By Annette M. Boyle
GAINESVILLE, FL — The VA is proving that “everything old is new again” with an unusual medical device — medicinal maggots. At the Malcom Randall Veterans Affairs Medical Center in Gainesville, the larvae of the green bottle fly are being used to clean non-healing diabetic foot wounds with impressive results.
Diabetes affects about one-fourth of patients receiving care through the VA, and nearly 25% of them will develop foot ulcers, which often persist for months and can deteriorate to the point that amputation is required.
Maggots have a long history in wound care, with even “free range” or opportunistic maggots credited with speeding healing and reducing infection. John Forney Zacharias, a surgeon during the American Civil War, is known to have applied maggots to battlefield wounds for medicinal purposes, according to the VA. During World War I, William Baer, MD, observed that American soldiers who had gaping wounds with thousands of maggots did not develop infections and the soldiers survived. He continued research at Johns Hopkins after the war, but his research fell out of favor with the advent of antibiotics.1
The Food and Drug Administration approved medicinal maggots (Phaenicia or Lucilia sericata) in 2004 for debriding nonhealing necrotic skin and soft tissue wounds, including pressure ulcers, venous stasis ulcers, neuropathic foot ulcers and nonhealing traumatic or post-surgical wounds.
The Gainesville wound care team is advancing Baer’s research with a new study that compares maggots to wound debridement with sharps — scalpel, scissors or other tools used to mechanically remove dead or unhealthy tissue. The study will enroll 128 patients, who will be randomized to the two arms. The researchers will evaluate speed of healing between the groups as well as the antibacterial properties of the maggots.
Patients will receive sharp debridement every seven days for two weeks or larval debridement therapy for eight days in two applications. Veterans randomized to the sharp group may choose to receive up to two applications of larval debridement after their initial treatment.
Unlike Baer’s maggots, the medicinal maggots used in Gainesville undergo an eight-step quality control process to ensure sterilization and come contained in fine mesh bags, which range in size from 2.5 cm x 4 cm to 10 cm x 10 cm. The size used varies with the size of the wound bed that needs debridement, lead investigator Linda Cowan, PhD, ARNP, a wound care specialist with the VA and clinical associate professor at the University of Florida College of Nursing, told U.S. Medicine.
Cowan had seen the effectiveness of maggots with patients previously and was intrigued by the emerging research on their use in wound care.
“As a clinician, I was very impressed by the literature on larval therapy. And sometimes we would have patients come into the clinic with what I call ‘free range’ maggots — they’re not sterile, they’re not produced specifically for medicinal purposes — the patients got them at home, unintentionally. But they really clean out the wound nicely,” she said.
Recent research has found that maggots have antimicrobial properties and can effectively combat infections with highly antibiotic-resistant bacteria such as Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus, as well as the fungus Candida albicans2 and Leishmania parasite.3
Larval therapy also appears to provide a novel and powerful method for eliminating biofilms. Biofilm, which can include bacteria, viruses and fungi, is a protective polymeric matrix generated by infecting pathogens that adheres to the surface of the wound and is resistant to antibiotics and immune system action.
“You can debride with a scalpel, and you can cut away what looks like dead or unhealthy tissue, but you can’t see biofilm,” Cowan said. “And if you don’t completely get rid of a biofilm growth, within 24 to 72 hours it can completely regenerate, with its protective coating.”
Cowan and her colleagues had tried a number of products to eliminate biofilms and, in a study published in 2013, found that maggots were the most successful.4 “At 24 hours, there were hardly any [bacteria] to count, and at 48 hours the biofilm was completely gone. Not one organism left,” she noted.
For veterans, the possibility of an effective treatment appears to outweigh the presumed “yuck” factor of dealing with maggots. “We have been quite surprised at the eagerness of our veterans to participate in the study, especially in the larval therapy group,” Cowan recounted. “We even had a patient withdraw from the study because he was randomized to the sharp therapy and only wanted to participate if he was in the larval group.”
Clinicians also have been keen to find patients for the study or obtain access to the maggots outside the study. “The podiatrists whose clinics are part of our study have been rather amazed at the debridement capabilities of the larvae,” Cowan said.
Surgeons, dermatologists and infectious disease clinicians “are eager to utilize this effective method of wound debridement, especially when other current treatments have failed at helping the wound close. They are also intrigued by the fact that the medicinal maggots ingest and inactivate bacteria in the wounds,” she added.
Beyond wound treatment, Cowan noted that there is growing evidence that maggots can help reduce bioburden and inflammation, increase perfusion and perhaps promote new granulation tissue, which could make larval therapy a valuable tool for many more clinicians.
1 Baer WS. The Treatment of Chronic Osteomyelitis With the Maggot (Larva of the Blow Fly). J Bone Joint Surg Am. 1931;13:438–475.
2 Margolin L, Gialanella P. Assessment of the antimicrobial properties of maggots. Int Wound J. 2010 Jun;7(3):202-4. doi: 10.1111/j.1742-481X.2010.00234.x. Epub 2010 Apr 23. PubMed PMID: 20455959.
3 Sherman RA. Mechanisms of maggot-induced wound healing: what do we know, and where do we go from here? Evid Based Complement Alternat Med. 2014;2014:592419. doi:10.1155/2014/592419. Epub 2014 Mar 13. Review. PubMed PMID: 24744812; PubMed Central PMCID: PMC3976885.
4 Cowan LJ, Stechmiller JK, Phillips P, Yang Q, Schultz G. Chronic wounds, Biofilms and the Use of Medicinal Larvae. Ulcers. 2013; article ID 4887024, 7 pages. doi:10.1155/2013/487024