Sporothrix schenckii

A Microbial Biorealm page on the genus Sporothrix schenckii

Classification(1)

Higher order taxa

cellular organisms; Eukaryota; KINGDOM: Fungi/Metazoa group; Fungi; Dikarya; PHYLUM: Ascomycota; SUBDIVISION: Pezizomycotina; CLASS: Sordariomycetes; SUBCLASS: Sordariomycetidae; ORDER: Ophiostomatales; FAMILY: Ophiostomataceae; mitosporic Ophiostomataceae; GENUS: Sporothrix

Species

NCBI: Taxonomy

Sporothrix schenckii

Description and significance

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

Sporothrix is a thermally dimorphic fungus which is distributed worldwide and isolated from soil, living and decomposing plants, woods, and peat moss. Sporothrix schenckii is an occasional cause of human infections. Ophiostoma stenoceras is the teleomorph of Sporothrix sp.

Despite the existence of the fungus worldwide, infections due to Sporothrix schenckii are more common at certain geographical areas. Peru is an area of hyperendemicity for Sporothrix schenckii infections The genus Sporothrix contains one active species, Sporothrix schenckii.

The species cyanescens, formerly classified in genus Sporothrix, was later included in genus Cerinosterus and now is classified in genus Fugomyces. Accordingly, the former Sporothrix cyanescens is now referred to as Fugomyces cyanescens, which is a basidiomycetous genus unlike the ascomycetous Sporothrix. You may want to refer to our synonym and classification page for more details and history of this taxonomic modification to genus Fugomyces.

Sporothrix schenckii is the pathogenic species, while Fugomyces cyanescens is considered to be nonpathogenic. Macroscopic and microscopic features of these species are different from each other. Sporothrix schenckii is a thermally dimorphic fungus. The nonpathogenic Sporothrix sp., on the other hand, may occasionally convert to a yeast phase at 37°C (2) In mammalian tissues, S. schenckii is yeast-like, appearing as spherical or cigar-shaped bodies measuring 4 to 6 μm in length that reproduce by budding (7). However, direct microscopic identification of the organism in biopsy sections is always difficult because of the paucity of the organism (3)

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

capsular stains prepared by the Muir method (1) indicate the presence of what is interpreted as a distinct capsular-slime layer about the cells (Fig. 4), although the material identified as a capsular-slime layer envelope is more profuse about the ovoid type cell than that observed for the elongated fusiform cell. The cell wall measures from approximately 100 to 300 nm in total thickness and appears to be present in two distinct electron-dense layers. Multiple storage granules are noted scattered throughout the cytoplasm along with cell membrane- associated intracytoplasmic membranes (Fig. 5). These membranes consist of circular, three-layered, electron-dense structures which clearly communicate with the cell membrane. Seen over the entire outer surface of the cell wall are electron-dense microfibrils which are intimately associated with the cell wall. Microfibrils were observed by both Kitamura and Lurie and Still in their respective studies on S. schenckii. These microfibrils are long and intertwining, although, depending upon the plane of sectioning, they are often seen as dots or in varying lengths.... The outer limit of the cytoplasm is the plasma membrane which has the characteristics of a "unit membrane" (17). Microfibrils and the layering effect of the cell wall are prominent The cell wall is thinner in the mycelial phase than in the yeastlike phase, and was never observed to show the electron-dense microfibrils characteristically seen in yeastlike phase preparations. (5) The effect of cell-wall compounds and exoantigen obtained from S schenckii in macrophage-fungus interactions was analyzed by Carlos et al with respect to nitric oxide and TNFa.154 The lipid compound of the cell wall plays an important role in the pathogenesis of this mycosis and was found to inhibit the phagocytic process and to induce high liberation of nitric oxide and TNFa in macrophage cultures.154 http://www.botany.utoronto.ca/courses/bot405/notes/Lupi%20et%20al.,%202005%20tropical%20fungal%20diseases.pdf

Sporothrix schenckii. It is a thermally dimorphic fungus and the macroscopic morphology varies depending on the temperature of growth. At 25°C, colonies grow moderately rapidly. They are moist, leathery to velvety, and have a finely wrinkled surface. From the front and the reverse, the color is white initially and becomes cream to dark brown in time ("dirty candle-wax" color). At 37°C, colonies grow moderately rapidly. They are yeast-like and creamy. The color is cream to beige. The conversion of the mould form to the yeast form is required for definitive identification of Sporothrix schenckii [1295, 2144, 2202]. Sporothrix schenckii. Similar to its macroscopic morphology, microscopic features of Sporothrix schenckii also vary depending on the temperature of growth. At 25°C, septate hyaline hyphae, conidiophores, and conidia are observed. Conidiophores are sympodial and appear weakly differentiated from the vegetative hyphae. They often have an inflated base and arise at right angles from the hyphae. Conidia have two types. The first type are unicellular, hyaline to brown, oval, thin-walled, and are typically arranged in rosette-like clusters at the tips of the conidiophores. The second type of conidia are brown (dematiaceous),oval or triangular, thick-walled, cessile, and are attached directly to the sides of the hyphae. The latter type of conidia are typically present only in freshly isolated strains. At 37°C, Sporothrix schenckii produces oval to cigar-shaped (also called "cigar bodies") yeast cells. Single or multiple buds may be produced by a single yeast cell [1295, 2144, 2202].

Sporothrix schenckii var. luriei differs from Sporothrix schenckii by producing large, often septate, budding cells and by not assimilating creatine and creatinine

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Ecology: Sporothrix schenckii is a cosmopolitan fungus, isolated from soil and decaying plant materials. Sphagnum moss and rose bushes are well known source of this organism. Laboratory Diagnosis: 1. Culture – Sporothrix schenckii is a thermal dimorphic fungus. At 25°C, on Sabouraud’s dextrose agar, colonies were initially white, becoming pinkish tan on the surface (Figure 7A) and reverse (Figure 7B). At 37°C, on enriched media like blood agar, brain heart infusion agar, colonies were cream to buff color, creamy in texture and grew in 2 weeks. 2. Microscopic morphology – Lactophenol cotton blue or Calcofluor mounts showed thin, hyaline septate hyphae; conidiophores were slender and tapering. At the end of conidiophores, ovoid, hyaline conidia were formed sympodially (rosette formation) (Figure 8). At 37°C, ovoid, single or multiple budding yeast cells were seen. 3. Differentiation from other molds – S. schenckii is differentiated from other fungi by its slow growth, initially white colonies turning black, and ovoid conidia produced sympodially (rosette formation). Nonpathogenic Sporothrix species do not convert to yeast phase at 37°C on enriched media. Ophiostoma stenoceras, a nonpathogenic fungus microscopically resembling Sporothrix, produces long necked perithecia after 2-3 weeks. Exophiala species produce annelloconidia, while Phialophora species produce phialoconidia, thus differentiating it from S. schenckii 4. In vitro susceptibility testing – Susceptibility testing results indicate that S. schenckii isolates are susceptible to amphotericin B, itraconazole, and ketoconazole, but less susceptible to fluconazole (3, 7). 5. Molecular tests –Karyotyping by pulse field gel electrophoresis (PFGE) of clinical isolates demonstrated 6-8 chromosomes and genome size of 28 Mbp (9). Mitrochondrial DNA analysis of Sporothrix schenckii for epidemiology purposes has been done (2).

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Sporothrix schenckii is the causative agent of sporotrichosis ("rose handler's disease") [1909]. Sporotrichosis is a subcutaneous infection with a common chronic and a rare progressive course. The infection starts following entry of the infecting fungus through the skin via a minor trauma and may affect an otherwise healthy individual. Following entry, the infection may spread via the lymphatic route. Nodular lymphangitis may develop [1240, 2242]. Interestingly, an epidemic of sporotrichosis after sleeping in a rust-stained camping tent has been reported and the tent was identified as the source of infection [369]. Patients infected with Sporothrix schenckii may be misdiagnosed as pyoderma gangrenosum due to the large ulcerations observed during the course of sporotrichosis [354].

Pulmonary [672, 879, 1164] and osteoarticular infections [647, 1322], granulamatous tenosynovitis and carpal tunnel syndrome [2178], bursal infection [2374], endophthalmitis [1266, 2450], meningitis [698, 1752], invasive sinusitis [1574], and disseminated [1575, 2377] sporotrichosis have been described. The infection remains localized in immunocompetent individuals while fungemia and disseminated infection may be observed in immunocompromised patients, such as those with AIDS [39, 647, 856, 1266, 1354, 1574, 1752, 2377]. Fatal fungemia may develop also in patients with diabetes mellitus and alcoholism [398]. Primary (granulamatous) pneumonia without any cutaneous disease may develop in alcoholics [672]. Laboratory-acquired sporotrichosis has also been reported.

Fugomyces cyanescens is frequently considered to be nonpathogenic. It is avirulent in animal models and human cases in general do not suggest a clinical syndrome [2104]. However, pulmonary lesions and pneumonia due to Fugomyces cyanescens have been reported in organ transplant recipients

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

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References

(1) NCBI: Sporothrix schenckii, Accessed August 15, 2007, <http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=29908&lvl=3&lin=f&keep=1&srchmode=1&unlock>

(2) Doctor Fungus: Sporothrix Species, Accessed August 19, 2007, <http://www.doctorfungus.org/thefungi/Sporothrix.htm>

(3) Sindy Hu,1 Wen-Hung Chung,1 Shuen-Iu Hung,2 Hsin-Chun Ho,1 Zen-Whe Wang,1 Chien-Hsun Chen,1 Shu-Chuan Lu,3 Tseng-tong Kuo,3 and Hong-Shang Hong. "Detection of Sporothrix schenckii in Clinical Samples by a Nested PCR Assay". J Clin Microbiol. 2003

(5) Lane JW, Grrison RG, Field MF. "Ultrastructural studies on the yeastlike and mycelial phases of Sporotrichum schenckii". J Bacteriol. 1969 Nov;100(2):1010-9

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by Whitney Johnson-Courtright of Rachel Larsen