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EPIDEMIOLOGY

Key Clinical Questions

  • image How are catheter-related infections diagnosed?

  • image What are the potential complications of catheter-related infection?

  • image What is the appropriate management of catheter-related infection?

  • image When is it appropriate to attempt salvage of an infected intravascular catheter?

  • image How can catheter-related infections 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 41,000 central line associated bloodstream infections (CLABSI) occurred in 2009, of which 18,000 were in the intensive care units (ICUs). Although these numbers represent an almost 50% reduction from the previous decade, CLABSIs are still associated with prolonged hospitalization up to 3 weeks, cost about $50,000 per episode, and continue to have an attributable mortality of 14% to 40%. CLABSI rates are now publically reported in the United States, and may be used as a basis to deny payment claims by the Centers for Medicare and Medicaid Services (CMS).

Staphylococci, including Staphylococcus epidermidis and Staphylococcus aureus, cause more than two-thirds to 90% of all CLABSI. Other infecting organisms include enteric Gram-negative rods, Pseudomonas aeruginosa, and Candida species. Less common pathogens include Serratia marcescens, Enterobacter species, Burkholderia cepacia complex, Citrobacter freundii, atypical mycobacteria, among others.

PATHOPHYSIOLOGY

Infections of vascular catheters arise from bacterial biofilm, comprised of bacteria embedded within an extracellular polysaccharide matrix on the catheter surface (Figure 188-1). 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.

Figure 188-1

Electron micrograph showing S. 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 and can demonstrate resistant phenotypes, 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, some antibiotics have ...

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