Comparison of susceptibility patterns using commercially available susceptibility testing methods performed on...

Area of Science:

• Medical Mycology
• Clinical Microbiology
• Infectious Diseases

Background:

• Invasive fungal infections, particularly candidiasis, are rising, often caused by non-albicans Candida species.
• Antifungal resistance is an increasing concern, complicating treatment strategies.
• Accurate and timely antifungal susceptibility testing (AST) is essential for effective patient management.

Purpose of the Study:

• To compare the performance of commercially available AST methods for Candida isolates.
• To assess the agreement of Etest, Vitek 2, and Sensititre with the Clinical and Laboratory Standards Institute (CLSI) broth microdilution reference method.

Main Methods:

• Seventy-four prospectively collected Candida isolates were tested.
• AST was performed using broth microdilution (CLSI), Etest, Vitek 2 (YS-05), and Sensititre.
• Essential agreement and categorical agreement (CA) were evaluated against the reference method.

Main Results:

• Candida albicans accounted for 38% of isolates; Candida glabrata was nearly as prevalent (29%).
• Categorical agreement varied by method and antifungal agent, with Sensititre showing high agreement (≥93%) for fluconazole and caspofungin.
• Etest demonstrated lower agreement for caspofungin (72%) compared to other methods.

Conclusions:

• Commercial AST methods show variable performance for Candida isolates.
• Clinicians must be aware of the specific strengths and limitations of each AST method when guiding antifungal therapy.
• Further studies with larger isolate populations may be warranted to confirm findings.