Utility of daily catheter-drawn blood cultures to predict catheter-related bacteremia in hematopoietic stem cell transplanted patients.

OBJECTIVE There is no diagnostic tool to identify which bacterial catheter colonization may eventually result in bloodstream infection. We speculated that a faster growth or repeated positivity of serial blood cultures drawn from the catheter might herald catheter-related bacteremia (CRB) before the onset of fever. METHODS We designed a prospective observational pilot study. All patients who underwent hematopoietic stem cell transplantation (HSCT) were prospectively included in the study over 10 months. Daily catheter-drawn blood cultures (DBC) were performed. We recorded the growth time of each blood culture and bacterial isolation. A fast-growing blood culture (positive <12 hours) or at least 2 positive identical cultures within 4 consecutive days in the DBC were defined as a marker of risk for CRB. The value of this marker to predict CRB was investigated. RESULTS A total of 82 patients (843 days of catheter) were included in the study. Fast- growing or repeated identical cultures were present in 20 patients; among them, 15 had clinical criteria of CRB. Among 62 patients without fast-growing or repeated identical cultures, 11 met the criteria of CRB. Consequently, for the defined marker of risk, the positive predictive value was 75%, negative predictive value 82%, sensitivity 70%, and specificity 91%. Sixty-two blood cultures were needed to detect one case of CRB prior to the onset of fever. CONCLUSION The use of routinely drawn catheter-blood cultures does not seem to be a useful tool for predicting CRB in HSCT patients.