How can antimicrobial susceptibility testing help laboratories and clinicians make more confident treatment decisions?

Antimicrobial resistance (AMR) is making infectious disease management increasingly complex, especially for multidrug-resistant Gram-negative infections. As new therapies enter clinical use, laboratories need reliable ways to generate clinically relevant susceptibility data that can support timely treatment decisions and antimicrobial stewardship.

Accurate antimicrobial susceptibility testing (AST), reproducible minimum inhibitory concentration (MIC) data, and relevant testing panels are becoming essential tools for clinical microbiology teams. These approaches can help laboratories detect emerging resistance, guide escalation or de-escalation, and give clinicians greater confidence when selecting therapy.

In this SelectScience® Editorial Feature, explore expert insights, videos, and technology highlights from Thermo Fisher Scientific focused on AMR stewardship and MIC-based AST workflows. Discover how Sensititre™ panels, custom AST solutions, and innovation in susceptibility testing are supporting laboratories as they respond to evolving resistance challenges.

Why are Gram-negative infections a major focus in AMR testing?

Gram-negative bacteria are a major concern in antimicrobial resistance because some species can develop multiple resistance mechanisms, including β-lactamase production, carbapenem resistance, porin changes, efflux mechanisms, and resistance to last-line therapies. Clinically important resistant Gram-negative organisms include:

• Carbapenem-resistant Enterobacterales
• Difficult-to-treat resistant Pseudomonas aeruginosa
• Carbapenem-resistant Acinetobacter baumannii
• Extended-spectrum β-lactamase-producing Enterobacterales
• Stenotrophomonas maltophilia

Because these infections can be difficult to treat, laboratories need AST panels that include clinically relevant agents and can generate susceptibility data to support timely treatment decisions.

How do MIC-based AST panels support treatment decisions?

MIC-based AST panels allow laboratories to test bacterial isolates against defined antimicrobial concentrations and generate MIC values for relevant drugs. These panels can support clinical microbiology workflows by:

• Providing reproducible susceptibility data
• Expanding testing options for resistant organisms
• Including newer and second-line antimicrobial combinations
• Helping clinicians determine whether a treatment option is likely to be active
• Supporting stewardship teams in therapy review and optimization

Panels such as Thermo Scientific™ Sensititre™ EUGN2F, EUGN3F, and EUMDR2F are designed to support Gram-negative AST workflows across first-line, expanded, and multidrug-resistant testing needs.

Why does communication between the lab and stewardship team matter?

AST results only improve patient care when they are interpreted and acted on effectively. Clinical teams may not always have time to review every microbiology result in detail, especially in high-pressure settings such as sepsis, bloodstream infection, or hospital-associated pneumonia. Collaboration between laboratories, infectious disease specialists, pharmacists, and stewardship teams can help ensure that AST results are:

• Delivered at the right time
• Interpreted in clinical context
• Linked to practical treatment recommendations
• Used to support escalation or de-escalation
• Integrated into local treatment pathways

This multidisciplinary approach helps turn susceptibility data into actionable decisions for patient care and antimicrobial stewardship.