Applied Nephrology Master Series

Chapter 11 Exit-Site and Tunnel Infections

CHAPTER MISSION Recognise catheter-related infection before superficial inflammation becomes tunnel disease or peritonitis; distinguish true exit-site infection from trauma, dermatitis, colonisation and granuloma; define the anatomical depth of infection; obtain useful microbiology; select and reassess antimicrobial treatment according to organism and response; and recognise the point at which an infected foreign body requires surgical source control rather than another antibiotic course.

Figure 11.1 — Catheter infection is a depth problem. Infection may remain at the catheter-epidermal interface, extend along one or both cuffs and the tunnel, or reach the peritoneal cavity. The deeper the reservoir, the lower the probability that antibiotics alone will achieve durable source control.

MASTER PRINCIPLE Do not treat the redness; treat the anatomical infection phenotype. Every suspected catheter infection requires four linked questions: Is this truly infection? How deep does it extend? What organism is present? Is the catheter still salvageable?

0. One-page chapter map

Table 11.1 — The eight decisions that govern PD catheter-infection care.

Decision	Core question	Bedside output
1. Confirm	Is this definitive exit-site infection or noninfectious inflammation/colonisation?	Named exit-site phenotype
2. Depth	Is disease confined to the exit site or extending along the tunnel/cuff?	ESI versus TI
3. Peritoneum	Is there cloudy effluent, abdominal pain or same-organism peritonitis?	Isolated catheter infection versus catheter-related peritonitis
4. Culture	What organism is present and is the isolate clinically meaningful?	Culture + susceptibility interpretation
5. Cover	What empiric treatment is appropriate while culture is pending?	Organism-risk-adjusted antimicrobial plan
6. Track	Is purulence, inflammation and tunnel disease resolving?	Response at approximately 1 week
7. Source control	Is the catheter now an infected foreign-body reservoir?	Preserve, salvage, replace or remove
8. Prevent	Why did infection occur and how is recurrence prevented?	Exit-site care + immobilisation + CQI

Learning outcomes

Define definitive exit-site infection using the current ISPD clinical definition.
Explain why erythema, tenderness, crusting or granuloma without purulent discharge do not alone establish definitive ESI.
Define tunnel infection and recognise when tunnel ultrasonography adds clinically useful information.
Distinguish true infection from colonisation, mechanical trauma, contact dermatitis and granulation tissue.
Perform a systematic exit-site-tunnel-peritoneum assessment.
Obtain and interpret catheter-related microbiology without treating colonisation as infection.
Select empiric treatment that covers Staphylococcus aureus while modifying treatment for prior MRSA or Pseudomonas risk and local susceptibility patterns.
Apply the 2023 ISPD response-adapted duration strategy for uncomplicated ESI.
Recognise why Pseudomonas, tunnel infection and nontuberculous mycobacteria require different management logic.
Identify refractory catheter-related infection and escalate from antimicrobial therapy to catheter source control appropriately.
Use cuff procedures, exit-site relocation, simultaneous catheter replacement and catheter removal selectively rather than interchangeably.
Build an exit-site prevention and catheter-infection surveillance programme.

EVIDENCE POSTURE The 2023 ISPD Catheter-related Infection Recommendations remain the principal adult guideline framework for ESI and TI. They clarified diagnostic definitions, introduced an overall ESI target of <=0.40 episodes/year at risk, replaced the routine fixed 2-week treatment concept with response-adapted treatment for uncomplicated ESI, retained >=3 weeks for Pseudomonas ESI and any TI, and expanded catheter-salvage options. The 2022 ISPD peritonitis guideline governs concomitant peritonitis and antifungal prophylaxis. Contemporary salvage and NTM evidence remains predominantly observational, so source-control decisions are anatomy- and patient-specific. [1–6]

1. Core concept: catheter infection is infection plus foreign-body biology

A PD catheter is not merely an opening in the skin. It is a continuous foreign body traversing the exit site, superficial cuff, subcutaneous tunnel and deep cuff before entering the peritoneal cavity. Organisms can therefore remain superficial, track inward along tissue planes, adhere to catheter material or cuff fibres, and persist within biofilm. [1,3]

This explains the clinical continuum from skin-barrier failure to exit-site infection, tunnel infection and catheter-related peritonitis. The continuum is not inevitable, but observational data show that ESI is followed by an increased risk of subsequent peritonitis, particularly in the period soon after the catheter infection. [7]

Table 11.2 — Catheter infection is three problems at once.

Problem	What is happening	Clinical question
Skin barrier failure	Trauma, colonisation or local inflammation permits microbial entry.	Is this truly infection?
Anatomical extension	Infection may spread from the exit site toward one or both cuffs.	How deep is it?
Foreign-body persistence	Catheter/cuff biofilm may prevent eradication despite in-vitro susceptibility.	Can antibiotics cure this without source control?

BEDSIDE TRANSLATION A susceptible organism plus a correct antibiotic does not guarantee cure. If infection persists, ask whether the problem is drug failure - or an infected catheter that the drug cannot sterilise.

2. Definitions: use the ISPD language precisely

Definitive exit-site infection

ISPD suggests defining definitive ESI as purulent discharge at the catheter-epidermal interface, with or without surrounding erythema. In the absence of purulent discharge, erythema, tenderness, swelling, granuloma or crust formation are insufficient by themselves to establish definitive ESI. [1]

Table 11.3 — Exit-site findings and what they mean.

Finding	Interpretation	Clinical consequence
Purulent discharge +/- erythema	Definitive ESI	Culture and treat; examine tunnel
Erythema alone	Not sufficient for definitive ESI	Consider irritation/trauma; monitor for evolution
Tenderness alone	Inflammation; cause uncertain	Assess traction, tunnel and local lesion
Granuloma without pus	Granulation/inflammation	Treat local tissue problem; do not assume infection
Crust alone	Does not define infection	Inspect after appropriate site care
Positive culture + normal site	Colonisation	Do not diagnose ESI from microbiology alone

DEFINITION DISCIPLINE Do not convert every red exit site into ESI. Conversely, erythema without pus can represent evolving early infection and deserves surveillance rather than dismissal.

Tunnel infection

Tunnel infection is defined clinically by erythema, swelling, tenderness and/or induration along the subcutaneous catheter tunnel, with or without ultrasonographic evidence of fluid surrounding the catheter. Ultrasound can support the diagnosis and define extent but is not required for the clinical definition. [1]

ESI or TI occurring within 30 days of catheter insertion is classified as catheter insertion-related infection. This quality marker helps identify problems in insertion, perioperative prophylaxis, postoperative wound care and early catheter handling. [1]

ISPD defines refractory catheter-related infection as failure to respond after 2 weeks of effective antibiotic therapy plus appropriately intensified exit-site care, or after 3 weeks when the infection is caused by Pseudomonas species. [1]

WORDING MATTERS "Two weeks of antibiotics" is not the definition. The antimicrobial must have been effective against the organism and accompanied by appropriate catheter-site care.

3. A red exit site is a differential diagnosis - not a prescription

Exit-site appearance should be interpreted relative to the patient's usual baseline. Several noninfectious processes can resemble ESI, and unnecessary antibiotic treatment creates resistance, adverse effects and fungal risk without correcting the underlying mechanical or dermatologic problem.

Table 11.4 — Red or abnormal exit site: rapid differential.

Phenotype	Typical clues	Corrective direction
True ESI	Purulent discharge +/- erythema	Culture + antimicrobial pathway
Mechanical trauma	Recent pull/twist, bleeding, tenderness, no pus	Immobilise catheter; correct traction
Contact dermatitis	Pruritus, geometric erythema, new adhesive/cleanser	Remove offending product
Granulation tissue	Friable tissue, minor bleeding, moisture	Local granuloma care; assess separately for infection
Early postoperative inflammation	Recent insertion; expected wound evolution possible	Assess timing, trajectory and surgical complications
Cuff extrusion	Visible superficial cuff, chronic local irritation	Determine whether infection coexists
Colonisation	Positive swab but clinically healthy site	Do not treat as ESI automatically

Catheter traction deserves particular attention. Repetitive movement can produce microtrauma at the epithelial interface and compromise the local barrier. ISPD therefore recommends immobilising the catheter as an infection-prevention strategy. [1]

CLINICAL PEARL If the redness exactly follows a new adhesive, cleansing product or repeated catheter pull, the diagnostic question changes from "Which antibiotic?" to "What damaged the barrier?"

4. Examine the catheter as a tract - not as a hole in the skin

The common examination error is inspecting the visible exit site and stopping. A complete catheter-infection examination moves from outside inward: catheter-epidermal interface -> superficial cuff -> full palpable tunnel -> deeper cuff region -> peritoneal symptoms and effluent.

Table 11.5 — Bedside catheter examination.

Step	What to assess	Why it matters
Look	Purulence, erythema, crust, bleeding, granuloma, visible cuff	Defines the exit-site phenotype
Palpate	Tenderness, swelling, induration	Detects occult tunnel disease
Trace	Entire catheter course	Prevents missing proximal infection
Express gently when appropriate	Drainage appearing from the tract	Supports tunnel involvement
Inspect fixation	Tension, twisting, mobile external segment	Identifies a recurring mechanical driver
Check effluent	Cloudiness +/- abdominal pain	Detects possible peritonitis

TUNNEL RULE Every definitive ESI deserves a tunnel examination. A clean tunnel cannot be assumed merely because the visible exit site appears mild.

5. Tunnel ultrasound: image a clinical question

Figure 11.2 — Tunnel ultrasound can map superficial versus deeper peri-catheter involvement and help determine whether a catheter is anatomically salvageable. A negative scan does not exclude clinically defined tunnel infection. [1,13,14]

Ultrasonography is most useful when the result can change the diagnosis, duration of treatment or source-control strategy. It can demonstrate peri-catheter fluid, localise disease around the superficial cuff and identify extension toward the deep cuff. Routine screening of an asymptomatic tunnel is not required. [1,13,14]

Table 11.6 — When tunnel ultrasound is most useful.

Clinical question	Why ultrasound helps	Management consequence
ESI + tunnel tenderness	Defines deeper extension	Reclassify as TI when appropriate
Persistent infection despite active therapy	Searches for a hidden reservoir	Moves toward source-control assessment
Pseudomonas or S. aureus with concerning examination	Detects cuff/tunnel disease	Lowers threshold for escalation
External cuff infection	Tests whether disease is truly superficial	Selects potential salvage candidate
Planning cuff/exit-site salvage	Maps remaining uninfected catheter	Avoids leaving deep infection behind
Residual focal tenderness after surface improvement	Assesses incomplete anatomical resolution	Continue/escalate rather than declaring cure

DO NOT AUTOMATE Tunnel ultrasound is not a ritual test for every catheter. Use it when the answer can change depth classification, response assessment or catheter-salvage strategy.

6. Microbiology: culture infection, not colonisation

When purulent drainage is present, obtain an exit-site swab for culture and susceptibility testing before or at antimicrobial initiation when feasible. Gram stain may be useful when there is a drainable purulent component. A positive swab from a clinically normal exit site represents colonisation rather than definitive ESI. [1]

Table 11.7 — Microbiology result -> interpretation.

Result	Clinical interpretation	Next question
S. aureus + purulent ESI	Clinically important pathogen	MRSA? tunnel involvement? recurrent source?
MRSA + ESI	Requires MRSA-active treatment	What is local susceptibility and allergy profile?
Pseudomonas + ESI	Difficult catheter pathogen	Is there occult tunnel/cuff involvement?
Corynebacterium/diphtheroid + healthy site	Colonisation may be more likely	Is there true purulence/inflammation?
Repeated diphtheroid + refractory drainage	NTM misidentification possible	Request AFB/mycobacterial studies
No growth + improving ESI	Prior antibiotic or limited yield possible	Is clinical resolution complete?
No growth + worsening disease	Atypical organism or wrong diagnosis	Repeat/special cultures and diagnostic reset

Culture-negative ESI can follow recent antibiotics, suboptimal specimen collection, slowly growing organisms, atypical mycobacteria, fungal infection or misclassification of a noninfectious lesion. [1]

MICROBIOLOGY RULE The swab identifies the organism after the clinical syndrome is established. It does not independently create the diagnosis.

7. The first visit: six tasks before the patient leaves

Figure 11.3 — A complete first visit confirms the syndrome, defines depth, obtains microbiology, checks the peritoneal compartment, starts appropriate treatment and creates an explicit reassessment point.

Table 11.8 — First-visit checklist.

Task	Bedside action	Failure if omitted
1. Confirm phenotype	Is purulent discharge present?	Overdiagnosis or missed true ESI
2. Examine tunnel	Palpate the entire subcutaneous tract	Occult TI is missed
3. Culture	Swab purulent drainage	Empiric treatment cannot be narrowed
4. Check peritoneum	Ask about pain and inspect effluent	Catheter-related peritonitis is missed
5. Treat	Use organism-risk and local microbiology	Initial coverage may be inappropriate
6. Follow	Review at approximately 1 week	Duration/failure decisions are delayed

During active ESI, ISPD suggests at least daily exit-site inspection and cleansing. The purpose is not simply hygiene; it allows recognition of worsening inflammation, tunnel extension and early treatment failure. [1]

8. Empiric therapy: cover the likely organism without losing stewardship

For a typical ESI, ISPD recommends empiric oral treatment providing appropriate S. aureus coverage, commonly with a first-generation cephalosporin or an antistaphylococcal penicillin. The empirical strategy changes when there is previous MRSA or Pseudomonas infection/colonisation, relevant allergy or resistant local microbiology. [1]

Table 11.9 — Empiric treatment reasoning.

Clinical context	Empiric priority	Do not assume
Typical uncomplicated ESI	S. aureus coverage	That every patient needs broad Gram-negative therapy
Previous MRSA	MRSA-active regimen	That a first-generation cephalosporin is adequate
Previous Pseudomonas	Antipseudomonal coverage	That surface appearance predicts depth
Severe systemic illness	Escalate beyond routine outpatient ESI pathway	That oral therapy alone is sufficient
Concomitant peritonitis	Chapter 10 regimen + source-control assessment	That ESI treatment alone treats the peritoneum
Refractory/atypical infection	Diagnostic reset and special microbiology	That another routine ESI antibiotic is the answer

Antifungal prophylaxis

The 2022 ISPD peritonitis guideline recommends antifungal prophylaxis whenever a PD patient receives an antibiotic course, irrespective of the indication. Catheter infection therefore triggers the same secondary-fungal-prevention reflex as any other antibiotic exposure. [2]

SAFETY HABIT ESI antibiotic started -> antifungal-prophylaxis decision automatically triggered. Do not cure one infection while creating avoidable fungal-peritonitis risk.

9. Duration: response determines uncomplicated ESI treatment

The 2023 ISPD update changed the old fixed-duration habit. A mandatory 2-week course is no longer required for every uncomplicated ESI. Duration should be adjusted to clinical response, culture and susceptibility. If clinical reassessment at approximately 1 week confirms complete resolution of an uncomplicated ESI, a total course of 7-10 days may be sufficient. [1]

Table 11.10 — Duration framework.

Phenotype	Current ISPD direction	Clinical safeguard
Uncomplicated ESI with confirmed resolution	7-10 days may suffice	Resolution must be verified clinically at approximately 1 week
ESI not resolved at ~1 week	Continue/reassess according to organism and mechanism	Search for resistance, adherence or tunnel disease
Pseudomonas ESI	>=3 weeks effective therapy	Do not shorten because surface drainage improves early
Any tunnel infection	>=3 weeks effective therapy	Follow anatomy and response
Refractory infection	Source-control assessment	Avoid indefinite antibiotic extension

THRESHOLD DISCIPLINE Seven to ten days applies only when uncomplicated ESI has actually resolved on clinical reassessment. It is not permission to give every catheter infection a short course.

10. Response trajectory: the 1-week review is part of treatment

The antimicrobial prescription is incomplete until response is checked. At approximately 1 week, reassess purulent drainage, erythema, tenderness, the entire tunnel, culture/susceptibility, adherence, local care, adverse effects and any new peritoneal symptoms. [1]

Table 11.11 — One-week response phenotypes.

Finding	Interpretation	Action
Purulence gone; inflammation resolved	Good uncomplicated response	Complete appropriate 7-10-day total course
Improving but residual inflammation	Partial response	Confirm active drug; continue and reassess
Persistent purulence	Ongoing infection	Re-culture; assess tunnel and source
New tunnel tenderness	Disease progression	TI pathway + ultrasound when useful
New cloudy effluent	Possible peritonitis	Enter Chapter 10 pathway immediately
Worsening despite susceptible isolate	Biofilm/depth/adherence/wrong diagnosis	Diagnostic reset
Repeated culture-negative failure	Atypical organism possible	Special microbiology including NTM

TRAJECTORY RULE The important question is not "Has the patient finished the antibiotics?" but "Has the infected phenotype disappeared?"

11. Pseudomonas: a high-risk catheter phenotype

Pseudomonas infection deserves deliberate escalation because eradication from a foreign body can be difficult and tunnel extension, recurrence and catheter loss are clinically important. ISPD recommends at least 3 weeks of effective antibiotic therapy for Pseudomonas ESI. If response is unsatisfactory, a second active antipseudomonal agent should be added. [1]

Table 11.12 — Pseudomonas checklist.

Step	Required question	Reason
Culture	Is species identification and susceptibility available?	Ensures true active therapy
Tunnel	Is there tenderness or induration?	Finds deeper infection
Ultrasound	Is cuff/tunnel involvement present?	Defines anatomy when clinically useful
Therapy	Is treatment genuinely antipseudomonal?	Avoids ineffective exposure
Duration	Has >=3 weeks been planned?	Prevents premature cessation
Response	Is the site and tunnel clearly improving?	Identifies failure early
Escalation	Is a second active agent required?	ISPD recommendation for unsatisfactory response
Source control	Is the catheter sustaining infection?	Prevents endless antibiotic cycling

PSEUDOMONAS RULE Do not repeatedly extend single-agent treatment while a tunnel reservoir persists. Once adequate antimicrobial treatment is failing, the problem has shifted toward source control.

12. Staphylococcus aureus and MRSA: think skin source, tunnel and biofilm

S. aureus remains a major catheter pathogen because of skin/nasal carriage, adhesion to foreign material, tunnel extension and association with subsequent peritonitis. Treatment should be narrowed according to susceptibility while the catheter anatomy is assessed in parallel. [1,7]

Table 11.13 — S. aureus questions that matter.

Question	Why it matters	Direction
Previous MRSA?	Changes empirical therapy	Use MRSA-active local protocol
Tunnel tenderness?	Detects deeper source	Classify/treat as TI when present
Recurrent same organism?	Suggests persistence or biofilm	Reassess catheter source
Concomitant peritonitis?	Raises source-control urgency	Chapter 10 + catheter decision
Slow response despite susceptibility?	Drug activity may not be the limiting problem	Recheck adherence, depth and source

For slowly responding S. aureus catheter infection, ISPD notes that rifampicin may be considered as an adjunct in selected circumstances. Evidence is limited, rifampicin should never be used as monotherapy, and clinically important drug interactions must be reviewed. [1]

13. Refractory or unusual infection: think beyond ordinary bacteria

Persistent catheter infection should broaden the diagnostic differential. Rapidly growing nontuberculous mycobacteria may initially be culture negative, reported as diphtheroids or mistaken for Corynebacterium, and they frequently respond poorly to standard antibacterial regimens. [1,11,12]

Table 11.14 — When to suspect NTM.

Clue	Why it matters	Next step
Refractory ESI/TI	Standard organism or strategy may be wrong	Request special microbiology
Repeated culture-negative drainage	Routine media may miss NTM	AFB stain + mycobacterial culture
"Diphtheroids" repeatedly reported	Possible misidentification	Species-level review
Granulation + persistent drainage	Chronic NTM phenotype possible	Do not keep recycling routine antibiotics
Failure despite apparently active standard antibiotic	Foreign body/atypical organism likely	Define anatomy + organism
Repeated recent antibiotic exposure	Can suppress routine organisms and delay diagnosis	Broaden diagnostic strategy

Important PD pathogens include Mycobacterium fortuitum, M. abscessus and M. chelonae. A 2024 systematic review of 335 published PD-related NTM infections identified M. abscessus most frequently and found that catheter removal was common, particularly when peritonitis was present. Treatment is species- and susceptibility-dependent and often requires multidrug therapy plus source control. [11]

ATYPICAL-ORGANISM RULE Persistent "diphtheroid" catheter infection is not automatically benign Corynebacterium. Ask whether the laboratory needs to look specifically for NTM.

14. When antibiotics are not enough: recognise a source-control problem

Figure 11.4 — The source-control threshold is crossed when active infection persists despite genuinely effective therapy and the catheter/cuff/tunnel remains an infected reservoir. Anatomy determines whether limited salvage, catheter replacement or removal is appropriate.

Antibiotic failure should not automatically generate another antibiotic prescription. Confirm that the organism is susceptible, treatment was delivered and taken, local care was appropriate and sufficient time has elapsed. Then search systematically for tunnel infection, cuff involvement, abscess, biofilm, Pseudomonas, NTM, concomitant peritonitis or an incorrect original diagnosis. [1]

Table 11.15 — Failure mechanism -> corrective direction.

Failure mechanism	Corrective direction	Why
Resistant isolate	Correct antimicrobial therapy	The prescribed drug was not truly effective
Poor adherence/delivery	Correct practical barrier	Apparent resistance may be underexposure
Tunnel infection	>=3-week treatment + anatomical assessment	Disease is deeper than ESI
External cuff-limited disease	Consider selected salvage	Infected compartment may be removable
Deep cuff infection	Move toward catheter removal	Limited superficial salvage leaves source behind
Same-organism peritonitis	Catheter removal/source control	Catheter likely connects infectious compartments
NTM / difficult organism	Specialist multidrug + source control	Routine ESI therapy is inadequate

15. Catheter interventions: preserve PD when safe, not infection at any cost

Current ISPD guidance recognises several catheter strategies rather than a binary choice between antibiotics and abandoning PD. The appropriate strategy depends on whether infection is isolated or accompanied by peritonitis, whether disease is limited to the superficial catheter and whether effective antimicrobial treatment has failed. [1,10]

Table 11.16 — Source-control options.

Situation	Direction	Key safeguard
Responsive uncomplicated ESI	Preserve catheter	Complete treatment and prevention review
Responsive TI	Preserve while completing >=3 weeks	Confirm clinical resolution
Refractory superficial ESI	Consider cuff procedure / exit-site relocation	Define deeper catheter as uninfected
Refractory isolated catheter infection	Consider simultaneous removal/reinsertion with new exit site	Use selected cases without uncontrolled peritonitis
Deep cuff involvement	Removal increasingly favoured	Avoid leaving infected foreign material
Catheter infection + same-organism peritonitis	Catheter removal	Treat peritonitis in parallel
Unresolved significant peritonitis	Staged source control	Do not place new catheter into uncontrolled infection
M. abscessus catheter infection	Strong removal bias	Difficult eradication with foreign material retained

Selected techniques include external cuff shaving/removal, exit-site relocation, deroofing, en-bloc resection and catheter diversion. A systematic review of 409 patients undergoing 445 salvage procedures reported an overall catheter-salvage rate of approximately 73% and a procedure-related complication rate of approximately 2.7%, but the evidence was predominantly observational and no single technique can be considered universally superior. [10]

SALVAGE PRINCIPLE Catheter salvage is justified when it removes the infected compartment. Preserving an infected deep cuff is not successful salvage - it is delayed source control.

16. Catheter infection plus peritonitis: two syndromes become one source

Always ask a patient with ESI or TI about abdominal pain, cloudy effluent and systemic illness. If peritonitis is suspected, enter the Chapter 10 PD-Associated Peritonitis pathway immediately. Catheter-related infection and peritonitis caused by the same organism strongly support a shared source and lower the threshold for catheter removal. [1,2]

Table 11.17 — Catheter infection + peritoneal findings.

Pattern	Interpretation	Immediate direction
ESI, clear effluent, no abdominal symptoms	Isolated catheter infection possible	ESI pathway + tunnel assessment
TI + clear effluent	Deep catheter infection without proven peritonitis	>=3-week treatment + source-control surveillance
ESI/TI + cloudy effluent	Possible catheter-related peritonitis	Chapter 10 diagnostic pathway immediately
Same organism in catheter + effluent	Strong catheter-source phenotype	Catheter removal/source control
Severe focal abdomen / polymicrobial effluent	Enteric/surgical source possible	Hospital imaging/surgical pathway

CROSS-REFERENCE Chapter 10 governs effluent diagnosis, empiric intraperitoneal therapy, organism-specific peritonitis treatment, refractory-peritonitis definitions and peritonitis-associated catheter-removal decisions.

17. Prevention and programme quality: protect the barrier every day

Catheter infection prevention is not a single antiseptic product. It is a system combining topical antimicrobial prophylaxis, appropriate cleansing, catheter immobilisation, patient/caregiver competency, early recognition, continued care while the catheter remains in situ and unit-level surveillance. [1,4–6,8,9,17,18]

Table 11.18 — Primary prevention bundle.

Intervention	Current guidance/evidence	Practice translation
Topical exit-site prophylaxis	ISPD recommends daily mupirocin or gentamicin	Choose according to local protocol/resistance and product compatibility
Exit-site cleansing	No single cleansing agent has consistent superiority	Clean at least twice weekly and after showering/vigorous exercise or relevant water exposure
Catheter immobilisation	ISPD prevention recommendation	Prevent traction and microtrauma
Long-term dressing	Not mandatory for every patient	Individualise to environment, skin and fixation needs
Training/competency	ISPD teaching framework	Return-demonstration and event-triggered reassessment
Catheter temporarily unused	Exit-site care still required	Continue while catheter remains in situ
Surveillance/CQI	Track overall and organism-specific infection rates	Use data to change practice

A landmark randomised trial found daily gentamicin exit-site cream highly effective against Pseudomonas catheter infection and comparable with mupirocin for S. aureus prevention, although subsequent antimicrobial-resistance and ecological concerns mean that local policy remains important. [8,16]

Antibacterial honey did not reduce PD-related infection in the HONEYPOT randomised trial and is not recommended as routine exit-site prophylaxis. [15]

Quality targets

ISPD recommends an overall ESI rate of <=0.40 episodes per year at risk and suggests that catheter insertion-related ESI/TI within 30 days should occur in <5% of inserted catheters. Programmes should also track tunnel infection, organism-specific infection, catheter removal and peritonitis following catheter infection. [1]

Table 11.19 — PD-unit catheter-infection dashboard.

Metric	Why track it	What a rise should trigger
Overall ESI rate	Core benchmark	Exit-site-care/prophylaxis review
TI rate	Measures deeper catheter morbidity	Examination/ultrasound/source-control audit
Organism-specific rate	Detects S. aureus, Pseudomonas and atypical clusters	Microbiology/environmental review
Early insertion-related infections	Tests insertion/postoperative process	Surgical/wound-care audit
Catheter removals for infection	Captures technique consequence	Treatment/source-control review
Peritonitis after ESI/TI	Measures inward progression	Link Chapter 10 and 11 CQI
Refractory infections	Identifies treatment/process failure	Adherence, microbiology and salvage audit

CQI RULE Infection surveillance is useful only if a change in the number triggers a change in practice: measure -> identify pattern -> intervene -> remeasure.

18. Major clinical algorithms

Flowchart 11.1 — Suspected exit-site infection. Purulence establishes definitive ESI; every case then proceeds through culture, tunnel assessment, peritoneal screening, organism-risk therapy and planned early reassessment.

Flowchart 11.2 — Tunnel infection. Clinical tunnel inflammation changes the duration and source-control logic; concomitant peritonitis moves the patient directly into the Chapter 10 catheter-source pathway.

$Flowchart 11.3 — Refractory catheter-related infection.$

Flowchart 11.3 — Refractory catheter-related infection. Confirm that therapy was genuinely effective, then reset the diagnosis and define the anatomical reservoir before choosing salvage, replacement or removal.

Flowchart 11.4 — Pseudomonas catheter infection. Treatment requires at least 3 weeks of active therapy, close tunnel assessment and early source-control escalation when response is unsatisfactory.

19. Retention tables: pattern recognition

Table 11.20 — If you see this, think this first.

Finding	First hypothesis	Immediate action
Purulent exit-site discharge	Definitive ESI	Culture + tunnel assessment + treatment
Redness without pus after new adhesive	Contact dermatitis possible	Remove trigger; reassess
ESI + tenderness 4 cm along tract	Tunnel infection	TI pathway +/- ultrasound
Positive swab + normal exit site	Colonisation	Do not automatically treat
Pseudomonas ESI	Difficult catheter organism	>=3 weeks + tunnel assessment
Persistent "diphtheroid" drainage	NTM possible	AFB/mycobacterial culture
ESI + cloudy effluent	Possible catheter-related peritonitis	Chapter 10 immediately
Same organism exit site + peritoneum	Catheter source	Removal/source-control pathway
External cuff extrusion + refractory ESI	Potential superficial source	Define depth; access review
Persistent infection despite active antibiotic	Biofilm/deep source	Anatomical reassessment

Table 11.21 — What not to confuse.

Do not confuse	With	Correction
Erythema	Definitive ESI	Purulence defines definitive ESI
Positive culture	Infection	Clinical phenotype comes first
Negative ultrasound	No TI	Clinical TI can exist despite negative scan
Susceptible organism	Guaranteed cure	Foreign-body biofilm may persist
Better-looking exit site	Resolved tunnel disease	Re-examine the full tunnel
7-10-day duration	Universal ESI duration	Only uncomplicated resolved disease
Two weeks of any antibiotic	Effective therapy	Refractory definition requires active treatment
More antibiotics	Better source control	Persistent foreign-body infection may require intervention
Cuff shaving	Treatment for deep TI	Use only in selected superficial disease
Stopping PD exchanges	Stopping catheter care	Continue exit-site care while catheter remains

20. Clinical pearls

Purulence carries more diagnostic weight than erythema.
Every ESI examination includes the entire tunnel.
A positive culture from a normal site is colonisation, not definitive ESI.
Tunnel ultrasound answers an anatomical question; it does not replace clinical examination.
Review uncomplicated ESI at approximately 1 week because duration depends on that review.
Properly resolved uncomplicated ESI can often finish treatment at 7-10 days.
Pseudomonas ESI requires at least 3 weeks of effective therapy.
Any tunnel infection requires at least 3 weeks of effective therapy.
Every antibiotic course in PD triggers an antifungal-prophylaxis decision.
Persistent infection despite susceptibility should trigger biofilm/source-control thinking.
Refractory diphtheroid or culture-negative infection should trigger NTM thinking.
Same-organism catheter infection and peritonitis is a catheter-removal phenotype.
External cuff disease can sometimes be salvaged; deep cuff infection changes the equation.
Catheter immobilisation is an infection-prevention intervention, not merely a comfort measure.
A PD catheter still requires exit-site care when temporarily unused.

21. Common pitfalls - and the correction

Table 11.22 — High-frequency errors in catheter-infection care.

Pitfall	Why it fails	Correction
Treating every red site with antibiotics	Overdiagnosis and resistance	Look for purulent discharge and alternative causes
Swabbing healthy sites and treating the result	Treats colonisation	Culture clinical infection
Inspecting only the external opening	Misses TI	Palpate the full tunnel
Assuming negative ultrasound excludes TI	False reassurance	Integrate scan with clinical findings
Giving every ESI exactly 14 days	Ignores response-adapted guidance	Review at ~1 week and individualise
Giving Pseudomonas a short course	Higher failure risk	Treat >=3 weeks
Treating TI like superficial cellulitis	Ignores depth and foreign body	>=3 weeks + anatomical reassessment
Repeated antibiotics despite persistent pus	Delays source control	Search for cuff/tunnel/biofilm
Forgetting antifungal prophylaxis	Increases secondary fungal risk	Pair prophylaxis with antibiotic course
Ignoring repeated diphtheroid cultures	Delays NTM diagnosis	Request AFB/mycobacterial studies
Cuff shaving without defining depth	Leaves deeper infection behind	Use anatomy/ultrasound to select salvage
Immediate replacement during uncontrolled peritonitis	Risks contaminating a new foreign body	Achieve appropriate source control first

22. Mini-cases: decisions, not trivia

Case 1 - Red but not infected

A patient on APD develops erythema around the exit site 24 hours after changing to a new adhesive. There is no purulent discharge, swelling, tunnel tenderness or systemic symptom.

BEST NEXT STEP This does not satisfy the definition of definitive ESI. Remove the likely irritant, ensure catheter immobilisation and arrange reassessment rather than automatically prescribing antibiotics.

Case 2 - Uncomplicated MSSA ESI

Purulent drainage is present at the catheter-skin interface. The tunnel is nontender and effluent is clear. Culture grows susceptible MSSA. At the 1-week review, drainage and inflammation have completely resolved.

BEST NEXT STEP Complete an appropriate response-adapted course. A total duration of 7-10 days is consistent with current ISPD guidance when uncomplicated ESI resolution is confirmed.

Case 3 - The hidden tunnel

A patient has modest purulent drainage but describes pain several centimetres proximal to the exit site. Palpation reproduces tenderness. Ultrasound shows peri-catheter fluid around the superficial cuff.

BEST NEXT STEP Diagnose TI. This is no longer short-course uncomplicated ESI: use effective antimicrobial treatment for at least 3 weeks, follow response closely and reassess source control if the tunnel abnormality persists.

Case 4 - Pseudomonas looks better quickly

Culture from ESI grows susceptible P. aeruginosa. Purulent drainage almost disappears after 8 days.

BEST NEXT STEP Do not stop treatment because the surface looks healed. Pseudomonas ESI requires at least 3 weeks of effective therapy. Examine the tunnel and consider ultrasound if deeper disease is possible.

Case 5 - Persistent susceptible organism

A patient with MSSA ESI has received an active antibiotic with good adherence for 2 weeks but still has purulent drainage and focal tenderness near the external cuff.

BEST NEXT STEP This is refractory catheter-related infection. Reassess tunnel/cuff anatomy, obtain ultrasound when useful and begin source-control planning rather than simply extending routine therapy.

Case 6 - The "Corynebacterium" that never disappears

A chronic draining exit site has failed several antibacterial courses. Two earlier cultures were reported as diphtheroids/Corynebacterium.

BEST NEXT STEP Request acid-fast staining, mycobacterial culture and species identification. Rapidly growing NTM must be excluded.

Case 7 - Same organism in exit site and peritoneum

A patient being treated for S. aureus ESI develops abdominal pain and cloudy effluent. Effluent culture subsequently grows the same organism.

BEST NEXT STEP Treat peritonitis according to Chapter 10 and manage this as a catheter source-control problem. Same-organism ESI/TI and peritonitis strongly favours catheter removal.

Case 8 - A potentially salvageable catheter

A patient has refractory infection around an extruded external cuff. Ultrasound suggests disease remains confined to the superficial cuff with no deep extension and no peritonitis.

BEST NEXT STEP This is a potential surgical-salvage phenotype. An experienced PD-access team may consider external cuff removal/shaving or exit-site relocation rather than automatically abandoning PD.

23. Active recall

MUST MEMORIZE Use the table below as the minimum bedside knowledge set. Exact antimicrobial doses, resistant-organism regimens and surgical details remain reference-level information.

Table 11.23 — Core facts.

Prompt	Answer
Definitive ESI?	Purulent discharge +/- erythema at catheter-epidermal interface
Is erythema alone enough?	No
Positive culture + normal site?	Colonisation
TI definition?	Tunnel erythema/swelling/tenderness/induration +/- ultrasound fluid
Does negative ultrasound exclude TI?	No
What should be cultured?	Purulent exit-site drainage
Main routine empirical target?	S. aureus
First major treatment review?	Approximately 1 week
Responsive uncomplicated ESI duration?	7-10 days may suffice
Pseudomonas ESI duration?	>=3 weeks
Any TI duration?	>=3 weeks
Refractory non-Pseudomonas infection?	Failure after 2 weeks effective therapy + intensified care
Refractory Pseudomonas?	Failure after 3 weeks effective therapy
Antibiotic-course companion?	Antifungal prophylaxis
Persistent diphtheroid infection?	Consider NTM
Same-organism catheter infection + peritonitis?	Catheter source-control/removal phenotype
Overall ESI quality target?	<=0.40 episodes/year at risk
Early insertion-related infection target?	<5% within 30 days
Key mechanical prevention?	Immobilise catheter
PD stopped but catheter remains?	Continue exit-site care

USE AS REFERENCE Exact antibiotic doses, MRSA regimen selection, antipseudomonal combinations, allergy substitutions, local resistance thresholds, NTM species-specific multidrug therapy, drug interactions, catheter-compatible topical preparations and operative timing should be checked against the current ISPD tables and local PD, microbiology, renal-pharmacy and surgical protocols.

24. Flashcards: spaced repetition

1. Q: Definitive ESI finding? A: Purulent discharge +/- erythema.

2. Q: Redness without pus? A: Not definitive ESI.

3. Q: Healthy exit site + positive swab? A: Colonisation.

4. Q: What must be examined after the exit site? A: The entire tunnel.

5. Q: Tunnel infection clinical signs? A: Erythema, swelling, tenderness or induration along the tunnel.

6. Q: Ultrasound required to diagnose TI? A: No.

7. Q: Negative ultrasound excludes TI? A: No.

8. Q: Routine empirical organism target? A: S. aureus.

9. Q: Review after starting ESI therapy? A: Approximately 1 week.

10. Q: Uncomplicated resolved ESI duration? A: 7-10 days may suffice.

11. Q: Pseudomonas ESI? A: At least 3 weeks effective antibiotics.

12. Q: Tunnel infection? A: At least 3 weeks effective antibiotics.

13. Q: Poor Pseudomonas response? A: Add a second active antipseudomonal agent and reassess source.

14. Q: Refractory ordinary catheter infection? A: Failure after 2 weeks effective treatment.

15. Q: Refractory Pseudomonas? A: Failure after 3 weeks effective treatment.

16. Q: Antibiotics in PD - secondary prevention? A: Antifungal prophylaxis.

17. Q: Repeated diphtheroid drainage? A: Consider NTM.

18. Q: Same-organism ESI/TI + peritonitis? A: Catheter-removal/source-control pathway.

19. Q: Refractory superficial cuff infection? A: Consider selected cuff/exit-site salvage.

20. Q: Deep cuff involvement? A: Strong argument against limited superficial salvage.

21. Q: ESI rate target? A: <=0.40 episodes/year at risk.

22. Q: Catheter insertion-related infection window? A: Within 30 days.

23. Q: Best protection against traction injury? A: Immobilise the catheter.

24. Q: Exit-site care after temporary PD cessation? A: Continue while the catheter remains.

25. Rapid differential / troubleshooting

Table 11.24 — Catheter-infection troubleshooting from problem to action.

Problem	Differential	First actions
Red site, no pus	Trauma, dermatitis, granuloma, early infection	Review products/traction; close follow-up
Purulent ESI, no tunnel signs	Uncomplicated bacterial ESI	Culture + empiric therapy + 1-week review
Purulent ESI + proximal pain	Tunnel infection	Ultrasound when useful + >=3-week pathway
Culture negative + improving	Recent antibiotics/limited culture yield	Continue clinically effective plan and verify cure
Culture negative + worsening	NTM, fungus, wrong specimen, wrong diagnosis	Repeat/special cultures; diagnostic reset
No response at ~1 week	Resistance, nonadherence, tunnel disease, biofilm	Check susceptibility/delivery; tunnel examination
Persistent infection at 2 weeks	Refractory disease	Source-control assessment
Pseudomonas not improving	Inadequate activity/deep infection	Second active drug + anatomical/source-control review
Diphtheroids repeatedly isolated	Corynebacterium vs NTM	AFB/mycobacterial studies
External cuff extrusion + ESI	Superficial cuff reservoir	Ultrasound when useful; consider cuff salvage
Tunnel collection persists	Infected cuff/biofilm	PD-access/surgical review
ESI/TI + cloudy effluent	Catheter-associated peritonitis	Chapter 10 urgently
Same organism in effluent/site	Catheter source	Removal pathway
Recurrent catheter infections in unit	Technique/prophylaxis/environmental process	CQI audit + organism surveillance

26. Final revision sheet

CORE CONCEPT PD catheter infection is a depth + organism + response + source-control problem. Confirm true infection, examine the entire tunnel, culture purulence, exclude peritonitis, treat according to organism, reassess early and stop expecting antibiotics to sterilise an infected foreign body when the clinical phenotype remains active.

Table 11.25 — One-minute revision.

Domain	Must remember
ESI definition	Purulent discharge +/- erythema
Not ESI by itself	Erythema, tenderness, granuloma or crust without purulence
TI	Clinical tunnel inflammation +/- ultrasound collection
Culture	Purulent drainage; normal site + positive culture = colonisation
Empiric therapy	Cover S. aureus; modify for MRSA/Pseudomonas/local resistance
Review	Approximately 1 week
Uncomplicated ESI	7-10 days if resolution confirmed
Pseudomonas	>=3 weeks
Tunnel infection	>=3 weeks
Refractory	2 weeks effective therapy; 3 weeks for Pseudomonas
Atypical failure	Think NTM
Peritonitis	Same-organism catheter infection -> source control/removal
Salvage	Selected superficial disease only
Prevention	Topical antimicrobial + cleansing + immobilisation + competency
Antibiotics	Add antifungal prophylaxis
Quality	ESI <=0.40/year at risk; early catheter infection <5%

TEN TAKE-HOME RULES 1) Purulence - not redness alone - defines definitive ESI. 2) Every ESI gets a complete tunnel examination. 3) A positive swab from a normal site is colonisation. 4) Ultrasound defines depth but a negative scan does not rule out TI. 5) Review treatment at approximately 1 week. 6) Resolved uncomplicated ESI may require only 7-10 days; Pseudomonas ESI and TI require >=3 weeks. 7) Every antibiotic course in PD triggers antifungal prophylaxis. 8) Persistent diphtheroid/culture-negative infection should trigger NTM investigation. 9) Persistent infection despite effective antibiotics is a source-control problem until proved otherwise. 10) Same-organism catheter infection and peritonitis strongly favours catheter removal.

Table 11.26 — One-minute bedside synthesis.

If you see...	Think...	Do now...
Pus at exit site	Definitive ESI	Culture + tunnel exam
Redness only	Infection not yet established	Differential + close observation
Tender tunnel	TI	>=3-week pathway +/- ultrasound
Pseudomonas	Difficult catheter infection	>=3 weeks + early source assessment
No improvement after adequate treatment	Refractory/biofilm	Re-image/re-culture/source control
Persistent diphtheroids	NTM	AFB/mycobacterial culture
External cuff + superficial infection	Potential salvage phenotype	Define depth
Same organism + peritonitis	Catheter reservoir	Remove/source control
Any antibiotic	Secondary fungal risk	Antifungal prophylaxis
Episode resolved	Prevention opportunity	Apparent-cause analysis + CQI

FINAL MENTAL MODEL Purulence -> tunnel -> culture -> peritoneum -> organism -> 1-week trajectory -> source control -> prevention.

Rapid oral viva

Define definitive ESI and explain why erythema alone is insufficient.
Define TI and explain the role and limitation of tunnel ultrasound.
Walk through the first visit for a patient with purulent catheter drainage.
Explain why a positive exit-site culture does not necessarily mean infection.
Compare treatment duration for uncomplicated ESI, Pseudomonas ESI and TI.
Define refractory catheter-related infection precisely.
Explain why persistent susceptible S. aureus infection may still require source control.
Describe the clues that should prompt investigation for NTM.
Compare cuff shaving, exit-site relocation, simultaneous replacement and catheter removal.
Explain how management changes when the same organism causes catheter infection and peritonitis.
Build a prevention programme including topical prophylaxis, cleansing, immobilisation, competency and surveillance.
State the ISPD catheter-infection quality targets.

SAFETY BOUNDARY This chapter teaches diagnostic architecture and guideline-based management reasoning. Exact antimicrobial doses, allergy substitutions, MRSA and resistant Gram-negative treatment, antipseudomonal combinations, NTM multidrug regimens, drug interactions, catheter-compatible topical products and operative timing require the current ISPD treatment tables, local antibiogram, renal pharmacy, infectious-disease expertise and PD-access protocol. Sepsis, abscess and concomitant peritonitis supersede routine outpatient ESI logic.

27. Selected authoritative references

1. Chow KM, Li PKT, Cho Y, et al. ISPD Catheter-related Infection Recommendations: 2023 Update. Perit Dial Int. 2023;43(3):201–219. https://doi.org/10.1177/08968608231172740. PMID: 37232412.

2. Li PKT, Chow KM, Cho Y, et al. ISPD peritonitis guideline recommendations: 2022 update on prevention and treatment. Perit Dial Int. 2022;42(2):110–153. https://doi.org/10.1177/08968608221080586. PMID: 35264029.

3. Crabtree JH, Shrestha BM, Chow KM, et al. Creating and maintaining optimal peritoneal dialysis access in the adult patient: 2019 update. Perit Dial Int. 2019;39(5):414–436. https://doi.org/10.3747/pdi.2018.00232. PMID: 31028108.

4. Chow JSF, Brunier G, Figueiredo AE, et al. Teaching peritoneal dialysis: A position paper for the International Society for Peritoneal Dialysis. Perit Dial Int. 2025;45(6):327–343. https://doi.org/10.1177/08968608251375512. PMID: 40966019.

5. Perl J, Teitelbaum I, Warady BA, et al. Core Interventions for the Prevention of Peritoneal Dialysis-Related Infections. Clin J Am Soc Nephrol. 2026;21(8):1439–1444. https://doi.org/10.2215/CJN.0000000976. PMID: 41348491.

6. Perl J, Fuller DS, Bieber BA, et al. Peritoneal Dialysis-Related Infection Rates and Outcomes: Results From the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS). Am J Kidney Dis. 2020;76(1):42–53. https://doi.org/10.1053/j.ajkd.2019.09.016. PMID: 31932094.

7. van Diepen ATN, Tomlinson GA, Jassal SV. The association between exit-site infection and subsequent peritonitis among peritoneal dialysis patients. Clin J Am Soc Nephrol. 2012;7(8):1266–1271. https://doi.org/10.2215/CJN.00980112. PMID: 22745277.

8. Bernardini J, Bender F, Florio T, et al. Randomized, double-blind trial of antibiotic exit-site cream for prevention of exit-site infection in peritoneal dialysis patients. J Am Soc Nephrol. 2005;16(2):539–545. https://doi.org/10.1681/ASN.2004090773. PMID: 15625071.

9. Htay H, Johnson DW, Wu SY, et al. Regional variation in the treatment and prevention of peritoneal dialysis-related infections in the Peritoneal Dialysis Outcomes and Practice Patterns Study. Perit Dial Int. 2019;39(3):212–220.

10. Soon JJY, Ng NZP, Lee SQW, Tan SG. Are salvage techniques safe and effective in the treatment of peritoneal dialysis catheter-related exit-site and tunnel infections? A systematic review. Perit Dial Int. 2022;42(6):591–601. https://doi.org/10.1177/08968608221116689. PMID: 35945909.

11. Kadota N, Ishikawa K, Kubono Y, et al. Systematic literature review of the diagnosis, prognosis, and treatment of peritoneal dialysis-related infection caused by nontuberculous mycobacteria. BMC Nephrol. 2024;25(1):432. https://doi.org/10.1186/s12882-024-03841-2. PMID: 39609738.

12. Bnaya A, Wiener-Well Y, Soetendorp H, Einbinder Y, Paitan Y, Kunin M, et al. Nontuberculous mycobacteria infections of peritoneal dialysis patients: a multicenter study. Perit Dial Int. 2021;41(3):284–91. https://doi.org/10.1177/0896860820923461. PMID: 32400280.

13. Vychytil A, Lilaj T, Lorenz M, et al. Ultrasonography of the catheter tunnel in peritoneal dialysis patients: what are the indications? Am J Kidney Dis. 1999;33(4):722–727.

14. Kwan TH, Tong MK, Siu YP, et al. Ultrasonography in the management of exit site infections in peritoneal dialysis patients. Nephrology (Carlton). 2004;9(6):348–352.

15. Johnson DW, Badve SV, Pascoe EM, et al. Antibacterial honey for the prevention of peritoneal-dialysis-related infections (HONEYPOT): a randomised trial. Lancet Infect Dis. 2014;14(1):23–30. https://doi.org/10.1016/S1473-3099(13)70258-5.

16. Tsai CC, Yang PS, Liu CL, Wu CJ, Hsu YC, Cheng SP. Comparison of topical mupirocin and gentamicin in the prevention of peritoneal dialysis-related infections: a systematic review and meta-analysis. Am J Surg. 2018;215(1):179–185. https://doi.org/10.1016/j.amjsurg.2017.03.005.

17. Nataatmadja M, Cho Y, Johnson DW. Continuous quality improvement initiatives to sustainably reduce peritoneal dialysis-related infections in Australia and New Zealand. Perit Dial Int. 2016;36(5):472–477.

18. Hurst H, Figueiredo AE, Perez Moran D, et al. Peritoneal dialysis training and interventions: A narrative review. Perit Dial Int. 2026;46(1):6–15. https://doi.org/10.1177/08968608251328517. PMID: 40221963.