Occurrence and determinants of enterococcal bloodstream infections: a population-based study.

Background: Although enterococci are common causes of bloodstream infections (BSIs), few studies have examined their epidemiology in non-selected populations.Objective: To examine the incidence and risk factors for development of enterococcal BSI.Methods: Surveillance for incident enterococcal BSI was conducted among all residents of the western interior of British Columbia, Canada during 2011-2018.Results: The overall annual incidence was 10.0 per 100,000 and was 6.6 and 2.7 per 100,000 for E. faecalis and E. faecium, respectively. Among the overall cohort of 145 incident cases of enterococcal BSI, 22 (15.2%) were community-associated, 63 (43.5%) were healthcare associated and 60 (41.4%) were hospital-onset. Enterococcal BSI was predominantly a disease of older adults with rare cases occurring among those aged less than 40 years. Males showed significantly increased risk compared to females (14.3 vs. 5.6 per 100,000; incidence rate ratio; IRR; 2.6; 95% confidence interval; CI; 1.8-3.8; p < .0001) and this was most pronounced with advanced age. Several co-morbid illnesses were associated with increased risk (IRR; 95% CI) for development of enterococcal BSI most importantly cancer (8.8; 6.0-12.9; p < .0001), congestive heart failure (5.7; 3.1-9.7; p < .0001), diabetes mellitus (4.4; 3.0-6.3; p < .0001) and stroke (3.7; 1.9-6.5; .0001). As compared to patients with E. faecalis, patients with E. faecium BSI were more likely to be of hospital-onset, more likely to have an intra-abdominal/pelvic focus, and trended towards higher 30-day case-fatality rate.Conclusions: Enterococci are relatively common causes of BSI. Although E faecalis and E faecium share commonalities they are epidemiologically distinguishable on several criteria.

Culturing rate and the surveillance of bloodstream infections: a population-based assessment.

OBJECTIVES: Diagnosis of a bloodstream infection (BSI) requires a positive blood culture. However, low culturing rates will underestimate the true incidence of BSI and high rates may increase the risk of false-positive results. We sought to investigate the relationship between culturing rates and the incidence of BSI at the population level. METHODS: Population-based surveillance was conducted in the western interior of British Columbia, Canada, between 1 April 2010 and 31 March 2017. RESULTS: Among 60 243 blood culture sets drawn, 5591 isolates were obtained, of which 2303 were incident, 1929 were repeat positive and 1359 were contaminants. Overall annual rates of culturing, incident, repeat positive and contaminant isolates were 4832, 185, 155 and 109 per 100 000 population, respectively. During the 84-month study, there was an increase in the culturing rate that reached a plateau at 48 months (5403 cultures per 100 000 per year). The rate of both repeat isolates and contaminants increased linearly with an increasing culturing rate. However, the incident isolate rate reached an inflection point at a rate of approximately 5550 per 100 000 annually, at which point the increase in incident isolates per culture sample was diminished. At a culturing rate above 6123 per 100 000 per year, the number of repeat isolates exceeded that of incident isolates. CONCLUSIONS: The determined incidence of BSI will increase with increased culturing in a population. Further studies are needed to explore optimal BSI culturing rates in other populations.

Burden of community-onset bloodstream infections, Western Interior, British Columbia, Canada.

Although community-onset bloodstream infection (BSI) is recognized as a major cause of morbidity and mortality, its epidemiology has not been well defined in non-selected populations. We conducted population-based surveillance in the Interior Health West region of British Columbia, Canada in order to determine the burden associated with community-onset BSI. A total of 1088 episodes were identified for an overall annual incidence of 117·8/100 000 of which 639 (58·7%) were healthcare-associated (HA) and 449 (41·3%) were community-associated (CA) BSIs for incidences of 69·2 and 48·6/100 000, respectively. The incidence of community-onset BSI varied by age and gender and elderly males were at the highest risk. Overall 964 (88·6%) episodes resulted in hospital admission for a median length of stay of 8 days; the total days of acute hospitalization associated with community-onset BSI was 13 530 days or 1465 days/100 000 population per year. The in-hospital mortality rate was 10·6% (102/964) and this was higher for HA-BSI (72/569, 12·7%) compared to CA-BSI (30/395, 7·6%, P = 0·014) episodes. Community-onset BSI, especially HA-BSI, is associated with a major burden of illness.