Endoluminal colonization as a risk factor for coagulase-negative staphylococcal catheter-related bloodstream infections in haemodialysis patients.

BACKGROUND: Approximately 25% of haemodialysis (HD) patients use catheters as vascular access. Catheter-related bloodstream infections (CRBSI) are a major risk in this population. The objective of our study was to determine whether endoluminal catheter colonization (ECC) predicts CRBSI.
METHODS: We followed up a cohort of HD patients in our institution who underwent HD with tunnelled cuffed central venous catheters (TCC) between December 2006 and June 2008. Colonization of the inner catheter lumen was assessed every 15 days immediately before HD by culture of blood-heparin mixture and the time to positivity (TTP) was recorded by the BacT/Alert automated system. CRBSI was confirmed by differential TTP (> 2 h) between TCC and peripheral blood cultures.
RESULTS: We studied 51 patients who required 64 TCC. The incidence of CRBSI was 1.65 episodes per 1000 catheter-days, with Staphylococcus epidermidis being the most common cause of infection (76.2%). ECC was more frequent in the CRSBI group than in the non-CRBSI group (100 vs 5.4%, P < 0.001). For S. epidermidis CRBSIs, the median time from ECC to CRBSI was 31.5 days (interquartile range, 27.0-79.0). The sensitivity, specificity and negative and positive predictive values of arterial lumen cultures for S. epidermidis CRBSIs were 100, 96.3, 92.3 and 100%, respectively, while for venous culture, these values were 92.3, 96.3, 92.3 and 96.3%, respectively. For predicting S. epidermidis CRBSI, endoluminal cultures with a TTP of ≤ 14 h had sensitivity and specificity of 52.1 and 97.7%, respectively.
CONCLUSIONS: This study shows that ECC may predict the risk of developing CRSBI. Surveillance cultures could, therefore, be used to triage individual HD patients who might benefit from specific intervention measures.