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Antimicrobial resistance (AMR) is a global threat to public health, with deaths attributed to resistant infections projected to exceed ten million per year by 2050.1 The rapid evolution of resistance requires early identification of patients at risk followed by administration of appropriate empiric antibiotic therapy. Collaboration between stewardship teams and the microbiology lab can play a critical role with the implementation of modern antibiograms that support a clinician’s choice of optimal antimicrobial therapy sooner. 

A Tool to Turn the Tide

The timely selection of appropriate empiric antibiotics has been impacted by the rise of AMR and the evolving expectations to employ antimicrobial stewardship (AMS) principles.

AMS at its best is a collaborative, multifaceted approach that engages a broad range of healthcare professionals to improve patient treatment and safety by ensuring the right drug for the right patient at the right time, and for the right duration. Antimicrobial susceptibility tests (AST) and compatible information technology are important enablers of AMS, particularly when a patient first presents with symptoms at a hospital. According to Andrea Prinzi, Clinical Microbiologist and Field Medical Director at bioMérieux, “Susceptibility test data helps understand how to treat an individual patient and how to dose antimicrobials or antivirals. This data can then be fed into an antibiogram that benefits future patients.”  

Local antibiograms are a compilation of antimicrobial susceptibility patterns for organisms over time, and they are often advocated for in stewardship guidelines as a means of supporting clinicians in empirical decision-making.  Microbiology data provided in a local antibiogram could help a clinician initiate a treatment plan based on a patient’s presentation of symptoms, even before culture results are available. And, because laboratory data and analytics have experienced significant advancements, compilation and reporting activities have been transformed into near-instant reporting. “13 or so years ago when I was in the lab helping put together the antibiogram, I was doing it by hand and tabulating things because that was our process. It is fantastic that there are now options for compiling these in real-time, with streamlined processes and platforms that are less prone to error”, Prinzi recalls.


Optimal Use of Antibiograms

Antibiograms created from and used for a single hospital or clinic, group of hospitals or clinics, or production system are preferred since the patient population will have more in common with the historical source data. Prinzi notes, “When a new patient comes into the hospital, healthcare providers generally already know what’s present in their community, and what tends to happen in their patient population—helping to guide how they might want to manage a patient before they have more information.”

Institutions and facilities also have an opportunity to create abbreviated antibiograms, in addition to the standard cumulative antibiograms for frontline users. For example, an abbreviated antibiogram could be one that lists relevant organisms most encountered in typical infections at a single facility, along with the common antibiotics used to treat them.

“Local antibiograms provide clinicians with reliable data to base empiric therapy decisions, supporting the initiation of antibiotics before a patient’s culture results are available.”

Andrea Prinzi, Ph.D., MPH, CPH, SM(ASCP)

Incorporating antibiogram data like this into institutional treatment pathways is intended to improve patient care and outcomes, therefore steps should be taken to protect the accuracy, reliability, and statistical validity of this modern decision support tool. One leader in this area is Clinical Lab Standards Institute, (CLSI) who has actively updated their guideline M39—Analysis and Presentation of Cumulative AST Data since 2000. Through careful monitoring of trends that impact preparation and use of antibiograms, the 5th edition release in 2022 included progressive updates in areas like:

  • Combining results from rapid diagnostics and resistance markers with the antibiogram.
  • Use of antibiograms in antimicrobial stewardship programs.
  • Defining antibiogram thresholds related to empirical therapy decisions.2

It is imperative that AMS initiatives, facilitated by a structured program or otherwise, elevate the collaboration between clinicians and the microbiology laboratory to ensure proper dissemination, education, and utilization of antibiograms. When carefully curated, updated, and correctly applied, antibiograms can support appropriate therapeutic decisions, describe local susceptibilities, and help monitor resistance trends. 


  1. O’Neill, J. The Review on Antimicrobial Resistance. Tackling drug-resistant infections globally: Final report and recommendations. May 2016. Available at: paper_with cover.pdf. Accessed January 5, 2024.
  2. Clinical and Laboratory Standards Institute. 2022. Analysis and Presentation of cumulative antimicrobial susceptibility test data, 5th ed. Approved guideline. Clinical and Laboratory Standards Institute, Wayne, PA.