Catheter-related bloodstream infections are more commonly associated with the use of central venous catheters than with small peripheral catheters. The microbes that colonize the catheter hub and the skin area surrounding the insertion site are usually the source of most catheter-related infections. Preventive strategies must be aimed at reducing microbe colonization at the insertion site and hub, and minimizing the bacterial spread extraluminally from the skin or intraluminally from the hubs toward the catheter tip lying in the bloodstream.
Mermel reviewed clinical studies of intravascular catheters described in the medical literature from 1966 to 1999 and developed recommendations for preventive strategies. Intravenous antimicrobial prophylaxis, especially with the use of vancomycin, is not recommended by the Centers for Disease Control and Prevention because of its low efficacy and the acquisition of vancomycin-resistant enterococci. Thrombus formation in patients with indwelling intravascular catheters is associated with catheter-related bloodstream infection. Very-low-dose warfarin reduces thrombosis that is associated with long-term use of central venous catheters. Prophylaxis with very-low-dose warfarin should be considered in this case. Daily administration of subcutaneous, low-molecular-weight heparin reduces the risk of catheter-related central venous thrombosis.
Although no randomized trials have assessed the risk of infection associated with catheter insertion into the subclavian, internal jugular or femoral vein, a few prospective, observational studies reveal that the risk of infection appears to be higher with internal jugular vein insertion than with subclavian vein insertion. Femoral venous catheterization appears to be more associated with deep venous thrombosis than subclavian or internal jugular insertion and should be avoided. Subcutaneous tunneling of short-term catheters may decrease the infection risk in patients when the catheter is not used for drawing blood.
Cutaneous antisepsis performed before catheter insertion should use chlorhexidine-containing antiseptics. Full sterile barrier precautions can significantly decrease the incidence of catheter-related bloodstream infection compared with standard precautions. The choice of catheter dressing type does not affect the risk of central venous catheter–related infection, but gauze dressings are preferred if blood is oozing from the catheter insertion site. Results of randomized studies assessing the efficacy of triple antibiotic ointment (e.g., polymyxin, bacitracin and neomycin) are indeterminate. On the basis of these studies, the possibility of a prophylactic effect cannot be ruled out. The use of triple antibiotic ointment has been associated with increased catheter colonization by Candida species. Application of mupirocin ointment to insertion sites for temporary hemodialysis catheters reduces the risk of catheter-related bloodstream infection with Staphylococcus aureus. However, prolonged use of mupirocin ointment has been associated with the development of mupirocin resistance. Therefore, the use of this ointment at catheter insertion sites is not recommended. Povidone-iodine ointment should be applied to the insertion site of hemodialysis catheters. Applying this ointment to the insertion site in immunocompromised patients with heavy S. aureus carriage should be considered.
Manipulation of the catheter increases the risk of catheter-related bloodstream infection. Catheter hubs and sampling ports should be disinfected with alcohol, povidoneiodine or chlorhexidine before they are accessed. Antimicrobial-coated or antimicrobial-impregnated devices and cuffs are an important preventive strategy. Benzalkonium chloride provides short-term antimicrobial activity. The efficacy of catheters impregnated with chlorhexidine and silver sulfadiazine on the outer surface reduces the risk for central venous catheter–related bloodstream infection during short-term use.
The author concludes that future prevention of catheter-related bloodstream infections may be enhanced by further study of the value of heparin on the catheter surface and the use of genetically developed antiadhesion molecules to coat the catheter and prevent the attachment of microbes. Meanwhile, much can be done to limit the incidence of intravascular catheter-related infections.
editor's note: Intravenous catheter infections are most frequently caused by S. aureus organisms that enter the bloodstream from the catheter lumen or the outside of the catheter surface. The factors most clearly associated with the increased risk of catheter-related infection include: (1) prolonged duration of placement, (2) frequent manipulation, (3) use of thrombogenic catheter materials, (4) inadequate sterile barrier protecting the catheter insertion site and (5) inadequate sterile technique during catheter insertion. Prevention of infection strategies are enhanced by skilled and careful catheter placement, maximal sterile barriers, the use of antimicrobial catheters, the use of topical antiseptics, and flushing the catheter with antimicrobial and antiatherogenic agents. The development of protocols to ensure that the proper technique is followed and that adequate catheter maintenance is performed should be a priority in all inpatient settings.—r.s.