BLASTOMYCES (SYSTEMIC MYCOSES)

Question 1

Describe Blastomyces spp.

Answer 1

• Include pathogens that cause a slow evolving chronic infection of the skin, subacute suppurative infection of lungs or a generalized systemic infection
• Infection may involve any or all organs of the body except the intestinal tract.

Question 2

What is the animal pathogen of Blastomyces spp.?

Answer 2

B. dermatitis (Ajellomyces dermatitidis)

Question 3

What are the morphological and staining features of Blastomyces spp.?

Answer 3

• Spherical in shape and thick walled in the yeast stage (blood agar)
• Saprophytic phase show hyphae produce conidiophores
• Positive for Periodic Acid Schiff stain
• Stain well with Silver impregnation technique

Question 4

What are the growth characteristics of Blastomycoses?

Answer 4

• Yeast form has not been cultured
• Cottony white colonies to tan and grows on most media in room temp. and at 37 C

Question 5

How many serotypes are present for Blastomyces spp.?

Answer 5

• 2 (geographic)

Question 6

What are the reservoirs for Blastomyces?

Answer 6

1. Animal waste
2. Decaying vegetation

Question 7

What are the transmission routes of Blastomyces spp.?

Answer 7

1. Respiratory exposure
2. Pericutaneous infection

Question 8

Describe the pathogenesis of Blastomyces spp.

Answer 8

• Disease originates from a pulmonary focus until it develops into a respiratory infection
• Marked by pyogranulomatous lesions in the terminal bronchioles, lymph nodes (superficial lymph nodes), skin, bones, eyes, viscera, mammary glands, urogenital tract
• Show locomotor disturbances and ocular diseases(disseminated infections)

Question 9

Describe the diseases induced in dogs.

Answer 9

• Cutaneous blastomycosis - Occurs as a primary skin infection in the form of Paulo-pustules; Yeast is isolated from skin lesions of dogs

Question 10

What are the common clinical signs induced by Blastomyces spp.?

Answer 10

• Coughing and dyspnea
• Cutaneous lesions (ulcers, furuncles, subcutaneous abscesses)
• Swollen joints, testicles and lymph glands
• Lameness and incoordination
• Dysphagia occurs due to compression of esophagus

Question 11

Describe the postmortem lesions of Blastomyces spp.

Answer 11

• Lesions in the lungs and adjacent lymph nodes
• Solidified nodules in the lungs
• Enlarged bronchial and mediastinal lymph nodes

Question 12

What are the virulence factors of Blastomyces spp.?

Answer 12

• Hemolysin
• Fatty acids
• Blastomycin
• Precipitins
• Proteins
• Chitins
• Protein adhesins
• Proteases
• Phospholipases
• Esterases
• Glycosidases
• Alpha esterase
• Catalase

Question 13

What are the diagnostic methods for Blastomyces spp.?

Answer 13

• Source of samples: Pus, lymph nodes, viscera and milk
• Preferred culture media and substrates
• SDA

Question 14

What are the treatment agents for Blastomyces spp.?

Answer 14

• Amphotericin B
• 2-hydroxy-stilbamine
• Ketoconazole