17.5 Infected wounds

Diagnosing wound infection is a clinical judgement. Micro-organisms are contained in all wounds however the majority do not become infected.

The potential for wounds to become infected is influenced by:

  • The ability of the patient to fight the bacteria (host resistance)
  • Number of bacteria introduced. A higher number is more likely to overcome host resistance
  • Type of bacteria – some bacteria have an increased disease producing ability (virulence) and may be able to cause disease in relatively low numbers

An increased level of suspicion for the likelihood of wound infection should be maintained in patients with:

  • Diabetes Mellitus
  • Autoimmune disease
  • Hypoxia/poor tissue perfusion
  • Immunosuppression

Wound swabs should be taken following wound cleansing (and debridement if appropriate) from wounds which are critically colonised or clinically infected. The following wound types should be swabbed:

  • Acute wounds with signs of infection
  • Chronic wounds with signs of spreading or systemic infection
  • Critically colonised/locally infected wounds that have not responded to or are deteriorating despite appropriate topical antimicrobial treatment

See below for signs and symptoms of wound infection.

Management

Management aims are to:

  • Optimise host resistance.
  • Reduce number of micro-organisms.

Topical antibiotics are of limited value and should generally be avoided.

Swabs

If the wound is clinically infected, then a swab is taken and patient is started on systemic antibiotics. The swab result is to confirm that the antibiotic regime is the appropriate one. If indicated, change antibiotics in response to swab.

For suspected critically colonised wounds a two week anti-microbial dressing challenge without microbiological swabbing is appropriate.

Systemic antibiotics should be used in the presence of systemic and spreading infection.

Antibiotics should be prescribed in line with local antibiotic prescribing policies. A swab should also be sent and antibiotic changed if indicated by result.

Key Points:

  • Diagnosis of wound infection is a clinical judgement
  • Wound management strategies must aim to provide optimal wound healing conditions
  • Long-term use of topical antimicrobial agents must be avoided, e.g. silver dressings a maximum of two weeks
  • Antibiotic use should be limited to specific clinical situations (e.g. overt infections) and directed to susceptible organisms
  • Wound status must be regularly reviewed and management strategies changed when progress towards healing is not achieved
  • Prescribing of antibiotics should adhere to employing organisations policies and local Joint Formularies. Doses need to be of a therapeutic level and for sufficient duration

Signs and symptoms of acute wounds

Burns – also skin graft rejection – pain is not always a feature of infection in full thickness burns.

Deep wounds – induration, wound extension, unexplained increase in white cell count or signs of sepsis may be signs of deep wound infection.

Immunocompromised patients – signs and symptoms may be modified and less obvious.

Localised Infection

  • Classical signs and symptoms
    • New or increasing pain
    • Erythema
    • Local warmth
    • Swelling
    • Purulent discharge
  • Pyrexia – in surgical wounds, typically 5-7 days post-operatively
  • Delayed healing
  • Abscess
  • Malodour
  • Rising C-Reactive protein (CRP) after previous fall

Spreading Infection

As for localised infection plus:

  • Extension of erythema
  • Lymphangitis (Inflammation of lymph vessels seen as red streaks running proximally from site of infection)
  • Crepitus in soft tissues (crackling feeling or sound detected on palpation of tissues due to gas within the tissues
  • Wound breakdown or dehiscence
  • Rising CRP after previous fall

Systemic infection

  • Sepsis – documented infection with pyrexia or hypothermia, tachycardia, tachypnoea, raised or lowered white blood cell count
    • Leading to
  • Severe sepsis –sepsis and multi-organ dysfunction
    • Leading to
  • Septic shock – sepsis and hypotension despite adequate volume resuscitation
    • Leading to
  • Death

Signs and symptoms of chronic wounds

Patients who are immunocompromised and/or who have neuropathy, symptoms may be modified and less obvious.

Arterial ulcers – previously dry ulcers may become wet when infected.

In diabetic foot ulcers inflammation is not necessarily indicative of infection, but remains the most likely cause and pain may be newly experienced in a previously insensate foot.

Local infection/critical colonisation

  • New, increased or altered pain
  • Delayed healing
  • Periwound oedema
  • Bleeding or friable granulation tissue
  • Distinctive or change in malodour
  • Wound bed discolouration
  • Increased or purulent exudate
  • Induration
  • Pocketing
  • Bridging

Spreading infection

As for local/critical colonisation plus:

  • Wound breakdown
  • Extending erythema
  • Crepitus, warmth, induration or discolouration spreading into peri wound area
  • Lymphangitis
  • Malaise or other non-specific deterioration in patient's general condition

Use of anti-microbial and silver dressings

Anti-Microbial

Anti-microbial dressings should be considered to reduce bio burden in acute and chronic wounds that are infected or are being prevented from healing by microorganisms

It is not appropriate to use anti-microbial dressings:

  • In the absence of signs of localised (overt or covert), spreading or systemic infection
  • Clean surgical wounds at low risk of infection e.g. donor sites, closed surgical wounds
  • Chronic wounds healing as expected according to co-morbidities and age
  • Small acute wounds at low risk of infection
  • Patients who are sensitive to any of the dressing components
  • Wounds being treated with enzymatic debridement
  • During pregnancy or lactation
  • When contra-indicated by the manufacturer, for example, some manufacturers recommend that their silver dressings are not used during magnetic resonance imaging (MRI), or on/near body sites undergoing radiotherapy

Silver

  • Silver dressings should only be considered for critically colonised and infected wounds
  • The two week challenge
    • It is recommended that silver dressings should be used for no longer than two weeks initially and then the wound, the patient and the management approach should be re-evaluated. If there is no improvement in the two weeks the silver product should be replaced with a non-silver
  • There is a large selection of anti-microbial dressings on the formulary, silver should be considered as a final option
  • There is no evidence to support the use of silver dressings under compression bandaging for the healing of venous leg ulcers when compared with non-silver low adherent dressings.
  • Silver can have a cytotoxic effect and there is evidence for bacterial resistance
  • There is little evidence of the efficacy of silver against anaerobes although these are often present in chronic wounds
  • Silver can permanently stain the skin (argyria) and will reduce keratinocyte (skin) production.
  • High deposits of silver can have a toxic effect on internal organs

Malodorous wounds

If a wound is malodorous:

  • Remove necrotic material and excess slough.
  • Exclude infection.
  • Topical antibiotics should not be first choice.
  • Consider use of activated charcoal product to combat malodour.
  • Contact Tissue Viability nurse specialists before using any alternative therapies.

Radiation skin reactions

Gentian violet or sliver dressings must not be used.

If the skin is hot, irritable and red:

  • Apply emollient or hydrogel as a balm.

or

  • Apply 1% hydrocortisone sparingly, up to twice daily.
  • Advise patient to wear loose cotton clothing.
  • Advise patient to have short nails to reduce skin damage from scratching.
  • Advise patient not to apply talcum powder, as it may interact with radiation treatment.

If the skin is dry, flaky and/or peeling

  • Skin should not be washed with soap and water.
  • Use suitable emollient to the skin.

If the wound is producing exudates, standard wound care management is indicated.

Gastrostomy site problems

Increasing numbers of patients who are fed via gastrostomy are looked after in their own homes or care homes. The nurses responsible for the management of the site are encountering problems, which need sound wound management principles applied together with a decision on the most appropriate dressing.

To reduce maceration:

  • Good hygiene and normal routine of movement of the tube and cleansing of the site.
  • Protect with Medi Derma-S® Barrier if necessary.
  • Use Non-adhesive dressing or foam i.e. ActivHeal® or Tegaderm Foam® if very wet.

To reduce overgranulation:

  • Polyurethane foams with a high water vapour transmission rate may be useful where there is overgranulation but no obvious infection.
  • In the presence of high exudate and overgranulation use fenestrated Tegaderm Foam.
  • If not successful after 4 weeks of treatment and there are no signs of a clinical infection, contact Tissue Viability.

Gastric Leakage / Acid Burn

This results in pain, redness and breakdown of skin and itching, confirmed by testing leakage around stoma with pH indicator paper.

  • Clean area with mild pH neutral solution;
  • Keep area as clean and dry as possible;
  • Use a barrier cream to protect skin.

Cause must be identified and corrected e.g.

  • Ensure external retention device of tube is correctly positioned.
  • If the tube has a balloon, check that it is correctly inflated.
  • Stoma may have enlarged/ allergy to tube material.
  • Review type and size of tube.
  • If the patient is suffering from constipation.
  • Delayed gastric emptying – consider medication to reduce gastric acidity.

Infection of Gastrostomy Sites

Infection can be caused by

  • Poor hygiene.
  • Loose external retention device.

Signs of Infection

  • Over granulation
  • Erythema
  • Exudate
  • Pus
  • Heat
  • Temperature

Aim: Treat infection.

Action: Swab prior to initiating empirical systemic antibiotics. Review sensitivity once available and modify therapy, if indicated.

Depending on amount of exudate and presence of over granulation use

  • Kendall AMD Foam (Fenestrated)

 

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