# Investigation of azole resistance in Aspergillus species isolated from clinical specimens by azole agar screening method

## TL;DR

This study examines azole resistance in Aspergillus species from clinical samples and finds resistance varies by species, with the agar plate method showing promise for some but not all.

## Contribution

The study provides new insights into species-specific azole resistance patterns and evaluates the effectiveness of different susceptibility testing methods.

## Key findings

- Azole resistance was detected in clinical Aspergillus isolates with species-specific variations.
- The agar plate screening method showed 100% specificity for non-fumigatus species but lower effectiveness for A. fumigatus.
- Cyp51A gene mutations were identified in six isolates with L98H and seven with M220 mutations.

## Abstract

Introduction. Aspergillosis represents a significant global health threat, with increasing concerns about azole resistance.

Hypothesis/Gap Statement. There is limited evidence on the prevalence and distribution of azole resistance among clinical Aspergillus isolates.

Aim. This study investigated the prevalence of azole resistance in clinical Aspergillus isolates and evaluated different susceptibility testing methods.

Methodology. A total of 125 Aspergillus spp. isolates were collected from clinical samples (abscess, corneal abscess, biopsy, tissue and respiratory samples). Species identification was performed using conventional morphological methods and Matrix assisted laser desorption Ionization time of flight massspectrometry (MALDI-TOF) MS. Azole susceptibility testing was conducted using the gradient test (E-test), the agar plate screening method and broth microdilution for voriconazole (VOR), itraconazole (ITR) and posaconazole (POS). Molecular analysis was performed to detect cyp51A gene mutations associated with resistance.

Results. Among 125 isolates, species distribution was 44% Aspergillus fumigatus, 33.6% Aspergillus flavus, 5% Aspergillus terreus, 3% Aspergillus niger and 14% Aspergillus spp. Using gradient testing, A. fumigatus showed 1.8% resistance to VOR, 5.45% to ITR and 1.8% to POS, with one isolate resistant to all azoles. A. terreus showed 16.7% resistance to VOR, A. niger 25% resistance to ITR and Aspergillus spp. showed various resistance patterns. The agar plate method detected resistance with 100% susceptibility/specificity for non-fumigatus species but 33.3% susceptibility for A. fumigatus ITR resistance. CypA-L98H mutations were detected in six isolates and CypA-M220 mutations in seven isolates.

Conclusion. This study confirms the presence of azole resistance in clinical Aspergillus isolates with species-specific variations. The agar plate screening method shows promise for non-fumigatus species but requires optimization for A. fumigatus.