What is Antibiotic Lock Therapy?

Antibiotic Lock Therapy (ALT)

Antibiotic lock therapy is a technique for treating and preventing catheter-related bloodstream infections (CRBSIs) by instilling high concentrations of antibiotics into the catheter lumen for extended periods, typically used in conjunction with systemic antibiotics to salvage long-term catheters when removal is not desirable. 1

Definition and Mechanism

• ALT involves filling the catheter lumen with supratherapeutic concentrations of antibiotics (100-1000 times greater than systemic levels) and leaving them indwelling for hours or days to eradicate intraluminal biofilm-associated bacteria 1
• The technique targets the fact that most infections in long-term catheters originate in the catheter hub and spread to the lumen, creating biofilms that are difficult to treat with conventional systemic antibiotics 1
• Antibiotic concentrations must be 100-1000 times greater to kill sessile bacteria within a biofilm than to kill planktonic (free-floating) bacteria 1

Clinical Applications

• ALT is indicated primarily for patients with CRBSI involving long-term catheters with no signs of exit site or tunnel infection where catheter salvage is the goal 1
• Most effective for intraluminal infections in catheters that have been in place for more than 2 weeks 1
• Should always be used in conjunction with systemic antimicrobial therapy for 10-14 days, not as standalone treatment 1
• Particularly useful for coagulase-negative staphylococcal infections, which respond better to ALT than S. aureus or Pseudomonas aeruginosa infections 1

Efficacy and Success Rates

• Success rates vary by pathogen:
  • 87-100% for gram-negative pathogens 1
  • 75-84% for Staphylococcus epidermidis 1
  • Only 40-55% for S. aureus infections 1
  • Poor results with fungal infections (70% failure rate) 1
• In clinical trials, ALT resulted in significantly higher catheter salvage rates (77% success) compared to standard parenteral therapy alone (67% success) 1

Practical Implementation

• ALT solutions typically contain:
  • High concentration antibiotic (e.g., vancomycin 5 mg/mL for staphylococci) 1
  • Anticoagulant (typically 50-100 units of heparin or normal saline) 1
  • Volume sufficient to fill the catheter lumen (usually 2-5 mL) 1
• Dwell times should not exceed 48 hours before reinstallation of lock solution; preferably every 24 hours for ambulatory patients with femoral catheters 1
• For hemodialysis patients, the lock solution should be renewed after every dialysis session 1

Contraindications and Limitations

• Not recommended for:
  • Catheters with extraluminal infection (tunnel or exit site inflammation) 1
  • CRBSI due to S. aureus or Candida species (catheter removal recommended instead) 1
  • Short-term catheters (<2 weeks) which are typically infected extraluminally 1
• ALT alone is inadequate for extraluminal infections; parenteral therapy plus ALT would not be much better than parenteral therapy alone in these cases 1

Emerging Approaches

• Alternative lock solutions being investigated include:
  • Taurolidine-containing lock solutions which have shown efficacy in reducing CRBSI incidence in hemodialysis patients 2
  • Ethanol locks (70%) which have shown promise in pediatric CRBSI cases 1

Potential Pitfalls and Caveats

• Not all antibiotic-heparin combinations can be used due to precipitation, especially with increasing antibiotic concentrations 1
• For vancomycin, concentration should be at least 1000 times higher than the MIC (e.g., 5 mg/mL) to maintain effectiveness throughout the dwell time 1
• ALT does not eliminate the need for systemic antibiotics in most cases, particularly with S. aureus infections or in neutropenic patients 1
• Catheters that have been in place for less than 2 weeks are most often infected extraluminally, making ALT ineffective as a standalone treatment 1