Medication Guide App

Maggots

Scientific Name(s): Phaenicia sericata or Lucilia sericata

Common Name(s): Maggot , fly larva , grub , botfly maggot , viable antiseptic , living antiseptic , surgical maggot

Uses

Maggot debridement therapy (MDT) is used in persistent ulcers, especially pressure ulcers and diabetic-related ulcers, although other wound applications have been reported. Cost effectiveness of the therapy, as well as effectiveness in reducing time to heal, has not been established.

Dosing

Standards for the growth and harvesting of P. sericata larvae have been published, and have been accepted by the Food and Drug Administration (FDA) in the approval of maggots in the medical management of wounds. Estimates of the quantity of maggots required for debridement include the use of 10 maggots per cm 2 of wound and 100 maggots per 50 g necrotic tissue over 4 days.

Contraindications

Contraindications may include life- or limb-threatening conditions, lack of wound hemostasis, deep-tracking wounds, psychological issues, and hypersensitivity. With wounds, contraindications may only exist until underlying pathology is addressed (ie, maggots have been successful in osteomyelitis and limb-threatening conditions).

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

When used therapeutically, maggots do not appear harmful to living tissues, but can produce pain and pruritus, as well as anxiety. Severe bleeding has resulted from maggot therapy.

Toxicology

Information regarding the toxicology of maggot exudate is limited.

Maggots are the larvae of various flies. The species P. sericata (green blow fly) has been therapeutically used with success for many decades, but other species such as Lucilia caesar , Phormia regina , and Musca domestica have also been used. 1 , 2 Standards for the growth and harvesting of P. sericata larvae have been published and have been accepted by the FDA for approval in the medical management of wounds. The second instar (stage) larvae are used to feed on tissue material before they develop into nonfeeding pupae after 5 to 7 days. These are removed before they enter the 1- to 3-week–long pupation stage leading to adult flies. 1 , 3 , 4 , 5

History

The effects of maggots on wounds have been known since the 1500s when it was observed that maggots cleaned untreated wounds, removing necrotic tissue without apparent harm to living tissue. Later, some military surgeons noticed that maggot-infested wounds responded better than noninfested wounds. The first scientific paper on the surgical use of maggots appeared in 1931, and interest in the technique continued throughout the 1930s and early 1940s. MDT was routinely performed in over 300 hospitals during this time. The first civilian use, based on observations during World War I, was in treating 4 children with osteomyelitis who did not respond to other available treatments. Subsequent occurrence of tetanus in other cases led to the development of bacteriologically sterile maggots. Early uses for maggot therapy included the treatment of abscesses, burns, cellulitis, gangrene, and ulcers. The use of maggots declined rapidly in the mid-1940s with the development of antibiotic drugs, but more recent cost-effectiveness evaluations and acceptability studies suggest a resurgence in interest. 1 , 3 , 6 , 7

Uses and Pharmacology

Wound debridement

The mechanisms by which maggots debride wounds and thereby promote healing have not been proven conclusively. However, a variety of mechanisms have been suggested, and studies are being undertaken to elucidate specific mechanisms. The exudate produced in response to the maggots physically washes bacteria out of the wound. The crawling larvae mechanically stimulate viable tissues to rapidly produce granulation tissue. They also enzymatically liquefy necrotic tissue. Bacteria are destroyed within the alimentary tracts of the larvae, which also use necrotic tissue as food. Maggots may produce antibacterial agents that are released in their secretions. They also increase the alkalinity of the wound, promoting healthy granulation. Substances proposed as beneficial secretions of maggots include allantoin, ammonium ions, and calcium carbonate. 1 , 6 , 8

Antibacterial action of the secretions of maggots has been determined and may include methicillin-resistant Staphylococcus aureus and Pseudomomas aeruginosa . 9 , 10 , 11 , 12

Clinical data

Numerous case reports and anecdotal evidence exist. A few prospective studies have been published among a limited pool of researchers, including those pursuing FDA approval of medical maggots, and even fewer randomized clinical trials have been undertaken.

In a prospective, but not randomized, study of MDT versus conventional therapy for pressure ulcers, positive findings were attributed to MDT. Reductions in wound size, time for debridement, and amount of necrotic tissue, as well as increases in granulation outcomes all reached statistically significant differences in the 61 wounds (50 patients) evaluated. 3 Other measures such as decreased odor from necrotic tissue and decreased wound pain were demonstrated for MDT in a similar prospective study evaluating pressure ulcers and chronic leg ulcers secondary to diabetes. 6

A randomized clinical trial evaluated the cost-effectiveness of MDT in leg ulcers. 13 Therapy with maggots was estimated to incur costs similar to those of the standard hydrogel treatment. Additionally, only slightly faster healing and greater general acceptance was found for MDT, with statistical significance not being attained. 13 A similar randomized trial (the VenUS II Trial) found time-to-healing did not differ between MDT and hydrogel; however, time-to-debridement was significantly faster for larval therapy versus hydrogel. Patient selection for inclusion in the trial may have influenced the study outcomes. 14

Conflicting data exist for the relative efficacy of contained (in a bag or pouch) versus free-range larvae. 15 , 16

Other case reports include reviews of the treatment of wounds secondary to arthroscopy, MDT in palliative and outpatient settings, and in patients with hemophilia or diabetes. 17 , 18 , 19 , 20 , 21

Some patients with severe tissue destruction may also receive antibiotics along with MDT. A report evaluates this combination. Larvae survival was decreased when very high doses of gentamicin and cefazolin were administered. Antibiotics showing no effect on survival rate included ampicillin, ceftizoxime, clindamycin, mezlocillin, and vancomycin. 22

Other uses
Forensic entomology

Analyses of maggots found in decomposing bodies can reveal information about the time of death and the presence of specific drugs, as well as providing clues about crime location and circumstances. 23

Dosage

Estimates of the quantity of maggots required for the use of debridement include 1 , 3 , 15 the use of 10 maggots per cm 2 of wound 1 and 100 maggots per 50 g necrotic tissue over 4 days. 15

In a trial evaluating loose maggots versus contained (bagged) maggots, the time for most efficient consumption of necrotic tissue was determined to be 4 days, in contrast to usual protocol regarding dressing changes. 15 Mean time-to-debridement in prospective studies of pressure ulcers suggests applications of maggots required 10 days to 3 weeks, depending on wound size and extent of necrosis. 3 , 6

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Myiasis, the infestation of tissue with fly larvae, is a recognized ICD-10 disease, but is distinct from the therapeutic application of larvae discussed in this monograph. 24

Pain, commonly associated with the end stage of treatment when healthy tissue has been exposed, has been reported and managed with analgesia. 6 , 13 Pruritus and discomfort, as well as anxiety have also been reported in a minority of patients; however, the incidence of reported adverse events may be a reflection of the type of wound and depend upon the (self-selecting) patient. 3 , 25

Case reports of serious bleeding exist. Contraindications may include life- or limb-threatening conditions, deep-tracking wounds, lack of wound hemostasis, psychological issues, and hypersensitivity. With wounds, contraindications may only exist until the underlying pathology is addressed (ie, maggots have been successful in osteomyelitis and limb-threatening conditions). 1 , 3 , 26 , 27

Toxicology

Information regarding the toxicology of maggot exudate is limited.

Bibliography

1. Claxton MJ, Armstrong DG, Short B, Vazquez JR, Boulton AJ. 5 questions—and answers—about maggot debridement therapy. Adv Skin Wound Care . 2003;16(2):99-102.
2. Li Q, Lu R, Huo R, Fu H. Maggots of musca domestica in treatment of acute intractable wound. Surgery . 2009;145(1):122-123.
3. Sherman RA. Maggot versus conservative debridement therapy for the treatment of pressure ulcers. Wound Repair Regen . 2002;10(4):208-214.
4. Sherman RA, Wyle FA. Low-cost, low-maintenance rearing of maggots in hospitals, clinics, and schools. Am J Trop Med Hyg . 1996;54(1):38-41.
5. US Department of Health and Human Services. Food and Drug Administration. Medical maggots and maggot confinement dressings. October 5, 2007. http://www.accessdata.fda.gov/cdrh_docs/pdf7/K072438.pdf . Accessed March 2, 2010.
6. Mumcuoglu KY, Ingber A, Gilead L, et al. Maggot therapy for the treatment of intractable wounds. Int J Dermatol . 1999;38(8):623-627.
7. McKeever DC. The classic: maggots in treatment of osteomyelitis: a simple inexpensive method. 1933. Clin Orthop Relat Res . 2008;466(6):1329-1335.
8. Horobin AJ, Shakesheff KM, Pritchard DI. Maggots and wound healing: an investigation of the effects of secretions from Lucilia sericata larvae upon the migration of human dermal fibroblasts over a fibronectin-coated surface. Wound Repair Regen . 2005;13(4):422-433.
9. Bexfield A, Nigam Y, Thomas S, Ratcliffe NA. Detection and partial characterisation of two antibacterial factors from the excretions/secretions of the medicinal maggot Lucilia sericata and their activity against methicillin-resistant Staphylococcus aureus (MRSA). Microbes Infect . 2004;6(14):1297-1304.
10. Steenvoorde P, Jukema GN. The antimicrobial activity of maggots: in-vivo results. J Tissue Viability . 2004;14(3):97-101.
11. van der Plas MJ, Jukema GN, Wai SW, et al. Maggot excretions/secretions are differentially effective against biofilms of Staphylococcus aureus and Pseudomonas aeruginosa . J Antimicrob Chemother . 2008;61(1):117-122.
12. Cazander G, van Veen KE, Bernards AT, Jukema GN. Do maggots have an influence on bacterial growth? A study on the susceptibility of strains of six different bacterial species to maggots of Lucilia sericata and their excretions/secretions. J Tissue Viability . 2009;18(3):80-87.
13. Soares MO, Iglesias CP, Bland JM, et al. Cost effectiveness analysis of larval therapy for leg ulcers. BMJ . 2009;338:b825.
14. Dumville JC, Worthy G, Bland JM, et al; VenUS II team. Larval therapy for leg ulcers (VenUS II): randomised controlled trial. BMJ . 2009;338:b773.
15. Blake FA, Abromeit N, Bubenheim M, Li L, Schmelzle R. The biosurgical wound debridement: experimental investigation of efficiency and practicability. Wound Repair Regen . 2007;15(5):756-761.
16. Steenvoorde P, Jacobi CE, Oskam J. Maggot debridement therapy: free-range or contained? An in-vivo study. Adv Skin Wound Care . 2005;18(8):430-435.
17. Wollina U, Kinscher M, Fengler H. Maggot therapy in the treatment of wounds of exposed knee prostheses. Int J Dermatol . 2005;44(10):884-846.
18. Steenvoorde P, van Doorn LP, Jacobi CE, Oskam J. Maggot debridement therapy in the palliative setting. Am J Hosp Palliat Care . 2007;24(4):308-310.
19. Sherman RA, Sherman J, Gilead L, Lipo M, Mumcuoglu KY. Maggot debridement therapy in outpatients. Arch Phys Med Rehabil . 2001;82(9):1226-1229.
20. Rojo S, Geraghty S. Hemophilia and maggots: from hospital admission to healed wound. Ostomy Wound Manage . 2004;50(4):30, 32, 34.
21. Frykberg RG, Zgonis T, Armstrong DG, et al; American College of Foot and Ankle Surgeons. Diabetic foot disorders. A clinical practice guideline (2006 revision). J Foot Ankle Surg . 2006;45(suppl 5):S1-S66.
22. Sherman RA, Wyle FA, Thrupp L. Effects of seven antibiotics on the growth and development of Phaenicia sericata (Diptera: Calliphoridae) larvae. J Med Entomol . 1995;32(5):646-649.
23. Beyer JC, Enos WF, Stajic M. Drug identification through analysis of maggots. J Forensic Sci . 1980;25(2):411-412.
24. Sherman RA, Roselle G, Bills C, Danko LH, Eldridge N. Healthcare-associated myiasis: prevention and intervention. Infect Control Hosp Epidemiol . 2005;26(10):828-832.
25. Teich S, Myers R. Maggot therapy for severe skin infections. South Med J . 1986:79(9):1153-1155.
26. Stockley RA, Hill SL, Drew R. Asthma associated with a circulating IgG antibody to Calliphora maggots. Clin Allergy . 1982;12(2):151-155.
27. Steenvoorde P, van Doorn LP. Maggot debridement therapy: serious bleeding can occur: report of a case. J Wound Ostomy Continence Nurs . 2008;35(4):412-414.

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