Methods A retrospective cohort study at two university hospitals was conducted. We retrieved all the medical recordsof those with E. coli bloodstream infection according to the records generated by their microbiology departments.Univariate and multivariate analyses were applied to identify clinical factors correlating with fast bacterial growth andsignificant prognostic factors for hospital mortality.Results Medical records of 353 episodes of E. coli bacteremia diagnosed between January 1, 2007 and December 31,2009 were retrieved in the investigation. Univariate analysis demonstrated that the TTP <7 hours group is associated withhigher incidence of active malignancies (41.7％ vs. 27.2%, P=0.010), neutropenia (30% vs.14.3%, P=0.007), primarybacteremia (55.0% vs. 33.4%, P=0.002), and poorer outcome (hospital mortality 43.3% vs. 11.9%, P=0.000) than the TTP>7 hours group. Multivariate analysis revealed that the significant predictors of hospital mortality, in rank order from highto low, were TTP (for TTP <7 hours, odds ratio (OR): 4.886; 95% confidence interval (Cl): 2.572-9.283; P=0.000),neutropenia (OR: 2.800; 95% Cl: 1.428-5.490; P=0.003), comedication of steroids or immunosuppressive agents (OR:2.670; 95% Cl: 0.971-7.342; P=0.057).Conclusions Incidence of malignancies, neutropenia and primary bacteremia correlates with fast bacterial growth inpatients with E. coli bacteremia. The parameter of TTP has been identified as a variable of highest correlation to hospitalmortality and therefore can be potentially utilized as a mortality prognostic marker.