How are catheter-related infections diagnosed?
What are the potential complications of catheter-related infection?
What is the appropriate management of catheter-related infection?
When is it appropriate to attempt salvage of an infected intravascular catheter?
How can catheter-related infection be prevented?
Indwelling vascular catheters are the most common cause of nosocomial bloodstream infections. They are particularly common among critically ill patients, hemodialysis-dependent patients, and persons receiving chemotherapy or total parenteral nutrition. In the United States, approximately 80,000 central venous catheter (CVC)-related bloodstream infections occur each year in intensive care units (ICUs). These infections prolong hospitalization by 7.5 to 22 days, cost in excess of $20,000 per episode, and have an attributable mortality of 11.5% to 35%.
Staphylococci, including Staphylococcus epidermidis and Staphylococcus aureus, cause more than two-thirds to 90% of all catheter-related bloodstream infections (CRBSIs). Other infecting organisms include enteric gram-negative rods, Pseudomonas aeruginosa, and Candida species. Less common pathogens include Serratia marcescens, Enterobacter species, Burkholderia cepacia complex, and Citrobacter freundii.
Infections of vascular catheters arise from bacterial biofilm, comprised of bacteria embedded within an extracellular polysaccharide matrix on the catheter surface (Figure 196-1). Bacterial biofilm may develop as early as 24 hours after catheter placement. As shown by electron microscopy, biofilm forms on the external surface of short-term catheters that have been in place for < 10 days, and may be found on the luminal surface of long-term catheters that have been in place for ≥ 10 days.
Electron micrograph showing Staphylococcus aureus bacteria embedded in biofilm on the luminal surface of an intravenous catheter. (Public Health Image Library, Centers for Disease Control and Prevention, Rodney M. Donlan, PhD and Janice Carr.)
The first step in biofilm formation is the binding of free-floating, or planktonic, organisms to the catheter surface by cell wall–associated adhesins. This is facilitated by the formation of a film of host fibrin and fibronectin on the catheter surface. Other factors favoring attachment include hydrophobic and electrostatic forces, cell surface structures such as pili or fimbriae, platelet binding, and shear stress from the fluid environment. Attached organisms multiply to form microcolonies and secrete an extracellular polysaccharide matrix that forms the architectural structure of the biofilm. Bacteria embedded in biofilm typically have a lower metabolic rate, making them less susceptible to the effects of antibiotics; the minimal inhibitory concentrations of microorganisms in biofilm can be up to 1000-fold higher than for planktonic organisms. Additionally, antibiotics have difficulty penetrating biofilm. This explains why biofilm-based infections are difficult to eradicate without removal of the infected device.
Catheter infection may arise by several routes. The external catheter may become colonized by skin flora during insertion, or subsequent migration of skin organisms along the catheter surface. Luminal colonization occurs when microorganisms are introduced through the hub of the catheter. The risk of luminal infection increases with ...