PD-Related Peritonitis

The contract between this chapter and the reader. If you can do all eight, the chapter has succeeded.

1. 1. Diagnose PD-related peritonitis from the diagnostic triad and obtain effluent samples correctly before any antibiotic is given.
2. 2. Prescribe empiric intraperitoneal antibiotics that cover both gram-positive and gram-negative organisms, by the correct route and dosing mode.
3. 3. Distinguish refractory, relapsing, recurrent, and repeat peritonitis, and state how each label changes the plan.
4. 4. Tailor organism-directed therapy and treatment duration once culture and sensitivity return.
5. 5. Decide when catheter removal is indicated and act within the correct time window rather than persisting with antibiotics.
6. 6. Explain the routes by which organisms reach the peritoneum and link each route to a specific prevention strategy.
7. 7. Interpret effluent cell count, differential, and Gram stain to guide immediate management.
8. 8. Construct a peritonitis-prevention plan for a PD programme, including exit-site care and procedural prophylaxis.

A sixty-second reading. Each bullet stands alone.

• Cloudy effluent is peritonitis until proven otherwise; treat it as such while the workup runs.
• Diagnosis needs two of three: clinical features, effluent white-cell count above 100 cells/µL with more than half neutrophils, and a positive culture.
• Sample the effluent — cell count, differential, Gram stain, culture — before the first antibiotic, and inoculate blood-culture bottles to lift the yield.
• Start empiric intraperitoneal antibiotics covering gram-positive (a glycopeptide or first-generation cephalosporin) and gram-negative (a third-generation cephalosporin or an aminoglycoside) the moment samples are taken.
• The intraperitoneal route is first-line; it delivers high local drug concentration and outperforms intravenous-only therapy for most episodes.
• Minimum duration is two weeks; three weeks for Staphylococcus aureus, Pseudomonas, and enterococci.
• Refractory peritonitis — effluent not clearing after five days of appropriate antibiotics — is the trigger for catheter removal, not for more antibiotics.
• Fungal peritonitis means prompt catheter removal plus an antifungal; antifungals alone with the catheter in place is a losing strategy.
• Multiple enteric organisms or anaerobes point to an intra-abdominal source; get a surgical review.
• Give antifungal prophylaxis during every antibacterial course to prevent secondary fungal peritonitis.
• Catheter loss after fungal peritonitis is roughly 9 in 10 episodes; after coagulase-negative staphylococci it is roughly 1 in 10.
• Death follows about 3 in 100 episodes overall, and more often when the organism is gram-negative, enteric, or fungal.
• Most prevention is mechanical and behavioural: aseptic exchange technique, exit-site topical antibiotic, treating contamination promptly, and prophylaxis before catheter insertion and gut or dental procedures.

The medical core. An expert should agree peritonitis is fully covered by this level alone.

What is it

Peritonitis is infection and inflammation of the peritoneal cavity in a patient on peritoneal dialysis, recognised at the bedside by cloudy effluent with or without abdominal pain. It is the dominant infectious complication of PD and the leading cause of catheter loss and technique failure — the single problem that most often ends a patient's time on the therapy.

• The working diagnosis requires at least two of three findings: clinical features (pain, cloudy bag); effluent white-cell count above 100 cells/µL after a dwell of at least two hours, with more than 50% polymorphonuclear neutrophils; and a positive effluent culture.
• A programme's culture-negative rate should sit below 15%; a higher rate signals a sampling or laboratory problem, not unusually fastidious organisms.

Why does it happen

• Intraluminal (touch contamination). Skin organisms — most often coagulase-negative staphylococci — enter the catheter lumen during an exchange when technique lapses. This is the classic, usually antibiotic-responsive episode.
• Periluminal. Organisms track from a colonised or infected exit site and tunnel down the outside of the catheter; Staphylococcus aureus and Pseudomonas dominate here, and the catheter itself is the reservoir.
• Transmural (enteric). Bowel organisms cross the wall in diverticulitis, ischaemia, or perforation, producing polymicrobial enteric peritonitis that signals an intra-abdominal source.
• Catheter biofilm. A polysaccharide biofilm on the catheter shelters organisms from antibiotics and from host defences, and is the mechanical reason relapsing and refractory episodes do not clear until the catheter comes out.
• Impaired local defence. Conventional dialysate — acidic pH, high glucose, glucose-degradation products — blunts peritoneal neutrophil and macrophage function, lowering the inoculum needed to establish infection.

How does it present

• Cloudy effluent is the cardinal and earliest sign, often preceding pain; patients are trained to inspect every drained bag.
• Abdominal pain is usual but variable in severity; diffuse pain with rebound or guarding raises the possibility of a surgical abdomen.
• Fever, nausea, and reduced ultrafiltration may accompany it; frank sepsis is uncommon but defines an emergency when present.

What else could it be

• Chemical or eosinophilic peritonitis: cloudy effluent with eosinophil predominance, often after a new catheter or icodextrin exposure, culture-negative and self-limiting.
• Fibrin or chyle: a cloudy bag that is sterile on analysis; fibrin is common early after insertion and is not infection.
• Haemoperitoneum: blood-stained rather than turbid effluent, with a different differential.
• A genuinely raised cell count with neutrophil predominance moves the case back to infective peritonitis regardless of an initially negative Gram stain.

Which tests change probability or management

• Effluent cell count and differential: the pivotal test; neutrophil predominance above the 100 cells/µL threshold establishes the diagnosis within the hour.
• Gram stain: low sensitivity but high value when positive — fungal elements or gram-negative rods change the plan immediately.
• Culture: inoculating 5–10 mL of effluent directly into aerobic and anaerobic blood-culture bottles, plus centrifugation of a larger volume, gives the highest yield and the organism-directed regimen.
• Peripheral blood cultures and imaging are reserved for systemic sepsis or suspected surgical source, not routine episodes.

How is it treated, monitored, and escalated

• Begin empiric intraperitoneal antibiotics as soon as samples are taken: a glycopeptide or first-generation cephalosporin for gram-positives, paired with a third-generation cephalosporin or aminoglycoside for gram-negatives.
• Dose intraperitoneally either continuously (drug in every exchange) or intermittently (once daily in a dwell of at least six hours); intermittent dosing relies on adequate dwell time for absorption.
• Add intravenous antibiotics and treat as an emergency only when the patient is septic or systemically unstable.
• Narrow to organism-directed therapy when culture returns, and set duration by organism: two weeks for most; three weeks for S. aureus, Pseudomonas, and enterococci.
• Reassess at 48–72 hours: clinical improvement and a falling cell count confirm the regimen; no improvement prompts re-culture and a coverage review.
• Give antifungal prophylaxis (an oral antifungal such as nystatin or fluconazole) throughout the antibacterial course to prevent secondary fungal peritonitis.
• Escalate to catheter removal for refractory, relapsing, or fungal peritonitis rather than extending antibiotics.

How it is performed — sampling, administration, removal

• Effluent sampling. Use aseptic technique at the medication port; send cell count and differential, Gram stain, and culture; collect before antibiotics; inoculate blood-culture bottles with adequate volume.
• Intraperitoneal administration. Add the drug to the bag with full asepsis; allow the prescribed dwell; intraperitoneal heparin may be added when fibrin threatens catheter flow.
• Catheter removal. Remove for refractory (day-5 non-clearing), relapsing, or fungal peritonitis; do not reinsert at the same sitting — wait at least two weeks before a new catheter, bridging on haemodialysis.

Refractory, relapsing, recurrent, repeat

• Refractory: effluent fails to clear after five days of appropriate antibiotics — remove the catheter.
• Relapsing: a further episode with the same organism (or culture-negative) within four weeks of finishing therapy — implies biofilm; treat and remove/replace the catheter.
• Recurrent: a further episode with a different organism within four weeks of finishing therapy.
• Repeat: the same organism more than four weeks after finishing therapy.

Red flags and special populations

• Faeculent or polymicrobial enteric effluent, a rigid abdomen, or systemic sepsis point away from simple touch-contamination peritonitis toward a surgical source.
• In patients with recent gut or gynaecological procedures, consider a procedural source and lower the threshold for surgical review.
• Diabetic and immunosuppressed patients tolerate delay poorly; the time-to-antibiotic target is unchanged but the consequences of missing it are larger.

Evidence base

• Randomised and meta-analytic evidence supports pre-insertion antibiotic prophylaxis and exit-site topical antibiotics for prevention.
• Comparative data favour the intraperitoneal route over intravenous-only therapy for non-severe episodes, chiefly on pharmacokinetic and observational grounds.
• The five-day refractory threshold and the timing of catheter removal rest largely on observational cohorts and international consensus rather than randomised trials.
• Antifungal prophylaxis during antibacterial therapy is supported by randomised and observational reductions in secondary fungal peritonitis.

Five fully-built tables. Sources are conventions of contemporary practice; no cell is left for later.

• Table A — Diagnostic criteria and effluent thresholds.
• Table B — Empiric intraperitoneal regimen (first dose, before culture).
• Table C — Organism-directed therapy and duration.
• Table D — Classification of repeat episodes.
• Table E — Indications for catheter removal.

Table A — Diagnostic criteria and effluent thresholds

Table B — Empiric intraperitoneal regimen (first dose)

Table C — Organism-directed therapy and duration

Table D — Classification of repeat episodes

Table E — Indications for catheter removal

Visualise & Map

Causal chains, figure-ready. Each starts at a mechanism and ends at a named clinical action.

Chain 1 — Touch contamination (ends at a prevention action)

Technique lapse at exchange → skin flora enter the lumen → coagulase-negative staphylococci reach the peritoneum → neutrophil influx, cloudy effluent → ACTION: aseptic-technique retraining and prompt contamination management.

Chain 2 — Biofilm (ends at a procedural go/no-go)

Organisms colonise the catheter → polysaccharide biofilm forms → antibiotics fail to penetrate → effluent does not clear / relapses → GO/NO-GO: remove the catheter rather than extend antibiotics.

Chain 3 — Enteric translocation (ends at surgical action)

Diverticulitis or ischaemia breaches the bowel wall → multiple enteric organisms enter → polymicrobial peritonitis with a surgical abdomen → ACTION: surgical review and source control, not antibiotics alone.

Chain 4 — Impaired local defence (ends at a therapeutic action)

Acidic, high-glucose dialysate → neutrophil and macrophage function blunted → lower inoculum establishes infection → ACTION: minimise episodes through prophylaxis and consider biocompatible solutions.

Chain 5 — Membrane injury (ends at a long-term decision)

Repeated peritonitis → mesothelial injury and fibrosis → ultrafiltration failure and EPS risk → ACTION: count episodes as a technique-survival metric and escalate prevention after recurrence.

Numbered rules, executable under time pressure. These numbers are the cross-reference handle for the cases and flowcharts.

Clinical Reasoning

Five cases. Each stops you at a decision before it tells you the answer.

Every mechanism from Level 3 earns a bedside consequence and an action.

Exhaustive, not a highlights reel. Every threshold and rule that appears anywhere in the chapter is here.

Safety & Evidence

Panel A — Red flags

Panel B — NEVER DO

Anti-patterns clinicians actually fall into. Each becomes a distractor in Level 22.

The grade reflects the strength of evidence behind each statement, not its importance.

Patient Decisions

Outcomes as natural frequencies a clinician and patient can act on. Figures are representative of contemporary cohorts; ranges vary by programme.

Apply & Test

Copy-paste chart notes that map to the real decisions in this chapter. Included because peritonitis generates notes clinicians actually write.

Template 1 — Peritonitis diagnosis and initial management note

• Presentation: cloudy effluent ± pain; dwell time of sampled bag ___ h.
• Effluent: WBC ___ /µL; PMN ___ %; Gram stain ___; cultures sent (bottles inoculated: yes/no).
• Diagnostic criteria met: ___ of 3.
• Empiric IP antibiotics started at ___ : gram-positive agent ___ ; gram-negative agent ___.
• Antifungal prophylaxis started: yes/no. IP heparin added: yes/no.
• Plan: reassess at 48–72 h; patient educated; technique reviewed.

Template 2 — Organism-directed therapy and monitoring note

• Organism: ___ ; sensitivities: ___.
• Directed regimen: ___ ; route IP/IV; duration planned ___ weeks.
• 48–72 h response: effluent clearing yes/no; repeat WBC ___ /µL.
• Classification if repeat event: refractory / relapsing / recurrent / repeat.
• Escalation decision: continue / re-culture / remove catheter.

Template 3 — Catheter-removal decision note

• Indication: refractory (day 5) / relapsing / fungal / enteric-surgical / refractory exit-site.
• Effluent status at decision: WBC ___ /µL; organism ___.
• Plan: remove catheter; bridge to haemodialysis; continue antimicrobial ___.
• Reinsertion: earliest date (≥2 weeks if refractory/fungal) ___.

Pre-rounds compression. Numbers and rules only.

Active recall. At least one card per objective.

Micro-teaching for rounds. Two scenarios, five steps each.

Metacognition anchored to this chapter's tensions. No answers provided.

1. 1. Why does the five-day refractory threshold rest on consensus rather than randomised evidence, and how should that uncertainty shape how firmly you hold to it?
2. 2. How would you explain to a reluctant patient that removing the catheter is treatment, not failure?
3. 3. What features at the bedside would move you from “routine catheter episode” to “surgical abdomen”, and how early can you detect them?
4. 4. When your programme's culture-negative rate climbs above 15%, what parts of the sampling pathway would you audit first?
5. 5. How do the routes of infection in this chapter map onto the specific prevention steps your unit already uses — and where are the gaps?

Ten items, each anchored in this chapter's own traps. At least one per objective.