Empiric Antibiotics for Peritoneal Dialysis Catheter Exit Site Infections
For peritoneal dialysis catheter exit site infections, empiric antibiotic therapy should include vancomycin for gram-positive coverage plus an agent for gram-negative coverage such as ceftazidime or gentamicin, with subsequent tailoring based on culture results. 1
First-Line Empiric Therapy Options
Option 1: Gram-positive + Gram-negative Coverage
- Vancomycin: 20 mg/kg loading dose followed by 500 mg during each subsequent dialysis session
PLUS one of the following for gram-negative coverage:
- Ceftazidime: 1 g IV after each dialysis session 1
- Gentamicin: 1 mg/kg (not to exceed 100 mg) after each dialysis session 1, 2
Option 2: Oral Regimen (for less severe infections)
- Ciprofloxacin: 500 mg orally twice daily (administer 2 hours after any phosphate binders or iron supplements) 3
Antibiotic Selection Considerations
Gram-positive Coverage
- Staphylococcus aureus and coagulase-negative staphylococci are common causative organisms for exit site infections 4
- Vancomycin is preferred in settings with high MRSA prevalence 1, 2
- For institutions where MRSA isolates have vancomycin MIC values >2 μg/mL, consider alternative agents such as daptomycin 1
Gram-negative Coverage
- Pseudomonas aeruginosa is a particularly concerning gram-negative pathogen in exit site infections, with a high rate of catheter removal (28%) 4
- For suspected Pseudomonas infection, ceftazidime is particularly effective 5
- Empirical coverage should be based on local antimicrobial susceptibility patterns 1
Special Considerations
Mycobacterial Infections
- Consider atypical mycobacteria in cases of exit site infections that fail to respond to conventional antibiotics
- For suspected mycobacterial infections, consider adding clarithromycin and/or a fluoroquinolone to the regimen 6
Fungal Infections
- For suspected fungal exit site infections, consider an echinocandin (caspofungin, micafungin, or anidulafungin) or fluconazole 1
- Catheter removal is typically necessary for fungal exit site infections 4
Antibiotic Administration
Intravenous Administration
- Vancomycin should be administered during the last hour of dialysis or post-dialysis to prevent significant drug removal 2
- Monitor vancomycin levels with target pre-dialysis levels of 10-20 μg/mL for most infections 2
- Administer vancomycin slowly (over 60 minutes) to minimize infusion-related events 7
Antibiotic Lock Therapy (as adjunctive treatment)
For persistent or recurrent exit site infections, consider antibiotic lock therapy with:
- Vancomycin: 2.5-5.0 mg/mL with 2500-5000 IU/mL heparin
- Cefazolin: 5.0 mg/mL with 2500-5000 IU/mL heparin
- Gentamicin: 1.0 mg/mL with 2500 IU/mL heparin 1, 2
Duration of Therapy
- Continue antibiotics for at least 2 weeks or until resolution of signs and symptoms 1
- For exit site infections associated with tunnel involvement, longer therapy (3-4 weeks) may be required 1
Monitoring and Follow-up
- Obtain follow-up cultures to ensure eradication of the infection
- Monitor for vancomycin toxicity, including nephrotoxicity (defined as an increase in serum creatinine of 0.5 mg/dL or 150% from baseline) 2
- For patients receiving aminoglycosides, monitor for ototoxicity 2
Common Pitfalls and Caveats
- Failure to cover both gram-positive and gram-negative organisms empirically
- Inadequate dosing of antibiotics in the dialysis setting
- Delayed recognition of tunnel involvement, which requires more aggressive therapy
- Failure to consider atypical organisms (mycobacteria, fungi) in non-responsive cases
- Not adjusting therapy based on culture results and antibiotic susceptibilities
- Administering vancomycin before dialysis, which significantly reduces drug efficacy
Remember that approximately 20% of all peritonitis cases are preceded by an exit site infection, with up to 50% of Staphylococcus aureus peritonitis associated with exit site infections 4. Therefore, prompt and appropriate treatment is essential to prevent progression to peritonitis.