Infiltrating Wound Vacuum-Assisted Closure With Topical Amphotericin for Mucormycosis Infection of the Achilles Tendon

Discussion

Mucormycosis is an infection caused by fungi in the class Zygomycetes and of the order Mucorales that typically occurs in immunocompromised patients, especially those with diabetic ketoacidosis and neutropenia. Given that this patient had no relevant medical history and was otherwise healthy, he was at extremely low risk of this type of infection. In this patient’s case, the spores of this nonseptate hyphae wide-branching species were most likely introduced at the time of left Achilles tendon repair. Mucormycosis is progressive and can be fatal unless treated, with a mortality rate approaching 70%.⁵ The rarity and heterogeneity of mucormycosis make treatment variable.⁶ No prospective or randomized clinical trials exist in plastic surgery literature.

The use of wound VAC in combination with the instillation of amphotericin B to treat cutaneous mucormycosis is not well documented. Mucormycosis infections are traditionally addressed with surgical debridement and antifungal therapy, specifically IV amphotericin B.^7,8 As previously noted, NPWT has become the gold standard in treating complex wounds.³ Additionally, wound VAC therapy with instillation has been noted in the literature as a reliable method to treat bacteria-infected wounds, providing a shorter treatment period and earlier wound closure.⁹ Instillation VAC therapy has proven particularly useful in complex, infected wounds, such as aggressive fungal infections.

Mucormycosis treatment is challenging particularly in the extremities as management must balance both mortality and limb salvage. In this case, the use of NPWT with wound VAC and intervals of instilling amphotericin B facilitated infection control in this lower extremity mucormycosis infection. The significant adverse effect profile of amphotericin B, particularly the nephrotoxicity, should be seriously considered when deciding the treatment regimen for patients affected by mucormycosis. Locally, topical amphotericin B has been reported to cause blistering, itchiness, redness, peeling, and dryness. However, topical preparations of amphotericin B are nontoxic unlike their IV counterpart, able to cross the physiological barriers of the skin while simultaneously targeting macrophages in the dermis and epidermis.¹⁰

Conclusions

Although the mainstay of treatment for systemic mucormycosis is radical debridement and IV amphotericin B, a more localized infection may benefit from an adjunct like an instillation wound VAC with topical amphotericin B, as presented in this case study. Swift treatment with wound VAC was beneficial in the overall recovery and tissue healing of this patient and may be beneficial in similar cases.