Time-to-positivity in patients with Escherichia coli bacteraemia

ABSTRACT The time from the start of incubation to a positive reading of blood cultures (time-to-positivity; TTP) is related to the concentration of bacteria in blood. Information concerning the correlation of TTP with clinical parameters, and its usefulness as a prognostic factor in patients with Escherichia coli bacteraemia, is limited. To investigate the relationship of TTP to clinical parameters, 459 cases of monomicrobial E. coli bloodstream infections from a single institution between 1997 and 2005 were reviewed. All cases involved patients who were not undergoing antibiotic treatment at the time of blood sampling. The in-hospital mortality rate was 6.3%. Median TTP was significantly shorter for patients who died than for those who survived (9.7 h, inter-quartile range 7.85–11.05 h vs. 11.2 h, inter-quartile range 10.1–11.4 h; p E. coli bacteraemia provides prognostic information beyond that provided by the presence of haematological illness, a Charlson score ≥3, a non-urinary tract origin of bacteraemia, and the presence of severe sepsis or shock.