Overview of Sporotrichosis (Rose Gardener’s disease) and laboratory diagnosis

Sporotrichosis is an an chronic infection of subcutaneous tissues caused by a fungus called Sporothrix schenckii, which is a dimorphic fungus. Human acquire sporotrichosis infection through trauma (throns, splinters), usually to the hand, arm, or leg.

What is the natural habitat of Sprothrix schenckii?
Sprothrix schenckii has a worldwide distribution. Its natural habitat is living or dead vegetation.

Who is commonly affected by Rose Gardner’s disease?

Pic is self illustrative: Rose Gardener’s Disease

Sporotrichosis disease is occupational hazards for farmers, nursery workers, gardeners, florists and miners.
Pulmonary infection may occur after inhalation of spores but is very rare.

How is Sporotrichosis diagnosed?
Clinical specimen: Exudate aspirated from unopened subcutaneous nodules or from open draining lesions.

Direct microscopy: It is very difficult to observe the yeast form of Sporothrix schenckii in the clinical specimen. So the diagnostic significance of direct microscopy is very less. Sporothrix schenckii appears as small, round to oval to cigar-shaped yeast cells. Periodic acid-schiff (PAS) method can be used to stain histological slides.
Culture: Colonies of Sprothrix schenckii grow rapidly (3-5 days) and may be mistaken with yeast colonies. On further incubation these colonies become membranous, wrinkled, dark brown or black in color. The consistency of the colony may be leathery. If the culture is incubated at 37oC Sprothrix schenckii colony transforms to a soft, cream colored to white yeast like colony (dimorphism). Conversion from mold form to yeast form takes place within 1-5 days.
Microscopy from the culture
The hyphae of Sprothrix schenckii are delicate, septate and branching. Flowerette arrangement of conidia (single celled conidia borne in clusters from the tip of single conidiophore) is seen. If the yeast like colony is taken form plate cultured at 37oC singly or multiply budding oval or elongate, cigar-shaped yeast cells are seen.