Cryptic Aspergillus from clinical samples in the USA and description of a new species in section Flavipedes

Background: In the last few decades there has been an emergence of cryptic Aspergillus as agents of human infections due to the increase in immunocompromised population and to the improvement of identification tools. Methods: Continuing our study on Aspergillus isolates from clinical origin deposited in a mycological reference centre in the United States, we selected 37 isolates belonging to less common sections of the genus, to study their species diversity and detect cryptic species by using a polyphasic approach. Results: From this set of isolates, a total of 16 species were identified; the most frequent being A. calidoustus (48.6%, section Usti), A. terreus (13.5%, section Terrei), and A. nidulans (5.7%, section Nidulantes). The remaining isolates corresponded to 13 species of rare or cryptic Aspergillus, i.e. A. europaeus (section Cremei); A. iizukae, A. micronesiensis, A. spelaeus (section Flavipedes); A. pachycristatus, A. quadrilineatus, A. spinulosporus, A. unguis (section Nidulantes); A. alabamensis, A. carneus, A. hortai (section Terrei), A. granulosus (section Usti); and the new species A. suttoniae (section Flavipedes), which is described here. Conclusions: Correct identification of cryptic species is crucial to reveal new potential pathogens, to gather accurate epidemiological data and to choose an appropriate treatment.