IDSA 2026 Guidance on the Treatment of Antimicrobial Resistant Gram-Negative Infections - Episode 1
Shifting AMR Gram-Negative Resistance Trends in the US
Overall gram-negative resistance rates have plateaued, but the carbapenemases driving carbapenem resistance have shifted, with NDM expanding alongside KPC and reshaping treatment considerations across the Enterobacterales.
Welcome back to another Contagion Live Peer Exchange series. In "Shifting AMR Gram-Negative Resistance Trends in the US," moderator Pranita D. Tamma, MD, MHS is joined by Ryan Shields, PharmD, MS, Jason Pogue, PharmD, and Ghady Haidar, MD to open the series on antimicrobial-resistant gram-negative infections. Gram-negative resistance in the United States remains entrenched, and the most consequential recent shift lies not in overall rates but in which carbapenemases are driving carbapenem resistance. Dr. Pogue frames the landscape organism by organism, noting that Pseudomonas aeruginosa resistance to the familiar antipseudomonal beta-lactams has held at a stubborn baseline, with local pockets running higher at referral centers.
He adds that resistance to the novel agents, while still uncommon after more than a decade of use, now appears often enough that clinicians caring for treatment-experienced patients should not assume these drugs will remain active. Carbapenem-resistant Acinetobacter, he says, behaves much as it always has and should be treated as carbapenem resistant until proven otherwise.
The sharpest change, in Dr. Pogue's view, is among the Enterobacterales. Extended-spectrum beta-lactamase (ESBL) production remains the most common concern for E. coli and Klebsiella, but carbapenemase-producing Enterobacterales have moved away from a near-total dominance of Klebsiella pneumoniae carbapenemase (KPC). Beginning around 2019 and accelerating after the COVID-19 pandemic, New Delhi metallo-beta-lactamase (NDM) producers have expanded across species, now rivaling or overtaking KPC depending on the organism.
Dr. Tamma sets the stage for the series by explaining that the panel will work through the 2026 Infectious Diseases Society of America (IDSA) guidance with a focus on mechanism-directed treatment, emerging clinical evidence, and practical implementation. She signals that NDM will return as a central theme because its treatment considerations diverge so sharply from those for KPC. For clinicians, the takeaway is that knowing which resistance mechanism circulates locally now matters as much as knowing how often resistance occurs.
Dr. Haidar explains how he weighs empiric coverage for multidrug-resistant organisms in the next episode, "Empiric Risk Assessment and Carbapenemase Classification in AMR Infections."
