# Clinical performance of the VITEK REVEAL fast antimicrobial susceptibility test within a real-world workflow for gram-negative bacteremia: comparison with QMAC-dRAST and conventional methods

## TL;DR

The VITEK REVEAL system provides fast and accurate antimicrobial susceptibility testing for gram-negative bloodstream infections, showing strong agreement with existing methods and faster results.

## Contribution

This study evaluates the clinical performance of the VITEK REVEAL system in a real-world setting, demonstrating its reliability and speed compared to established AST methods.

## Key findings

- REVEAL showed 94.1% categorical agreement and 98.4% essential agreement with QMAC-dRAST.
- The system achieved 94.5% categorical agreement and 97.9% essential agreement with VITEK2.
- REVEAL provided results in a median of 8 hours, significantly faster than conventional methods.

## Abstract

Fast antimicrobial susceptibility testing (AST) is essential for appropriate antimicrobial therapeutic guidance in patients with bloodstream infections, reducing the time required for optimal treatment. We aimed to evaluate the clinical performance of the VITEK REVEAL (REVEAL), a volatile organic compound-based fast AST system, compared with our already established AST workflow for bloodstream infections. We prospectively collected a total of 107 gram-negative isolates from positive blood cultures and performed rapid species identification using the BIOFIRE BCID2 panel, followed by AST using the REVEAL system. We conducted parallel comparative tests (QMAC-dRAST, VITEK 2, and ETEST for selected antimicrobials) and analyzed the results for categorical agreement (CA), essential agreement (EA), and categorical discrepancies. Moreover, we compared the time to results between the REVEAL vs QMAC-dRAST and VITEK2. Compared with QMAC-dRAST, REVEAL demonstrated 94.1% CA and 98.4% EA across 1,200 pairwise comparisons, with very major discrepancy (VMD) and major discrepancy (MD) rates of 1.4% and 0.7%, respectively. Compared to VITEK2 (872 comparisons), REVEAL yielded 94.5% CA and 97.9% EA, with VMD and MD of 0.5% and 0.6%, respectively. For ceftazidime/avibactam and ceftolozane/tazobactam, REVEAL showed 100% and 98.6% CA, respectively, compared to ETEST. The median final and per-antibiotic time to results for REVEAL were 8.00 h (range: 6.50–8.15 h) and 5.97 h (range: 3.17–8.15 h), respectively. The REVEAL system demonstrated high concordance with existing fast and conventional AST methods and enabled reliable susceptibility testing. These results support the potential integration of the REVEAL system into routine microbiological workflows for time-sensitive clinical decision-making in bloodstream infections.

Fast antimicrobial susceptibility testing is critical for initiating appropriate therapy in patients with gram-negative bacteria-induced bloodstream infections. Conventional antimicrobial susceptibility testing methods often require extended turnaround times, thereby delaying optimal treatment. In this study, we prospectively evaluated the VITEK REVEAL system, which detects bacterial growth-associated volatile organic compounds to directly determine antimicrobial susceptibility in positive blood cultures. We assessed the system against our already established identification and antimicrobial susceptibility testing methods, including both fast and conventional platforms currently implemented in routine clinical practice. The volatile organic compounds-based system demonstrated high concordance, shorter time-to-results, and reliable performance for newer antimicrobial agents. By directly comparing its performance with established clinical diagnostic tools, this study provides relevant support for the potential integration of this approach into real-world laboratory workflows, with implications for improved patient management and antimicrobial stewardship.