An expanded agar-based screening method for azole-resistant Aspergillus fumigatus.

Area of Science:

• Mycology
• Antimicrobial Resistance
• Clinical Diagnostics

Background:

• Antifungal susceptibility testing guides therapy but reference methods are complex and lab-dependent.
• Azole resistance in Aspergillus fumigatus is a growing clinical concern.
• Identifying resistance mechanisms typically requires genetic sequencing.

Purpose of the Study:

• To develop and validate an expanded agar-based screening method for detecting azole-resistant Aspergillus fumigatus.
• To enable presumptive identification of azole resistance mechanisms.
• To provide a rapid screening tool for surveillance and clinical management.

Main Methods:

• Modification of an existing agar-based method with updated azole concentrations based on EUCAST breakpoints.
• Inclusion of environmental azoles to broaden resistance detection.
• Testing against a panel of 54 azole-resistant and 50 azole-susceptible Aspergillus fumigatus isolates with known Cyp51A modifications.

Main Results:

• The expanded screening method accurately detects azole-resistant Aspergillus fumigatus isolates within 48 hours.
• The growth patterns across seven azoles correlate with specific Cyp51A resistance mutations.
• The method successfully differentiated resistant and susceptible isolates based on growth.

Conclusions:

• The developed agar-based screening method is effective for detecting azole resistance in Aspergillus fumigatus.
• This method offers a valuable tool for rapid surveillance and presumptive identification of resistance mechanisms.
• It can support clinical decision-making for patients with potential azole-resistant fungal infections.