What is the infection risk associated with total parenteral nutrition (TPN) and what measures can reduce it?

Total Parenteral Nutrition and Infection Risk

Total parenteral nutrition significantly increases the risk of catheter-related bloodstream infections (CRBSI), with rates ranging from 2.5 per 1000 catheter-days in oncology patients to 11.4 per 1000 catheter-days in hospitalized patients, but this risk can be substantially reduced through evidence-based bundle interventions including chlorhexidine skin antisepsis, maximal barrier precautions, single-lumen catheters, and dedicated TPN lines. 1, 2, 3

Why TPN Increases Infection Risk

TPN creates multiple mechanisms for infection:

• Glucose-containing fluids facilitate microbial adhesion to catheter surfaces by producing a "slime"-like biofilm, particularly increasing risk for Candida species 2
• Lipid emulsions provide an ideal growth medium for both bacterial and fungal organisms, though most infections arise from catheter contamination rather than infusate contamination 2
• Frequent line manipulation and long-term catheterization required for TPN delivery increase colonization risk 2
• Duration of TPN infusion is the single most important independent risk factor, with risk multiplying 5-fold when TPN exceeds 14 days 3

Infection Rates by Catheter Type and Site

The hierarchy of infection risk from highest to lowest:

• Femoral catheters carry the highest risk: 22.1% CRBSI rate, with 42% positive catheter tips versus 6.9% for non-femoral sites—femoral access should be avoided in adults 1, 4, 5
• Non-tunneled central catheters: Intermediate risk 1
• Peripherally inserted central catheters (PICCs): Lower infection risk than conventional CVCs, though higher thrombotic complications 1
• Tunneled catheters and totally implantable ports: Lowest infection rates, approximately 2.5 per 1000 catheter-days 1

Subclavian vein placement is preferred over internal jugular when possible due to lower infection risk 1, 2

Common Pathogens

The microbial profile in TPN-related CRBSI:

• Coagulase-negative staphylococci: 30-40% of cases 2, 6
• Staphylococcus aureus: 7.7-17.2% 2, 6
• Gram-negative bacteria: 30-40% 2
• Candida species: 4.6-14.4% 2, 6

Evidence-Based Prevention Bundle

During Catheter Insertion

Implement all of the following simultaneously to achieve maximum risk reduction:

• Use 2% chlorhexidine gluconate for skin antisepsis before insertion and during all dressing changes 1
• Apply maximal sterile barrier precautions: cap, mask, sterile gown, sterile gloves, and full-body sterile drape 1
• Utilize real-time ultrasound guidance for all central venous access to reduce insertion attempts and complications 1
• Position catheter tip in the lower third of superior vena cava or upper third of right atrium, confirmed during the procedure 1
• Use sutureless securement devices with needleless connectors 1

Catheter Selection Strategy

• Choose single-lumen catheters whenever possible—multi-lumen catheters increase infection risk 1, 2
• If multi-lumen catheter is necessary, dedicate one lumen exclusively to TPN and never administer medications through the nutrition line 2
• Consider antimicrobial-coated catheters (minocycline-rifampin or chlorhexidine/silver sulfadiazine) for short-term use, though this protective effect may be lost with TPN administration 1, 2
• Select tunneled catheters for long-term TPN (>2-3 weeks) or home parenteral nutrition 1

Ongoing Maintenance

• Apply chlorhexidine-impregnated sponge dressings at the insertion site for patients older than 2 months with short-term catheters at high infection risk 1, 7
• Change transparent dressings every 7 days, or sooner if damp, loosened, or soiled 1
• Disinfect hubs, stopcocks, and needleless connectors before each access 1, 2
• Change administration sets routinely per protocol 1
• Perform meticulous hand hygiene before all catheter manipulations 1
• Remove catheters as soon as they are no longer necessary—duration of catheterization beyond 20 days significantly increases risk 1, 6, 3

Critical Pitfalls to Avoid

Do NOT implement these interventions—they are ineffective or harmful:

• Routine catheter replacement on a scheduled basis: Does not reduce infection risk 1, 2
• Systemic antibiotic prophylaxis: Not recommended and may promote resistance 1, 2
• Heparin locks: Not effective for infection prevention and may increase infection risk in home PN patients 1, 2
• In-line filters: Do not reduce CRBSI rates 1
• Topical antimicrobial ointments at insertion site: May promote fungal infections and antimicrobial resistance 1

When to Remove the Catheter

Remove short-term central lines immediately if:

• Evident signs of local infection at exit site 1
• Clinical signs of sepsis or septic shock 1
• Positive paired blood cultures (peripheral and catheter) 1
• Positive catheter culture if exchanged over guidewire 1

For long-term catheters, removal is required for:

• Tunnel infection or port abscess 1
• Septic shock 1
• Persistent bacteremia despite appropriate antibiotics 1

Special Populations

In pediatric patients receiving long-term PN:

• Tunneled CVCs are strongly recommended over non-tunneled catheters 1
• Regular training and education of healthcare staff must be implemented 1
• Multimodal protocols should be developed and regularly audited 1

In intensive care patients:

• CRBSI rates are approximately double those in non-ICU settings (1.98% versus 0.93% per 100 line-days) 5
• All-in-one bag systems should be used to minimize line manipulations 1

Organizational Strategies

Establish a nutrition support team including a physician, nutrition nurse specialist, senior dietician, and senior clinical pharmacist to minimize complications through adherence to standardized protocols 8

Implement multimodal protocols with regular auditing to standardize clinical practice for insertion and maintenance of intravascular devices 1