Molecular epidemiology of Sporothrix schenkii isolates in Malaysia.

Sporothrix schenkii is a dimorphic fungus that causes infections in both humans and animals. We report on 25 S. schenkii isolates collected in 2017 from humans and cats clinically diagnosed with sporotrichosis, in Malaysia. These isolates were phenotypically identified as S. schenkii sensu lato and further defined as S. schenckii sensu stricto based on partial calmodulin gene sequence. Isolates from both humans and cats were genotypically identical but displayed phenotypic variation. Phylogenetic analyses based on partial calmodulin sequence showed that the Malaysian isolates clustered with global S. schenkii sensu stricto strains, in particular, of the AFLP type E. This analysis also revealed that partial calmodulin sequence alone was sufficient for classifying global S. schenckii sensu stricto strains into their respective AFLP types, from A to E. The genetically conserved S. schenkii sensu stricto species isolated from humans and cats is suggestive of a clonal strain present in Malaysia. To the best of our knowledge, this is the first report on molecular identification of Sporothrix schenkii strains from human infections in Malaysia. Further studies are required in order to elucidate the clonal nature of Malaysian S. schenkii isolates. Our findings indicate the presence of a predominant S. schenkii genotype in the environment, causing infections in both cats and humans in Malaysia.

Morphology, Phenotype, and Molecular Identification of Clinical and Environmental Fusarium solani Species Complex Isolates from Malaysia.

Fusarium infections in humans (fusariosis) and in economically important plants involve species of several Fusarium species complexes. Species of the Fusarium solani species complex (FSSC) are the most frequent cause of human fusariosis. The FSSC comprises more than 60 closely related species that can be separated into three major clades by multi-locus sequence typing (MLST) using translation elongation factor 1-alpha (TEF1-α) and RNA polymerase II (RPB2) DNA sequences. The MLST nomenclature for clade 3 of the FSSC assigns numbers to species types (e.g., FSSC 2) and lowercase letters to identify unique haplotypes. The aim of this study was to analyse the genotypic and phenotypic characteristics of 15 environmental and 15 clinical FSSC isolates from Malaysia. MLST was used for the genotypic characterisation of FSSC isolates from various locations within Malaysia, which was complemented by their morphological characterisation on potato dextrose and carnation leaf agar. MLST identified eight different FSSC species: thirteen Fusarium keratoplasticum (i.e., FSSC 2), six Fusarium suttonianum (FSSC 20), five Fusarium falciforme (FSSC 3+4), two Fusarium cyanescens (FSSC 27), and one each of Fusarium petroliphilum (FSSC 1), Fusarium waltergamsii (FSSC 7), Fusarium sp. (FSSC 12), and Fusarium striatum (FSSC 21). Consistent with previous reports from Malaysia, most (11 of 15) clinical FSSC isolates were F. keratoplasticum and the majority (9 of 15) of environmental isolates were F. suttonianum (5) or F. falciforme (4) strains. The taxonomic relationships of the isolates were resolved phylogenetically. The eight Fusarium species also showed distinct morphological characteristics, but these were less clearly defined and reached across species boundaries. Although TEF1-α and RPB2 sequences were sufficient for the species identification of most FSSC isolates, a more precise MLST scheme needs to be established to reliably assign individual isolates of the species-rich FSSC to their geographically-, epidemiologically-, and host-associated sub-lineages.