ArticlesRapid diagnosis of central-venous-catheter-related bloodstream infection without catheter removal
Introduction
Central venous catheterisation is essential for the intensive management of both medical and surgical patients. An estimated 5 million central venous catheters (CVC) are used in the USA alone each year, a figure likely to increase as care of patients becomes more specialised and intensive.1 Complications of catheterisation include those associated with catheter insertion (pneumothorax and arterial and nerve injuries) and those associated with long catheter use (thrombosis and infection). CVC infection encompasses many definitions that may or may not represent a clinical concern. Catheter-related bloodstream infection is the most serious infection associated with catheters and occurs in 3–7% of patients with CVC; it is simply defined as peripheral bacteraemia caused by the same microorganism as cultured from the catheter.2 Conventional methods to diagnose catheter-related bloodstream infection generally require that the catheter is removed so that the microorganisms colonising it can be cultured. However, in up to 85% of patients the culture is negative, despite clinical suspicion of catheter-related infection.3, 4 Furthermore, culture results for peripheral blood and CVC are not available for at least 24 h, and hence even in-situ methods, such as quantitative blood cultures and endoluminal brushing, require clinicians to make empirical judgments on the need for CVC removal. Therefore, there is a need for a rapid method to diagnose catheter-related bloodstream infection that does not require removal of the catheter. The gram stain and acridine-orange leucocyte cytospin (AOLC) test, done on blood samples withdrawn through the CVC, is effective in the rapid diagnosis of bloodstream infection in neonates,5 but has yet to be proven in adults. This technique has the potential for both the rapid detection of microorganisms (bacteria or fungi), and permits early gram-stain classification of pathogens, allowing targeted antibiotic therapy. This study aimed to assess the accuracy of the gram stain and AOLC test in the detection of catheter-related bloodstream infection in a predominantly adult surgical population.
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Methods
Between January, 1996, and December, 1997 we reviewed surgical patients with CVC every day for clinical signs of catheter-related bloodstream infection (temperature >37°C, white-blood-cell count >11×109/L, or evidence of infection at the site of catheter skin entry). The presence of other sources of infection was noted, but this diagnosis was not used to exclude the catheter as a potential source of infection. The type of CVC, duration of catheterisation, site of catheter insertion, and the
Results
128 cases of suspected catheter-related bloodstream infection were assessed in 124 adult surgical patients. In 16 (13%) cases we were not able to obtain throughcatheter blood samples and have subsequently excluded these from the analysis. The implicated catheters were 20 single-lumen lines, seven Hickman catheters, nine double-lumen renal-dialysis catheters, and 76 triplelumen catheters. 80% of these catheters had been used to deliver total parenteral nutrition. The median duration of CVC
Discussion
Bloodstream infection is associated with a significant degree of morbidity; case mortality of catheter-related bloodstream infection is 10–20%.9 There has been an increase of two to three fold in primary nosocomial bloodstream infections in the past decade,10 most caused by CVC. Such a large number of cases has large medical and financial implications for health-care institutions, with cost estimates of $28 000–40 000 for each case of bloodstream infection.11, 12 Since most CVC removed after
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