Adoption of Rapid Diagnostic Tools, Susceptibility Testing for Gram-Negative Infections

This is part of a short series looking at gram-negative infections, including diagnostics, treatment coordination, and newer agent uptake.

When thinking of diagnosing and treating gram-negative infections, there are some inherent challenges, including quick development of antimicrobial resistance, the time-consuming nature of traditional tests, and the limitations of rapid diagnostics in this area. And the unique cellular structure of gram-negative bacteria, which includes an additional outer membrane, can make antibiotic treatment more difficult.^1-4

One of the emerging areas within infectious disease is the development of diagnostic tools and how they are applicable to gram-negative infections. Some of these innovations include rapid diagnostics, next-generation sequencing, clustered regularly interspaced short palindromic repeats–based methods, utilizing artificial intelligence for data analysis and prediction, and the expansion of point-of-care testing, enabling faster, more accurate diagnoses.⁵

Rodney E. Rohde, PhD, SV/SM/MB(ASCP)CM, FACSc, University Distinguished and Regents’ Professor and Chair for the Clinical Laboratory Science Program in the College of Health Professions at Texas State University, mentions a few of the rapid tests for identifying gram-negative bacteria, including the Biofire FilmArray for blood culture identification and the Cepheid GeneXpert, a platform to rapidly detect carbapenemase resistance genes. The Verigene Blood Culture Gram-Negative test is a rapid, microarray-based nucleic acid test that identifies common gram-negative bacteria and detects specific antibiotic resistance genes directly from positive blood culture results within hours. The BD MAX Enteric Bacterial Panel is a real-time polymerase chain reaction diagnostic test that identifies common enteric bacterial pathogens, and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is a rapid method for identifying microorganisms and other biomolecules by analyzing their unique protein "fingerprints." He notes the last one’s growth in hospitals and testing facilities.

“The MALDI-TOF, in general, as many of our audience will know, is becoming more and more implemented, especially in larger health care systems across the country, including Texas; it gives you a faster turnaround,” Rohde said.

In terms of susceptibility testing for newer antimicrobials, Rohde says there are a lot of variables involved, including location, access to these tools, and the patient’s underlying comorbidities.

“There's a variety available to different microbiology laboratories, in which clinicians are ordering those tests…. You still might need to know as a clinician to interact with that microbiology laboratory team, the pharmacist, and others involved to pick the right susceptibility profile test.”

With the underlying challenges of identifying gram-negative infections and finding the right antimicrobials, Rohde stresses the importance of an all-hands-on-deck approach of building a team that includes providers, laboratory professionals, pharmacists, and everyone who touches patient care.

He believes everyone on these care teams should be pulling together, using their education and clinical experience for “collaborative communication.”

He stresses this to people in the field now, but he wants to see this approach taught in educational institutions, where they are training future professionals.

“That should be a part of the bread and butter of the education process now—no silos,” Rohde said. “We can’t operate like that anymore in the global world we live in.”

Check out Rohde’s podcast, From Pathogen to Infectious Disease Diagnosis.

Watch the next episode in the series when Monica Mahoney, PharmD, BCPS, BCIDP, FCCP, FIDSA, FIDP, FMSHP, provides insights on the outpatient side of therapy.

References
1. Giacobbe D, Giani T, Bassetti M, Marchese A, Viscoli C, Rossolini G. Rapid microbiological tests for bloodstream infections due to multidrug resistant gram-negative bacteria: therapeutic implications. Clin Microbiol Infect. 2020;26(6):713-722. doi:10.1016/j.cmi.2019.09.023
2. Anton-Vazquez V, Planche T. Gram-negative blood stream infections: prospects and challenges of rapid antimicrobial susceptibility testing. Expert Rev Anti Infect Ther. 2022;20(4):483-485. doi:10.1080/14787210.2022.1999805
3. Why are gram negative bacteria harder to kill due to antibiotic resistance? Crestone. Accessed September 15, 2025. https://crestonepharma.com/why-are-gram-negative-bacteria-harder-to-kill-with-antibiotics
4. Ducret YV. Gram-negative bacteria: unveiling the complexity and resilience of a diverse group. J Arch Ind Biot. 2023;7(3):147.
5. Ciotti B, Nicolai E, Pieri M. Development and optimization of diagnostic assays for infectious diseases. Lab Med Discov. 2024;1(2):100032. doi:10.1016/j.lmd.2024.100032