Catheter-related vs. catheter-associated blood stream infections in the intensive care unit: incidence, microbiology,...

Catheter-associated blood stream infections (CA-BSI) and catheter-related blood stream infections (CR-BSIs) differ in the degree of proof required to show that the catheter is the cause of the infection. The U.S. Centers for Disease Control and Prevention (CDC) National Healthcare Safety Network (NHSN; formerly the National Nosocomial Infections Surveillance [NNIS] group) collects data regarding CA-BSI nationally. We hypothesized that there would be a significant difference in the rates reported according to the definition.

Prospective surveillance of CA-BSI (defined as bacteremia with no extravascular source identified) is performed in all intensive care units (ICUs) at our institution and reported as the rate per 1,000 catheter-days. In January 2006, we initiated cultures of all catheter tips to evaluate for CR-BSI (defined as a catheter tip culture with >15 colony-forming units of the same microorganism(s) found in the blood culture) in the surgical, trauma-burn, and medical ICUs.

The CA-BSI rate across all ICUs for the 24-mo study period was 1.4/1,000 catheter-days. The CR-BSI rate was 0.4/1,000 catheter days, for a rate difference of 1.0 infections/1,000 catheter-days (p < 0.001 vs. CA-BSI). The pathogens identified in CA-BSI included many organisms that are not associated with catheter-related BSIs.

The CR-BSI rate is significantly lower than the CA-BSI rate. The organisms identified in CA-BSI surveillance often are not common in catheter-related infections. Reporting CR-BSI thus is a more accurate measure of complications of central venous catheter use, and this rate may be more sensitive to catheter-specific interventions designed to reduce rates of BSI in the ICU.