P. mirabilis BSI due to genitourinary focus as compared to 60% and 22% for Providencia species and M. morganii, respectively. Comorbid illnesses that increased the risk for development of MPP group BSI (incidence rate ratio; 95% CI) were HIV infection (37.0; 4.4–139.6), dementia (11.5; 6.1–20.7), cancer (6.4; 3.2–11.9), stroke 6.5 (2.8–13.3), and diabetes 2.7 (1.3–5.0). Thirteen, one, and none of the cases with P. mirabilis, M. morganii, and Providencia species BSI died within 30 days of index culture for respective all cause case-fatalities of 27%, 11%, and 0% (p = 0.1). CONCLUSIONS: Although collectively responsible for a substantial burden of illness, the epidemiology of MPP group BSI varies significantly by species.</p

Staphylococcus aureus bloodstream infection: Secular changes associated with the implementation of a de novo clinical infectious diseases service in a Canadian population

Objective: To investigate the epidemiology of Staphylococcus aureus bloodstream infections (BSI) in a mixed rural to small city population and examine secular changes associated with the implementation of a regional clinical infectious diseases program. Methods: Population-based surveillance for incident S. aureus BSI was conducted in the western interior of British Columbia, Canada between April 2010 and March 2020. An infectious diseases service was progressively implemented starting in 2013. Results: 581 incident S. aureus BSI were identified. There was an increasing incidence during the study and the overall age- and gender-adjusted annual rate was 32.9 per 100,000 population. Implementation of the infectious diseases program was associated with an increase in rates of blood culture sampling, documentation of persistent bacteremia, use of transthoracic and transesophageal echocardiography, and a reduction in cases of relapsed BSI. Infectious diseases consultation was independently associated with a reduced risk for death (odds ratio 0.5; 95% CI 0.3–0.9). Conclusions: Although the implementation of a clinical infectious diseases service was associated with changes in management and improved outcome, S. aureus BSI still causes a major burden of illness.</p

Burden of bloodstream infection in older persons: a population‐based study

Background: Advancing age is a major risk factor for developing and dying from bloodstream infections (BSI). However, there is a paucity of population-based studies investigating the epidemiology of BSI in older persons. Objective: To define the incidence, clinical determinants, and risk factors for death among those aged 65 years and older with BSI. Methods: Population-based surveillance was conducted in the western interior of British Columbia, Canada, between April 1, 2010 and March 31, 2020. Chart reviews were conducted for clinical details and all cause case-fatality was established at 30-days follow-up. Results: A total of 1854 incident BSI were identified among 1657 individuals aged 65 and older for an annual incidence of 533.9 per 100,000 population; the incidence for those aged 65-74, 75-84, and ≥85 years was 375.3, 678.9, and 1046.6 per 100,000 population, respectively. Males were at significantly increased risk as compared to females (incidence rate ratio, IRR 1.44; 95% confidence interval, CI, 1.32-1.59; p<0.0001). The crude annual incidence increased by 50% during the study. However, this was related to shift in population demographics with no increase evident following age- and sex-standardization. Older patients were more likely to have healthcare-associated infections and genitourinary sources and less likely to have bone/joint or soft tissue infections. The proportion of patients with underlying congestive heart failure, stroke, and dementia increased, whereas diabetes and liver disease decreased with older age. The overall 30-day all cause case-fatality rate was 22.0% (364/1657). After adjustment for clinical focus, onset of infection, etiology, and co-morbidity in a logistic model, those aged 75-84 years (odds ratio, OR, 1.66; 95% CI, 1.25-2.21) and ≥ 85 years (OR, 1.98; 95% CI, 1.41-2.77) were at significantly increased risk for death as compared to those aged 65-74 years. Conclusion: Bloodstream infection is common in older persons and is a major cause of death. Countries with aging populations worldwide should expect an increase burden associated with BSI in the coming years.</p

Risk factors associated with bloodstream infections in end-stage renal disease patients: a population-based study

Background: Bloodstream infections (BSI) commonly complicate end-stage renal disease (ESRD) and are the second most common cause of death in these patients. The objective of this study was to define risk factors for development of BSI and its outcome among ESRD patients. Methods: A retrospective, population-based, matched cohort design was utilized. All adult (18 or older) residents of the western interior of British Columbia with ESRD who had a first BSI between April 2010 and March 2017 were included. Subject cases were then matched 1:1 with an ESRD patient from the regional registry who did not have a BSI. Results: During the study period a total of 53 cases of incident BSI were identified among patients with ESRD. The median age was 70.7 (interquartile range, 61.9–79.6) years and 28 (53%) were male. The most common organism isolated was Staphylococcus aureus (17 cases; 32%). Compared to controls, case patients were significantly (p Conclusions: ESRD patients with higher co-morbid illness, and lower serum albumin are at an increased risk for development of a BSI. Development of BSI among ESRD patients is associated with higher fatality rates.</p

Streptococcus anginosus group bloodstream infections in the western interior of British Columbia, Canada

Background: The epidemiology of Streptococcus anginosus group (SaG) bloodstream infections (BSI) has not been well defined in non-selected populations. The objective of this study was to determine the incidence, risk factors and outcome associated with SaG BSI. Methods: Population-based surveillance was conducted in the western interior region of British Columbia, Canada between 1 April 2010 and 31 March 2017. Results: Forty-six episodes were identified for an overall annual incidence of 3.7 per 100,000 population. The incidence increased with older age and males were at significantly higher risk (5.2 vs. 2.1 per 100,000; incidence rate ratio, 2.5; 95% confidence interval, 1.3–5.1; p =.004). Nearly one-half (22; 48%) of patients had no chronic co-morbid illness, whereas 17 (40%) had 1–2, six (13%) had 3–4 and one (2%) had 5 Charlson scores with diabetes and cancer being the most common. Predisposing factors for development of SaG BSI were identified in 30 (65%) cases. The gastro-intestinal tract was the most common focus of infection (13; 28%) followed by cardiovascular and skin/soft tissue (six cases each; 13%) and in seven (15%) cases no focus was identified. Drainage procedures were required in 21 (46%) patients of whom seven (15%) patients had percutaneous drains and 14 (30%) required surgical operations. Forty-one (89%) patients were admitted to hospital for a median hospital length stay of 11 (interquartile range, 7–18) days. The in-hospital and 30-day all cause case-fatality rates were 3/41 (7%) and 4/46 (9%), respectively. Conclusion: SaG BSI is an important cause of morbidity and mortality.</p

Determinants and outcomes of bloodstream infection in adults associated with one versus two sets of positive index blood cultures

Objectives: To investigate whether positivity in one or both index sets of blood cultures influences clinical determinants and mortality when diagnosing bloodstream infections (BSI). Methods: Retrospective population-based surveillance of all mono-microbial BSI was conducted among residents of the western interior of British Columbia. Clinical details were obtained by chart review and all-cause case-fatality was established at 30 days. Index cultures were defined as the first two sets of cultures initially drawn to diagnose incident BSI. Results: A total of 2500 incident BSI were identified of which 945 (37.8%) and 1555 (62.2%) were based on one and two positive index cultures, respectively. There was an overall difference in the distribution of pathogens, with both Staphylococcus aureus and Streptococcus pneumoniae more likely to have two positive index cultures. Different foci of infection were associated with one versus two positive index cultures. Overall, 409 patients died within 30 days of index BSI for an all-cause case-fatality of 16.4%; with no difference between two positive (250/1555; 16.1%) and one positive (159/945; 16.8%; p 0.3) index blood culture. The number of positive index blood cultures was not associated with 30-day case-fatality after adjustment for confounding variables using logistic regression analysis. Conclusions: Although approximately one-third of BSI are diagnosed on the basis of a single positive blood culture and are associated with different clinical determinants, whether one or both index blood cultures are positive is not associated with lethal outcome.</p

Risk of bloodstream infection in patients with renal dysfunction: A population-based cohort study

Although patients with end-stage renal disease (ESRD) are known to be at high risk for developing bloodstream infections (BSI), the risk associated with lesser degrees of renal dysfunction is not well defined. We sought to determine the risk for acquiring and dying from community-onset BSI's among patients with renal dysfunction. A retrospective, population-based cohort study was conducted among adult residents without ESRD in the western interior of British Columbia. Estimated glomerular filtration rates (EGFR) were determined for cases and incidence rate ratios were calculated using prevalence estimates. Overall, 1,553 episodes of community-onset BSI were included of which 39%, 32%, 17%, 9%, 2%, and 1% had preceding EGFRs of ≥90, 60-89, 45-59, 30-44, 15-29, and 2, respectively. As compared to those with EGFR ≥60 mL/min/m2, patients with EGFR 30-59 mL/min/m2 (incidence rate ratio, IRR, 4.4; 95% confidence interval, CI, 3.9-4.9) and EGFR 2 (IRR, 7.0; 95% CI, 5.0-9.5) were at significantly increased risk for development of community-onset BSI. An EGFR 2 was an independent risk factor for death (Odds ratio, 2.3; 95% CI, 1.01-5.15). Patients with renal dysfunction are at increased risk for developing and dying from community-onset BSI that is related to the degree of dysfunction.</p

Occurrence and determinants of Klebsiella species bloodstream infection in the western interior of British Columbia, Canada

Background: Klebsiella species are among the most common causes of bloodstream infection (BSI). However, few studies have evaluated their epidemiology in non-selected populations. The objective was to define the incidence of, risk factors for, and outcomes from Klebsiella species BSI among residents of the western interior of British Columbia, Canada. Methods: Population-based surveillance was conducted between April 1, 2010 and March 31, 2017. Results: 151 episodes were identified for an incidence of 12.1 per 100,000 population per year; the incidences of K. pneumoniae and K. oxytoca were 9.1 and 2.9 per 100,000 per year, respectively. Overall 24 (16%) were hospital-onset, 90 (60%) were healthcare-associated, and 37 (25%) were community-associated. The median patient age was 71.4 (interquartile range, 58.8-80.9) years and 88 (58%) cases were males. Episodes were uncommon among patients aged Conclusions: Klebsiella species BSI is associated with a significant burden of illness particularly among those with chronic co-morbid illnesses.</p

Inhospital death is a biased measure of fatal outcome from bloodstream infection

Purpose: Inhospital death is commonly used as an outcome measure. However, it may be a biased measure of overall fatal outcome. The objective of this study was to evaluate inhospital death as a measure of all-cause 30-day case fatality in patients with bloodstream infection (BSI). Patients and methods: A population-based surveillance cohort study was conducted, and patients who died in hospital within 30 days (30-day inhospital death) were compared with those who died in any location by day 30 post BSI diagnosis (30-day all-cause case fatality). Results: A total of 1,773 residents had first incident episodes of BSI. Overall, 299 patients died for a 30-day all-cause case fatality rate of 16.9%. Most (1,587; 89.5%) of the patients were admitted to hospital, and ten (5.4%) of the 186 patients not admitted to hospital died. Of the 1,587 admitted patients, 242 died for a 30-day inhospital death rate of 15.2%. A further 47 patients admitted to hospital died after discharge but within 30 days of BSI diagnosis for a 30-day case fatality rate among admitted patients of 18.2%. Patients who died following discharge within 30 days were older and more likely to have dementia. Conclusion: The use of inhospital death is a biased measure of true case fatality.</p