HISTOPLASMA (SYSTEMIC MYCOSES) Flashcards
Describe Histoplasma spp.
Show pathogenic forms which initiate infections of the reticuloendothelial system and massive infection of the bone marrow characterized by neutropenia with relative lymphocytosis.
What are the animal pathogens?
- H. capsulatum
- H. farciminosum
Describe the morphology and staining features.
- With septate hyphae with spherical microconidia
- Small, oval, yeast-like fungus in tissue and in media when incubated at 37C
- White to brown cottony aerial mycelium
Describe the cultural and biochemical features.
- Strongly aerobic but the yeast form inot cultured
- Grow on plain nutrient agar, broth and coagulated egg or serum media
- Appear as small greyish white granules in solid media
- Scanty granular sediments in liquid media
Resistance can be achieved via ?
Freezing, thawing and heating
What are the reservoirs?
- Topsoil layers
- Birds
- Bats
What are the transmission routes?
Inhalation, ingestion and wound infection
Describe the pathogenesis.
- Fatal pulmonary disease in man and animals
- Enlargement of thoracic lymph nodes
- Caseation, necrosis and calcification
- Associated with feces of starling roosts
What are the common clinical signs?
- Ulcers and keratitis
- Enlraged regional lymph nodes
- Conjunctivitis and sinusitis
- Pneumonia
- Coughing
- Regional lymphadenopathy
- Ascites
Give the host range.
dogs, cats, cattle, horses, man, foxes, ferrests, rats, mouse
Give the virulence factors.
- Polysaccharide and protein extract from the mycelium
- Histoplasmin
- Mannan
- Manoprotein
- Lipid
- Peptidolipids
Give the immunologic profile.
- Delayed hypersensitivity reaction
- Increased level of antibody
Give the diagnostic methods.
- Source of samples: Aspirates and tissue samples
What are the preferred culture media and substrates?
- Blood agar
- Sabhi, Sabouraud’s dextrose agar
How do you ID the spp.?
- Prepared smear stained with PAS and silver impregnation
- Cultivation of Histoplasma capsulatum from CSF
- CFT
- Immunodiffusion test
- Staining pathogen using Romanowsky stain
Main culture and isolation method
Histoplasmin test
What are the treatment agents?
Amphotericin B
Ethyl vanillate
Ketoconazole
Miconazole
Nystatin
Sulfonamides
Sodium iodide
Itraconazole
Fluconazole
