SPOROTHRIX (INTERMEDIATE MYCOSES)

Question 1

Describe sporothrix.

Answer 1

A dimorphic saprophyte that causes chronic ulcerative lymphangitidis of the skin and the subcutis.

Question 2

What is the animal pathogen?

Answer 2

S. schenckii

Question 3

What are the morphology and staining features?

Answer 3

• Dimorphic fungus, growing in yeast form in tissues and in culture (37C) but filamentous with septate mycelium at 30 C.
• Forms cluster of conidia

Question 4

What are the growth characteristics?

Answer 4

• Grows on all ordinary laboratory media
• Maltose enhances growth of Sporothrix sp.
• Form short aerial hyphae (forms wooly surface)
• Old cultures form convoluted, wrinkled surfaces
• Yeast stage is not cultured

Question 5

What are biochemical reactions?

Answer 5

Slowly liquefies gelatin

Question 6

What are the reservoirs?

Answer 6

1. Plant materials and soil
2. Mucous membranes of animals

Question 7

What are the transmission routes?

Answer 7

Inhalation
Ingestion

Question 8

Give the pathogenesis of Sporothricosis.

Answer 8

• Lymphocutaneous disease which causes nodules along the lymphatics
• Chronic progressive pyro-granulomatous infection of the skin and subcutaneous tissues characterized by Sporotrichotic chancre
• Infect immune-suppressed animals and man
• Ulcerating cutaneous lymph channels
• Lesions start as a red nodule which exudes a thin, seropurulent fluid
• Limbs thicken or harden due to the accumulation of lymph fluid that fails to return to the general lymphatic circulation

Question 9

What is the host range?

Answer 9

Horses, mules, dogs, rats, mice, cats, cattle, camel, fowl, swine, hamsters, chimpanzees and man

Question 10

What are the virulence factors?

Answer 10

• Cell wall glycoprotein
• Mannose and rhamnose are important components of the polysaccharides in cell wall
• Proteases

Question 11

Give the immunologic profile.

Answer 11

• Immune mechanism of the disease
• Induction of humoral and cell-mediated responses
• Production of agglutinins to the yeast
• Production of Complement-fixing antibodies

Question 12

Source of samples?

Answer 12

Tissues, pus, exudates

Question 13

Preferred culture media and substrates ?

Answer 13

BHI, SDA and Glucose blood agar

Question 14

How do you identify?

Answer 14

• FAT
• Use PAS,Gomori methenamine silver to stain fungus prepared smear
• Intraperitoneal inoculation of mice with tissue macerates of exudates
• Cultivation of organisms

Question 15

Treatments ?

Answer 15

• Miconazole
• Ketoconazole
• Amphotericin B
• IV or Oral administration of potassium iodide
• Iodide treatment