Evans, Scott

Importance Novel blood culture diagnostics provide rapid antimicrobial susceptibility testing (AST) results for bacteria causing bloodstream infections (BSIs) but have unclear clinical impact. Objective To evaluate clinical outcomes of blood culture testing using a rapid AST method compared with standard AST in patients with BSIs caused by gram-negative bacilli in regions with high prevalence of antimicrobial resistance. Design, Setting, and Participants Open-label randomized clinical trial that enrolled participants from December 2023 to May 2025 (final follow-up, June 18, 2025) at 7 medical centers in Greece (n = 2), India (n = 1), Israel (n = 3), and Spain (n = 1). Hospitalized patients (adults and children) with BSIs caused by gram-negative bacilli were eligible. Statistical analysis was conducted from August 2025 to January 2026. Intervention Patients were randomized to undergo blood culture evaluation using rapid, phenotypic AST directly from positive blood cultures plus standard susceptibility testing (n = 413) vs standard susceptibility testing alone (n = 437). Local antimicrobial stewardship teams reviewed all patients and provided treatment recommendations. Main Outcomes and Measures The primary outcome was a desirability of outcome ranking (DOOR) at day 30, with 3 categories (alive without deleterious events, alive with deleterious events, and death). The difference between rapid and standard testing was summarized as the probability that the DOOR outcomes were more desirable in the rapid testing group. Superiority was concluded if the lower limit of the 95% CI exceeded 50%. Secondary outcomes included 30-day mortality, length of hospitalization, intensive care unit admission, acquisition of hospital-acquired infections, time to effective antibiotic therapy within 3 days, and time to antibiotic escalation or deescalation within 3 days. Results Of the 899 patients randomized, 850 were included in the primary outcome analysis (median [IQR] age, 72 [21] years; 43% female). The probability that DOOR outcomes were more favorable in the rapid testing group was 48.8% (95% CI, 45.3%-52.4%). Median time to effective antibiotic therapy was not different between the groups in the as-randomized population. Median time to antibiotic escalation or deescalation was faster in the rapid testing group by 14 hours (95% CI, 6-22) in the as-randomized population. There were no differences between the groups in other secondary outcomes. In the prespecified subgroup with carbapenem-resistant infections, median time to effective therapy was 9.5 hours in the rapid testing group vs 28 hours in the standard testing group (difference, −18 hours [95% CI, −42 to 6]). Conclusions and Relevance Among patients with gram-negative bacilli BSIs, rapid blood culture AST was not superior to standard testing by DOOR. When considered with other efficacy and safety outcomes, these findings may help inform the use of rapid susceptibility testing in clinical practice. Trial Registration ClinicalTrials.gov Identifier: NCT06174649

ABSTRACT Standardized approaches to phage susceptibility testing (PST) are essential to inform selection of phages for study in patients with bacterial infections. There is no reference standard for assessing bacterial susceptibility to phage. We compared agreement between PST performed at three centers: two centers using a liquid assay standardized between the sites with the third, a plaque assay. Four Pseudomonas aeruginosa phages: PaWRA01ø11 (EPa11), PaWRA01ø39 (EPa39), PaWRA02ø83 (EPa83), PaWRA02ø87 (EPa87), and a cocktail of all four phages were tested against 145 P . aeruginosa isolates. Comparisons were made within measurements at the two sites performing the liquid assay and between these two sites. Agreement was assessed based on coverage probability (CP 8 ), total deviation index, concordance correlation coefficient (CCC), measurement accuracy, and precision. For the liquid assay, there was satisfactory agreement among triplicate measurements made on different days at site 1, and high agreement based on accuracy and precision between duplicate measurements made on the same run at site 2. There was fair accuracy between measurements of the two sites performing the liquid assay, with CCCs below 0.6 for all phages tested. When compared to the plaque assay (performed once at site 3), there was less agreement between results of the liquid and plaque assays than between the two sites performing the liquid assay. Similar findings to the larger group were noted in the subset of 46 P . aeruginosa isolates from cystic fibrosis. Results of this study suggest that reproducibility of PST methods needs further development.

Abstract Clinical research networks conduct important studies that would not otherwise be performed by other entities. In the case of the Antibacterial Resistance Leadership Group (ARLG), such studies include diagnostic studies using master protocols, controlled phage intervention trials, and studies that evaluate treatment strategies or dynamic interventions, such as sequences of empiric and definitive therapies. However, the value of a clinical research network lies not only in the results from these important studies but in the creation of new approaches derived from collaborative thinking, carefully examining and defining the most important research questions for clinical practice, recognizing and addressing common but suboptimal approaches, and anticipating that the standard approaches of today may be insufficient for tomorrow. This results in the development and implementation of new methodologies and tools for the design, conduct, analyses, and reporting of research studies. These new methodologies directly impact the studies conducted within the network and have a broad and long-lasting impact on the field, enhancing the scientific value and efficiency of generations of research studies. This article describes innovations from the ARLG in diagnostic studies, observational studies, and clinical trials evaluating interventions for the prevention and treatment of antibiotic-resistant bacterial infections.

AbstractDeveloping and implementing the scientific agenda of the Antibacterial Resistance Leadership Group (ARLG) by soliciting input and proposals, transforming concepts into clinical trials, conducting those trials, and translating trial data analyses into actionable information for infectious disease clinical practice is the collective role of the Scientific Leadership Center, Clinical Operations Center, Statistical and Data Management Center, and Laboratory Center of the ARLG. These activities include shepherding concept proposal applications through peer review; identifying, qualifying, training, and overseeing clinical trials sites; recommending, developing, performing, and evaluating laboratory assays in support of clinical trials; and designing and performing data collection and statistical analyses. This article describes key components involved in realizing the ARLG scientific agenda through the activities of the ARLG centers.

AbstractIn this overview, we describe important contributions from the Antibacterial Resistance Leadership Group (ARLG) to patient care, clinical trials design, and mentorship while outlining future priorities. The ARLG research agenda is focused on 3 key areas: gram-positive infections, gram-negative infections, and diagnostics. The ARLG has developed an innovative approach to clinical trials design, the desirability of outcome ranking (DOOR), which uses an ordinal measure of global outcome to assess both benefits and harms. DOOR was initially applied to observational studies to determine optimal dosing of vancomycin for methicillin-resistant Staphylcococcus aureus bacteremia and the efficacy of ceftazidime-avibactam versus colistin for the treatment of carbapenem-resistant Enterobacterales infection. DOOR is being successfully applied to the analysis of interventional trials and, in collaboration with the US Food and Drug Administration (FDA), for use in registrational trials. In the area of diagnostics, the ARLG developed Master Protocol for Evaluating Multiple Infection Diagnostics (MASTERMIND), an innovative design that allows simultaneous testing of multiple diagnostic platforms in a single study. This approach will be used to compare molecular assays for the identification of fluoroquinolone-resistant Neisseria gonorrhoeae (MASTER GC) and to compare rapid diagnostic tests for bloodstream infections. The ARLG has initiated a first-in-kind randomized, double-blind, placebo-controlled trial in participants with cystic fibrosis who are chronically colonized with Pseudomonas aeruginosa to assess the pharmacokinetics and antimicrobial activity of bacteriophage therapy. Finally, an engaged and highly trained workforce is critical for continued and future success against antimicrobial drug resistance. Thus, the ARLG has developed a robust mentoring program targeted to each stage of research training to attract and retain investigators in the field of antimicrobial resistance research.

Abstract Addressing the treatment and prevention of antibacterial-resistant gram-negative bacterial infections is a priority area of the Antibacterial Resistance Leadership Group (ARLG). The ARLG has conducted a series of observational studies to define the clinical and molecular global epidemiology of carbapenem-resistant and ceftriaxone-resistant Enterobacterales, carbapenem-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii, with the goal of optimizing the design and execution of interventional studies. One ongoing ARLG study aims to better understand the impact of fluoroquinolone-resistant gram-negative gut bacteria in neutropenic patients, which threatens to undermine the effectiveness of fluoroquinolone prophylaxis in these vulnerable patients. The ARLG has conducted pharmacokinetic studies to inform the optimal dosing of antibiotics that are important in the treatment of drug-resistant gram-negative bacteria, including oral fosfomycin, intravenous minocycline, and a combination of intravenous ceftazidime-avibactam and aztreonam. In addition, randomized clinical trials have assessed the safety and efficacy of step-down oral fosfomycin for complicated urinary tract infections and single-dose intravenous phage therapy for adult patients with cystic fibrosis who are chronically colonized with P. aeruginosa in their respiratory tract. Thus, the focus of investigation in the ARLG has evolved from improving understanding of drug-resistant gram-negative bacterial infections to positively affecting clinical care for affected patients through a combination of interventional pharmacokinetic and clinical studies, a focus that will be maintained moving forward.

Abstract The advancement of infectious disease diagnostics, along with studies devoted to infections caused by gram-negative and gram-positive bacteria, is a top scientific priority of the Antibacterial Resistance Leadership Group (ARLG). Diagnostic tests for infectious diseases are rapidly evolving and improving. However, the availability of rapid tests designed to determine antibacterial resistance or susceptibility directly in clinical specimens remains limited, especially for gram-negative organisms. Additionally, the clinical impact of many new tests, including an understanding of how best to use them to inform optimal antibiotic prescribing, remains to be defined. This review summarizes the recent work of the ARLG toward addressing these unmet needs in the diagnostics field and describes future directions for clinical research aimed at curbing the threat of antibiotic-resistant bacterial infections.

Abstract Background Carbapenem-resistant Acinetobacter baumannii (CRAb) is 1 of the most problematic antimicrobial-resistant bacteria. We sought to elucidate the international epidemiology and clinical impact of CRAb. Methods In a prospective observational cohort study, 842 hospitalized patients with a clinical CRAb culture were enrolled at 46 hospitals in five global regions between 2017 and 2019. The primary outcome was all-cause mortality at 30 days from the index culture. The strains underwent whole-genome analysis. Results Of 842 cases, 536 (64%) represented infection. By 30 days, 128 (24%) of the infected patients died, ranging from 1 (6%) of 18 in Australia-Singapore to 54 (25%) of 216 in the United States and 24 (49%) of 49 in South-Central America, whereas 42 (14%) of non-infected patients died. Bacteremia was associated with a higher risk of death compared with other types of infection (40 [42%] of 96 vs 88 [20%] of 440). In a multivariable logistic regression analysis, bloodstream infection and higher age-adjusted Charlson comorbidity index were independently associated with 30-day mortality. Clonal group 2 (CG2) strains predominated except in South-Central America, ranging from 216 (59%) of 369 in the United States to 282 (97%) of 291 in China. Acquired carbapenemase genes were carried by 769 (91%) of the 842 isolates. CG2 strains were significantly associated with higher levels of meropenem resistance, yet non-CG2 cases were over-represented among the deaths compared with CG2 cases. Conclusions CRAb infection types and clinical outcomes differed significantly across regions. Although CG2 strains remained predominant, non-CG2 strains were associated with higher mortality. Clinical Trials Registration. NCT03646227.

Abstract Background Carbapenemase-producing (CP) Escherichia coli (CP-Ec) are a global public health threat. We aimed to describe the clinical and molecular epidemiology and outcomes of patients from several countries with CP-Ec isolates obtained from a prospective cohort. Methods Patients with CP-Ec were enrolled from 26 hospitals in 6 countries. Clinical data were collected, and isolates underwent whole-genome sequencing. Clinical and molecular features and outcomes associated with isolates with or without metallo-β-lactamases (MBLs) were compared. The primary outcome was desirability of outcome ranking (DOOR) at 30 days after the index culture. Results Of the 114 CP-Ec isolates in Consortium on resistance against carbapenems in Klebsiella and other Enterobacterales-2 (CRACKLE-2), 49 harbored an MBL, most commonly blaNDM-5 (38/49, 78%). Strong regional variations were noted with MBL-Ec predominantly found among patients in China (23/49). Clinically, MBL-Ec were more often from urine sources (49% vs 29%), less often met criteria for infection (39% vs 58%, P = .04), and had lower acuity of illness when compared with non–MBL-Ec. Among patients with infection, the probability of a better DOOR outcome for a randomly selected patient with MBL-Ec as compared with non–MBL-Ec was 62% (95% CI: 48.2–74.3%). Among infected patients, non–MBL-Ec had increased 30-day (26% vs 0%; P = .02) and 90-day (39% vs 0%; P = .001) mortality compared with MBL-Ec. Conclusions Emergence of CP-Ec was observed with important geographic variations. Bacterial characteristics, clinical presentations, and outcomes differed between MBL-Ec and non–MBL-Ec. Mortality was higher among non-MBL isolates, which were more frequently isolated from blood, but these findings may be confounded by regional variations.

Abstract Background Ceftriaxone-resistant (CRO-R) Escherichia coli bloodstream infections (BSIs) are common. Methods This is a prospective cohort of patients with E coli BSI at 14 United States hospitals between November 2020 and April 2021. For each patient with a CRO-R E coli BSI enrolled, the next consecutive patient with a ceftriaxone-susceptible (CRO-S) E coli BSI was included. Primary outcome was desirability of outcome ranking (DOOR) at day 30, with 50% probability of worse outcomes in the CRO-R group as the null hypothesis. Inverse probability weighting (IPW) was used to reduce confounding. Results Notable differences between patients infected with CRO-R and CRO-S E coli BSI included the proportion with Pitt bacteremia score ≥4 (23% vs 15%, P = .079) and the median time to active antibiotic therapy (12 hours [interquartile range {IQR}, 1–35 hours] vs 1 hour [IQR, 0–6 hours]; P < .001). Unadjusted DOOR analyses indicated a 58% probability (95% confidence interval [CI], 52%–63%) for a worse clinical outcome in CRO-R versus CRO-S BSI. In the IPW-adjusted cohort, no difference was observed (54% [95% CI, 47%–61%]). Secondary outcomes included unadjusted and adjusted differences in the proportion of 30-day mortality between CRO-R and CRO-S BSIs (−5.3% [95% CI, −10.3% to −.4%] and −1.8 [95% CI, −6.7% to 3.2%], respectively), postculture median length of stay (8 days [IQR, 5–13 days] vs 6 days [IQR, 4–9 days]; P < .001), and incident admission to a long-term care facility (22% vs 12%, P = .045). Conclusions Patients with CRO-R E coli BSI generally have poorer outcomes compared to patients infected with CRO-S E coli BSI, even after adjusting for important confounders.