Detection of two Blastomyces dermatitidis serotypes by exoantigen analysis

Area of Science:

• Medical Mycology
• Immunology
• Diagnostic Microbiology

Background:

• Blastomyces dermatitidis is a fungus causing blastomycosis, a serious infection.
• Accurate identification of B. dermatitidis is crucial for diagnosis and treatment.
• Existing diagnostic methods may require refinement for differentiating fungal isolates.

Purpose of the Study:

• To evaluate the diagnostic utility of the Blastomyces dermatitidis A antibody.
• To differentiate B. dermatitidis isolates using the exoantigen technique.
• To investigate potential serotypes within B. dermatitidis.

Main Methods:

• Exoantigen testing was performed on 101 B. dermatitidis isolates from diverse geographic origins.
• Antigen extracts were tested against the Blastomyces dermatitidis A antibody.
• Heterologous fungal isolates were included to assess specificity.

Main Results:

• The Blastomyces dermatitidis A antibody reacted with isolates from North America, India, Israel, and one from Africa.
• Eleven African isolates did not react with the A antibody, indicating a distinct group.
• North American isolates possessed antigen A and another common antigen, while African isolates showed antigen K.

Conclusions:

• At least two serotypes of Blastomyces dermatitidis exist.
• Serotype 1 (including North American, Indian, and Israeli isolates) is characterized by antigen A.
• Serotype 2 (most African isolates) is deficient in antigen A but possesses antigen K.