How long does it take to "rule out" bacteremia in children with central venous catheters?

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.