Antibiotic Lock Solutions in the Prevention of Catheter Related Bacteremia

Scope of the problem. A large number of hemodialysis patients in this country rely on indwelling tunneled and non-tunneled catheters as vascular access for hemodialysis even though the K/DOQI guidelines discourage their use. In a study performed by ESRD network 11, [to which all Michigan dialysis centers submit data] 63% of patients initiated HD with a catheter as their sole form of vascular access. At 6 months after initiation of HD, 40% of these patients were still using a catheter. Other studies had shown that the prevalence of overall catheter use to be around 20% of all accesses.

Catheter associated infection. Current literature indicates that these catheters are associated with a disproportionate risk for infection, particularly CRB, resulting in high morbidity, mortality and healthcare expenditure. The 'epidemic' of ESRD in this country has seen an ever increasing reliance on these catheters not only to initiate the HD but also for long term treatment in those patients who have no other access options. It has been estimated that intravascular catheters are associated with more than 60,000 cases of nosocomial bacteremia each year. HD catheters pose a particularly high risk for developing infections because of their frequent use as well as their long-term use. All indwelling vascular catheters are colonized by micro-organisms within 24 hours after insertion. The deposition of biofilm on the external and internal surface of vascular catheters is thought to play an important role in the colonization process. The biofilm is produced by a combination of host factors (e.g., fibrinogen, fibrin, fibronectin and extracellular polysaccharides) and microbial products (e.g., glycocalyx or "slime").

Failure of antibiotics. Systemic antibiotics used to treat bacteremia do not penetrate catheter lumen and therefore do not eradicate the biofilm, leading to potential treatment failures and eventual sacrifice of the catheter. Recently published data suggests that using a combination solution with antibacterial/anticoagulant agents prevents the formation of the 'biofilm' in the catheter lumen thereby preventing CRB, as well as salvage the catheters in cases of established CRB. However, there continues to be a debate on the appropriate antibacterial agent as well as its optimal concentration, in order to eradicate a wide variety of organisms. Several other strategies were studied in the past 10 years to prevent CRB and CRI. These include eradication of nasal Staphylococcal carriage with mupirocin, using chlorhexidine for catheter hub cleaning and exit site disinfection and using mupirocin or Polysporin ointments to the exit site along with standard dressing. But emergence of antibiotic resistance as well as the high costs of administrating these methods continue to be barriers to their widespread use and cannot be relied upon to manage the high rate of infection by themselves.

Salvaging catheters. In the past, infected catheters were routinely removed, especially for Staphylococcus aureus infections, per the CDC guidelines. However, recent small studies indicate that strategies such as ALS packing or changing catheter over a guide wire can salvage a significant fraction of these catheters, thereby saving expense and morbidity, and preserving the site. Thrombotic occlusions and infection are the two most common complications of the HD catheters, each predisposing to the other. Some studies have shown that ALS packing has also improved the long-term catheter function by preventing the formation and propagation of the biofilm. Studying this aspect of catheter maintenance is also an important outcome for our proposed study.

Antibiotic Lock Solutions. We have identified 10 clinical trials (attached as appendix) in the published literature describing the results of antibiotic lock therapy for preventing infections in indwelling vascular catheters. All but one have demonstrated efficacy of ALS packing. Of the 9 successful trials, only 6 were randomized controlled trials and only 3 of these were done on HD catheters, as described below.