Mucormycosis is an aggressive opportunistic fungal infection caused by filamentous Mucorales [1]. It commonly affects immunocompromised patients and is associated with high morbidity and mortality. While rhino cerebral and pulmonary mucormycosis are the most common forms of the disease; cutaneous, gastric, and intestinal manifestations are becoming more prevalent as the numbers of immunocompromised hosts expands [1]. Cutaneous mucormycosis is less common than other clinical forms, however, it can be lethal if not identified and treated early [2].

Our patient is a 51-year-old African-American female with multi-system sarcoidosis and steroid-induced hyperglycemia. She was hospitalized, prior to current presentation, for a neurosarcoid flare requiring pulse dose of IV steroids. At the time of discharge the patient noted mild erythema on the right forearm, at the site of intravascular catheter placement. On a follow-up appointment with her primary care physician, one week post-discharge, the erythema was worsening. She was started on a 7-day course of cephalexin for treatment of presumed cellulitis. Despite the antibiotic therapy, her symptoms progressed as she developed purulent bloody discharge. On initial evaluation in the emergency department, the patient had no complaints of fevers, chills, numbness or pain. The right forearm appeared swollen, red, and tender to palpation. Superficial eschar was visualized over the medial aspect. Initial laboratory results were significant for leukocytosis of 12.8x109 per liter. A computed tomography (CT) of the right forearm reveled diffuse soft tissue swelling of the ulnar aspect with scattered subcutaneous gas. There was evidence of small focal fluid collection with no gas seen within deep muscular compartment.

The patient was diagnosed with right forearm abscess and started on IV vancomycin. Plastic surgery team performed an intraoperative right forearm superficial debridement. Intraoperative wound cultures grew Escherichia coli, Enterococcus faecalis, and Morganella morganii. Based on the results of in vitro susceptibility, antibiotics were then escalated with the addition of intravenous meropenem.

The patient continued to deteriorate despite aggressive therapy. On day-five of her hospitalization an extensive debridement of the forearm was performed. Histopathology of muscular and subcutaneous tissue revealed necrotizing infection with angioinvasion, surrounding infarction as well as perineural invasion secondary to zygomycetes (mucormycosis) (Figure 1). Liposomal amphotericin B was then initiated. Rhizopus subsequently grew on the intraoperative cultures 72 hours later. A full body CT ruled out any evidences of disseminated infection. The patient continued to have extensive muscle and tissue necrosis requiring right arm amputation with shoulder disarticulation to prevent systemic dissemination of the infection.

Hospital course was complicated by acute renal failure that was attributed to the amphotericin B. At that time, she was switched to oral isavuconazole and discharged home to continue a prolonged course of therapy. On follow-up with infectious disease clinic at 2 and 4 weeks post- discharge she had no evidence of disease recurrence. It was decided to continue the patient on lifelong treatment with isavuconazole.

Healthcare associated mucormycosis is a growing concern as the number of immunocompromised patients increase [3]. Necrotizing infection secondary to cutaneous mucormycosis is an infrequent presentation of a relatively rare infection. Reports have associated cutaneous mucormycosis to minor skin breaks and trauma resulting in spore inoculation into the dermis [4] [5]. The entry site of the fungi in the health care setting has been previously associated with an intravenous catheters [3], as appears to be the case with our patient.

The diagnosis of mucormycosis relies upon the identification of organisms in tissue by histopathology with culture confirmation. As our case demonstrates, culture often yields no growth initially, and histopathology identification may be the only evidence of infection. High clinical suspicion coupled with early identification is crucial as treatment of mucormycosis involves a combination of aggressive surgical debridement with adjunctive antifungal therapy and decreased in immunosuppressive therapy [6] . Lipid formulation of amphotericin B is currently the recommended first-line antifungal [6]. However, as in our case, it is often associated with dose-related toxicity resulting in renal damage limiting its use. Isavuconazole is a newly approved extended spectrum triazole with activity against mucormycosis [7]. Advantages of using isavuconazole include great oral bioavailability, predictable pharmacokinetics in adults, and availability of a water-soluble intravenous formulation [8][9]. Recent open-label case control trial have showed isavuconazole was similar in efficacy to amphotericin B and posaconazole for mucormycosis primary and salvage treatment [10]. Recent data also shows that isavuconazole is well tolerated, has fewer serious side effects and less drug-drug interaction when compared to amphotericin B [9] .

In summary, mucormycosis emerges as concerning infection especially in the immune suppressed population. Our case demonstrates the need for prompt diagnosis and early treatment of mucormycosis, especially for the less common clinical form. The availability of new broad-spectrum antifungal antibiotics provides more options for patients in whom amphotericin B is not well tolerated.

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