Loading ...

TOPLINE:

In a multinational randomized trial, rapid antimicrobial susceptibility testing (AST) shortened the time to antibiotic modification in patients with gram-negative bacteremia but did not improve the primary outcome of desirability of outcome ranking (DOOR) at 30 days compared with standard testing.

METHODOLOGY:

• Researchers conducted an open-label randomized clinical trial of 850 patients spanning all age groups with gram-negative bacteremia from 2023 to 2025 across Greece, India, Israel, and Spain.
• Patients were randomly assigned to undergo rapid AST plus standard susceptibility testing (n = 413; median age, 73 years; 42% women) or standard susceptibility testing alone (n = 437; median age, 72 years; 43% women).
• The primary endpoint was DOOR — categorized as alive without deleterious events, alive with deleterious events, or death — at day 30. Deleterious events included poor clinical outcomes such as failure to discharge, infection relapses or complications, kidney failure, or acquisition of hospital-acquired multidrug-resistant infections.
• The secondary outcomes included 30-day mortality, length of hospitalization, ICU admission, infection with multidrug-resistant organisms or Clostridioides difficile, time to effective antibiotic therapy within 3 days, and time to antibiotic escalation or de-escalation within 3 days.

TAKEAWAY:

• The probability of more favorable DOOR outcomes with rapid vs standard AST was 48.8% (95% CI, 45.3%-52.4%), which did not meet the prespecified criterion of a lower limit > 50% for superiority.
• All-cause 30-day mortality rates were similar between the rapid AST and standard AST groups (24.2% vs 22.7%), with no significant differences in hospital stay, ICU admission, acquisition of multidrug-resistant organisms, or time to effective antibiotic therapy within 3 days.
• Patients in the rapid AST group underwent antibiotic escalation or de-escalation 14 hours earlier than those in the standard testing group (22 vs 36 hours; 95% CI, 6-22 hours).
• Among patients with carbapenem-resistant infections, fewer patients in the rapid AST arm than in the standard AST arm remained hospitalized at day 30 (15.1% vs 28.0%), and the median time to effective therapy was shorter with rapid AST than with standard AST (9.5 vs 28 hours; 95% CI, -42 to 6 hours).

IN PRACTICE:

"Among patients with GNB BSI [gram-negative bacilli blood stream infection], rapid blood culture AST was not superior to standard testing by DOOR," the authors wrote. "When considered with other efficacy and safety outcomes, these findings may help inform the use of rapid susceptibility testing in clinical practice," they concluded.

SOURCE:

The study was led by Ritu Banerjee, MD, PhD, Vanderbilt University Medical Center, Nashville, Tennessee. It was published online on April 18, 2026, in JAMA.

LIMITATIONS:

The study was limited by several factors, including differences across sites in antimicrobial resistance rates, clinical practices, and implementation of the intervention, which may have affected outcomes. The findings may not be generalizable to all healthcare settings. Nearly 20% of patients had organisms not covered by the rapid AST panel, potentially reducing the benefit of the test. Additionally, the study evaluated rapid AST in combination with antimicrobial stewardship rather than independently.

DISCLOSURES:

The study was funded by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health. One author reported receiving grants from the National Institutes of Health and nonfinancial support from bioMérieux during the conduct of the study. Several authors reported receiving grants, consulting fees, or royalties; holding patents or stock options; or having other relationships with multiple healthcare and pharmaceutical organizations. Full disclosures are available in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.