Cryptic and rare Aspergillus species in Brazil: prevalence in clinical samples and in vitro susceptibility to triazoles.

Abstract

Aspergillus spp. are among the most common causes of opportunistic invasive fungal infections in tertiary care hospitals. Little is known about the prevalence and in vitro susceptibility of Aspergillus species in Latin America, because there are few medical centers able to perform accurate identification at the species level. The purpose of this study was to analyze the distribution of cryptic and rare Aspergillus species among clinical samples from 133 patients with suspected aspergillosis admitted in 12 medical centers in Brazil and to analyze the in vitro activity of different antifungal drugs. The identification of Aspergillus species was performed based on a polyphasic approach, as well as sequencing analysis of the internal transcribed spacer (ITS) region, calmodulin, and β-tubulin genes and phylogenetic analysis when necessary. The in vitro susceptibility tests with voriconazole, posaconazole, and itraconazole were performed according to the CLSI M38-A2 document (2008). We demonstrated a high prevalence of cryptic species causing human infection. Only three isolates, representing the species Aspergillus thermomutatus, A. ochraceus, and A. calidoustus, showed less in vitro susceptibility to at least one of the triazoles tested. Accurate identifications of Aspergillus at the species level and with in vitro susceptibility tests are important because some species may present unique resistance patterns against specific antifungal drugs.