Wound Infection in Clinical Practice Notes

Foreword

International Consensus Update 2022: Wound Infection in Clinical Practice (Third Edition) by the International Wound Infection Institute (IWII) emphasizes that wound infection remains a major clinical, psychosocial, and economic challenge. The edition updates the 2016 consensus using rigorous methodology: systematic literature review, Delphi process refining terminology, critical appraisal of topical antimicrobials, and global peer review. It includes an updated IWII Wound Infection Continuum (IWII-WIC) poster for bedside use, with other language versions available on the IWII website. The IWII is a volunteer organization promoting prevention, identification, and management of wound infection since 2006, and provides this document free through Wounds International and the IWII site. The 2022 edition expands chapters, addresses new controversies, and introduces updated terminology from a consensus process. The document supports antimicrobial stewardship and biofilm-based wound care, and encourages awareness of antibiotic resistance.

• Key contributors: development team and IWII authors, reviewers, and international experts (e.g., Swanson, Ousey, Haesler, Bjarnsholt, Carville, Idensohn, Weir, Kalan, Percival, Schultz, Sussman, and others).
• Core outputs include: updated IWII-WIC continuum, practical guidance for clinical practice, and resources to support implementation (Made Easy, Top Ten Tips).
• The methodology underpinning the update includes: systematic literature review; Delphi refinement of consensus definitions; critical appraisal of topical antimicrobial efficacy; and global peer review.

Supporting Best Practice in Wound Infection

The update frames wound infection through five interacting determinants that influence whether colonization becomes infection and how it progresses:

• Host immune status: the host’s immune system must contend with potential pathogens; this is influenced by multiple factors discussed throughout the document.

• Microbial burden: higher microbial load increases the probability of overcoming host defenses.

• Microorganism virulence: certain species have greater pathogenic potential and biofilm-forming capacity, influencing tissue damage and persistence.

• Microbial interactions: the combined microflora can act synergistically or competitively, affecting infection dynamics and healing.

• Biofilms and antimicrobial stewardship: biofilms slow healing and increase resistance; stewardship aims to optimize antimicrobial use and minimize resistance.

• Terminology and standardization are central. The IWII emphasizes consistent language across clinicians, researchers, and patients. The document traces prior consensus (2016) debunking the term “critical colonisation” and endorsing “local wound infection” for covert, pre-overt stages. A 2022 consensus refined definitions (including biofilm terminology) to harmonize use across guidelines. The IWII-WIC terminology now underpins the document and glossary.

• Biofilm definitions have evolved: the 2022 consensus distinguishes a biofilm concept distinct from earlier 2016 definitions, aligning with advances in understanding biofilm’s role in wounds.

• Practical takeaways for practice include: holistic prevention and management, antimicrobial stewardship, and integration of patient- and family-centered care into wound infection management.

Wounds at Risk of Infection

All open wounds are contaminated or colonised with microorganisms, but not all contaminated wounds become infected. The transition to infection depends on host factors, wound factors, and the environment. The document outlines risk determinants and presents a structured approach to risk assessment and prevention:

• Host (individual) risk factors include:
  • Poorly controlled diabetes (hyperglycemia), peripheral neuropathy, neuroarthropathy, prior radiotherapy/chemotherapy, hypoxia/poor tissue perfusion (anemia, cardiac/respiratory disease, PAD, renal impairment, rheumatoid arthritis), immune disorders (e.g., HIV), connective tissue disorders, corticosteroid use, malnutrition or obesity, alcohol/smoking, treatment non-adherence.
• Wound risk factors differ by wound type:
  • Acute wounds: contaminated/dirty wounds, traumatic injury, contaminated or dirty surgery, improper hair removal, prolonged surgery, transfusion, hypothermia.
  • Chronic wounds: longer duration, larger size, proximity to contamination sites (perineum, sacrum), presence of foreign bodies (drains, sutures, dressing fragments), hematoma, necrotic/sloughy tissue, impaired perfusion, increased exudate/oedema.
  • Acute and chronic wounds share factors like foreign bodies, hematoma, perfusion impairment, wound dimensions, and depth beyond skin/subcutaneous tissue.
• Environmental risk factors include: unhygienic environments, hospitalisation (antibiotic exposure risk), inadequate hand hygiene and aseptic technique, moisture management issues, and high interface pressure.
• Risk assessment tools (Table 2) summarize existing tools (ACRI, BHIS, MUST, MUST-like scores, WAR, Wound Infection Calculators, WIRE, etc.). These tools vary in type, population, and predictive power (AUC values range from ~0.62 to ~0.81 for different surgical and non-surgical contexts). None offer a universal, validated measure across all wound types; they are best used to inform, not replace, clinical judgment. Some tools show strong predictive signals for specific wound types (e.g., Wound Infection Calculator in spinal surgery, AUC ~0.81).
• Preventive strategies focus on reducing patient-specific risk factors, employing holistic assessment (07 Holistic Assessment and Management), and considering topical antimicrobials in very high-risk wounds (see 09 Topical Antimicrobial Therapy). Antimicrobial stewardship principles should guide decisions to minimize resistance while protecting healing.

Identifying and Assessing Infection in a Wound

Wound infection is the invasion and proliferation of microorganisms in a wound to a level that provokes local, spreading, or systemic host responses. The IWII-WIC provides a staged continuum to conceptualize microbial presence and its impact on healing. The continuum stages, with clinical indicators, are:

• Contamination: microorganisms present but not proliferating; no significant host reaction; no wound healing delay. Host defenses typically clear via phagocytosis.

• Colonisation: microorganisms present with limited proliferation; no significant host reaction; no delay in healing. Skin microbiome provides baseline colonization.

• Local infection (covert and overt): microorganisms proliferate and provoke host responses localized to the wound and periwound (<2 cm). Covert signs include hypergranulation, friable granulation with bleeding, pocketing, increasing exudate, and delayed healing. As infection progresses, overt signs appear: erythema, warmth, swelling, purulent discharge, wound breakdown, new/pain increase, malodour.

• Spreading infection (cellulitis): invasion of surrounding tissues; signs extend beyond wound border (induration, lymphangitis, crepitus, satellite lesions).

• Systemic infection: infection spreads via vascular/lymphatic systems; signs include malaise, fever, anorexia, sepsis, organ failure, death.

• Clinical assessment requires holistic appraisal of the person, wound, and environment. Clinical signs/symptoms are not perfectly sensitive or specific; microbiology and imaging may assist but cultures take time. Practitioners should synthesize signs/symptoms with history, comorbidities, and risk factors, aiming for earlier identification and timely treatment to promote healing and reduce systemic risk.

• Wound infection assessment tools (Table 3) include ASEPSIS, CSSC, Infection Management Pathway, IWGDF/IDSA PEDIS, IWII-WIC, NERDS/STONES, TILI score, WIRE, among others. These tools vary in wound type focus, psychometrics, and usage; no single tool is universally definitive. A wound infection assessment tool often relies on multi-sign-based criteria rather than a single indicator.

• Box 2 outlines criteria indicative of wound biofilm (e.g., failure of appropriate antibiotics, recalcitrance to therapy, persistent delayed healing, increased exudate, low-grade inflammation). When a wound is hard-to-heal and not responding to standard care, assume biofilm presence unless proven otherwise.

• The IWII-WIC and Management Guide (back of document) offer practical steps: holistic identification of infection, recognition of biofilm indicators, appropriate cleansing, debridement, wound dressing choice, and biofilm-based wound care (BBWC) in step-down/step-up fashion. Microbiological testing complements but should not delay treatment; point-of-care tests may augment decision-making where available.

• Wound-type-specific considerations (Table 4) emphasize that infection risk and presentation vary by wound etiology, including surgical site infection, pressure injuries, diabetic foot ulcers, chronic leg ulcers, and skin tears. For example, DFUs often harbor deep infections requiring careful assessment for osteomyelitis (probing to bone plus imaging and biomarkers).

• The chapter endorses a systematic approach to diagnosis (05 Diagnosis of Wound Infection) and emphasizes that microbiology should guide therapy only after a clinical diagnosis of infection is established.

Diagnosis of Wound Infection

Diagnosis relies on visual and sensory signs consistent with local infection, in conjunction with laboratory data when available. Key points:

• Clinical diagnosis is based on signs and symptoms (cardinal signs: heat, pain, swelling, purulent discharge, erythema, fever).

• Microbiological testing identifies organisms and informs antibiotic choices but should be reserved for wounds with clinical signs or high suspicion of infection. Elevated inflammatory markers and positive blood cultures help quantify systemic involvement.

• Since all wounds are contaminated/colonised, cultures should be obtained only after a clinical diagnosis of infection or when there is high suspicion. The aim is to identify causative organisms and susceptibilities to tailor therapy.

• Box 1 lists indications for initiating microbiological analysis: acute or chronic wounds with signs of spreading or systemic infection; wounds failing to respond to antimicrobials; compliance with surveillance of drug-resistant organisms; scenarios where certain species impact procedures (e.g., beta-hemolytic strep before grafting).

• Investigations to diagnose wound infection (Table 5) include blood tests (WBC, CRP, ESR), blood cultures, wound culture, radiological imaging (X-ray, MRI, CT, PET, leukocyte scintigraphy, ultrasound), and other imaging as appropriate. The wound culture methods include tissue biopsy, wound fluid aspirate, debrided tissue, and wound swab. Tissue biopsy is the preferred method for accurate culture but is costlier and technically demanding; wound swabs are easier but assess surface bacteria only. The Levine technique is recommended for swabbing over the Z-swab method for better yield. Direct Gram staining provides rapid presumptive identification while cultures identify exact species.

• Box 1 also stresses informed consent and proper labeling of specimens, and that lab results should be interpreted in the clinical context rather than in isolation.

• A practical, evidence-informed workflow is described for using microbiology to guide therapy while prioritizing clinical assessment and patient safety.

Wound Biofilms

Biofilms are a central theme in chronic wounds and contribute to persistent infection and delayed healing. Key points include:

• Biofilms are pervasive in chronic wounds, with early studies showing ~60% prevalence in chronic wounds vs ~6% in acute wounds; later studies report ~80% prevalence in chronic wounds. Biofilms increase tolerance to antibiotics, antiseptics, and immune clearance.

• In vivo wound biofilms are embedded in extracellular matrices and can be located on surfaces, slough, debris, necrotic tissue, or dressing materials. The exact in vivo matrix components and their origins are not fully known.

• In vitro biofilms have a well-described matrix of extracellular polymeric substances (EPS) composed of polysaccharides, proteins, extracellular DNA, and cross-linking ions (e.g., Ca2+, Mg2+, Fe). However, translating in vitro biofilm behavior to wounds is not straightforward due to the in vivo wound environment (hypoxia, pH shifts, slow-growing organisms).

• Identification of biofilms in wounds is challenging; macroscopic visuals are not reliable indicators. There is no gold standard for wound sampling to identify biofilm; clinical management often proceeds based on signs of chronic inflammation and non-resolving infection.

• Box 2 provides criteria indicating potential biofilm in a wound (e.g., recurrent non-response to antibiotics, persistent inflammation, and recurring delayed healing). If a wound is hard to heal and does not respond to standard care, assume biofilm presence.

• Clinical implications: biofilms confer antimicrobial tolerance; thus, BBWC (biofilm-based wound care) with a step-down/step-up approach is recommended. This includes aggressive debridement, judicious topical antiseptics, and strategies to disrupt biofilm reformation, followed by maintenance with cleansing, dressings, and antimicrobial strategies as needed.

• The continuum treatment approach integrates BBWC with holistic wound care (07 Holistic Assessment and Management). Debridement strategies (surgical, sharp, conservative sharp, mechanical, enzymatic, autolytic, biosurgical, etc.) aim to physically remove biofilm and necrotic tissue to enhance antimicrobial efficacy.

• Practical indicators of suspected biofilm and suggested management strategies emphasize debridement and regular reassessment, with a willingness to escalate therapy if healing is not progressing.

Holistic Assessment and Management

A central theme is patient-centered, whole-person care that integrates wound infection management with broader health status, comorbidity management, and psychosocial factors:

• Goals: identify factors contributing to infection, set feasible care goals with patient and caregiver input, and develop a comprehensive prevention/management plan aligned with patient preferences.
• Holistic assessment areas include: history of the person and wound, comorbidities, nutrition, inflammatory and immune factors, tissue healing factors, psychosocial wellbeing, and the wound itself.
• Engagement and collaboration with patients and families are emphasized to improve adherence and outcomes; multidisciplinary teams are encouraged, with the patient as an active participant.
• Models to guide holistic wound assessment and management are summarized in Table 7, including Wounds UK Best Practice Statement, Infection Management Pathway (TIMe tool), Adult Burns Patient Concerns Inventory, Wound Healing Strategies for Palliation, Universal Team Model for Wound Care, TIMERS framework, and Wound Bed Preparation 2021. These models help structure patient-centered wound care planning, transitions between healing, maintenance, and palliation, and cross-disciplinary coordination.
• The figure and discussion highlight the importance of addressing host factors, environmental factors, and wound care practices to optimize healing and minimize infections.
• Early patient engagement and education improve self-management and confidence; examples include nurse-led patient education and discharge support.

Holistic Prevention and Management of Wound Infection

This section reiterates early recognition and a broad, patient-centered approach to wound infection prevention and management:

• The prevention and management plan should optimize host response, reduce local microbial burden, and create a healing-friendly environment.
• An interdisciplinary approach is essential, with emphasis on nutrition, glycemic control (especially in diabetes), vascular and perfusion optimization, infection control, and psychosocial support.
• The plan should be tailored to patient goals and resources, and should integrate wound infection prevention with antimicrobial stewardship principles.
• Practical resources include the IWII-WIC pathway and supporting materials to implement non-pharmacologic strategies and patient education.

Wound Bed Preparation: Cleansing and Debridement

This chapter links the TIME framework (Tissue, Infection/Inflammation, Moisture, Edge) with biofilm-based wound care (BBWC):

• Wound bed preparation (WBP) aims to advance endogenous healing and maximize the effectiveness of therapies by preparing a clean, well-vascularized wound bed. The role of debridement is central to BBWC, removing non-viable tissue and biofilm to reduce microbial burden and facilitate healing.
• Therapeutic wound cleansing is defined as actively removing surface contaminants, debris, non-viable tissue, microorganisms, and remnants of previous dressings. Indications for vigorous cleansing include chronic wounds with slough/debris, suspected biofilm, high exudate, or prior sampling.
• Cleansing solutions vary: sterile normal saline, sterile water, potable water (where sterile options are limited), surfactant-based cleansers, hypochlorous/hypochlorite solutions, povidone-iodine (cadexomer iodine included), and other antimicrobial/antiseptic agents. The choice depends on wound type, goal, resources, and infection status. Generally, inert solutions are preferred for most non-infected wounds; antiseptics or surfactants may be used for suspected biofilm or infection, with consideration of cytotoxicity and tissue compatibility.
• Wound cleansing parameters emphasize temperature, pressure, and technique: inert solutions are used after warming; mechanical irrigation should be 4–15 PSI; aim for thorough cleansing while avoiding periwound maceration; ensure aseptic technique or clean technique as appropriate; cleanse periwound skin out to 10–20 cm where feasible. Table 8 provides syringe size, gauge, and PSI relationships to achieve desired irrigation pressures.
• Wound cleansing is followed by debridement when indicated. Debridement methods (Table 10) include surgical, sharp, conservative sharp, autolytic, enzymatic, mechanical, biosurgical (larval therapy), and combinations. Each method has advantages and considerations (e.g., surgical debridement is fast but invasive; autolytic is gentle but slower; enzymatic can be selective but slower). The optimal method is context-dependent, guided by goals of care, clinician skill, and resources.
• Debridement aims to disrupt biofilm and remove devitalized tissue; post-debridement, edge refashioning may be required to support epithelial advancement. Post-debridement cleansing and antimicrobial dressings help prevent reformation of biofilm.
• BBWC principles emphasize physical removal of tolerant organisms, maintenance of a healing environment, and regular evaluation. The step-down/step-up BBWC approach supports progression from aggressive initial interventions to maintenance therapy as healing proceeds.

Topical Antimicrobial Therapy

This core section distinguishes antiseptics, antibiotics, and their proper roles in wound management:

• Antimicrobial terminology: antiseptics (on living tissue) vs disinfectants (inanimate objects) with broad mechanisms of action and low likelihood of resistance; disinfectants should not be used on wounds. Antimicrobials include antiseptics, antibiotics (systemic or topical), antifungals, etc.
• Most wounds heal without antimicrobials; judicious antimicrobial use is essential to prevent toxicity and resistance. Topical antiseptics should be considered when there is a high risk of infection, or when biofilm is suspected/confirmed, in conjunction with appropriate wound care. Systemic antibiotics are reserved for spreading/systemic infection or deep-seated infection with systemic signs.
• Topical antiseptics (Table 11) include algin gels with lactoperoxidase/glucose oxidase, cadexomer iodine, DACC-coated dressings, honey, octenidine dihydrochloride (OCT), polyhexamethylene biguanide (PHMB), povidone-iodine (iodophors), and silver preparations. Each has specific antimicrobial and anti-biofilm properties, with varying cytotoxicity and tissue effects. Surfactant formulations and hypochlorous/hypochlorite preparations are commonly used adjuncts. Key notes include:
  • Cadexomer iodine shows broader efficacy but potential cytotoxicity; benefits include biofilm reduction and wound healing improvement in certain wound types.
  • PHMB and OCT show broad-spectrum activity and are generally well tolerated, with evidence of biofilm disruption.
  • Iodine-based products show broad-spectrum activity but may carry cytotoxic risks at higher concentrations or with prolonged exposure.
  • Silver-based dressings show benefits in chronic wounds and burns but may have cytotoxic effects at higher concentrations.
  • Hypochlorous acid and hypochlorite-based solutions have broad antimicrobial action with favorable safety profiles in many wounds.
• The evidence base for topical antiseptics is uneven; much comes from in vitro/animal studies. Clinical efficacy data are limited and often of low certainty. There is no universal consensus on optimal agents, doses, or durations; decisions should be individualized to the wound, patient, and care setting, with emphasis on antimicrobial stewardship. The document reviews Tables 12–16, which summarize clinical efficacy for complete healing, wound burden reduction, biofilm reduction, and signs/symptoms: evidence quality ranges from high to low certainty depending on the agent and outcome. A common practice point is to trial a topical antiseptic for at least 2 weeks (often up to 4 weeks in BBWC step-down therapy) before evaluating efficacy.
• Topical antibiotics and antifungals are discussed critically: topical antibiotics can drive resistance when used indiscriminately; use should be restricted to specific, infected wounds and guided by culture/susceptibility; their prophylactic use is discouraged. Antifungal therapy may be needed for fungal-associated biofilms, but penetration into biofilms can be limited. Diagnosis should guide therapy.
• The document emphasizes combination strategies: topical antiseptics with proper wound cleansing and possibly systemic antibiotics for spreading/systemic infection, while preserving antimicrobial stewardship goals.

Topical Antimicrobial Therapy: Evidence and Guidance

• Tables 12–16 summarize clinical evidence for antiseptics in healing, microbial burden, biofilm, and signs/symptoms, highlighting variability in quality and transferability to real-world wounds. The evidence ranking uses a scale: High certainty, Moderate certainty, and Low/critical certainty. The data show that:
  • Cadexomer iodine, PHMB, OCT, silver, and SOS (hypochlorous/hypochlorite formulations) have varying impacts on healing time, infection metrics, and tissue type outcomes across different wound types.
  • Honey and alginogel often show favorable healing signals in some contexts, particularly for burns and chronic wounds, but results depend on formulation and comparator.
  • Povidone iodine generally shows mixed results for healing and infection control, with concerns about cytotoxicity at higher concentrations; cadexomer iodine and cadexomer-based products show potential for specific wound types.
• The practice points emphasize: use topical antimicrobials in wounds with local infection or suspected biofilm; when diagnosing systemic infection, combine topical and systemic therapies as appropriate; tailor duration and rotation strategies to the wound’s response; and avoid routine long-term use due to AMR concerns.
• The methodology section (14 Methodology) describes the scoping approach, AMSTAR-2 quality appraisal, and ROB assessments used to derive the evidence for topical antiseptics. The evidence base is dominated by reviews, with primary studies limited in quality; thus, clinical decisions demand careful interpretation and integration with clinical judgment.

Topical Antibiotics and Antifungal Therapies

• Antibiotics (topical and systemic) target bacteria with variable cytotoxic profiles and risks of resistance. Topical antibiotics, particularly when used without clear indication, can contribute to resistance and poor clinical outcomes. The document cautions that topical antibiotics should be reserved for infected wounds under specialist supervision, with clear indications and culture-guided selection when possible.
• Topical antifungal therapy may be indicated when fungal infection or fungal-associated biofilms are suspected or confirmed; however, penetration and efficacy within biofilms can be limited, and systemic therapy may be warranted for invasive fungal infections or high-risk settings (e.g., burns). Accurate identification of fungi is essential for selecting appropriate therapy.

Principles of Aseptic Technique in the Management of Wounds

Aseptic technique minimizes iatrogenic infection during wound dressing procedures (WDPs). Two standards are described:

• Sterile/Surgical aseptic technique: true sterile field, sterile equipment, sterile gloves, clean-to-sterile sequence, and use of PPE. The environment and instruments are maintained under strict sterility, with universal precautions and careful handling of sterile dressings to preserve asepsis.
• Clean/Standard aseptic technique: non-sterile gloves, clean equipment, routine infection-control precautions, and only sterile equipment for debridement.
• Universal infection control precautions apply regardless of technique, including hand hygiene and PPE. The environment should be appropriate for aseptic work and avoid contamination (e.g., avoid performing WDPs in toilets; isolate the area, control airflow, etc.).
• Selecting an aseptic technique depends on patient risk factors, wound complexity, location, the probability of exposure to infection, and resource availability. Higher-risk wounds (deeper wounds, exposed tendons/bones, complicated anatomies) typically require sterile/surgical aseptic technique. A practical sequencing guide (Box 3) outlines 20 steps from history review to documentation during a WDP using sterile technique. The accompanying flow diagram (Figure 5) provides a stepwise visual for implementing aseptic WDPs.

Antimicrobial Resistance and Stewardship

• Antimicrobial resistance (AMR) occurs when microorganisms evolve to withstand antimicrobial medications, including topical agents. The global burden is projected to rise dramatically, with estimates up to 10 million deaths per year by 2050 if unchecked. Antimicrobial stewardship (AMS) is the structured, supervised use of antimicrobials to reduce resistance, optimise clinical outcomes, and preserve antimicrobial effectiveness.
• AMR in wound care is driven by overuse/misuse of antimicrobials, inadequate infection prevention, poor sanitation, lack of access to diagnostics, and insufficient surveillance. AMS in wound care includes organizational governance (policies, monitoring, audits), clinical decision pathways, and education for clinicians, patients, and families.
• The document provides a detailed table of AMS initiatives at government, organizational, and clinical levels (Table 17). It emphasizes narrow-spectrum agents when possible, avoids prophylactic antimicrobial use except in high-risk circumstances, and encourages non-medicated dressings when feasible. It also highlights the potential role of non-medicated wound dressings (NMWDs) that reduce microbial burden via physical/mechanical or sequestration mechanisms, thereby limiting AMR risk.
• The overall message is to integrate precise diagnosis and culture-guided therapy with stewardship principles, and to prefer antiseptics over routine topical antibiotics when appropriate.

Future Directions in Wound Infection Science and Practice

• Biofilm research is expanding, but substantial gaps remain about in vivo biofilm behavior, quorum sensing, and interspecies interactions. Future directions include improved in vitro models, better understanding of antibiotic-biofilm interactions, and development of adjuvants that enhance antimicrobial efficacy against biofilms (e.g., enzymes, nutrients, or metabolites).
• New diagnostic tools are evolving, including point-of-care wound pH testing, odour sensing, neutrophil-derived enzyme biomarkers, presepin, autofluorescence imaging, and wound blotting to map biofilms. Autofluorescence devices detect bacterial burden in real time by emitting 405 nm light and visualizing porphyrin-producing bacteria (red fluorescence indicates moderate-to-heavy bacterial presence; cyan indicates Pseudomonas). Wound blotting maps biofilms by pressing membranes onto wounds and staining with cationic dyes to reveal biofilm matrix components. While promising, these technologies require further validation and standardization, and their signals cannot differentiate planktonic bacteria from biofilms.
• Emerging wound infection management strategies include antibiofilm agents (nanoparticles, antimicrobial peptides, bacteriophages) and delivery systems (nanoparticles, nanofibers, hydrogels, fibers, and microneedle devices) to enhance antimicrobial penetration, biofilm disruption, and targeted delivery. Regulation and commercialization are ongoing.
• Terminology consensus: IWII continues to refine definitions for antimicrobial resistance, antiseptics, biofilms, colonisation, contamination, chronic wounds, and other terms to promote consistency across guidelines and practice. A comprehensive glossary is included (13 Terminology).

Terminology

The document features an extensive glossary and abbreviations (e.g., AMR, AMS, BBWC, CFU, CSI, DACC, DFU, ES R, etc.). The terminology section clarifies definitions and standard abbreviations used throughout the document (see Table of abbreviations). Key terms include:

• AMR: Antimicrobial resistance; AMS: Antimicrobial stewardship; BBWC: Biofilm-based wound care; CFU: Colony forming units; CSSC: Clinical Signs and Symptoms Checklist; DACC: Dialkyl carbamoyl chloride; DFU: Diabetic foot ulcer; ESR: Erythrocyte sedimentation rate; FISH: Fluorescence in situ hybridisation; HOCl: Hypochlorous acid; IWII: International Wound Infection Institute; IWII-WIC: IWII Wound Infection Continuum; MRSA: Methicillin-resistant Staphylococcus aureus; NMWD: Non-medicated wound dressing; OCT: Octenidine dihydrochloride; PCT: Procalcitonin; PHMB: Polyhexamethylene biguanide; PCR: Polymerase chain reaction; PCI: Prophylaxis; SOS: Super-oxidised solution; WIC: Wound Infection Continuum; WIRE: Wound Infection Risk Assessment and Evaluation tool.

• The Terminology chapter consolidates the consensus terms used in subsequent chapters, enabling consistent communication across clinicians, researchers, and educators.

Methodology

The 2022 IWII update is grounded in a targeted literature search of articles published since 2016, using MeSH and EBSCO terms across Medline, PubMed, Embase, CINAHL, and Cochrane Library. The process included grouping by concept, expert review, and re-screening of prior references. The methodology included: systematic literature review, Delphi consensus for terminology, critical appraisal of topical antimicrobial efficacy, and peer review by global experts. The document also includes a robust set of supplementary materials about the IWII-WIC and recognition of biofilm-based approaches.

Boxed and Standalone Elements (Key Tools & Points)

• Box 1: Indications for initiating microbiological analysis (Box 1). This comprises infection suspicion, non-resolving wounds, antibiotic resistance surveillance, and procedure-relevant considerations.

• Box 2: Criteria indicative of possible wound biofilm (from expert consensus). These include poor responses to antimicrobial therapy and signs of chronic inflammation, among others.

• Box 3: Sequencing example for a wound dressing procedure using sterile technique (Box 3), detailing a 20-step protocol from history to documentation.

• Box 4: Boxed practice points appear in several sections (e.g., practice points for swab collection and wound cleansing).

• IWII Wound Infection Continuum poster: the poster represents the continuum stages (Contamination → Colonisation → Local infection (covert to overt) → Spreading infection → Systemic infection) with clinical indicators. It is designed for bedside use and education, and is available in multiple languages.

• Figures and Tables referenced across sections (e.g., Table 1 risk factors; Table 2 risk assessment tools; Table 3 wound infection assessment tools; Table 4 wound infection assessment in specific wound types; Table 5 diagnostic investigations; Table 6 microscopy types; Tables 8–10 cleansing and debridement details; Tables 11–16 topical antiseptic data; Table 17 AMS initiatives; Table 18 PICO elements; Table 19 evidence ranking). These tables and figures provide quick-reference data to support clinical decision-making.

• Notable numerical references and formulas:

  • Microbial threshold historically described as approximately $10^5$ CFU/mL (105 CFU/mL) used in some older concepts of critical colonisation, though current IWII terminology emphasizes continuum rather than a single threshold.
  • Diagnostic performance metrics include area under the curve (AUC) values for various risk tools (e.g., WAR score and other surgical risk indices; e.g., AUCs ranging from ~0.62 to ~0.81 in Table 2).
  • Wound cleansing irrigation pressures recommended: 4–15 psi (PSI).
  • Wound infection continuum stages and their clinical indicators are defined in the IWII-WIC: Contamination, Colonisation, Local infection (covert/overt), Spreading infection, Systemic infection.
  • The document includes several LaTeX-compatible formulas for emphasis (e.g., $10^5$ CFU/mL, $AUC = 0.81$) to present numerical relationships precisely.

• Practical implications:

  • Clinicians should perform holistic assessments integrating host factors, wound status, and environment.
  • When signs of local infection escalate or fail to respond to standard care, escalate to appropriate debridement, cleansing, and antiseptic strategies aligned with BBWC and AMS principles.
  • Diagnosis should triangulate clinical signs with microbiology and imaging results, considering patient comorbidities and immunocompetence.
  • An antimicrobial stewardship framework should guide antibiotic use, prioritizing targeted therapy guided by microbiology, while leveraging non-medicated dressings and antiseptics as appropriate to minimize resistance.

• Summary of practical workflow (integrated across chapters):
  1) Screen for risk using host, wound, and environmental factors; 2) Assess wound infection using signs/symptoms and IWII-WIC; 3) If infection suspected, obtain appropriate samples (prefer tissue biopsy; swabs with Levine technique when biopsy not feasible); 4) Initiate appropriate therapy guided by culture/susceptibilities and consider BBWC; 5) Debride and cleanse to disrupt biofilm; 6) Choose wound dressings (medicated or non-medicated with antimicrobial action as per AMS policy); 7) Reassess healing trajectory; 8) Implement AMS governance and education; 9) Consider future diagnostic tools and adjuvant therapies as evidence evolves.

• Final note on implementation: The 2022 IWII edition provides a comprehensive framework that can guide clinicians from initial wound assessment through healing, with emphasis on biofilm-based care, prudent antimicrobial use, patient engagement, and multidisciplinary collaboration to optimize outcomes in the face of evolving wound infection science.