title: How long does it take to "rule out" bacteremia in children with central venous catheters?
abstract: BACKGROUND
  Children with central venous catheters and suspected bloodstream infection are often hospitalized for 48 hours to receive empiric antibiotic therapy pending blood-culture results. Continuous monitoring blood-culture systems allow for more rapid detection of bloodstream infection than previous blood-culture systems, a feature that may facilitate earlier determination of the true presence or absence of bloodstream infection and shorten empiric antibiotic therapy and duration of hospitalization.
  
  
  METHODS
  This retrospective cohort study included children with central venous catheters who were diagnosed with laboratory-confirmed bloodstream infection after evaluation in the ambulatory care setting.
  
  
  RESULTS
  Two-hundred episodes of bloodstream infection were included. The median patient age was 5.5 years. Central venous catheters were in place for a median of 80.5 days. Gram-negative bacteria accounted for 51% of infections as part of either a monomicrobial (25%) or polymicrobial (26%) infection. The overall median time to blood-culture positivity was 14 hours. The predicted probability for a culture being positive at 36 hours was 99.2% for infections caused by gram-negative bacteria and 96.6% for any infection after adjusting for age, catheter type, and recent antibiotic use. In a multivariate Cox proportional-hazards regression model, polymicrobial infections with > or = 1 gram-negative bacteria and monomicrobial infections caused by gram-negative bacteria were independently associated with an earlier time to blood-culture positivity after adjusting for age, catheter type, and recent antibiotic use.
  
  
  CONCLUSIONS
  The time to blood-culture positivity depends on bacterial category. Bloodstream infections caused by gram-negative bacteria are detected most quickly. Our data suggest that discontinuation of empiric antibiotic coverage may be warranted in clinically stable children with central venous catheters if the blood-culture results remain negative 24 to 36 hours after collection.
authors.affiliation: Children's Hospital of Philadelphia, Division of Infectious Diseases, Room 1526, North Campus, 34th Street and Civic Center Boulevard, Philadelphia, PA 19104, USA. shahs@email.chop.edu
authors.forename: Samir S
authors.initials: SS
authors.lastname: Shah
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Downes
authors.forename: Michael R
authors.initials: MR
authors.lastname: Elliott
authors.forename: Louis M
authors.initials: LM
authors.lastname: Bell
authors.forename: Karin L
authors.initials: KL
authors.lastname: McGowan
authors.forename: Joshua P
authors.initials: JP
authors.lastname: Metlay
mesh_terms: D016470:Bacteremia / Q000175:diagnosis* / Q000209:etiology*; D001431:Bacteriological Techniques / Q000379:methods; D001769:Blood / Q000382:microbiology*; D002405:Catheterization, Central Venous / Q000009:adverse effects* / Q000295:instrumentation*; D002408:Catheters, Indwelling / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D042241:Early Diagnosis; D004866:Equipment Contamination; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D006776:Hospitals, Pediatric; D006801:Humans; D007223:Infant; D017053:Infection Control; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D015143:Philadelphia; D011237:Predictive Value of Tests; D011336:Probability; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D013997:Time Factors