Infection of the chronic wound how to decide


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Infection of the chronic wound how to decide

  1. 1. Lee C. Ruotsi, MD, FACCWS, UHM
  2. 2. SIGNS AND SYMPTOMS PRIMARY SECONDARY Rubor (erythema)  Delayed healing Dolor (pain)  Changes in wound bed color Calor (warmth)  Friable/hyper granulation Edema/swelling  Abnormal/increased odor Purulence  Increased drainage Fever
  3. 3. RISK FACTORS FOR WOUND INFECTION SYSTEMIC LOCAL Vascular disease  Large wound area Edema  Increased wound depth Malnutrition  Degree of chronicity  Anatomic location Diabetes  Foreign bodies Alcoholism  Necrotic tissue Prior surgery or radiation  Mechanism of injury Drugs i.e. corticosteroids  Degree of contamination Immune deficits  Reduced perfusion
  5. 5. WOUND CONTAMINATION Presence of non-replicating micro-organisms on the wound surface that evoke no clinical host response All chronic wounds are contaminated Bacterial colony counts low Wound healing occurs in spite of presence of bacteria Not the presence of bacteria but interaction with host that determines their impact on wound healing
  7. 7. WOUND COLONIZATION Presence of replicating micro-organisms within a wound in the absence of any detectable host injury Most organisms are normal skin flora Staph epi and other coag negative staph, corynebacterium, propionibacterium, Gram negatives; Proteus and Pseudomonas
  9. 9. SUPERFICIAL CRITICAL COLONIZATION Replicating microbial burden in the wound surface compartment with subtle clinical signs of host injury aka: covert/localized infection, increased bacterial burden
  11. 11. DEEP WOUND INFECTION Level of microbial burden or virulence has overwhelmed the host responses and the micro-organisms cause clinical injury by invading locally or deeply below the wound base Stage before systemic sepsis
  13. 13. SYSTEMIC SEPSIS (BACTEREMIA) Relatively uncommon as a result of wound infections Found in 10-20% of severely infected wounds; diabetic foot wounds and deep pressure ulcers are most common Small wounds, if infected with Group A Strep or MRSA can rapidly progress from contamination to systemic infection (sepsis) Example- MRSA outbreaks in athletes
  14. 14. CONFOUNDING VARIABLES Pain; may be absent in infected diabetic foot wound Warmth; may be absent with ischemia Erythema; may be absent in diabetes and ischemia may be venous insufficiency, not infection Purulence; may be normal exudates produced by healthy granulation tissue Fever; may be absent in compromised host Edema; may be manifestation of venous disease rather than infection
  15. 15. INCREASED BACTERIAL BURDEN May only appear as mild erythema and hyperemia Objectively- wound may not appear infected Bacteria compete for nutrients and oxygen Exotoxins, endotoxins and proteases impair normal cellular functions Wound Healing is compromised when: a) more than 4 pathological species present b) tissue bacteria levels > 105
  16. 16. PATHOGENS AS A FUNCTION OF TIME Early Acute 4 weeks Long Term Chronic
  17. 17. EARLY ACUTE Predominance of usual skin flora Staph aureus and Beta Hemolytic strep follow in early weeks
  18. 18. 4 WEEKS Facultative anaerobic gram – rods begin to colonize Most common: Proteus, E. Coli, Klebsiella As wound deteriorates, deeper structures become affected and anaerobes become more common Environment becomes more polymicrobial (4-5 sp.)
  19. 19. LONG TERM CHRONIC Often more anaerobic than aerobic Also, aerobic Gram – rods: Pseudomonas Acinetobacter Xanthomonas
  21. 21.  THE WOUND ENVIRONMENT  Chronic wounds differ biochemically from acute ones  Prolonged inflammatory response leads to increase in inflammatory cytokines and MMP’s  Debridement, control of infection and inflammation, moisture control and excision of wound edges and callous  Sharp debridement gold standard
  22. 22.  DEBRIDEMENT  Excisional or selective  Excisional: surgical removal of clearly identifiable tissue by cutting outside wound margins  Selective: removal of devitalized tissue, ie slough, fibrin, crusts, exudates  Debridement changes wound physiology; chronic to acute  Universally accepted and should rely on intuition  Better healing with more frequent debridement (Well supported)
  23. 23. SURGICAL / SHARP DEBRIDEMENT Scalpel, Curette ADVANTAGES:  DISADVANTAGES Fastest and most effective  Requires skill and method of removal of advanced training devitalized wound tissue  Can damage blood vessels, Very selective  Nerves, tendons, etc Stimulates wound healing  Can be painful and may through release of inflammatory cytokines require anesthesia
  24. 24. ENZYMATIC DEBRIDEMENT Collagenase Advantages:  Disadvantages Most selective of non-  Slow surgical methods  Expensive Painless  Requires prescription Low risk of damage to  May cause inflammation other structures but rare Daily, patient applied therapy
  25. 25. AUTOLYTIC DEBRIDEMENT Proteolytic enzymes, Hydrogels Advantages  Disadvantages Occurs naturally, to some  Slow extent, in all moist wounds  Wound must be monitored Can be augmented with closely for signs of hydrogels, etc infection – anaerobic if Safe occlusive dressing used Selective Inexpensive
  26. 26. MECHANICAL DEBRIDEMENT Wet to dry, Pulse lavage, Whirlpool Advantages  Disadvantages Inexpensive  Non-selective Can be effective short-term  Traumatizes and debrides in proper setting healthy as well as devitalized tissue  Painful
  27. 27. MISCELLANEOUS Pseudomonas: Frequently cultured from deteriorating wounds and tends not to be invasive unless in compromised host Enterococcus: Frequently cultured and need not be treated unless only organism cultured and wound clinically infected Candida: Same as above for Enterococcus
  28. 28. CULTURE METHODS Quantitative Deep tissue  “Gold standard” Biopsy Culture  >105 org/gm of tissue  Any level B Hemolytic Strep  Invasive  Usually requires local  Caution with PAD  Time consuming/$$$ for lab
  29. 29. CULTURE METHODS Levine swab technique  Best supportive evidence outside quantitative biopsy culture 1) Cleanse/irrigate w saline 2) Firm pressure of swab tip in cleanest portion of wound base 3) Rotate 360 degrees 4) Transport media
  30. 30. NERDS AND STONEES Cross sectional validation study of 112 patients Studied clinical assessment variables to determine presence and quantity of wound bacteria Wounds evaluated using mnemonics to assess for: 1) Critical colonization (NERDS) 2) Infection (STONEES) Results compared to semi-quantitative swab cultures
  31. 31. NERDSN Non-healing wound - Wounds that are not 20% - 40% smaller in 4 weeks by hx or recordsE Exudative wound - Increase in wound exudate with >50% of dressing stained with exudateR Red and bleeding – Wound bed tissue bright red with exuberant granulation tissue. Bleeds easily with gentle manipulationD Debris – Presence of discolored granulation tissue, slough and necrotic / nonviable tissue.S Smell – Unpleasant or sweet, sickening odor
  32. 32. STONEESS Size - Wound size is increasing. Longest length x widest width (right angles). Only very deep wounds and most stage III / IV pressure ulcers should have depth measured with probe.T Temperature increased – Increased periwound margin temperature by > 3˚ F difference between mirror image sites.O Os (Probes to or exposed bone) - Wounds that have exposed bone or probed to bone at time of examN New areas of breakdown or satellite lesionsE Erythema/Edema – Reddening/swelling in periwound skinE Exudate - Increased amount of drainageS Smell - Unpleasant or sweet, sickening odor
  33. 33. RESULTS Predictability compared to semi-quantitative cultures obtained via Levine Technique
  34. 34. RESULTS Suggest that level of bacterial growth can be assessed using the clinical variables in the mnemonics NERDS: Scant to light growth STONEES: Moderate to heavy growth When any 3 clinical signs were combined in either group: Sensitivity = 73% for scant/light (NERDS) Sensitivity = 90% for mod/heavy (STONEES) Woo, Sibbald; OWM 2009;55(8):40-48
  35. 35. I.D.S.A. D.F.U. CLASSIFICATION Clinical Description IDSA Class Wound without purulence or any  Uninfected manifestations of infection >2 of following:(purulence, erythema,  Mild pain, tenderness, warmth, induration). Cellulitis <2cm around ulcer and infection limited to skin or superficial sub-cut. tissues Systemically well with >1 of following: Cellulitis >2 cm, lymphangitis, deep tissue  Moderate abscess, gangrene, muscle, tendon, bone inv. Systemic toxicity/metabolic instability  Severe (fever/chills, tachy, hypotension, confusion, vomiting, increased WBC’s
  36. 36. ACCURACY OF SYMPTOMS AND SIGNS 2 studies from Gardner, et al showed that likelihood of infection increases when increased pain present. Absence of pain was not a useful predictor of absence of infection Gardner, Hillis, Frantz; 2009 Gardner, Frantz, Doebbeling; 2001
  37. 37. ACCURACY OF SYMPTOMS AND SIGNS Purulent exudate, erythema, heat and edema (classic signs) not helpful in diagnosing infection in chronic wounds Wounds without serous exudates or those healing rapidly were less likely to be infected Foul odor did not significantly predict infection Examined application of IDSA DFU scale to chronic wounds – 46% and 52% sensitivity. Not helpful. Gardner, Hillis, Frantz; 2009
  38. 38. ACCURACY OF NONINVASIVE TESTS Four studies evaluated utility of swab cultures and lab markers compared with deep tissue biopsy culture. 4 studies included 198 patients Levine Technique: Positive culture predictive of infection and negative culture predictive of absence of infection Z - Technique: Not useful in predicting or excluding wound infection Reddy, Gill, Wu, Kalkar, Rochon; JAMA 2012
  40. 40. BOTTOM LINE Classic signs of infection not particularly helpful in diagnosing infection in chronic wound Serous exudate more predictive (higher LR) than purulent exudate in predicting infection Combinations of findings (IDSA DFU) not useful for predicting chronic wound infection Increasing pain is the most useful indicator of infection when there is suspicion of infection but absence of pain does not predict absence of infection
  41. 41. MORE BOTTOM LINE Quantitative swab culture via Levine Technique has highest quality evidence of any noninvasive test for infection in chronic wounds; both positive and negative predictive value Presence of increasing pain, along with a quantitative swab culture, might help physicians estimate the probability of infection. Reddy, Gill, Wu, Kalkar, Rochon; JAMA 2012
  42. 42. 5 QUESTIONS1) Which organisms, regardless of quantity, need to be treated?2) Which organisms usually do not need to be treated?3) What are the most reliable clinical indicators of chronic wound infection?4) What constitutes the best combination of diagnostic tools (clinical/lab) to diagnose chronic wound infection?5) Is TMP/SMZ still appropriate, in our community, to treat MRSA wound infection without systemic illness?
  43. 43. Which organisms, regardless of quantity, need to be treated? Staph aureus; MSSA or MRSA Group A Strep (S. pyogenes) Group B Strep (S. agalactiae) Group C and G Strep Pseudomonas aeruginosa E.coli, Klebsiella pneumoniae, Proteus sp.
  44. 44. Which organisms usually do not need to be treated? Coagulase negative Staph (epi, warneri, capitis) Stenotrophomonas Acinetobacter species Enterococcus Strep viridans isolates
  45. 45. What are the most reliable clinical indicators of chronic wound infection? Pain in immediate periwound area Friable bloody granulation tissue Advancing pweriwound erythema Malodor Fever or other systemic signs and symptoms of illness in absence of other identifiable source of infection Crepitance in surrounding tissues
  46. 46. What constitutes the best combination ofdiagnostic tools (clinical/lab) to diagnose chronic wound infection Positive swab (Levine) for appropriate organisms Increasing pain in and around wound Careful with validity of probe to bone for osteo
  47. 47. Is TMP/SMZ still an appropriate choice, in our community, to treat MRSA wound infection without systemic signs/symptoms? Yes – 90% Watch for acute adverse events, ie, Steven-Johnson