Antimicrobial Stewardship Depends on AST Data and Most Hospitals Are Still Catching Up

Antimicrobial stewardship programs aim to answer one key question: Is this the right antibiotic, at the right dose, for the right duration, for this infection? This decision relies on antimicrobial susceptibility testing (AST). AST shows if a pathogen is susceptible, intermediate, or resistant to a drug and provides minimum inhibitory concentration values to guide treatment. Without this data, prescribing relies on assumptions.

For years, stewardship programs were seen as best practices. Now, they are part of hospital operations. The AST diagnostic layer is becoming essential for clinical decision-making and system-wide accountability.

According to Kings Research, the global antimicrobial susceptibility testing market size was valued at USD 5.67 billion in 2024 and is projected to grow from USD 5.95 billion in 2025 to USD 8.74 billion by 2032. Behind this market growth lies a clear divide between having stewardship programs in place and making them work in practice.

Every U.S. Hospital is Required to Have an ASP. Only 16% Have Fully Implemented One.

The difference between requirements and execution is now clear. Data from the Centers for Disease Control and Prevention indicates that in 2024, only 16% of U.S. hospitals had all six Core Element Priorities in place. However, 36% have five of the six priorities in place. The priorities focus on enhancing quality rather than just having a program in place.

This is where the difference in requirements and execution comes in. Most hospitals have their antibiotic stewardship programs in place. They have their teams, policies, and guidelines in place. However, antibiotic stewardship is also about receiving accurate diagnostic information in a timely manner. Without accurate data from AST, there is always a delay.

The difference is in execution rather than requirements. Most hospitals using manual or hybrid approaches have difficulty providing accurate data, which is essential for making appropriate antibiotic prescriptions. This is where the requirements differ from the execution.

All Regulatory Bodies and Requirements Depend on AST Data

Regulatory alignment has now made stewardship a system-level requirement. The Centers for Medicare and Medicaid Services (CMS) has issued regulations requiring all U.S. hospitals and critical access hospitals to implement antimicrobial stewardship programs as a Condition of Participation. This has been in effect since March 2020. Updates to the guidance were issued in 2022, emphasizing integration with infection prevention programs.

The Joint Commission, along with CMS, CDC, and SHEA, has issued stewardship standards for hospitals, nursing centers, and care facilities. This includes requiring hospitals to demonstrate proper prescribing, track resistance patterns, and take corrective actions.

All of these regulations depend on the data generated by AST. This includes the ability to select therapy, make de-escalation decisions, and track resistance patterns through susceptibility results. A hospital may be structurally compliant, but if it cannot use the data generated by AST, it cannot meet the operational goals outlined in the regulations. This is what the mandate requires; AST shows how well the mandate is being met.

Automated AST Generates Actionable Decisions

This difference between manual and automated AST can be seen in the results that are used by stewardship programs. According to clinical evaluations from the National Institutes of Health (NIH), automated AST systems are significantly better than traditional manual methods. For critical gram-negative pathogens, very major error rates are reduced to less than 1% by automated AST, and results are available in as few as 6 hours, a significant reduction from the traditional 36-48 hours.

A major error occurs when resistant pathogens are misidentified as susceptible. This type of error can impact patient safety. Reducing very major errors provides greater confidence in therapy decisions. Faster results mean that therapy decisions are based on current, not outdated, diagnostic information.

Automation also helps improve connectivity. This enables a stronger link between clinical decision tools and lab results, enabling real-time resistance tracking and automated antibiogram construction.

Hospitals that are utilizing automated AST systems are also working to improve the entire stewardship program. The key is using diagnostic test results to make timely, informed decisions that improve clinical outcomes and meet regulatory requirements.

Appropriateness of Antimicrobial Prescribing Improves by 20% With ASP Implementation

Clinical evidence emphasizes the significance of effective stewardship. The U.S. National Strategy for Combating Antibiotic-Resistant Bacteria sets forth specific goals. In addition, extensive clinical meta-analyses performed by the National Institutes of Health (NIH) indicate hospital-based stewardship programs can reduce rates of improper antimicrobial use by 20%.

This improvement leads to clear results. Better prescribing cuts resistance development, shortens hospital stays, lowers treatment costs, and reduces adverse drug events. These benefits are real and seen in many healthcare systems. But the level of improvement depends on the quality of the data. Stewardship interventions need accurate susceptibility results. Delays or errors in AST reduce the effectiveness of these interventions and limit improvements in prescribing.

Hospitals that invest in fast, accurate AST platforms see better clinical outcomes. Their decisions rely on trustworthy data. Ultimately, better data lead to better decisions, which in turn result in better patient outcomes.

The U.S. Mandate is the Template

Stewardship is also expanding worldwide. The World Health Organization has listed antimicrobial stewardship as an essential element of national action plans against antimicrobial resistance. The concept is being implemented in various forms across countries through domestic regulations. India, for example, has already adopted stewardship guidelines that include implementing structured programs and policies across settings where healthcare is provided, similar to U.S. regulations.

Conclusion

This mandate for antimicrobial stewardship, as a requirement, has been active in all U.S. hospital settings since March 2020. However, as recent data show, most facilities have yet to achieve full quality in this area. The difference between structural compliance and performance, as it relates to this issue, is increasingly defined by diagnostic capabilities.

AST represents the foundational information necessary for this type of program to operate as required. As regulatory environments continue to evolve and expand worldwide, facilities need to not only demonstrate the existence of these stewardship programs but also their success. The facilities that invest in accurate, connected, and timely AST capabilities will be able to meet these demands.