title: 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 <0.001). Patients with TTP in the lowest quartile were more likely to be female, to have a non-urinary tract or an unknown origin of bacteraemia, to have severe sepsis or shock, and to subsequently die. In a multivariable Cox regression model, the hazard ratio for death from any cause for patients with a short TTP was 3.13 (95% CI 1.28-7.64; p 0.01). TTP in patients with E. coli bacteraemia provides prognostic information beyond that provided by the presence of haematological illness, a Charlson score > or =3, a non-urinary tract origin of bacteraemia, and the presence of severe sepsis or shock.
authors.affiliation: Internal Medicine Service, Sierrallana Hospital, Torrelavega, Cantabria, Spain. gpf@mundivia.es
authors.forename: G
authors.initials: G
authors.lastname: Peralta
authors.forename: M P
authors.initials: MP
authors.lastname: Roiz
authors.forename: M B
authors.initials: MB
authors.lastname: Sánchez
authors.forename: J C
authors.initials: JC
authors.lastname: Garrido
authors.forename: B
authors.initials: B
authors.lastname: Ceballos
authors.forename: M J
authors.initials: MJ
authors.lastname: Rodríguez-Lera
authors.forename: F
authors.initials: F
authors.lastname: Mateos
authors.forename: I
authors.initials: I
authors.lastname: De Benito
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000097:blood / Q000382:microbiology*; D004926:Escherichia coli / Q000254:growth & development* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000097:blood / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate