Mucormycosis-causing fungi in humans: a meta-analysis establishing the phylogenetic relationships using internal transcribed spacer (ITS) sequences.

Mucormycosis is a severe angio-invasive fungal infection caused by mucormycetes, a group of fungi that are ubiquitous in the environment. The incidence of mucormycosis has been surging rapidly due to the global corona virus disease 2019 (COVID-19) pandemic. The complete picture of the causative fungi associated with mucormycosis and their phylogenetic relationships are not well defined. This meta-analysis aimed to collate all confirmed fungal pathogens that cause mucormycosis, and assess their taxonomic relationships. All types of articles in the PubMed database that report fungi as a cause of mucormycosis were reviewed. We summarized the fungal morphological characteristic up to the genus level. The internal transcribed spacer (ITS) nucleotide sequences of these fungi were retrieved from the National Center for Biotechnology Information (NCBI) and UNITE databases whenever available, and multiple sequence analysis was conducted using Clustal W. The phylogenetic tree was constructed using mega version 7. Forty-seven fungal species were identified as pathogens causing mucormycosis in humans. Thirty-two fungal species were phylogenetically grouped into three clades, and it was evident that the ITS sequences have well-conserved regions in all clades, especially from the 400th to 500th base pairs. The findings of this work contribute to the descriptive data for fungi that cause mucormycosis, emphasizing the need for robust phylogenetic approaches when identifying clinical isolates from infected patients.