VMC 311: Systematic Veterinary Bacteriology and Mycology (2+1)

DIAGNOSIS, TREATMENT AND CONTROL

Diagnosis

• Based on Direct Examination of Specimens
  • Animal fluids and tissues are examined for spherules by wet mount in saline containing 10% KOH.
  • Spherules are 10 to 80 μm in diameter, have a thick wall, and contain endospores.
  • When the spherule bursts, it releases endospores (2-5 um) and leaves a ghost spherule and the endospores are stained by a fungal stains such as hematoxylin and eosin and Gomori methanamine silver.
• Based on Culture
  • Blood agar and Sabouraud's agar with antibiotics are inoculated, tape-sealed, and incubated at 37°C and 25°C, respectively.
  • Mycelial growth should be evident within a week and is examined for presence of arthroconidia in a lactophenol cotton blue wet mount, the isolate can be reconverted to the sporangia! phase by animal inoculation or cultivation in a spherule medium.
• Based on serological test
  • Serologic tests include the coccidioidin skin test (which is useful for prognostic purposes), immunodiffusion test, complement fixation test, latex agglutination test, and tube precipitin test.
  • Serological tests may be more useful than culture. A negative skin test is a poor prognostic sign.
  • For the immunodiffusion test, multiple lines are associated with progressive infection, whereas a single band usually indicates a stable, chronic infection.

Treatment and control

• As for the other fungal pathogens, amphotericin B is the drug of choice.
• Nystatin is also effective, but is more toxic. Ketoconazole may be effective. Vaccines are not available.