A case of sporotrichosis caused by different Sporothrix brasiliensis strains: mycological, molecular, and virulence analyses

BACKGROUND Sporotrichosis is a subcutaneous mycosis caused by dimorphic pathogenic fungi belonging to the Sporothrix genus. Pathogenic Sporothrix species typically produce melanin, which is known to be a virulence factor. OBJECTIVES The aim of this study was to perform phenotypic, genotypic, and virulence analyses of two distinct Sporothrix brasiliensis strains isolated from the same lesion on a patient from Rio de Janeiro. METHODS AND FINDINGS Genotypic analyses by partial sequencing of the calmodulin, β-tubulin, and chitin synthase genes, as well as polymerase chain reaction (PCR)-fingerprinting by T3B, M13, and GACA, showed that the isolates were very similar but not identical. Both isolates had similar phenotypic characteristics and effectively produced melanin in their yeast forms, accounting for their ability of causing disease in a murine sporotrichosis model. Remarkably, isolate B was albino in its environmental form but caused more severe disease than the pigmented A isolate. CONCLUSIONS These findings indicate that the patient was infected by two genetically and biologically distinct S. brasiliensis that vary in their production of melanin in their environmental forms. The results underscore the importance of characterizing phenotypically different isolates found in the same clinical specimen or patient.

The Sensitivity of ERIC-PCR in the Mixed Bacteria System / 微生物学通报

Genomic DNA of the two bacterial strains including Escherichia coli DH5? and Enterobacter cloacae E 26R were amplified by PCR with specific primers of ERIC sequence Each strain showed the stable and unique DNA fingerprint when PCR products were analyzed in agarose gel electrophoresis The stability of the genomic DNA fingerprint wasn't influenced by the templet from 10ng to 100ng In the fingerprints there were characteristic bands The unique band was influenced difficultly due to the change of the environment and condition of experiment DH5? and E 26R were mixed proportionately, and examined by ERIC PCR The result showed that the DNA fingerprints of the mixture were the superposition of each pure bacterium's Analysis of the main bands showed that DH5? can be examined by ERIC PCR when its concentration gets to 0 5% of the total mixed bacteria The study provides the reference for the research of soil microbe and environmental microbe, and especially can be used for quick identification and examination of the sundry bacterial contamination in the fermentation industry