Title: Isolation and identification of phaeoid/dematiaceous fungi from phaeohyphomycosis in a tertiary care hospital in Chandigarh (India).
Objectives: Phaeohyphomycosis refers to infections caused by phaeoid/dematiaceous or darkly pigmented fungi. The colonies are typically brownish to black in color. The clinical spectrum ranges from superficial, cutaneous and subcutaneous infections to life-threatening systemic infections in the form of cerebral abscesses. As awareness is gradually increasing, newer species of phaeoid fungi are being recognized. Hence, the present study is being undertaken to further increase our knowledge about the causative agents and risk factors involved in causing phaeohyphomycosis. This promotes, prompt and specific diagnostic and therapeutic interventions, which may be life-saving for the patients.
Methods: This study was conducted on samples received from patients with unresolving infections ranging from superficial infections, subcutaneous cysts, pneumonia, brain abscess and disseminated infection. These samples were collected in two sterile containers containing normal saline and 10% formalin and were processed in the Department of Microbiology and Pathology, respectively. Patients in whom direct microbiological examination or cytology/histopathology was positive showing dark grey, brown or black colored fungi were included in the study irrespective of their age and sex. Fungal culture on Sabouraud’s dextrose agar (SDA) was put up and the growth obtained as dark brown/black colonies with/without black reverse, was examined by lactophenol cotton blue (LCB) mount. Slide culture was put up wherever needed for further identification. Antifungal susceptibility testing was done on the basis of CLSI guidelines using M38-A2.
Results: We isolated phaeoid fungi from five cases of phaeohyphomycosis from August 2017 to January 2018. Of these, two were females and three were males. One belonged to pediatric age group and four were adults. Two patients presented with subcutaneous cyst (malleolar swelling), one with splenic abscess, one with right foot abscess and one was a case of right hip septic arthritis with fluid collection around the joint. Direct KOH and growth of phaeoid fungi on SDA was positive in all the cases. Cytology was positive for phaeoid fungi in two cases. We isolated Nigrospora species, Curvularia species, Exophiala species and Exserohilum species from these cases. The phaeoid fungus from the fifth case is yet to be identified. Surgical removal of the lesions was done in all cases. There was significant improvement after surgical removal in four cases, hence the clinician decided not to start antifungals. However, in the fifth case, the lesion recurred after one week hence the patient was started on oral fluconazole 150 mg OD for seven days and is currently on follow up.
Conclusion: Black fungi are no longer viewed as neglected, rare or exotic fungi. We now realize that they are all around us. Dematiaceous fungi are particularly significant because they cause infections which range from mild cutaneous infections to fatal brain disease. In developing countries, phaeohyphomycosis is often confused with other diseases with similar presentations like tuberculosis and cancer. This study has created more awareness about this disease at the clinician, pathologist and microbiologist level.