Peritonitis and exit site infection in dialysis in exam point of view in easy
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Peritonitis & Exit Site Infection in Peritoneal Dialysis (PD) - Exam Notes
PERITONEAL DIALYSIS-ASSOCIATED PERITONITIS
Background / Why It Happens
- Most common reason for discontinuation of CAPD
- Caused by skin organisms migrating along the Tenckhoff catheter (NOT endogenous gut flora like in secondary peritonitis)
- Route: inadvertent contamination during bag exchange, OR extension from an exit site/tunnel infection
- Usually monomicrobial (polymicrobial = think bowel perforation/fistula)
Causative Organisms (High-Yield Order)
| Rank | Organism | Notes |
|---|---|---|
| #1 | Staphylococcus spp. (~45%) | Coag-negative staph historically most common, but decreasing |
| S. aureus | More common in nasal carriers; #1 in exit-site infections | |
| ~30% | Gram-negative bacilli | E. coli, Klebsiella, Pseudomonas |
| Rare | Fungi (Candida) | Usually refractory - mandates catheter removal |
| 10-20% | No organism identified | Culture-negative peritonitis |
Key rule: Polymicrobial organisms = rule out secondary peritonitis (bowel perforation)
Clinical Features
- Cloudy dialysate - often the first/only sign noticed by the patient
- Diffuse abdominal pain
- Fever (not always present)
- Nausea, vomiting, hypotension in severe cases
Diagnosis
The 3 criteria (any 2 of 3 = diagnosis):
- Symptoms - abdominal pain, cloudy effluent
- Cell count - dialysate WBC > 100 cells/μL with > 50% neutrophils (PMNs)
- Positive culture of dialysate fluid
Exam tip for APD patients: If dwell time is short, the absolute WBC count may not reach 100 - use PMN % > 50% as the key criterion instead.
Culture method: Use blood culture bottles (improves yield). Centrifuge several hundred mL of dialysis fluid before culturing.
Treatment
Empirical intraperitoneal (IP) antibiotics - covers gram-positive AND gram-negative:
| Setting | Choice |
|---|---|
| Standard (low MRSA area) | Cefazolin (gram+) + Ceftazidime or fluoroquinolone (gram-) |
| High MRSA prevalence | Vancomycin instead of cefazolin |
| Severe illness / exit-site infection | Include vancomycin regardless |
| Fungal peritonitis | Remove catheter immediately |
- Loading doses given IP, then:
- Continuous (with every exchange), OR
- Intermittent (once daily, dwell at least 6 hours)
- Duration: 14 days standard; 21 days if exit-site/tunnel infection present
If no response in 48-96 hours - repeat cultures and consider catheter removal
Indications for Catheter Removal
- No response after 48-96 hours
- Fungal peritonitis (remove immediately)
- Tuberculous peritonitis
- Concomitant tunnel/exit-site infection
- Repeated peritonitis from same organism
- Poor response to antibiotics
After removal: switch to hemodialysis, wait for full clearance, then re-insert new catheter
Complications of Repeated Peritonitis
- Permanent alteration of peritoneal membrane permeability
- Intraabdominal adhesions
- Peritoneal membrane failure - requires permanent switch to hemodialysis
EXIT SITE INFECTION (ESI)
Definition & Diagnosis
- Clinically diagnosed: marked erythema, discharge (especially purulent), crusting, swelling, pain at catheter exit site
- A scoring system exists (points for crusting, swelling, pain, discharge) - purulent discharge always mandates treatment
Most Common Organism
- S. aureus (most common by far)
- Pseudomonas aeruginosa (hardest to treat)
Progression
Exit Site Infection → Tunnel Infection → Peritonitis
Tunnel infection signs:
- Repeated peritonitis caused by same organism
- Difficult to detect clinically - use ultrasound to look for fluid collection around catheter
Treatment of ESI
| Situation | Treatment |
|---|---|
| Standard ESI (no MRSA/Pseudomonas history) | Oral penicillinase-resistant penicillin (cloxacillin/dicloxacillin/flucloxacillin) OR first-gen cephalosporin |
| MRSA ESI | Systemic vancomycin |
| Gram-negative organism | Ciprofloxacin 500-750 mg OD orally |
| Pseudomonas ESI | Two antibiotics, extended course |
| Systemically ill | IV antibiotics until improvement |
| Tunnel infection | Hospitalization + parenteral antibiotics + urgent catheter removal |
Duration:
- Minimum 2 weeks
- 3 weeks for Pseudomonas
If no improvement at 7 days - do ultrasound of tunnel (look for fluid = tunnel infection)
If not healed at 4 weeks - consider shaving/exteriorizing the outer cuff
If infection persists/relapses - catheter removal (high risk of progressing to peritonitis)
Prevention (Exam Favourite)
- Topical mupirocin at exit site - strongest evidence for preventing S. aureus ESI
- Topical gentamicin also used (but watch: increased ESI from Enterobacteriaceae, Pseudomonas, non-tuberculous mycobacteria after switching from mupirocin to gentamicin)
- Prophylactic IV vancomycin + oral nystatin/fluconazole at catheter insertion
- Modern Y-set disconnect system - reduced peritonitis rate from 1 episode/9 months to 1 episode/24 months
- APD (automated PD) use and longer patient training periods also reduce rates
QUICK COMPARISON TABLE
| Feature | Peritonitis | Exit Site Infection |
|---|---|---|
| Key symptom | Cloudy dialysate + abdominal pain | Erythema/discharge at exit site |
| Diagnostic cut-off | WBC >100/μL, >50% PMNs | Clinical (scoring system) |
| Most common bug | Coag-negative Staph / S. aureus | S. aureus |
| Route | Skin → catheter → peritoneum | Direct skin flora at exit site |
| Treatment route | Intraperitoneal antibiotics | Oral antibiotics (usually) |
| Duration | 14 days (21 if tunnel involved) | Min 2 weeks (3 for Pseudomonas) |
| Fungal → | Immediate catheter removal | - |
| Worst complication | Membrane failure → switch to HD | Tunnel infection → peritonitis |
HIGH-YIELD EXAM FACTS (1-LINERS)
- Peritonitis = #1 reason CAPD is discontinued
- Cloudy dialysate = first sign of peritonitis
- Diagnosis: WBC > 100/μL + >50% PMNs + positive culture (any 2 of 3)
- Single organism = CAPD peritonitis; multiple organisms = think bowel perforation
- Culture method = blood culture bottles + centrifuge fluid
- No culture growth in 10-20% of cases
- Fungal peritonitis = immediate catheter removal
- No response at 48-96 h = reconsider catheter removal
- ESI #1 bug = S. aureus; hardest to treat = Pseudomonas (needs 2 antibiotics, 3 weeks)
- Prevention: mupirocin topically at exit site
- Nasal S. aureus carriage = risk factor for both ESI and peritonitis
Sources: Harrison's Principles of Internal Medicine 22E; Comprehensive Clinical Nephrology 7E; Rosen's Emergency Medicine; Goldman-Cecil Medicine
Peritonitis and exit site infection in dialysis in exam point of view in easy way for exam theory 100 words
Peritonitis & Exit Site Infection in PD - Exam Theory (Short Answer)
PERITONITIS IN PERITONEAL DIALYSIS
Definition: Infection of peritoneal cavity in patients on CAPD/APD.
Most common reason for stopping CAPD.
Cause: Skin organisms travel along Tenckhoff catheter.
Commonest bug: Staphylococcus (coag-negative staph + S. aureus = ~45%)
Diagnosis (any 2 of 3):
- Cloudy dialysate + abdominal pain
- Dialysate WBC >100/μL, >50% neutrophils
- Positive dialysate culture (use blood culture bottles)
Treatment: Intraperitoneal (IP) antibiotics for 14 days
- Cefazolin + Ceftazidime (empirical)
- Use Vancomycin if MRSA suspected
Remove catheter if: Fungal peritonitis, no response at 48-96 hrs, tunnel infection, same bug recurring.
EXIT SITE INFECTION (ESI)
Signs: Redness, swelling, purulent discharge at catheter exit site.
Commonest bug: S. aureus
Hardest to treat: Pseudomonas (needs 2 antibiotics, 3 weeks)
Treatment: Oral cloxacillin / cephalosporin for minimum 2 weeks
Prevention: Topical mupirocin at exit site (strongest evidence)
Danger: ESI → Tunnel infection → Peritonitis
KEY 1-LINERS
| Fact | Answer |
|---|---|
| #1 reason to stop CAPD | Peritonitis |
| First sign of peritonitis | Cloudy dialysate |
| Polymicrobial organisms | Think bowel perforation |
| Fungal peritonitis | Immediate catheter removal |
| ESI prevention | Topical mupirocin |
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