Molecular identification of chromoblastomycosis clinical isolates in Guangdong.

Chromoblastomycosis is a chronic fungal infection of the skin and subcutaneous tissue. The most common etiologic agent encountered in Southern China is from the genus Fonsecaea. Fonsecaea species are often misidentified due to indistinct morphology features; furthermore, recent taxonomy revision was done on the fungi genus. Herein, a comprehensive evaluation with molecular sequencing data based on internal transcribed spacer (ITS) ribosomal DNA regions as molecular targets were implemented to 37 clinical isolates from chromoblastomycosis patients. Twenty strains that were formerly identified as Fonsecaea pedrosoi through morphological characteristic were verified to be either Fonsecaea nubica or Fonsecaea monophora, while 17 strains were appropriately identified as F. monophora. A phylogenetic method was further performed to establish the species delimitation. Our investigations validate that the clinical isolates from Guangdong consist of F. monophora and the recently found new species, F. nubica. In this study, F. pedrosoi has not been isolated from chromoblastomycosis patients in Guangdong, Southern China. Reevaluation of previous reports regarding F. pedrosoi as chromoblastomycosis etiologic agent in China is necessary for a comprehensive assessment of geographic distribution pattern of Fonsecaea species. This study is the first reported study presenting large samples of F. nubica domestic or abroad.