Schizophyllum commune as an emerging fungal pathogen: a review and report of two cases

Abstract

We report Schizophyllum commune as the aetiological agent of one case each of allergic broncho-pulmonary mycosis (ABPM) and pulmonary fungal ball, and present a literature review. The fungus was characterised by clamp connections, hyphal spicules, and formation of basidiocarps with basidiospores. The phenotypic identification was confirmed by sequencing of the ITS region. To-date, ABPM and pulmonary fungal ball to S. commune have been reported exclusively from Japan and North America respectively. Of the 71 globally reported cases due to S. commune, 45 (63%) were bronchopulmonary, 22 (31%) sinusitis and 4 extrapulmonary. Taken together, cases of bronchopulmonary disease and sinusitis numbered 67 (94%), indicating the respiratory tract as the primary target of disease. Concerning the country-wise distribution, Japan topped the list with 33 cases (46%), followed by Iran - 7 cases (10%), U.S.A. - 6 cases (9%), and a lower prevalence of 1.4-6% for the remaining 12 countries. The preponderance of the disease in Japan may be attributed to its greater awareness vis-à-vis that in other countries rather than to any geographical/climatic factors. We believe that the burden of S. commune-incited disease is currently underestimated, warranting comprehensive prospective studies to determine its prevalence.

Clinical Significance and Molecular Characterization of Nonsporulating Molds Isolated from the Respiratory Tracts of Bronchopulmonary Mycosis Patients with Special Reference to Basidiomycetes

“…It is known that basidiomycetous molds chronically colonizing the lung can precipitate invasive disease and/or sensitize individuals to fungal antigens, leading to allergic fungal cough, allergic sinusitis, asthma, and ABPM (13,(26)(27)(28)(29). In the present study, these molds were most frequently identified as asymptomatic colonizers in patients with respiratory ailments.…”

Schizophyllum radiatum, an Emerging Fungus from Human Respiratory Tract

“…In routine laboratories, the induction of sporulation usually requires about 3 weeks and is associated with high failure rates (34). Therefore, molecular methods, such as DNA sequence analysis, are required for accurate identification of this kind of fungus that fails to sporulate (13). The most commonly sequenced markers in Schizophyllum are the ITS and D1/D2 regions of the LSU (13,33,34).…”

“…Therefore, molecular methods, such as DNA sequence analysis, are required for accurate identification of this kind of fungus that fails to sporulate (13). The most commonly sequenced markers in Schizophyllum are the ITS and D1/D2 regions of the LSU (13,33,34). However, Schizophyllum has a highly conserved ITS region, which is often difficult to amplify and to sequence.…”

“…In addition, some species, such as S. commune and S. radiatum, have long been considered conspecific due to their morphological similarity (2). Recently, molecular methods have more successfully discriminated between various basidiomycetous molds (13,33,34). Singh et al (34) proposed sequencing the internal transcribed spacer (ITS) and D1/D2 regions for the identification of basidiomycetes.…”

“…It also has been studied for many years as a model for understanding mating interactions (8,9). In recent years, S. commune has become clinically relevant as an etiological agent of respiratory infections in humans (10)(11)(12)(13)(14)(15). However, it has been reported to be an etiological agent of other types of infections and conditions, such as a brain abscess (16,17), meningitis (18), an eye infection (19), palate ulceration (20), and onychomycosis (21).…”