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FDA-Recognized Antimicrobial Susceptibility Test Interpretive Criteria

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Antibacterial Susceptibility Test Interpretive Criteria

Antifungal Susceptibility Test Interpretive Criteria

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These web pages provide information about the in vitro susceptibility of bacteria or fungi to certain drugs. The safety and efficacy of these drugs in treating clinical infections due to such bacteria or fungi may or may not have been established in adequate and well-controlled clinical trials and the clinical significance of such susceptibility information in those instances is unknown. The approved product labeling for specific drugs provides the uses for which the product is approved.


The 21st Century Cures Act (Cures Act) , signed into law on December 13, 2016, helps accelerate medical product development and bring new innovations and advances to patients who need them faster and more efficiently. Section 3044 of the Cures Act created a system to expedite the recognition of antimicrobial susceptibility test interpretive criteria also known as “breakpoints” (abbreviated as STIC) and provide up-to-date information to the healthcare community in a more streamlined manner.

Changes made by the 21st Century Cures Act

Susceptibility Test Interpretive Criteria (STIC) – new online information

The Cures Act requires FDA to post information online about FDA’s recognition, or withdrawal from recognition, in whole or in part, of STIC established by a standards development organization (SDO) and online lists of exceptions or additions to the recognized STIC that the SDO established. This information should be referred to as the most up-to-date STIC for antibacterial and antifungal drugs. Online references allow FDA to more quickly communicate updated STIC than updating and re-updating labeling.

STIC are listed by therapeutic category (antibacterial or antifungal):

The agency will update this information at least every six months through publication of a notice on this page. Annually FDA will publish a compilation of these notices on the Federal Register for public comment. Changes could include:

  • Recognizing new or updated STIC standards, or parts of standards;
  • Withdrawing recognition of STIC standards, or parts of standards; and/or
  • Making any other necessary updates to the published lists.

As applicable, FDA will also post STIC on these web pages for newly approved drugs at the time of their approval.

Susceptibility Test Interpretive Criteria in drug labels – a shift to online updates (Guidance for Industry – Systemic Antibacterial and Antifungal Drugs: Susceptibility Test Interpretive Criteria Labeling for NDAs and ANDAs)

To ensure that the most up-to-date STIC are available, holders of approved drug applications will have until December 13, 2018, to remove the STIC information and related information from the labeling of approved systemic antibacterial and antifungal drugs and replace it with a reference to information on these new pages. FDA has published a final guidance to further explain these requirements.

New antibacterial and antifungal drugs approved on or after December 13, 2017 will include a reference to information on these new pages in labeling in lieu of STIC and related information.

Enabling physicians to select appropriate antibacterial or antifungal drugs is critical to individual patient care and public health. Generally, physicians rely on antimicrobial susceptibility testing (AST) performed by clinical microbiology laboratories to help choose an appropriate treatment. STIC are the criteria used to interpret AST results. STIC identify whether bacteria or fungi are considered susceptible or resistant to a particular drug. Bacteria and fungi change over time. When this occurs, STIC need to be updated. Laboratories and AST device manufacturers need to be able to use up-to-date interpretive criteria for the reports provided to physicians to inform appropriate treatment choices. Up-to-date AST results are an important component in addressing the problem of antimicrobial resistance.

Before the Cures Act was signed into law, each antibacterial and antifungal drug manufacturer was responsible for updating its drug labeling with new STIC and each device manufacturer updated its device algorithm and labeling only after the drug labeling was updated. This process of updating and re-updating labeling for hundreds of drug and device products was an inefficient means to provide updated information to the practicing community.

The Cures Act clarifies FDA’s authority to identify and efficiently update STIC, including through FDA recognition of standards established by SDOs. According to the Cures Act, FDA retains full authority to accept a standard in whole or in part, or to establish alternative STIC.

The Cures Act requires STIC standards be established by a nationally or internationally recognized SDO that:

  • Establishes and maintains procedures to address potential conflicts of interest and ensure transparent decision making;
  • Holds open meetings to ensure that there is an opportunity for public input by interested parties, and establishes and maintains processes to ensure that such input is considered in decision making; and
  • Permits its standards to be made publicly available, through the National Library of Medicine or another similar source acceptable to the Secretary of Health and Human Services.

Once FDA has determined that an SDO fulfills these requirements, FDA may then recognize STIC standards set by the SDO, if the agency determines that they are appropriate.

After publishing a Federal Register notice on October 30, 2017, requesting publicly available information illustrating how an SDO fulfills these requirements, FDA has determined that the Clinical and Laboratory Standards Institute (CLSI) fulfills these statutory requirements at this time.

Medical device manufacturers may use these criteria

The Cures Act also clarifies that sponsors of AST devices may rely upon these FDA-recognized or listed STIC to support premarket authorization of their devices so long as certain conditions are met. This provides for a more streamlined process for incorporating up-to-date information about antimicrobial resistance into such devices. Questions regarding the clearance, classification, or approval of antimicrobial susceptibility testing devices should be directed to the Division of Industry and Consumer Education (DICE) in FDA’s Center for Devices and Radiological Health (CDRH) at 1-800-638-2041, 301-796-7100 or at dice@fda.hhs.gov.

FDA recognizes consensus standards for performance standards, methods standards, and quality control parameter standards for antimicrobial susceptibility testing. Occasionally, consensus standards for methods and quality control parameters may not be established by an SDO at the time a new drug is approved. If appropriate, FDA will list acceptable methods and quality control information for the drug along with the STIC identified for such drug.

FDA has established a docket for public comment where interested third parties or drug sponsors may provide information that FDA could consider in determinations concerning recognition of a susceptibility test interpretive criteria standard or could use as a basis for listing new or for updating susceptibility test interpretive criteria. FDA will review all substantive submissions to support updating of susceptibility test interpretive criteria. When the review is completed, FDA will provide information in the Notice of Updates section of these webpages.

Contact Information: Questions regarding STIC should be directed to the Office of Antimicrobial Products (OAP), Office of New Drugs (OND), Center for Drug Evaluation and Research (CDER) at 301-796-1300 or stic@fda.hhs.gov.

Questions regarding the clearance, classification, or approval of antimicrobial susceptibility testing devices should be directed to the Division of Industry and Consumer Education (DICE) in FDA’s Center for Devices and Radiological Health (CDRH) at 1-800-638-2041, 301-796-7100 or at dice@fda.hhs.gov.


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