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

Abstract

Background Aspergillus spp. is identified morphologically without antifungal susceptibility tests (ASTs) in most clinical laboratories. The aim of this study was to examine the clinical impact of the morphological identification of Aspergillus spp. to ensure the adequate clinical management of Aspergillus infections. Patients/Methods Aspergillus isolates (n = 126) from distinct antifungal treatment‐naïve patients with aspergillosis were first identified morphologically, followed by species‐level identification via DNA sequencing. An AST for itraconazole (ITC) and voriconazole (VRC) was performed on each Aspergillus isolate. Results Based on the genetic test results, morphology‐based identification was accurate for >95% of the isolates at the species sensu lato level although the test concordance of Aspergillus spp. with low detection rates was low. The rates of cryptic species were found to be 1.2% among the isolates of A. fumigatus complex and 96.8% in the A. niger complex. Cryptic species with lower susceptibilities to antifungal drugs than sensu stricto species among the same Aspergillus section were as follows: The A. lentulus (n = 1) isolates had low susceptibilities to azoles among the A. fumigatus complex species (n = 86), and A. tubingensis isolates (n = 18) exhibited lower susceptibility to azoles among the A. niger complex species (n = 31). Conclusion Diagnostic accuracy was high at the A. fumigatus and A. niger complex level. However, in the presence of cryptic species, a solely morphological identification was insufficient. Particularly, ITC and VRC might be inappropriate for aspergillosis treatment when the A. niger complex is identified morphologically because it is possible that the Aspergillus isolate is A. tubingensis.

Validity of Platelia Aspergillus IgG and Aspergillus Precipitin Test To Distinguish Pulmonary Aspergillosis from Colonization

“…We think that the possibility of contamination could be reduced by including cases in which respiratory tract specimens were detected more than once. Third, the coincident ratio between morphological and genetic identification at our institution was high at the complex level, 97.1% for A. fumigatus and 96.8% for A. niger ( 25 ), but identification of the species was done by morphological methods; genetic analysis could not be performed in this study.…”

Status and Challenge of Antifungal Stewardship at the Osaka Metropolitan University Hospital

“…With the recent development of genetic classification methods, fungal species called cryptic species, which are difficult to distinguish morphologically from representative fungal species such as Aspergillus fumigatus, have been increasingly identified and become challenging to treat. Notably, many cryptic species have low susceptibility to azole and polyene 16) . We have experienced cases in our hospital that we identified as cryptic species; namely, Aspergillus felis and Aspergillus thermomutatus.…”

Chronic pulmonary aspergillosis: comprehensive insights into epidemiology, treatment, and unresolved challenges

“… 25 – 33 Cryptic species that are pathogenic to humans and have shown low drug susceptibility include the following strains: A. fumigatus complex ( A. lentulus, A. udagawae, A. viridinutans, A. felis, A. fischeri , and A. thermomutatus ); A. niger complex ( A. welwitschiae, A. tubingensis ). 34 – 43 Reports from Indonesia indicate that cryptic species were identified in 24% of patients with CPA, emphasizing the need for accurate identification. 44 Matrix-assisted laser desorption ionization coupled to time-of-flight mass spectrometry (MALDI-TOF/MS) is increasingly being used for identification, and some closely related species can now be identified.…”