Genetic Diversity in Blastomyces dermatitidis From Different Geographic Regions in the USA

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Blastomyces dermatitidis (Bd) is the agent of blastomycosis, a systemic mycosis endemic to the eastern USA. The goal of this study was to assess genetic diversity at the regional and local levels. Isolates from 14 patients were typed by using RAPD-PCR: 5 from Tennessee (TN), 1 from Kentucky (KY), and 8 from Wisconsin (WI) (three of these were epidemiologically related). Twenty-eight 10-nucleotide primers were tested for their ability to produce strong, reproducible DNA bands from Bd strains. Four primers produced 15 DNA bands that fit this criterion. An analysis of variation based on presence or absence of DNA bands showed no evidence of wide scale geographical differentiation, that is, WI- and TN-derived isolates did not form discrete genetic clusters. Nevertheless, there was a strong association among a subset of six of the WI isolates and this cluster included all three isolates from a suspected outbreak. Moreover, three isolates (two from TN, one from WI) recovered from cutaneous ulcers formed a cluster. RAPD-PCR demonstrated genetic diversity in our Bd isolates and could be a useful tool in evaluating outbreaks of blastomycosis.

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