Species identification, antifungal susceptibility, and clinical feature association of Aspergillus section Nigri isolates from the lower respiratory tract

Abstract

Species of Aspergillus section Nigri are generally identified by molecular genetics approaches, whereas in clinical practice, they are classified as A. niger by their morphological characteristics. This study aimed to investigate whether the species of Aspergillus section Nigri isolated from the respiratory tract vary depending on clinical diagnosis. Forty-four Aspergillus section Nigri isolates isolated from the lower respiratory tracts of 43 patients were collected from February 2012 to January 2017 at the National Hospital Organization (NHO) Tokyo National Hospital. Species identification was carried out based on β-tubulin gene analysis. Drug susceptibility tests were performed according to the Clinical and Laboratory Standards Institute (CLSI) M38 3rd edition, and the clinical characteristics were retrospectively reviewed. A. welwitschiae was isolated most frequently, followed by A. tubingensis. More than half of the A. tubingensis isolates exhibited low susceptibility to azoles in contrast to only one A. welwitschiae isolate. Approximately three quarters of the patients from whom A. welwitschiae was isolated were diagnosed with colonization, whereas more than half the patients from whom A. tubingensis was isolated were diagnosed with chronic pulmonary aspergillosis (CPA). More attention needs to be given to the drug choice for patients with CPA with Aspergillus section Nigri infection because A. tubingensis, which was found to be frequently azole-resistant, was the most prevalent in these patients.

Aspergillus fumigatusand aspergillosis: From basics to clinics

“…2019 , Alshehri & Palanisamy 2020 , Carrara et al. 2020 , Takeda et al. 2020 ).…”

MALDI-TOF MS in a Medical Mycology Laboratory: On Stage and Backstage

“…In addition, Bruker's database offers limited discrimination among the Aspergillus genus. Notably, in the Nigri section (A. tubingensis and A. welwitschiae misidentified as A. niger), the Fumigati section (A. thermomutatus misidentified as A. lentulus) and the Nidulantes section (A. spinulosporus misidentified as A. nidulans) for which antifungal susceptibility differs greatly [19,32,33]. Overall, our results confirmed a previous study showing that the MSI database provided more accurate identifications than Bruker and that the systematic combination of the two databases significantly improves the rate of correct identifications for filamentous fungi [34].…”

The accuracy and clinical impact of the morphological identification of Aspergillus species in the age of cryptic species: A single‐centre study

“…The impact of incorrect morphological identification of the A. fumigatus complex might be minimal on clinical management because of the frequency of cryptic species. In contrast, in the A. niger complex, A. tubingensis and A. welwitschiae were most frequently detected (approximately 50%–60% of the time) 12,14,25,33 . The majority of A. tubingensis isolates exhibited significantly lower susceptibility to azoles than other strains, such as A. welwitschiae .…”

“…exhibit lower susceptibility to antifungal drugs than sensu stricto species: Aspergillus lentulus , A. udagawae , A. thermomutatus , A. felis , and A. fischeri in Aspergillus section Fumigati , 11 A. tubingensis in Aspergillus section Nigri , 12 and A nomius in Aspergillus section Flavi 13 . Furthermore, we previously reported that A tubingensis , which is often resistant to azoles, causes chronic pulmonary aspergillosis more frequently than A welwitschiae 14 …”