Investigation of the case numbers of catheter-related bloodstream infection overestimated by the central line-associated bloodstream infection surveillance definition

Background/PurposeDiagnosis of catheter-related bloodstream infection (CRBSI) requires specific laboratory evidence. A simpler definition, central line-associated bloodstream infection (CLABSI), is recommended for surveillance purposes. Because exclusion of all other infection sources is difficult, CRBSI cases may be overestimated by using the CLABSI definition.MethodsA retrospective observational study was performed at a regional hospital in southern Taiwan from September 2012 to December 2013. All 106 reported CLABSI cases were assessed. Cases with catheter tip cultures were reviewed. CRBSI was defined as the identification of same organisms from the paired blood and catheter tip cultures (≥15 colony-forming units) without evidence of secondary bacteremia from other infection sources.ResultsOverall, 64 cases were included and 31 (48.4%) were defined as CRBSI cases. In 30 (46.9%) cases, catheter tips were cultured after the corresponding blood cultures were performed. Later tip cultures were significantly more frequent in cases with other catheter types (18/22, 81.8%) than those with central lines (12/42, 28.6%; p < 0.0001). The same significant difference was also found among the CRBSI cases (central lines, 3/17, 17.6%; others, 13/14, 92.9%; p < 0.00005). Twelve bacterial species were identified from the CRBSI cases, with Staphylococcus aureus being the most frequent (13, 41.9%), followed by Pseudomonas aeruginosa (5, 16.1%).ConclusionThe positive predictive value of the CLABSI definition for CRBSI cases was 48.4%. One should be aware of this discrepancy and should interpret the CLABSI surveillance definition with care.