Introduction
The incidence of opportunistic fungal infections principally in immunocompromised patients has increased in recent years accounting to 1.5% of all infections in renal transplant patients. Aureobasidium species are the surging cause for deep fungal infections. It is a ubiquitous dematiaceous fungus. Clinically significant species are Aureobasidium pullulans, Aureobasidium proteae, Aureobasidium mansoni Common organs to be involved are lungs causing pneumonia and pulmonary embolism, brain leading to brain abcess, gastro intestinal tract causing peritonitis.1,2
Herein we report a case of subcutaneous deep fungal infection caused by an unusual group of fungus, Aureobasidium species in a renal transplant patient.
Case Report
A 36 year-old male referred from nephrology ward, presented with asymptomatic nodules with crusting and ulceration over both knee regions and palmar aspect of right hand. History of present illness started in January, 2018 as asymptomatic papule over left knee region, gradually increased in size and number.Figure 1,Figure 2 . No history of other systemic complaints. Past history of kidney transplantation done for the end stage renal disease secondary to diabetic nephropathy in April, 2017 and he was on methyl prednisolone 500mg on the day of operation followed by 50mg of methyl prednisolone for a period of 1 month followed by tapering doses of prednisolone at a dose of 0.5mg/kg/day for 2 months followed by maitainance on tacrolimus 0.1mg/kg/day and mycophenolate mofetil 500mg bid. Differential diagnosis considered were carbuncle and deep fungal infection.
Investigations
Renal function tests were in abnormal parameters, viral screening for HIV, HbsAg, HCV were non-reactive. Other biochemical and haematological tests were normal. Excision biopsy from the ulcerated lesion over right knee region Figure 3 was sent for histopathology Figure 4 and culture Figure 5. Histopathology showed fragments of epidermis with focal ulceration, lymphocytic infiltration in dermis, multiple microabcesses and multinucleate giant cell granulomas, few spores and hyphae of fungal elements and organism isolated in culture of excised skin bit belongs to Aureobasidium species. Pus for culture showed no growth after 48 hours of aerobic incubation
Discussion
Immunosuppression is partial or complete supresssion of immune system which can be congenital or acquired. Most common causes are uncontrolled diabetes mellitus, HIV/AIDS, post transplant patients, malignancies (leukemias and lymphomas). Post transplant patients owe a higher risk of opportunistic fungal infections attributed to prolonged treatment on immunosuppressive therapy as to prevent the chances of organ rejection.
Opportunistic fungal infections are the major cause of morbidity and mortality in post transplant patients. One among the emerging cause being Aureobasidium species.
kingdom : Fungi
Phylum : Ascomycota
Class : Euascomycetes
Order : Dothideales
Family : Dothioraceae
Genus : Aureobasidium.
These are saprophytic dematiaceous fungus with confounding feature of melanin pigment in their cell wall which plays an imperative role in the pathogenesis by protecting against reactive oxygen species and providing heat resistance.2,3 Quick growth is seen at 25 ° C as yellowish light brown groups of conidia.
Auriobasidium pullulans is the most common etiological agent of human disease. Most commo n route of infection is through traumatic inoculation. Most common presentation is ulcerative nodules with disseminated systemic infection. Diagnosis is confirmed by skin biopsy and culture.
Treatment options are oral voriconazole 200mg BD or oral itraconazole 3-5 mg/ kg/day. Systemic involvement is better treated with intravenous voriconazole 6mg / kg 12th hourly or intravenous liposomal amphotericin B 3mg / kg 6th hourly.
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