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Recognising and treating the causes of chronic malodorous wounds

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Samantha Holloway, RGN, CertEd (FE), ILTM.

Lecturer, Wound Healing Research Unit, Cardiff Medicentre, Cardiff

Patients with a range of wound types are at risk of developing malodour (Haughton and Young, 1995; Benbow, 1999; Williams and Griffiths, 1999; Bryant, 2000). However, in spite of the fact that exuding, malodorous wounds are recognised as a difficult clinical problem (Grocott, 1995a), the exact incidence and/or prevalence of such wounds is not known. Problems associated with malodorous wounds include social isolation, loss of appetite, inhibition of intimacy and distress for the patient and carers (Neal, 1991; Clark, 1992; Boardman et al, 1993; Grocott, 1995b).

This paper examines the causes of wound malodour and outlines strategies to manage patients. The causes of malodour are outlined in Box 1, some of which stem from wound aetiology, while others arise because of the wound-management strategies employed.

Malodour and infection

Malodorous wounds are often polymicrobial, that is they contain both anaerobes and aerobes (Bowler et al, 1999), and the level and type of bacteria present will affect the wound environment. Anaerobic bacteria that cause infection include bacteroides such as Bacteroides fragilis, prevotella, Fusobacterium nucleatum, Clostridium perfringens and anaerobic cocci, which generate odour by emitting compounds such as putrescine or cadaverine.

The odours emanating from such infected wounds will be obvious to anyone in close proximity to the patient (Van Toller, 1994). They can induce a vomit or gagging reflex, and are often described as acrid - this is commonly reported by patients with fungating breast carcinomas.

Aerobic bacteria such as the proteus, pseudomonas and klebsiella species can also produce offensive odours (Hampson, 1996). Traditionally, it was solely the presence of odour that was seen as a sign of infection; however, a sudden increase in exudate levels may also indicate infection and can be associated with malodour (Collier, 2001).

Malodour and devitalised tissue

In chronic wounds, such as pressure ulcers, leg ulcers, diabetic foot ulcers and fungating wounds, the odour may also be due to tissue degradation. Devitalised tissue can play host to anaerobic and aerobic bacteria, increasing the risk of infection. Necrotic wounds tend to have a more offensive odour than clean wounds (van Rijswijk, 2001).


Odours that are produced by necrotic or sloughy tissue may be due to the presence of dead, devitalised tissue, the proliferation of anaerobic micro-organisms, or the interaction between anaerobic and aerobic bacteria (Bowler et al, 1999). The effects on patients is particularly devastating, as they have to live with the consequences of having a foul-smelling, discharging wound, which can affect body image (Haughton and Young, 1995). The key to management is undertaking accurate patient and wound assessments (Pudner, 2001).

All wounds produce an odour: healthy wounds have ‘a faint but not unpleasant odour akin to fresh blood’ (Cutting and Harding, 1994), and this is generally less of a problem in granulating wounds than sloughy/necrotic wounds (Rolstad and Nix, 2001). However, the nurse must recognise malodour as a potential warning sign (Benbow, 1999) and be alerted to the need to pinpoint the cause - infection or devitalised tissue.

Assessment of odour is subjective. A descriptive assessment can provide important information because a change in type or amount of odour may indicate a change in wound status (van Rijswijk, 2001). Descriptions of odour may include phrases such as ‘sweet’, ‘like fresh blood’, ‘putrid’, as well as descriptions, for example, that it filled the room (van Rijswijk, 2001). For the purposes of documentation and ongoing evaluation it may be useful to use an assessment tool such as the one outlined in Table 1.

Following assessment the nurse will need to have knowledge of other strategies to assist in managing the wound, which may include the use of systemic antibiotics, topical antimicrobials and wound dressings (Collier, 2001).

Management strategies

Management of patients with malodorous wounds often calls for the practitioner to be resourceful in using topical treatments and in applying dressings. The main treatment aim must be to prevent/ eradicate infection, which may require the use of one, or combination of, the following:

- Systemic antibiotics

- Topical antimicrobials or metronidazole (Haisfield-Wolfe and Rund, 1997)

- Debridement.

The source of the problem - the infection - may be treated systemically with oral antibiotics (Grocott, 1993) such as metronidazole, which can also be used locally in gel form (Thomas and Hay, 1991; Collinson, 1993; Boardman et al, 1993; Banks and Jones, 1993). The first-line treatment for patients with fungating wounds is often oral metronidazole, used in conjunction with topical metronidazole, especially for treating infection with anaerobic bacteria. Routine use of metronidazole - that is, where infection is not an issue - is discouraged because of potential patient sensitivities and resistance problems.

Topical metronidazole gel

This is a topical antimicrobial, which is applied directly to the wound surface (after cleansing). It can be used with both shallow and cavity wounds. It is usually effective within two days (although the onset can be between one and 30 days) (Moody, 1998).

Newman et al’s (1989) trial involved using topical metronidazole in 68 patients who had malodorous wounds. In 34 patients there was complete odour control, and reasonable control in 31 patients, with the remaining three finding the treatment ineffective. Although metronidazole is not a cure-all, it can be effective in cases of anaerobic infections. Preparations include Anabact, Metrogel and Zyomet gel, which are colourless and contain 0.75% metronidazole. Metrotop is an amorphous hydrogel containing 0.8% metronidazole.

These preparations can be used with, for example, fungating carcinomas and necrotic pressure ulcers (Morison et al, 1999). The odour disappears quickly with the use of metronidazole. These are prescription-only treatments; they require generous application and need a secondary dressing. Cavity dressings may need to be smeared with gel to aid application (Moody, 1998). Treatment also requires daily application and is not indicated for long-term use.

Other topical antimicrobials used in clinical practice continue to cause debate. These include:

- Wound-cleansing products that contain antiseptics

- Silver preparations that are used for local wound infection and odour management

- Iodine, available as cadexomer, is indicated for debridement; iodine and povidone preparations are indicated for use with locally infected wounds.

The disputes about the use of these preparations are based on the fact that all can be harmful to cells. However, the practitioner has to weigh up the evidence for their use in the clinical situation, especially where treatment of bacterial burden or infection is the aim of management (Robson, 1999; Wright et al, 1998a, 1998b; Gulliver, 1999).


The presence of necrosis or slough in a wound predisposes it to infection, as this provides an ideal environment for bacterial proliferation (Haughton and Young, 1995; Morison et al, 1999; Bowler et al, 1999). The smell associated with such wounds, and the embarrassment of others smelling the unpleasant odour, can result in a patient becoming socially isolated. If slough or necrotic tissue is present, this may require debridement. A practitioner should consider a number of options, based on both patient and wound assessment. The options include surgical, sharp or autolytic methods of debridement (Bale, 1997).

Surgical debridement

This necessitates a patient being taken to theatre, which is not always a practical option.

Sharp debridement

This method is described as ‘the removal of dead or foreign material, just above the level of viable tissue’ (Poston, 1996) and is defined as an enhanced role for the nurse (Fairburn et al, 2002). Only those with the appropriate skills should undertake this invasive procedure: it requires the use of a scalpel or scissors to remove devitalised tissue and carries the risk of complications such as bleeding. The patient requires careful assessment, informed consent must be obtained and pain relief provided.

Autolytic debridement

This procedure describes the natural breakdown of devitalised tissue, which may be enhanced by the use of moist wound healing dressings such as hydrogels. The use of larval therapy has increased as a method of debridement in clinical practice because the larvae break down and ingest devitalised tissue (Thomas et al, 1996).

Fungating wounds produce necrotic tissue (owing to poor vascularisation of the tissues); however, debridement is not always an option. Consequently, it is crucial to give careful consideration to the choice of management method, with the decision based on a holistic assessment and framed within the context of available resources.

Odour-controlling dressings

Other methods can be used to reduce malodour. For example, maintaining an intact dressing is an important element in odour control (Grocott, 1993; Boardman et al, 1993) and the use of charcoal dressings is advocated for their odour-absorption properties (Lawrence et al, 1993; Haughton and Young, 1995).

The first successful use of charcoal cloth - to treat fungating breast cancer, gangrene and postoperative colostomy management to reduce odour - was reported by Butcher et al (1976). Charcoal is known to be a powerful deodoriser and it has the capability to absorb bacterial spores (Coombs, 1981). Activated charcoal dressings are therefore advocated to treat malodorous wounds (Thomas et al, 1998), and have been successfully used to treat fungating wounds (Williams, 1998).

Charcoal dressings with silver can be effective deodorisers, because of the bacteriostatic properties of silver. Some preparations are incorporated into a woven fabric or a fibrous mat backed by a nylon sleeve, a semipermeable film or a polyurethane foam (Turner, 2001). The dressing must be large enough to cover the entire malodorous area. These products are designed to act like filters and absorb the odour-causing molecules.

The efficiency of such dressings depends on the presentation of the activated charcoal (Thomas et al, 1998). Odour-absorbing dressings are listed in Table 2: some of these are multilayered and include alginates to aid absorption of exudate, which is often associated with malodorous wounds. There is no evidence to show that using any one of these dressing is advantageous over any other, so choice will depend on wound exudate levels and the frequency of dressing changes necessary (Williams and Griffiths, 1999).

To optimise odour control, the wound may require cleansing and/or debriding before application of the dressing (Pudner, 2001). Further practical measures to optimise odour control include:

- Cleansing the wound to reduce the volume of odour-causing bacteria - this is usually done with normal saline due to the toxicity of some antiseptic solutions

- Ensuring general good hygiene measures

- Nursing the patient in a single room with the window open (Morison et al, 1999)

- Increasing the frequency of dressing changes

- Changing bed linen and clothing as soon as they becomes soiled (Morison et al, 1999)

- Using wound drainage bags, for example, on surgical wounds where exudate management is a problem

- Using external deodorisers to mask odour (Collier, 2001).

Other approaches used in clinical practice, but that continue to arouse debate, are the application of honey and sugar paste.


This has been shown to have antimicrobial properties (Efem et al, 1992; Cooper and Molan, 1999), but more controlled research is necessary. It is important to stress to patients interested in this treatment that unprocessed raw honey is not sterile.

Sugar paste

It has been shown to draw out exudate and tissue fluid, resulting in increased osmotic pressure which, in turn, inhibits bacterial growth (Haughton and Young, 1995). However, it requires twice daily applications, so it is costly in terms of nursing time.


There can be major psychological repercussions for patients living with a chronic malodorous wound, resulting in altered body image, feelings of rejection, shame and embarrassment. This can lead to social withdrawal; patients may also find they have a reduced appetite, arising from feelings of nausea.

The presence of odour occurs to varying degrees with many wound types, but a malodorous wound should alert the practitioner to the possibility of infection.

The treatment of such wounds depends on the cause of the odour and should follow a holistic assessment that involves the patient. The use of an odour-assessment tool may facilitate a more subjective measurement of the problem. Various adjunctive means of odour control have been outlined and should be considered as part of any management strategy.



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