VITEK REVEAL matches Accelerate Pheno on rapid antibiotic susceptibility testing for Gram-negative bloodstream infections

Why this matters: Gram-negative bloodstream infections can progress to sepsis, and patients usually start on broad-spectrum antibiotics chosen empirically. Conventional identification and susceptibility testing can take 24–48 hours, and roughly half of bloodstream infections involve resistant organisms, so the first antibiotic may be ineffective. Faster susceptibility results let clinicians de-escalate or switch therapy sooner, which supports both patient outcomes and antimicrobial stewardship.

What was studied: Researchers at Tampa General Hospital compared VITEK REVEAL, an FDA-cleared system that tests susceptibility directly from positive blood cultures, with Accelerate Pheno, the hospital's standard-of-care rapid method. VITEK REVEAL detects volatile metabolic byproducts of bacterial growth with a sensor array, which allows real-time monitoring. Residual, de-identified positive blood cultures were collected prospectively from November 2023 to April 2024. Only monomicrobial Gram-negative cultures from 12 organism groups were included, among them E. coli, Klebsiella, Enterobacter, Citrobacter, Proteus, Serratia, Pseudomonas aeruginosa and the Acinetobacter baumannii complex. Accelerate Pheno was run within 30 minutes of culture positivity. VITEK REVEAL was run within 16 hours of positivity, as its instructions require. Purity plates were prepared, and frozen aliquots were kept for reference broth microdilution to resolve discrepancies.

Key results: In 128 positive blood cultures, categorical agreement between the systems was 94.3% and essential agreement (MICs within one doubling dilution) was 96.0%. Very major, major and minor discrepancy rates were 7.5%, 0.5% and 4.1%. VITEK REVEAL's mean sequential time to result, meaning each antibiotic reported as soon as it is ready, was 6.1 hours (range 3.0–8.2). Its mean final time to result was 7.9 hours (6.5–8.2). Accelerate Pheno's mean final time was significantly shorter at 7.1 hours (6.8–7.7). Sequential results on VITEK REVEAL arrived 1.4 hours earlier on average for resistant isolates than for susceptible or intermediate ones (P < 0.001).

Implications: VITEK REVEAL performed comparably to an established rapid platform on agreement metrics. Its real-time, per-antibiotic MIC reporting could deliver actionable resistance information earlier than a batch result, even though its final result was about 0.8 hours slower. This may help stewardship teams intervene sooner.

Caveats: The 7.5% very major discrepancy rate means one system called an isolate susceptible when the other called it resistant, and this needs careful interpretation. In this analysis Accelerate Pheno was the comparator, not a gold-standard reference method. The study was a single-center evaluation funded by bioMérieux, the maker of VITEK REVEAL, and several authors are company employees. The full text available for this summary ended partway through the methods section, so the discrepancy analysis, organism-specific performance and any outcome data could not be reviewed. The paper also gives inconsistent sample counts (128 in the abstract, 158 in the introduction).