Surgical Wound Mucormycosis Necessitating Hand Amputation

Written By: Sam Savage

Published Date: September 3, 2008 Last Edited: September 3, 2008

By Chew, H H Abuzeid, A; Singh, D; Tai, C C

ABSTRACT We report an unusual case of cutaneous mucormycosis in a 17-year-old man who had no risk factors for fungal infection. The aggressive nature of cutaneous mucormycosis is illustrated. A high index of suspicion is crucial for identifying and preventing progression of this disease, which can lead to limb amputation, even death. Extra vigilance should be given to those who are immunocompromised, including those receiving short courses of steroids. Early recognition, prompt surgical intervention and initiation of an appropriate antifungal treatment are crucial in the management of this rare but potentially limb- and life-threatening infection.

Key words: amputation; fungi; mucormycosis; surgical wound infection

INTRODUCTION

Mucormycosis is usually an opportunistic infection in patients with chronic debilitating diseases, particularly uncontrolled diabetes, or those receiving immunosuppressive agents. It is caused by fungi of the class Zygomycetes, order Mucorales. Mucorales are the third commonest cause of invasive fungal infections in humans and cause the highest mortality.1 Once established, mucormycosis spreads rapidly with widespread vascular invasion and can result in death. Cutaneous infection can occur in patients with traumatic injuries to the skin and soft tissues,2,3 but has not been reported in an immunocompetent patient in a sterile environment. We present an unusual case of cutaneous mucormycosis that eventually led to amputation of the hand.

CASE REPORT

In 2003, a 17-year-old man presented to our hospital with a closed Smith’s fracture of his right hand following a traffic accident. He underwent open reduction and internal fixation under general anaesthesia within 6 hours of injury. A 3-cm incision was made on the volar radial aspect of his wrist, and the fracture was reduced and fixed with a buttress plate. The wound was closed with subcuticular sutures and dressed in sterile Mepore (Molnlycke, Sweden) and cotton wool. A below-elbow plaster of Paris cast was applied.

At extubation, the patient developed acute laryngospasm and was admitted to the intensive care unit for ventilation. He subsequently developed adult respiratory distress syndrome and was treated with hydrocortisone (100 mg twice a day) for 2 weeks and intravenous cefuroxime (750 mg 3 times a day) for 10 days. On day 9, the surgical wound was inspected and noted to be clean, dry, and healed. The wound was redressed with sterile Mepore and cotton wool, and a Futura splint was applied.

On day 12, a blister was noted at the distal site of the incision. The blister burst on day 16 and left an erythematous area that subsequently became necrotic with an overlying dark eschar that bled spontaneously. On day 17, his white blood cell count rose to 12×109 cells/l. No neutrophil function tests for neutrophil phagocytosis, chemotaxis, and intracellular killing were performed. Microscopy and cultures of wound swabs revealed a mixed growth of Enterococcus faecalis and methicillin-resistant Staphylococcus aureus. Intravenous teicoplanin (400 mg once daily) was commenced but the infection progressed rapidly. Surgical debridement was performed at day 20. An extensive area of tissue necrosis with invasion of the underlying vascular structures was noted. Microscopy of the excised tissue revealed non-septate hyphae and vascular invasion consistent with mucormycosis (Fig.). The patient was immediately started on a course of intravenous amphotericin B (0.5 mg/kg/ day) and the hydrocortisone was stopped, but the vascular invasion had led to thrombosis of the right ulnar and radial arteries. A right forearm amputation was performed on day 24. The patient made an uneventful recovery and was discharged on day 37.

DISCUSSION

Fungi belonging to the order Mucorales are ubiquitous in the environment and have been isolated in up to 22% of hospital air samples.1 Despite this continual exposure, they are not common infectious agents, which is evidence of their avirulence. Healthy individuals have strong natural immunity to the Mucorales; mucormycosis usually only occurs in immunocompromised patients with any of the predisposing factors (Table 1). Depending upon the primary site of involvement, mucormycosis can be classified as rhinocerebral, pulmonary, gastrointestinal, disseminated, miscellaneous or cutaneous.4 Cutaneous mucormycosis, as seen in our patient, constitutes about 10% of all cases.1

Mucorales are incapable of penetrating intact skin, and infection requires direct inoculation through a compromised cutaneous barrier. Patients who are at risk usually have multiple injuries or burns associated with extensive tissue damage or soil contamination.2,4 Infection of a clean surgical wound is extremely rare. Three cases of postoperative mucormycosis in non-trauma patients following exposure to contaminated surgical adhesive (Elastoplast) have been reported.5 Mucoraceae spores have been subsequently demonstrated in non-sterile adhesive dressings (Elastoplast), cloth tape, and even tongue depressors.6 We do not know whether the sterile dressing used on our patient was contaminated as the dressings were discarded before the diagnosis of mucormycosis was made. Tests performed on the same batch of sterile dressings did not reveal any evidence of contamination with mucoracae spores. Investigations of the ventilator, endotracheal tube, intravenous/central venous lines, and air sampling of the intensive care unit also failed to detect any mucoracae spores. Neutrophil function tests should have been conducted to screen for a heterozygous chronic granulomatous disease of childhood that can present much later, particularly when the affected person is taking mild immunosuppressants. Even severe glucose 6 phosphate dehydrogenase deficiency can affect neutrophil and monocyte function.

One possibility is that the spores were on the skin of the patient, as part of the skin flora, or introduced at the time of accident. It is known that solutions such as providone iodine used to prepare skin preoperatively are unable to eradicate inert spores from a patient, and this may be the source of the initial inoculum. Our patient had no risk factors for the development of mucormycosis. Short courses of steroids, as given to our patient, have not been known to predispose patients to mucormycosis but it is possible that the 2-week course of hydrocortisone compromised his immune system sufficiently to make him vulnerable to fungal infection.

The most characteristic feature of mucormycosis is hyphal invasion of blood vessels. There are 3 clinical stages of cutaneous mucormycosis, based on the degree of vascular invasion achieved by the fungus (Table 2). Early tissue biopsy is the gold standard for diagnosis, but a frozen section may be performed if a rapid diagnosis is required. Cultures of the wound discharge and exudates can be unreliable as results are positive in only 30% of cases with histology-proven mucormycosis.6 Treatment of virulent cutaneous mucormycosis involves discontinuing all immunosuppressive drugs and commencing parenteral antifungal therapy. The mainstay of treatment, however, is early and aggressive surgical debridement. This approach has been reported to reduce overall mortality from 60% to 11%.7 Mortality from cutaneous mucormycosis usually results from spread of the fungus to vital organs not amenable to surgical excision, and is directly dependent upon the speed of diagnosis and institution of treatment. A high index of suspicion is crucial for identifying and preventing progression of the disease and mucormycosis must always be considered as a differential diagnosis, particularly when wound infections respond poorly to antibiotic therapy and display features of mucor infection. Extra vigilance should be given to those who are immunocompromised, even those who are only receiving short courses of steroids. Early recognition, prompt surgical intervention and initiation of an appropriate antifungal treatment are crucial in the management of this rare but potentially limb- and life-threatening infection.

Table 1

Risk factors for mucormycosis

Diabetes mellitus

Myeloproliferative disorders

Acquired immunodeficiency syndrome

Organ transplantation

Renal failure

Polytrauma

Burns

Intravenous drug abuse

Long-term corticosteroid therapy

Cytotoxic chemotherapy

Broad-spectrum antibiotic therapy

Deferrioxamine therapy

REFERENCES

1. Losee JE, Selber J, Vega S, Hall C, Scott G, Serletti JM. Primary cutaneous mucormycosis: guide to surgical management. Ann Plast Surg 2002;49:385-90.

2. Hay RJ. Mucormycosis: an infectious complication of traumatic injury. Lancet 2005;365:830-1.

3. Andresen D, Donaldson A, Choo L, Knox A, Klaassen M, Ursic C, et al. Multifocal cutaneous mucormycosis complicating polymicrobial wound infections in a tsunami survivor from Sri Lanka. Lancet 2005;365:876-8.

4. Hammond DE, Winkelmann RK. Cutaneous phycomycosis. Report of three cases with identification of Rhizopus. Arch Dermatol 1979;115:990-2.

5. Spellberg B, Edwards J Jr, Ibrahim A. Novel perspectives on mucormycosis: pathophysiology, presentation, and management. Clin Microbiol Rev 2005;18:556-69.

6. Greenberg RN, Scott LJ, Vaughn HH, Ribes JA. Zygomycosis (mucormycosis): emerging clinical importance and new treatments. Curr Opin Infect Dis 2004;17:517-25. 7. Eucker J, Sezer O, Graf B, Possinger K. Mucormycoses. Mycoses 2001;44:253-60.

HH Chew, A Abuzeid, D Singh, CC Tai

Department of Orthopaedic Surgery, Barnet General Hospital, London, United Kingdom

Address correspondence and reprint requests to: Dr Cheh-chin Tai, Department of Orthopaedic Surgery, University of Malaya, 50603 Kuala Lumpur, Malaysia. E-mail: [email protected].

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