Eschericha coli findings in urine and blood among patients with suspected bacterial infection admitted to an emergency department: a single center prospective population-based study

Background.<br/>Ongoing research is exploring vaccines that may prevent sepsis due to Escherichia coli (E. coli) urinary tract infections (UTIs), a leading cause of sepsis. However, more data on the epidemiology of E. coli UTIs and bacteremia among Emergency Department (ED) patients admitted with infections, and potentially preventable sepsis, are needed to provide context for vaccine research.AimThis study aimed to examine the occurrence of E. coli UTIs and E. coli bacteremia among patients admitted to an ED with a suspected bacterial infection. Furthermore, we aimed to estimate 28-day mortality and determine the proportion of patients diagnosed with sepsis.<br/>Methods<br/>We conducted a secondary analysis of data from a prospective cohort study at Slagelse Hospital's ED in Denmark from October 1, 2017, to March 31. We included adult patients treated with antibiotics within 24 hours of admission for suspected bacterial infections, continuing for at least 48 hours. Microbiological findings from urine and blood samples were obtained via linkage between our research database and the local microbial laboratory data system. Vital measurements were retrieved from the database. Survival status was obtained from the Danish Civil Registration System. Sepsis was defined as a Sequential Organ Failure Assessment score of ≥ 2 upon admission, corrected for chronic diseases. Proportions are presented with 95% confidence intervals (CI) and compared using the Chi-square test. Logistic regression analysis was used to estimate the odds ratio (OR) for 28-day mortality. Outcomes were compared among three groups: patients with E. coli-positive urine and positive blood cultures (group 1), patients with E. coli-positive urine cultures but negative blood cultures (group 2), and patients with E. colipositive urine without concurrent blood cultures (group 3).<br/>Results<br/>A total of 2,110 (51.3% female) patients with a median age of 73.1 years (IQR 60.1-82.7) were included, with 262 (12.4%) having at least one urine culture positive for E. coli. Among these, 137 (49.8%) had at least one blood culture obtained, with 23 (16.8%) in group 1, (73.7%) in group 2 and 138 (50.2%) in group 3. The unadjusted (OR) for 28-day mortality among patients with E. coli-positive urine was 1.5 (0.97-2.29). 28-day mortality rates among patients with E. colipositive urine according to blood culture status were 4.4% (CI: 0.1-21.9), 9.9% (CI: 4.9-17.5), and 8.7% (CI:<br/>4.6-17.5) (non-significant), and the prevalence of sepsis during hospitalization was estimated at 52.2% (CI: 30.6-73.2), 37.6% (CI: 28.2-47.8) and 24.6% (CI: 17.7-32.7) in groups 1, 2 and 3, respectively<br/>(p=0.01).<br/>Conclusions<br/>Patients suffering infections with E. coli UTIs and E. coli bacteremia are common in ED admissions, often leading to sepsis and mortality. Our data on E. coli in blood and urine, along with clinical outcomes, may be helpful in assessing vaccine preventive benefits. However, the selection of patients may have introduced bias, and ongoing analyses may uncover if other common causes of exposure and serious outcomes biased a causal effect of E. Coli in our study. <br/>