ISSN 2398-2950      

Sporothrix schenckii

ffelis
Contributor(s):

Rosanna Marsella

Synonym(s): Sporothrix asteroides, Sporothrix beurmannii


Introduction

Classification

Taxonomy

  • Kingdom: Fungi.
  • Phylum: Ascomycota.
  • Class: Euascomycetes.
  • Family: Ophiostomataceae.
  • Genus: Sporothrix.
  • Species: schenckii.
  • The genus Sporothrix contains one active species, Sporothrix schenckii.
  • This genus is a mold that lacks a known sexual state and thus belongs to the Fungi Imperfecti.

Etymology

  • New Latin, from Sporotrich-, Sporothrix, genus name, from spor- + Greek trich-, thrixhair.

Active Forms

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Clinical Effects

Epidemiology

Habitat

  • In nature Sporothrix lives as a saprophyte on wood, decaying vegetation (including rose thorns), Sphagnum moss, animal excreta and soil.
  • It is believed to exist in the soil as distinct, multibranched, mycelial forms, but this has not been directly demonstrated.
  • The content of organic material in the soils is fundamental for mycelium development.
  • The fungus shows growth in soils rich in cellulose in the pH range from 3.5-9.4 and temperatures of 31°C.
  • The development of the mycelium does not show alterations in phenotypical characteristics.

Lifecycle

  • Once it enters the body, conversion from mycelial to yeast form occurs.

Transmission

  • S. schenckii does not typically cause systemic diseaswe, however, incoulation of S. schenckii into the skin causes cutaneous lesions that frequently spread via the lymphatic system.
  • Sporothrix can also cause lung infections.
  • Sporothrix is particularly evident in areas where Sphagnum moss is abundant, and it can naturally grow on it. It is only rarely transmitted to humans in the field, however, when this moss is collected and used for floral arrangments, this provides the right conditions for Sporothrix to thrive. Workers who are exposed to large quantities of the Sphagnum moss are likely to inhale large quantities of Sporothrix spores.

Pathological effects

Immunological

  • The immunological mechanisms involved in the prevention and control of sporotrichosis are not yet fully understood.
  • In mice, antigens from S. schenckii induce a specific humoral response.
  • Acquired immunity against S. schenckii is expressed mainly by macrophages activated by CD4+ T cells.
  • The lipid compound of the cell wall appears to play an important role in the pathogenesis of this mycosis as it was found to inhibit the phagocytic process and to induce high liberation of nitric oxide and TNF-alpha in macrophage cultures.
  • It is hypothesized that a defective cell-mediated response is responsible for chronic infections.

Pathological

  • Once infection has been established the fungus spreads through the lymphatics.
  • Three clinical forms of the disease are described: cutaneous, cutaneous-lymphatic and systemic disease.

Control

Control via animal

  • Care should be taken when handling affected animals as the exudates may contain fungal organisms.
  • They are particularly abundant in cats.

Control via chemotherapies

  • Antifungal therapies can be used and include azoles and iodides.
  • Treatment should be continued for 30 days post-clinical cure.
  • Usual therapies are 2-3 months long.

Control via environment

  • Sporothrix is present in the environment as saprophytic organism.
  • Elimination of decaying vegetation may decrease exposure.
Care should be taken to avoid trauma of the skin since that is a pre-requisite to establish cutaneous infection.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Kong X, Xiao T,  Lin J et al (2006) Relationships among genotypes, virulence and clinical forms of Sporothrix schenckii infection. Clin Microbiol Infect 12 (11), 1077-1081 PubMed.
  • Dixon D M, Salkin I F, Duncan R A et al (1991) Isolation and characterization of Sporothrix schenckii from clinical and environmental sources associated with the largest U.S. epidemic of sporotrichosis. J Clin Microbiol 29 (6), 1106-1113 PubMed.
  • Grotte M & Younger B (1981) Sporotrichosis associated with sphagnum moss exposure. Arch Pathol Lab Med 105 (1), 50-51 PubMed.

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