title: Differential time to positivity of blood cultures: a valid method for diagnosing catheter-related bloodstream infections in the intensive care unit.
abstract: OBJECTIVE
  The validation in critical patients with short-term catheters of a method for diagnosing catheter-related bloodstream infection (CR-BSI), based on the differential time to positivity (DTP) of blood cultures.
  
  
  METHODS
  Patients suspected of having CR-BSI were included. Two peripheral vein blood cultures and a catheter hub blood culture were simultaneously carried out. The responsible catheter was removed and tip cultured. Times to positivity of all blood cultures were automatically registered. CR-BSI was diagnosed when all the cultures were positive for the same microorganism and DTP≥120 min. This diagnosis was compared with the one obtained using the standard method.
  
  
  RESULTS
  226 cases suspected of CR-BSI were analyzed during a 20-month period. A total of 19 removed catheters were associated with CR-BSI. Seven cases of polymicrobial cultures (4 with CR-BSI) were discarded from the final analysis due to the impossibility of determining the time to positivity for each individual microorganism. Using the DTP method, 12 out of 15 CR-BSI cases were diagnosed (sensitivity 80%, specificity 99%, PPV 92%, NPV 98%). In a ROC curve, we found a cut-off value of 17.7 h in positivity of hub blood cultures that may be useful for diagnosing CR-BSI.
  
  
  CONCLUSIONS
  DTP can be a valid method for CR-BSI diagnosis in critically ill patients, avoiding unnecessary catheter withdrawal.
authors.affiliation: Critical Care Center, Hospital de Sabadell, CIBER enfermedades respiratorias, Institut Universitari Parc Taulí-Autonomous University of Barcelona, Sabadell, Spain. xgarcia@tauli.cat
authors.forename: X
authors.initials: X
authors.lastname: García
authors.forename: C
authors.initials: C
authors.lastname: Sabatier
authors.forename: R
authors.initials: R
authors.lastname: Ferrer
authors.forename: D
authors.initials: D
authors.lastname: Fontanals
authors.forename: M
authors.initials: M
authors.lastname: Duarte
authors.forename: M
authors.initials: M
authors.lastname: Colomina
authors.forename: A
authors.initials: A
authors.lastname: Artigas
authors.forename: J
authors.initials: J
authors.lastname: Vallés
mesh_terms: D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000175:diagnosis* / Q000209:etiology; D055499:Catheter-Related Infections / Q000097:blood / Q000175:diagnosis*; D057785:Catheters / Q000382:microbiology; D003422:Critical Care / Q000379:methods*; D003428:Cross Infection / Q000097:blood / Q000175:diagnosis*; D004866:Equipment Contamination; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013997:Time Factors; D019564:Unnecessary Procedures; D014680:Veins