Mucor as a cause of surgical site infection

Introduction

Despite various strategies aimed at reducing surgical site infections (SSI), they are the commonest cause of healthcare-associated infection in low- and middle-income countries, with an incidence of 2%–30%. They lead to increased morbidity, costs, hospital stay and even mortality.^1–3

SSIs are seen more commonly in those who are elderly, diabetic and immunosuppressed; depending on the type of surgery performed (emergency versus elective/ clean versus contaminated/laparoscopic versus open), the prolonged duration of operation as well as the type of wound closure and experience of the operating surgeon. Normally, SSIs are mono-microbial, with Staphylococcus, Escherichia coli and Klebsiella predominating. Fungi are an extremely rare cause.^3,4 When they are implicated, Candida species are the most commonly found. ⁵ Other fungi such as Mucor are extremely uncommon in producing SSI.

Case report

A 40-year-old non-diabetic, HIV-negative man was referred to our emergency clinic with a large, foul-smelling, ulcerated wound over the left greater trocanter (Figure 1), with a frank purulent discharge surrounded by grossly necrotic tissues extending to the lower abdomen, buttock and upper leg. The margins, as well as the base of the ulcer, showed a whitish mould seen typically in cutaneous mucormycosis, suggesting the diagnosis. OPEN IN VIEWER

The patient had sustained a closed fracture of his left femur in a road accident about six weeks previously, for which he had undergone intramedullary fixation. Two weeks after this, he had developed a wound dehiscence leading to ulceration associated with a foul-smelling discharge. This infection was considered to be a ‘bed sore’, but because of deterioration and the development of septicaemia, shock and multi-organ failure, he was referred to our centre.

After optimising his general condition, a radical debridement under general anaesthesia was performed (Figure 2), after which he required ventilatory support. Despite this, he died within a few hours due to overwhelming sepsis and multiple organ failure. OPEN IN VIEWER

The histopathology report later confirmed the diagnosis of invasive mucormycosis.

Discussion

Our case highlights the need of awareness, timely diagnosis and treatment of cutaneous mucormycosis. Mucor are fungi belonging to the class of Zygomycetes (order Mucorales) that are normally present in the environment. Occasionally, they can lead to infection in humans when conditions are favourable, typically the immunosuppressed. Human disease is seen as rhinocerebral, pulmonary, cutaneous, gastrointestinal, disseminated or miscellaneous depending on the site of involvement. In purely cutaneous disease, the fungi are usually inoculated after a breach in the skin barrier due to surgery, trauma, burns, injections, site of intravenous lines, insect bites, etc. and progress to cellulitis, ulceration or frank necrotsis along with severe systemic sepsis.^6,7

Mucor have rarely been reported as a cause of SSI: one such case was a patient who developed cutaneous mucormycosis due to Apophysomyces after cosmetic surgery and needed aggressive management. ⁸ Early diagnosis, aggressive and often repeated debridement, along with amphotericin B is the mainstay of treatment; any delay contributes to mortality.^6–8 Early debridement of SSI is mandatory, and in this particular case, may have tilted the scales towards a better outcome; the typical whitish mould suggestive of fungal mucor infection should alert the clinician to the severity of the problem. Histopathology is confirmed by intracellular aseptate hyphae that are the hallmark of invasive mucormycosis. ⁹ Further identification of species is rarely needed for treatment purposes.