Prognostic roles of time to positivity of blood cultures in patients with Escherichia coli bacteremia

Abstract

The time to positivity (TTP) of blood cultures has been considered a predictor of clinical outcomes for bacteraemia. This retrospective study aimed to determine the clinical value of TTP for the prognostic assessment of patients with Escherichia coli bacteraemia. One hundred and sixty seven adult patients with E.coli bacteraemia identified over a 22-month period in a 3500-bed university teaching hospital in China were studied. The standard cut-off TTP was 11 hours in the patient cohort. Septic shock occurred in 27.9% of patients with early TTP (= 11h) and in 7.1% of those with a prolonged TTP (>11h) (p = 0.003). The mortality rate was significantly higher for patients in the early than in the late group (17.7% vs. 4.0%, p > 0.001). Multivariate analysis showed that an early TTP (OR 4.50, 95% CI 1.70–11.93), intensive care unit admission (OR 8.39, 95% CI 2.01–35.14), and neutropenia (OR 4.20, 95% CI 1.55– 11.40) were independently associated with septic shock. Likewise, the independent risk factors for mortality of patients were an early TTP (OR 3.80, 95% CI 1.04–12.90), intensive care unit admission (OR 6.45; 95% CI 1.14–36.53), a Pittsburgh bacteremia score = 2 (OR 4.34, 95% CI 1.22–15.47) and a Charlson comorbidity Index = 3 (OR 11.29, 95% CI 2.81–45.39). Overall, a TTP for blood cultures within 11 h appears to be associated with worse outcomes for patients with E.coli bacteraemia.