Fungal Carbuncle Due to Apophysomyces elegans—A Case Report

Background: Deep seated cutaneous fungal infection is a rare entity in surgical practice and is very often under diagnosed. Due to the atypical presentation and slow but aggressive progression of the disease, the associated mortality is high. Aim: The aim of this article to update clinicians about the peculiar presentation of mucormycosis caused by Apophysomyces elegans. Case Presentation: A 50 year old gentleman with a painful swelling and fever was admitted into our care. He had history of trivial trauma and no medical comorbid. His initial labs came back relatively unremarkable. He did not respond to an empirical antibacterial regimen and progressively worsened. The region was debrided and found to have granular secretions with sloughed tissue. On opening the dressing post operatively, a fungal mould was found. Fungal etiology was suspected and KOH mount confirmed the diagnosis. He was started on empirical IV antifungals, and local therapy while awaiting culture and sensitivity reports. However, he progressively deteriorated and succumbed to the disease eventually. Conclusion: Here we describe a deep seated cutaneous fungal infection in an immunocompetent patient and the challenges we faced during the course of his management. Fungal etiology is generally encountered in immunocompromised hosts. Deep seated cutaneous fungal infections with poor response to antifungal therapy and systemic sepsis led to this patients’ demise. This being the case, the onus is on the clinicians to diagnose a fungal etiology early and start appropriate anti fungal measures.


Introduction
Deep seated cutaneous infections are a relatively rare entity in surgical practice, with varied ethology and significant morbidity. Mucormycosis, previously known Case Reports in Clinical Medicine as Zygomycosis has been found to have significantly worse prognosis as compared to their bacterial counterparts. Multiple organisms are implicated to cause Mucormycosis such as, but not limited to, Rhizopus spp., Mucor spp. and Apophysomyces spp. Their presentations are atypical, require longer duration to arrive at a clinching diagnosis, require prolonged intensive care and have worse manifestations of sepsis with high mortality. Here, we describe an atypical case of a soft tissue infection of the back, wherein the patient was immunocompetent with a very trivial injury. He was diagnosed with a fungal etiology and was debrided extensively. Here we discuss his presentation, challenges in diagnosis and therapy and the associated mortality.

Case Presentation
A 50 year old gentleman, a daily wage worker who carries gunny sacks for a living, from Thiruvallur district in Tamil Nadu, presented to us with pain and swelling over the upper back for a period of 10 days. He gave a history of fever for 2 -3 days and a preceding history of trauma (a thorn prick) about 10 days back, over the affected region, prior to onset of the complaints. He had no known medical comorbid conditions. At admission, he was febrile but haemodynamically stable. Systemic examination was unremarkable. Local examination of the back showed a 12 × 8 cm region of induration over the interscapular region of the upper back, with minimal fluctuation in the centre, with a discharging sinus (greenish serous fluid). Local warmth and tenderness was present.
He was admitted to our ward with a working diagnosis of cellulitis of the back and routine investigations along with a culture of the fluid. He was started on IV Cefotaxim and IV Metronidazole. His labs showed a raised total count (19,900/mm 3 ) and neutrophils. He was found to have high random sugars (206 mg/dl), with normal HbA1c (5.9). Ultrasonogram showed soft tissue oedema with no collection ( Figure 1). Aerobic and anaerobic cultures were found to have no growth.
After 3 days of bed rest, regular local care and IV antibiotics, he still had fever spikes, with increasing total leucocyte counts (26,000/mm 3 ). IV Antibiotics were stepped up to Cefaperazone + Sulfbactem. Locally a central necrotic patch with multiple discharging sinuses, resembling a carbuncle was found on day 3. He was taken up for emergency deroofing of the carbuncle ( Figure 2). Intraoperatively, a cruciate incision was placed and deepened. White to straw coloured flakes was found deep in the subcutaneous, up to the muscular plane, with minimal granular fluid exudating. Devitalised necrotic tissue was excised.
Tissue was sent for culture and histopathology. Debridement was done. Post operatively his total leucocyte counts continued to increase (39,000/mm 3 ). On      The fungal culture sent was later found to have slow growing cottony colonies which was further inoculated in potato dextrose agar and was found to grow Apophysomyceselegans.
The patients' relatives present were informed regarding the rarity of the case and their informed consent was obtained to publish his case in a journal.

Discussion
Cellulitis is often caused by gram positive cocci.  [3] showed promise in treatment of cutaneous mucormycosis post debridement. Case Reports in Clinical Medicine The overall prognosis depends on several factors, including the rapidity of diagnosis and treatment, the site of infection, and the patient's underlying conditions and degree of immunosuppression. The overall mortality rate is approximately 50% [1], although early identification and treatment can lead to better outcomes.
Fungi typically are identified by use of special stains (e.g. potassium hydroxide (KOH), India ink, methenamine silver, or Giemsa). Initial identification is assisted by observation of the form of branching and septation in stained specimens or in culture. Final identification is based on growth characteristics in special media, similar to bacteria, as well as on the capacity for growth at a different temperature (25˚C vs. 37˚C), which takes around 2 weeks. No sporulation has been noted on slide cultures even after 7 days of incubation on SDA, corn meal dextrose agar, or potato dextrose agar. Stimulation of sporulation has been attempted by the method of Ellis and Ajello [2]. Abundant sporulation has been noted after 5 days on 1% water agar by this procedure [4]. The use of Soil extract media to enhance sporulation of A. elegans was attempted. The growth of A. elegans in this media was observed much earlier as compared to other methods [5]. However this method has been only documented once in literature and requires further study.
Apophysomyces elegans [6] is a filamentous fungi that is found in soil and decaying vegetables. It's a thermotolerant fungus that grows at temperatures of 26˚C and 37˚C. It goes rapidly at 42˚C. It produces cottony colonies. It is a rare cause for mucormycosis, which is often fatal. It is usually acquired via traumatic implantations associated with still or decaying vegetables matter. Unlike other  [10].
Mucormycosis is treated with IV antifungal agents, mainly Amphotericin B, Isavuconazole, Posaconazole. Early initiation of antifungals is essential in enhancing the survival of patients. Amphotericin B is most commonly initiated, with a loading dose of 0.25 -0.5 mg/kg over 2 -6 hours followed by maintenance dose of 0.25 -1 mg/kg qDay or upto 1.5 mg/kg qOD. It is highly nephrotoxic, and creatinine clearance must be calculated prior to administration. If CrCl < Case Reports in Clinical Medicine sis, in which cases, 0.5 -1 mg/kg q24 hr after dialysis session may be given. Recently, resistance to Amphotericin B has been noted [11]. In these patients Posaconazole has been shown effective. It is given as 300 mg IV twice on day 1 and followed by 300 mg IV daily. IV administration can be changed to oral (300 mg BD on day 1 followed by 300 mg daily) if eGFR < 50 ml/min in patients with moderate to severe renal impairment. Posaconazole, Itraconazole have been shown to be most active against A. elegans [12]. Liposomal Amphotericin B can be used to minimize nephrotoxicity. Caspofungin, is an echinocandin, used in antifungal therapy. Its role in mucormycosis has not been specifically documented, but has been used in treatment of aspergillosisand candidiasis. Other azoles such as fluconazole, voriconazole are ineffective against Mucorales species.
In this particular case, the patient presented to us with a trivial trauma to the back and cellulitis. He was an immunocompetent patient with no known comorbid illnesses. He did not respond to empirical antibiotics and the subsequently added higher generation antibiotics. On debridement granular exudate was noted which gave rise to the suspicion of a fungal aetiology. However, it was the presence of a fungal mould that confirmed our suspicions. The diagnosis was confirmed by KOH mount and empirical antifungals were started. Fungal cultures were sent. Experimental local therapy with fluconazole ointment and candid powder was initiated. The side which was dressed with fluconazole showed considerably better granulation tissue. The wound bled severely during debridements and dressing changes and this proved to be a challenge. He required repeated transfusions and prolonged ICU care. The fungal culture required long incubation periods and were not available until the patients eventual demise.

Conclusion
Apophysomyces elegans affects immunocompetent hosts and causes severe morbidity and mortality. Hence high degree of suspicion is required to identify deep seated fungal infections and initiate appropriate management at the earliest.