Authors: Park K-H et al., J Clin Microbiol 2014 Jul 52:2566
Differential time to positivity appeared useful in predicting catheter-related infection.
Differential time to positivity (DTP) — the difference in time to positivity between blood cultures drawn simultaneously from a central venous catheter (CVC) and a peripheral vein — has been useful in identifying patients with CVC-related bacteremia. In a recent retrospective cohort study conducted at a single large medical center in Seoul, South Korea, researchers explored DTP’s usefulness for diagnosing catheter-related candidemia (CRC).
Ninety-nine patients were identified who had Candida-positive blood cultures from both a CVC and a peripheral vein. The patients were designated as having definite CRC (n=47), probable CRC (n=14), or candidemia from another source (n=38), based on predefined criteria. Ninety-one (92%) of 99 patients underwent catheter removal, with catheter-tip cultures being performed.
Overall, the sensitivity and specificity of a DTP greater than 120 minutes for diagnosing CRC were 85% (95% confidence interval, 74% to 93%) and 82% (95% CI, 66% to 92%), respectively. For neutropenic patients, these values were 75% (95% CI, 19% to 99%) and 100% (95% CI, 75% to 100%).
Findings from this investigation support the practice of diagnosing CRC based on DTP and should help to inform the often-difficult decision of whether to remove a catheter.