Technology update The use of larval therapy in modern wound care
FREQUENTLY ASKED QUESTIONS
n Can larval therapy be used underneath compression? Larval therapy can be used under compression providing the bandaging does not occlude air from the wound.
n Do larvae kill bacteria? Larval therapy can eliminate any type of bacteria from an infected wound. As larvae ingest necrotic tissue they also ingest any bacteria present. Bacteria are destroyed as they pass through a larvae’s gut[9,26,27]
.
n Can larvae multiply in the wound? There are fears that larvae may multiply when on the wound. However, when the sterile larvae are applied, they are only at the ‘juvenile’ phase of their life cycle, meaning they are unable to reproduce. Therefore, there is no risk that the larvae will reproduce while in a wound[10]
.
n Do clinicians need to count the number of larvae? There may be fewer larvae at the end of treatment as some may perish naturally. Larvae may also eat each other. For this reason, it has never been recommended practice that individual larvae should be counted at any point. Post-treatment counts will never match the numbers originally applied to the wound.
n Why does exudate production initially increase? Exudate production is often increased during larval therapy. This is due to the production of secretions that liquefy dead tissue and the movement of the larvae. This movement may stimulate the production of serous fluid by the wound[28]
and there may be an
odour associated with the increase in exudate, particularly if the wound is infected. Larvae ingest bacteria and release foul-smelling organic molecules as they liquefy necrotic tissue. Larvae can also produce malodourous ammonia-containing by-products during protein digestion[10]
.
n Why is the wound fluid dark red? Wound exudate may be dark red in colour for the duration of the larval therapy, due to the aforementioned ammonia-containing by-products. This is normal and an indication that the larvae are thriving and feeding well.
n What happens if a larvae remains in the wound? Any larvae left in the wound after discontinuation will perish and be washed away at dressing change. The life cycle is stalled in the wound environment as it is too moist to support pupation[9]
.
n How long can a patient receive larval therapy for? Typically, larval therapy products can be used for a maximum of three days per application with free range larvae, and five days per application of netted/ pouch applications. Larval therapy treatments can be repeated as many times as is necessary to achieve complete debridement. However, due to the rapid nature of debridement achieved by larval therapy, multiple applications are unlikely to be required.
n How can larval therapy be accessed? At present larval therapy has to be prescribed by the appropriate healthcare professional. The prescription is placed with the pharmacy who will then order direct from the supplier.
n What is the shelf life of the larvae? The larvae should be kept in their delivery box and stored between 6–25o
C, usually at room temperature until application. The application needs to be on the day of delivery, as indicated by the expiry date on the packaging.
References
22. Dumville J, Worthy G, Bland M et al. Larval therapy for leg ulcers (VenUS II): randomised controlled trial. BMJ 2009; 338: b773.
23. Namias N, Varela JE, Varas RP, Quintana O, Ward CG. Biodebridement: a case report of maggot therapy for limb salvage after fourth-degree burns. 2000; J Burn Care Rehab 21(3): 254–57.
24. Armstrong DG, Mossel J, Short B et al. Larval debridement therapy: a primer. J Am Podiatr Med Assoc 2002; 92: 398–401.
25. Hawthorn G, Davidson B. Use of larval therapy in a chronic diabetic foot ulcer: A case study. The Diabetic Foot Journal 2010; 13(3):142–45.
26. Thomas S, Andrews A, Hay P, Bourgoise S. The antimicrobial activity of maggot secretions: results of a preliminary study. J Tissue Viability 1999; 9(6): 127–32.
27. Mumcuoglu KY, Miller J, Mumcuoglu M, Friger M, Tarshis M. Destruction of bacteria in the digestive tract of the maggot of Lucilia Sericata. J Med Entomol 2001; 38(2): 161–66.
28. Beasley WD, Hirst G. Making a meal of MRSA — the role of biosurgery in hospital acquired infection. J Hosp Infect 2004; 56: 6–9.
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Technology and product reviews
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