THE ROLE OF MAGGOTS IN CHRONIC WOUNDS

Saldy Yusuf, S.Kep.Ns.ETN

Wound Care Specialist

A. INTRODUCTION.

Chronic wounds is the silence epidemiology, it happens all around the world, both western and eastern, from rural to urban area. Chronic wound occurs when reparative process does not proceed through an orderly and timely process as anticipated and healing complicated and delayed by intrinsic and extrinsic factors that impact on person, the wound and the environment.¹ Chronic wound higs risks leading to infection due to increse bacterial load on wound bed and decrese host resistance as result of longterm care. The presence of bacteria in wound may results in; contamination (the bacteria do not increse in number or cause clinical problems), colonisation (the bacteria multiply, but wound tissue are not damaged) and next results is nfection (the bacteria multiply, healing is disrupted and wound tissue are damaged).² Moreover the problem of chronic wound not only on wound site but including patient’s quality of life due to malodour, exudate leakage, and longstay care further more it’s not only patients but including spouse, children, and environment.

Effective management of wound infection often requires a multi-disciplinary approach and may involve specialist referral. It aims to readjust the interaction berween the patient and the infecting microorganism(s) in favour of the patient by optimising host response anf reducing the number of micro-organisms.² In order to reducing bacterial load on wound bed, debridement is still essential approach. By definition debridement is the removal of dead material from a wound. It can accomplished by several different methods: sharp, chemical, mechanical and autolytic and less frequent is the use of biodebridement.³

B. HISTORY.

Biodebridement or Maggot Debridement Therapy or Larval Therapy is debridement by usng maggots where is maggots put into the wound bed for several days. It’s believe that maggot has a proteolyitc enzymes which can degrade dead materials on wound bed including bacteria.

The benefit of maggots in wound care have been known for centuries. One of the first written reports of larval therapy is credited to Ambroise Paré.^4-9 Paré, chief surgeon to France's Charles IX and Henri III, noted the beneficial effects of maggots in the wounds of soldiers in 1557. Next Napoleon’s military surgeon Baron D.J.Larrey observed that maggots enhanced granulation formation,⁹ and only attacked necrotic tissue and promoted healing of wounds.⁴ Furthermore during the Civil War, Confederate surgeons Joseph Jones and J.F. Zacharias began using maggots to treat wounds.^4-9

The useful of maggots still exiss untill 19th centuries. William Baer, while at Johns Hopkins University in Baltimore, Maryland, may have been the first in the Northern Hemisphere to have intentionally applied larvae to wounds in order to induce wound healing. During the late 1920's, he identified specific species, raised them in the laboratory, and used their larvae to treat several children with osteomyelitis and soft tissue infections. He presented his findings at a surgical conference in 1929. Two years later, after treating 98 children, his findings were published posthumously.⁵ The therapy became incrasingly more popular and was widely used to treatment of chronic wounds across North America and Europe during 1930.⁹

C. WHAT IS MAGGOTS.

Maggots is fly larvae or immature flies and there are thousands species of flies but not all species of flies are safe and effective as medicinal maggots. each with its own habits and life cycle. Some fly larvae feed on plants or animals, or even blood (i.e., mosquitoes), Others feed on rotting organic material.⁵

Some maggots will feed only dead tissue, some only on live tissue, and some on live or dead tissue.⁵ The larvae of the green-bottle fly lucilia (Phaenicia) sericata are the most commonly used for wound management. ^4,5,7,9 they are 2-3 mm in long , but they can reach 8-10 mm in size when fully grown. Hatch from their eggs in 12-24 hours⁹ and it takes 10-14 days for a newly maggot to complete a lifecycle and turn into a fly.⁷

D. HOW IT DOES WORKS.

Actually maggots has three roles in wound care:^6-9

1. 1. Wound debridement.

The larvae feed on the necrotic tissue of the wound. Proteolytic enzymes secreted by the maggots degrade dead material into a nutrient-rich liquid which is then ingested by the maggots.^4,6,7 Maggots use a pair of mandibles/hooks for movement and attachment, and it was believed that the probing from the hooks may facilitate wound debridement.⁹ This action is likely to aid debridement, so it also known as biosurgical debridement ⁶

2. 2. Antimicrobial activity.

Secretions from the larvae changing the wound pH,⁴ so it’s not suitable for bacteria furthermore bacteria being destroyed in the larval alimentary tract due to antibacterial substances.⁴ Larval have shown to be active against bacterial biofilm by degrading the polysaccharide slime which makes up the film. This is important since biofilms are highly resistant to other treatments, protecting the contained bacteria from antibiotics and host immune responses.⁶

So using maggots for debridement is particularly useful, as they have been found to ingest and destroy bacteria including MRSA (Thomas, 2001).¹⁰

3. 3. Growth promoting activity.

Larval secretions directly stimulate the wound healing process.^4,6 The crawling action of the larvae stimulating granulation tissue.⁴ Probably the most significant effect is the proteolytic lysis of fibrin cuffs which are associated with the reduced blow flow at the site of the wound. Furthermore fibronectin fragments and the larval proteases themselves directly induce the activity of human cells involved in the wound healing process.⁶. They also can stimulate the formation og granulation tissue (Prete, 1997)⁷

E. ADVANTAGES AND DISADVANTAGES.

According to Vowden and Vowden (2002), potential advantages of larval therapy are⁷:

1. Rapid but selective debridement.

2. Reduced bacterial burden.

3. Possible control MRSA.

4. Possible ‘micromassage’ effect stimulating healing.

5. No reported toxicity or allergnicity.

Beside of upon advantages, there are some disadvantages of larval therapy in wound care, such as:

1. Availability (not available on Drug traiff).

2. Slower than sharp or surgical debridement.

3. Not suitable for all wounds.

4. Effectiveness limited by environment (wound pH, fluid and oxygen).

5. Aesthetic aspects for patients and staff.

6. Disposal.

F. INDICATION VERSUS CONTRAINDICATION.

1. INDICATIONS

Larval therapy can be used to treat many types of wound including leg ulcers, presure ulcers, diabetic foot ulcers, surgical wounds and burns. It has also been proven to be effective on infected, necrotic anf sloughy tissue (Thomas and Jones, 1999).⁸ Various clinical studies has demonstrated the efficacy of MDT in treating wounds that fail to heal following alternative forms of treatment.⁹ The Benefits of MDT have been reported for a variety of chonic wounds as listed below:⁹

Types of wounds/lessions for whivh maggot therapy may be used

Diabetic Ulcers

Venous Ulcers

Neurophatic ulcers (non-diabetic ulcers)

Arterial/ischemic ulcers

Pressure sores

Thromboangitis obliterans

Post traumatic wounds/ulcers

Necrotising fascitis

Pyoderma gangrenosum

Excised abscess on malleolus

Pilonidial sinus

Grossly infected toe

Osteomyelitis

Infected wound after forearm replantation

Wound of exposed knee prostheses

Wound infection after breast surgery

Infected gun shot wound

Malignant wounds

Burns

Non-healing surgical wound

Methicillin-resistant Staphylococcus aureus-infected wound

Mixed arterial-venous ulcer

Sub acute mastoiditis

2. CONTRAINDICATIONS

Larval should not be applied to wounds that have a tendency to bleed easily, or be introduced into wounds that communicate with a body cavity or internal organ. They should also not be applied to any large blood vessels.^8,9 Also, maggots should not be used in patients who are allergic to eggs, soybeans, or fly larvae.⁹

Jose Contreras-Ruiz, divided contraindications of Maggot Debridement Therapy (MDT) into three categories¹¹:

a. Absolute.

Using MDT is contraindicated in the absence of a well-informed patient or their care givers. Using non sterile maggots can cause severe deadly infections so sterile maggots should always be used. MDT is contraindicated in active pyoderma gangrenosum in the absence of proper treatment moreover MDT can cause fatal consequences if it applicate on wounds likely to communicate to the central nervous system, a large blood vessel, body cavities or vital organs. MDT is contraindicated in necrotizing or rapidly advancing infections (necrotizing fasciitis, gaseous gangrene) and sepsis since regular surgery is faster and life saving.

b. Relative.

Dry wounds are a relative contra-indication as maggots require a moist environment.⁹ In deep fistulas or undermining MDT application and removal becomes difficult and sometimes incomplete and If a patient can’t stay off the maggots the therapy is useless.

c. Theoritical.

Some maggot producers utilize egg albumin or soy to breed them so a history of allergies to these substance must be taken and other potential allergies could be from maggots secretions or the dressing used to encage them. Another potential complication could be ammonia toxicity that could induce encephalopathy in patients with liver failure.

G. HOW TO APPLY

Care should be taken to avoid having a larvae come in contact with healthy skin which can damage the skin by proteolytic enzymes.¹² A hole is cut out of a hydrocolloid dressing the same size and shape as the lesion and the dressing is applied to the wound. This provides a base for the outer dressing and protects the surrounding skin from the proteolytic enzymes of the larvae.⁴ and a mesh net over the wound to contain the larvae and an absorben pad to contain exudates (Sherman, 1997).¹¹

Sterile maggots are inserted into the wound and a dressing applied so they are contained within the wound.³ Approximately 10 larvae per square centimeter of lesion are then placed into the lesion.⁴ The wound and larvae are then covered by a fine nylon net which is attached with adhesive tape. An absorbent pad is then placed on top of the netting in order to absorb the exudate and liquefied necrotic tissue and it can be changed as often as necessary as its removal will not disturb the larvae.⁴ The maggot dressing is removed as soon as the maggots have finished secreting their proteolytic (tissue-dissolving) enzymes (within 48-72 hours).⁵ They are flushed from the wound and disposed of as the biological waste (Thomas et all 1998). If the wound needs further debridement additional maggots are applied and the process is repeated.^3,4 Untill the wound bed is clean and viable tissue is present, debridement is no longer indicated.¹¹

H. CONLUSION

Chronic wound higs risks leading to infection due to increse bacterial load on wound bed, using Maggot Debridement Therapy (MDT) can be a choice because it has 3 functions; wound debridement, wound desinfection and promoting wound healing. It also could be used in widespread chronis wounds such as diabetic ulcers, pressure ulcers and leg ulcers.

REFERENCES:

1. Carville. Wound Care Manual 3^rd ed. St. Osborne Park: Silver Chain Foundation, 1998:44
2. Members Of Expert Working Group. Principles of best practice. Wound Infection in Clinical Practice: an international consensus. WCET Journal 2008;28 (4):5-14
3. Stotts.Wound Infection: Diagnosis and Management in: Chronic Wound Care; A Problem-Based Learning Approach, Mosby;2004.p.108

4. Hinshaw Janet. Larval therapy: A review of clinical human and veterinary studies.2000. Available at: http://www.worldwidewounds.com/2000/oct/Janet-Hinshaw/Larval-Therapy-Human-and-Veterinary.html. [cited Februari 13^th 2009].

5. Sherman Ronald A. Maggot Debridement Therapy (MDT).2008. Available at: http://www.medicaledu.com/maggots.htm

6. Adrian Koerber, John ward & Susan Franks: The Role Of Maggots in Wound Healing. Available from URL: http://www.maths-in-medicine.org/uk/2001/maggots/
7. Kathryn Vowden, Peter Vowden. Wound Bed Preparation. Available from URL: http://www.worldwidewounds.com/woundbedpreparation.html
8. Acton Claire. A Know how guide to using lerval therapy for wound debridement. Available from URL: www.footindiabetes.org/Guidelines/larvae-therapy.pdf

9. Chan Dominic CW, Fong Daniel HF, Leung June YY, Patil NG, Leung Gilberto KK. Maggot debridement therapy in chronic wound care. Available from URL: http://www.hkmj.org

10. Dealay. The care Of Wounds. A gudie for nurses.Blackwell Publishing Ltd;2005. p.72-75
11. Contreras Jose-Ruiz. Contraindications to Maggot Debridement Therapy. Available from URL: www.cawc.net/open/wcc/3-1/contreras.html
12. Ramundo. Wound Debridement in: Bryant (editor). Acute & Chronic Wounds, Current Management Concepts 3^rd ed.St. Louis: Mosby;2007. p.182