Antibiotic Lock Technique: Review of the Literature

Megan B. Bestul, PharmD; Heather L. VandenBussche, PharmD


Pharmacotherapy. 2005;25(2):211-227. 

In This Article

Catheter-Related Infection

Catheter-related infections are reported to occur in 2-40% of patients with indwelling devices.[5,6,7,8,9,10,11,12,13,14,15,16] Of these infections, 45-70% are caused by gram-positive bacteria, most commonly Staphylococcus aureus and coagulase-negative staphylococci, whereas gram-negative organisms account for approximately 28%.[17,18,19,20,21,22] Catheter-related infections may be classified as intraluminal or extraluminal (or outer surface contamination), including soft-tissue infections in tunneled CVCs. Endogenous microorganisms residing on the skin or in the catheter hub are the major causes of catheter infections ( Table 1 ).[23,24,25,26,27,28,29,30,31,32,33] Normal skin flora are usually responsible for infecting catheters that have been in place for less than 10 days, whereas organisms residing in catheter hubs are most likely to cause infection in catheters that have been in place longer.[34,35]

The ability of microorganisms to attach to catheters depends on properties of the catheter surface, organism, and host. Factors that determine catheter adherence include the physical irregularities and charge differences of the catheter surface, the presence of host proteins (i.e., fibronectin, fibrinogen, fibrin, laminin, thrombospondin, and collagen) that act as adhesins, the ability of organisms to form "slime" or a biofilm, and the organism's hydrophobicity.[36,37]

Once a catheter is inserted into the vasculature, host proteins coat the interior and exterior surfaces of the device and serve as a site to which certain organisms bind. For example, coagulase-negative staphylococci bind to fibronectin, S. aureus binds to fibronectin and fibrinogen, and Candidaalbicans binds to fibrin.[38,39,40] Micro-organisms that are bound within these complex matrixes of host proteins are difficult to eradicate since antimicrobials do not penetrate well into areas surrounded by fibrin or similar complex proteins. Microorganisms that infect catheter surfaces may produce slime consisting of fibrous glycocalyx or microbial biofilm composed of exopolysaccharides, or they may "free-float" over the catheter surface. Bacteria that produce a biofilm are more resistant to antibiotics, in particular glycopeptides, because of the relative inability of drugs to penetrate this film.[23,24,25,41,42] In addition, these organisms are not affected by phagocytes or antibodies produced by the host.[36,37]

When medical management is selected for the treatment of catheter-related infections as opposed to device removal, therapy usually consists of systemic antimicrobial administration through the infected line. Systemic treatment alone is often not sufficient to eradicate organisms from infected catheters and may lead to eventual device removal. In an attempt to improve organism eradication rates and prevent removal of permanent and semipermanent indwelling vascular devices, antibiotic lock technique has been used alone and in conjunction with systemic antibiotics for the prevention and treatment of intraluminal infections of a CVC. Guidelines from the Infectious Diseases Society of America and the Centers for Disease Control and Prevention- Healthcare Infection Control Practices Advisory Committee include use of antibiotic lock technique as a therapeutic option for intraluminal infections where the device is not removed and, although not routine, as prophylaxis for CVC infection in select patient populations.[43,44]