Gloniopsis spp. causing subcutaneous phaeohyphomycosis: Clinical spectrum, phenotypic, and molecular characterization, antifungal susceptibility and literature review

Gloniopsis spp. are emerging dematiaceous fungi implicated in subcutaneous infections. Its phylogenetically close relation to Rhytidhysteron rufulum based on internal transcribed spacer (ITS) region alone often leads to misidentification of Gloniopsis spp. as R. rufulum. The study aimed to decipher clinical spectrum, molecular characterization, and antifungal susceptibility of Indian R. rufulum and Gloniopsis isolates. We retrieved 13 isolates identified as either R. rufulum or Gloniopsis from subcutaneous lesions in our culture collection and confirmed identification by Sanger sequencing. Phenotypic and genotypic characterization (targeting ITS, TUB, and LSU) was performed, followed by antifungal susceptibility testing (AFST). We also performed systematic review of all cases of 'Rhytidhysteron' or 'Gloniopsis' reported till date. Of 13 patients, majority were male with diabetes or renal transplantation. Diabetes mellitus was particularly noted in all patients infected with G. calami. Microscopic examination showed pigmented septate aerial hyphae in G. calami and septate hyphae with swellings in G. percutanea. All our isolates belonged to genus Gloniopsis rather than Rhytidhysteron. We report G. calami in human infection, for the first time. Molecular identification based on ITS, TUB, and LSU sequencing accurately differentiates among the species; however, TUB GenBank database needs to be expanded. AFST is challenging, but available data elucidate role of triazoles as potent therapy, along with surgical excision. This is the first study delineating clinical and microbiological characteristics and antifungal susceptibility of Gloniopsis species from India. Globally, maximum reports of infection by Gloniopsis spp. are from India, possibly due to its tropical temperature conducive for fungal growth, and warrants epidemiological investigation.