Maggot debridement therapy effective for patients with critical limb ischemia

John Murphy, MDLinx | October 24, 2017

Maggot debridement therapy (MDT) for wound bed preparation produced higher wound healing rates than conventional treatment in patients with critical limb ischemia (CLI), researchers in Japan reported in the Journal of Wound Care.

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Maggots at work

Maggot debridement therapy on a diabetic foot wound. (Photo: Alexsey Nosenko/Maggot Medicine; CC BY 3.0)

“More favorable wound bed preparation and successful graft take were achieved in the MDT group, suggesting the effectiveness of MDT for wound healing in CLI patients,” wrote researchers led by Akio Nishijima, MD, Department of Plastic and Reconstructive Surgery, New Tokyo Hospital, Chiba, Japan.

Normal wound healing is problematic in patients with CLI due to reduced blood flow to the limb. And, debridement of wounds that lack sufficient blood flow can deteriorate ischemic lesions. Therefore, surgical treatments, including MDT, are not recommended for patients with CLI.

But for this study, Dr. Nishijima and colleagues sought to test whether MDT could successfully prepare the wound bed. They retrospectively investigated 39 patients who underwent mid-foot amputation after angioplasty between April 2014 and October 2016, and whose wounds appeared not clean enough to be closed. All patients had CLI and all underwent revascularization by endovascular therapy (EVT).

Of these, 32 received conventional wound bed preparation (ie, cleansing the open wound after surgery, then application of antibiotic ointment once or twice daily). Seven other patients who hadn’t achieved successful healing with conventional therapy received MDT for preparing the wound bed.

Wound debridement with maggots (sterilized live fly larvae) has been used in North America since the 1930s, but fell out of use in the 1940s after the development of improved surgical techniques and antibiotics.

Interest in MDT resurfaced in recent years due to the increasing need for treating intractable ulcers along with the emergence of drug-resistant bacteria. In 2004, the US Food and Drug Administration cleared maggots for the medical use of debriding non-healing necrotic skin and soft tissue wounds. MDT is now considered as an alternative strategy when surgical debridement is unfeasible or unavailable, as maggots can consume tiny parts of necrotic tissue not accessible with normal surgical debridement.

In the current study, the researchers found that the proportion of wound healing that averted major amputation was significantly higher in the MDT patients than in those given conventional therapy (86% vs 38%; P=0.035). Patients with favorable wound bed preparation received a skin graft 1 week after MDT ended.

Six months after amputation, however, there were no significant differences in amputation-free survival (AFS; 71% vs 47%; P=0.41) or ambulatory capability (43% vs 28%; P=0.65) between the groups. “[T]he reason for no significant AFS difference in our two groups may be due to the absence of any significant differences in their clinical backgrounds,” wrote Dr. Nishijima and colleagues.

“MDT is considered a valid adjuvant treatment strategy for patients with CLI after revascularization treatment is conducted,” they concluded.

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