title: Time to positivity of blood cultures in patients with bloodstream infections: A useful prognostic tool.
abstract: OBJECTIVE
  The time to positivity (TTP) of blood cultures in patients with bloodstream infections (BSIs) has been considered to be a possible prognostic tool for some bacterial species. However, notable differences have been found between sampling designs and statistical methods in published studies to date, which makes it difficult to compare results or to derive reliable conclusions. Our objective was to evaluate the clinical and microbiological implications of TTP among patients with BSI caused by the most common pathogens.
  
  
  METHODS
  A total of 361 episodes of BSI were reported for 332 patients. The survival of the entire cohort was measured from the time of blood culture sampling. In order to compare our results with those of previous studies, TTP was divided in three different groups based on log rank (short TTP <12h; medium TTP ≥12h to ≤27h, and long TTP >27h). Cox proportional hazard models were used to calculate crude and adjusted hazard ratios (HR).
  
  
  RESULTS
  The Cox proportional hazard model revealed that TTP is an independent predictor of mortality (HR=1.00, p=0.031) in patients with BSIs. A higher mortality was found in the group of patients with the shortest TTP (<12h) (HR=2.100, p=0.047), as well as those with longest TTP (>27h) (HR=3.277, p=0.031).
  
  
  CONCLUSIONS
  It seems that TTP may provide a useful prognostic tool associated with a higher risk of mortality, not only in patients with shorter TTP, but also in those with longer TTP.
authors.affiliation: Infectious Diseases, Clinical Microbiology and Preventive Medicine Unit, Virgen Macarena and Virgen del Rocío University Hospitals, Calle Manuel Siurot s/n, 41013 Seville, Spain; Institute of Biomedicine of Seville (IBiS), Virgen del Rocío, Calle Manuel Siurot s/n, 41013 Seville, Spain. Electronic address: guiller_mg86@hotmail.es.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Martín-Gutiérrez
authors.affiliation: Centro de Salud Marquesado, Área Nordeste de Granada, Carretera los Pozos, 2, Alquife, 18518 Granada, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Martín-Pérez
authors.affiliation: Institute of Biomedicine of Seville (IBiS), Virgen del Rocío, Calle Manuel Siurot s/n, 41013 Seville, Spain; Spanish Clinical Research Network, Virgen del Rocío University Hospital, Calle Manuel Siurot s/n, 41013 Seville, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Gutiérrez-Pizarraya
authors.affiliation: Infectious Diseases, Clinical Microbiology and Preventive Medicine Unit, Virgen Macarena and Virgen del Rocío University Hospitals, Calle Manuel Siurot s/n, 41013 Seville, Spain; Institute of Biomedicine of Seville (IBiS), Virgen del Rocío, Calle Manuel Siurot s/n, 41013 Seville, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Lepe
authors.affiliation: Infectious Diseases, Clinical Microbiology and Preventive Medicine Unit, Virgen Macarena and Virgen del Rocío University Hospitals, Calle Manuel Siurot s/n, 41013 Seville, Spain; Institute of Biomedicine of Seville (IBiS), Virgen del Rocío, Calle Manuel Siurot s/n, 41013 Seville, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Cisneros
authors.affiliation: Infectious Diseases, Clinical Microbiology and Preventive Medicine Unit, Virgen Macarena and Virgen del Rocío University Hospitals, Calle Manuel Siurot s/n, 41013 Seville, Spain; Institute of Biomedicine of Seville (IBiS), Virgen del Rocío, Calle Manuel Siurot s/n, 41013 Seville, Spain; Microbiology Department, University of Seville, Avda. Sánchez Pizjuan, s/n, 41009 Seville, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Aznar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000382:microbiology* / Q000401:mortality; D000071997:Blood Culture; D017714:Community-Acquired Infections / Q000097:blood / Q000382:microbiology / Q000401:mortality; D003428:Cross Infection / Q000097:blood / Q000382:microbiology / Q000401:mortality; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018805:Sepsis / Q000097:blood / Q000382:microbiology / Q000401:mortality; D062606:Tertiary Care Centers; D013997:Time Factors; D055815:Young Adult
keywords: Bacteriemia; Blood culture; Bloodstream infection; Hemocultivo; Mortalidad; Mortality; Tiempo de positividad; Time to positivity