title: Diagnosis of catheter-related bacteraemia: a prospective comparison of the time to positivity of hub-blood versus peripheral-blood cultures.
abstract: BACKGROUND
  A method of diagnosing catheter-related infection (CRI) without removing the catheter would be useful. An earlier positivity of central compared with peripheral venous-blood cultures may be associated with catheter-related bacteraemia. We evaluated prospectively the differential time to positivity (DTP) of paired blood cultures drawn simultaneously via the catheter hub and from a peripheral venous site.
  
  
  METHODS
  Over a 14-month period in an intensive-care unit of a cancer referral centre, simultaneous hub-blood and peripheral-blood cultures (a mean of two per patient) were obtained from patients with a suspected CRI. According to clinical criteria and quantitative culture of the catheter tip, cases were classified as CRI or sepsis of other origin. At least one pair of hub-blood and peripheral-blood cultures was obtained within 48 h before catheter removal, and we recorded the DTP between hub-blood and peripheral-blood cultures with an automatic device for detection of blood culture positivity.
  
  
  RESULTS
  We analysed 93 catheters removed because of suspicion of CRI. In 28 episodes, the same micro-organisms were found in both hub-blood and peripheral-blood cultures. A diagnosis of definite bacteraemic CRI was made in 16 of the 17 patients in whom a positive hub-blood culture was detected at least 2 hours earlier than peripheral-blood culture. About half (9/17) of these episodes occurred in long-term (>30 days) devices. CRI was excluded in ten of the 11 patients with a DTP lower than 2 h. The DTP of paired blood cultures was significantly greater in patients with CRI than in others (p<10(-4)). A cut-off DTP value of 120 min had 91% specificity and 94% sensitivity for the diagnosis of CRI. Three of 17 episodes with only hub-blood culture positive were associated with CRI.
  
  
  CONCLUSIONS
  This prospective study suggests that measurement of the differential time to positivity between hub-blood and peripheral-blood cultures is a simple and reliable tool for in-situ diagnosis of catheter-related sepsis in cancer patients. Further studies are needed to confirm these data for short-term catheters.
authors.affiliation: Service de Réanimation Polyvalente, Institut Gustave Roussy, Villejuif, France.
authors.forename: F
authors.initials: F
authors.lastname: Blot
authors.forename: G
authors.initials: G
authors.lastname: Nitenberg
authors.forename: E
authors.initials: E
authors.lastname: Chachaty
authors.forename: B
authors.initials: B
authors.lastname: Raynard
authors.forename: N
authors.initials: N
authors.lastname: Germann
authors.forename: S
authors.initials: S
authors.lastname: Antoun
authors.forename: A
authors.initials: A
authors.lastname: Laplanche
authors.forename: C
authors.initials: C
authors.lastname: Brun-Buisson
authors.forename: C
authors.initials: C
authors.lastname: Tancrède
mesh_terms: D016470:Bacteremia / Q000145:classification / Q000175:diagnosis* / Q000209:etiology*; D001419:Bacteria / Q000302:isolation & purification; D001769:Blood / Q000382:microbiology*; D002405:Catheterization, Central Venous / Q000009:adverse effects* / Q000379:methods; D002406:Catheterization, Peripheral / Q000009:adverse effects* / Q000379:methods; D004866:Equipment Contamination; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors