FDA Finalizes Guidance on Evaluating the Microbial Food Safety Risks Posed by Antimicrobial New Animal Drugs

On August 5, 2025, the U.S. Food and Drug Administration (FDA) Center for Veterinary Medicine (CVM) published a Final Guidance titled “Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to their Microbiological Effects on Bacteria of Human Health Concern” (Guidance for Industry (GFI) #152) (Final Guidance). The Final Guidance replaces the original version published in 2003, but the overall scope and purpose remain the same—to serve as CVM’s primary framework for evaluating potential antimicrobial resistance risks from animal drug use in food-producing animals as part of the new animal drug application (NADA) process.

Background

To approve an antimicrobial NADA, CVM must determine that the drug is safe and effective for its intended use. For drugs intended for use in food-producing animals, CVM must also determine that the drug is safe for human health.^[1] CVM considers an antimicrobial new animal drug to be “safe” if there is reasonable certainty of no harm to human health from the proposed use of the drug in food-producing animals.

CVM first issued GFI #152 in 2003 (2003 Guidance) to establish a qualitative risk assessment methodology for evaluating foodborne antimicrobial resistance concerns related to the use of antimicrobial drugs in food-producing animals. The 2003 Guidance included, among other things, a list (commonly referred to as “Appendix A”) ranking medically important antimicrobial drugs into three tiers based on their importance to human medicine (i.e., “critically important,” “highly important,” or “important”). CVM stated it would periodically reassess these rankings “to align with contemporary science and current human clinical practices.”

Given the scientific advancements since 2003, FDA announced a public meeting in October 2020 and requested comments on a concept paper that proposed modifications to the antimicrobial ranking criteria. FDA subsequently published draft revised GFI #152 (Draft Guidance) in December 2022, outlining an updated risk assessment approach for evaluating the microbial food safety risk posed by antimicrobial drug use in food-producing animals. See our previous alert for more details, including a summary of key changes introduced in the Draft Guidance relative to the 2003 Guidance.

Key Changes in the Final Guidance

CVM received 22 substantive comments on the Draft Guidance from animal pharmaceutical companies, food animal producers, veterinarians, consumer and public health interest groups, a State agriculture department, and other stakeholders, as well as over 9,200 comments from two write-in campaigns expressing broad policy views that CVM explained in the Notice of availability accompanying the publication of the Final Guidance generally did not address the specific recommendations in the Draft Guidance. Based upon the substantive comments, the Final Guidance:

• Provides a more detailed description of hazard characterization (step one of the risk assessment) including circumstances where a complete qualitative risk assessment may not be necessary;
• Combines sections on risk management and defines the term as “[s]pecific actions or approaches (e.g., modifying conditions of use for the product) intended to mitigate any adverse impacts on human health as a result of the proposed use of the antimicrobial new animal drug”;
• Clarifies that Appendix A rankings should inform the consequence assessment component of the overall risk assessment methodology, and not serve as a standalone guide for risk management decisions;
• Clarifies that the medical importance designations in Appendix A are generally made at the drug class level, but may be adjusted for specific drugs if certain information (e.g., regarding mechanism of action) supports the conclusion that the drug is distinct from others within its class; and
• Explains why antimicrobials approved only for topical use in humans are excluded from Appendix A.

In other respects, the Final Guidance is largely consistent with the Draft Guidance.

If you have any questions concerning the material discussed in this client alert, please contact the members of our Animal Food and Drug practice.