Development of a duplex real-time PCR assay for the differentiation of Blastomyces dermatitidis and B. gilchristii and a retrospective analysis of culture and primary specimens of blastomycosis cases from New York (2005-2019)

Blastomycosis due to Blastomyces dermatitidis and B. gilchristii is a significant cause of respiratory mycoses in North America with occasionally reported outbreaks. We developed a highly sensitive, specific, and reproducible Taqman duplex real-time PCR assay for the differentiation of B. dermatitidis and B. gilchristii The new assay permitted retrospective analysis of Blastomyces cultures (2005-2019) and primary clinical specimens from blastomycosis cases (2013-2019) from NY patients. We identified B. dermatitidis as the predominant pathogen in 38 cases of blastomycosis, while B. gilchristii was a minor pathogen involving five cases; these findings expand understanding of blastomycosis in New York. The duplex real-time PCR assay could be implemented in reference and public health laboratories to further understand the ecology and epidemiology of blastomycosis due to B. dermatitidis and B. gilchristii.