By Michael Smith, North American Correspondent, MedPage Today
Published: September 21, 2011
Reviewed by
Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
CHICAGO -- Diabetic patients facing lower limb amputation because of non-healing lesions may get a leg up from the insect world, a researcher said here.
Biosurgery using the sterile larvae of the green blow-fly (
Lucilia sericata) may be an alternative to amputation in many cases, according to Lawrence Eron, MD, of the University of Hawaii in Honolulu.
In a series of 37 patients with complicated limb wounds, the approach, which used the larvae to debride the lesion, yielded a successful outcome in 27, Eron reported at the Interscience Conference on Anti-Microbial Agents and Chemotherapy.
The larvae, commonly referred to as maggots, only eat "devitalized" tissue, leaving living tissue alone, Eron said. This makes them ideal to clean up diabetic lesions that have not responded to standard therapy with antibiotics.
But the process might someday be useful in patients earlier in the disease course, he told
MedPage Today after his oral presentation.
The use of maggots to clean wounds goes back centuries particularly during wartime, but it had fallen out of favor. Now, Eron said, several groups are trying to see if the larvae have a clinical role in modern medicine, and especially in patients with diabetic limb wounds.
For the analysis, the researchers defined success as complete debridement of devitalized tissue, formation of robust granulation tissue, and at least 50% closure of the wound.
The 37 patients had lesions that had been present in some cases for up to five years and were resistant to all attempts at cure. The lesions included 18 abscesses, six infected ulcers, nine cases of osteomyelitis, and four cases of gangrene.
Eron said the researchers applied 50 to 100 maggots, left them in place for two days, and then removed them, repeating the process an average of five times per wound.
In 73% of the patients, the maggot debridement therapy was successful, although Eron noted that complete closure of the wound was not part of the definition of success. Other methods were used to finish the job.
"There's no question that these little critters are able to debride tissue very efficiently," Eron said.
The 10 failures were linked to excessive inflammation surrounding the wound, bleeding from the wound, fistulae from infected bones that closed after single treatment, and severe peripheral vascular disease.
One patient stopped because of pain, but most patients either couldn't feel the maggots working or found the "creepy-crawly" sensation reassuring, Eron said.
One reason to use the approach, he noted, is cost: a simple uninfected diabetic foot ulcer can cost up to $10,000 to treat, while amputation if treatment fails costs up to $65,000.
In contrast, the medical grade maggots sell for about $100 for about 200, so that an average five-cycle treatment would cost around $500, he said.
"This biosurgery is a different approach that gets us around the problem of antibiotic resistance," Catherine Bennett, PhD, of Deakin University in Melbourne, Australia, who moderated the session at which the research was presented.
"It's a very targeted, selective approach to tissue removal," she told
MedPage Today.
She noted that the patients in the study had serious wounds, and it's not clear that the process would be acceptable in patients earlier in the disease course, even if it might be medically advisable.
She said formal trials are needed and "if the evidence is good, it will convince patients as well as physicians."
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