Evaluation of a Novel Rapid Phenotypic Antimicrobial Susceptibility Testing System

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Diagnostic Technology

Background:

• Phenotypic antimicrobial susceptibility testing (AST) is crucial for effective antibiotic therapy and antimicrobial stewardship.
• Rapid AST results enable timely treatment optimization and reduce broad-spectrum antibiotic use.

Purpose of the Study:

• To evaluate the Selux DX Next-Generation Phenotyping AST system's performance.
• Comparison against the MicroScan WalkAway Plus system and broth microdilution reference methods.

Main Methods:

• Tested 332 clinical and 97 reference isolates using Selux DX and MicroScan systems.
• Assessed performance via categorical agreement (CA), error rates (VMEs, MEs, mEs), and turnaround time.

Main Results:

• Selux DX achieved ≥90% CA for most drug-organism combinations, meeting CLSI thresholds.
• Shorter average turnaround time (5.5 h) for Selux DX versus MicroScan (16 h).
• Elevated error rates observed for specific agents (e.g., erythromycin, aztreonam) and higher VME/ME/mE counts noted.

Conclusions:

• Selux DX provides rapid, reliable phenotypic AST, aiding clinical decisions and stewardship.
• Discrepancies with certain antimicrobials, especially in resistant isolates, necessitate further multicenter validation.