Catheter-related bloodstream infection (CRBSI) accounts for 10% to 20% of hospital-acquired infections in the UK and is associated with both increased ICU stay and mortality. Rates of CRBSI may be modified by clinical care during insertion and utilisation of central venous catheters (CVCs) . As such, the incidence of CRBSI has been proposed as a quality indicator. There is currently no consensus regarding the definition of CRBSI.
We applied two internationally recognised guidelines [1,2] to evaluate the CRBSI prevalence in a prospective study of CVC replacements over 3 months on an adult cardiothoracic ICU. We utilised these criteria for confirmed CRBSI but considered additionally CVC colonisation and possible CRBSI. CVC tips were sent for semiquantitative culture, and contemporaneous blood was drawn for qualitative culture from both the CVC and a peripheral vein. Possible CRBSI was defined as positive CVC blood culture and tip in the absence of a peripheral blood culture; colonised CVC was defined as a positive tip and negative blood culture.
A total of 33 CVCs were replaced for: clinical suspicion of a CRBSI (64%); duration of use (24%); incidental positive blood culture (9%); and clinical evidence of catheter site infection (3%). Ninety-one per cent of CVC tips were sent for culture. Fifty-eight per cent of cases had paired blood cultures sent. The incidence of antimicrobial therapy at the time of blood sampling was 85%. Only a single CVC replacement (3%) was associated with a confirmed CRBSI. By contrast, the incidence of possible CRBSI was greater (45%).
Clinical suspicion of CRBSI was associated with infrequent microbiological confirmation. The impact of antibiotic therapy on diagnostic sensitivity is unknown. The incidence of possible CRBSI was much greater; we believe this entity encompasses unknown proportions of both colonised CVCs and CRBSI. The widely used definitions of CRBSI probably therefore underestimate the true incidence: this limits their utility to describe a parameter that may benchmark different ICUs and drive quality improvement processes within an ICU. We propose that both confirmed and possible CRBSI rates should be recorded as (different) surrogates for the true rate. Finally, this illustrates the shortcomings of assessing outcomes (CRBSI rate). Measuring adherence to quality control processes (care bundles) may be a better comparator.
J Hosp Infect 2007, 65S:S1-S64. Publisher Full Text