Reporting Associated with New Animal Drug Applications

# 152
Guidance for Industry
Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to
Their Microbiological Effects on Bacteria of Human Health Concern
This document discusses a recommended approach for assessing the safety of antimicrobial new
animal drugs with regard to their microbiological effects on bacteria of human health concern.
Comments and suggestions regarding this document should be sent to the Division of Dockets
Management (HFA 305), Food and Drug Administration, 5630 Fishers Lane, Room 1061,
Rockville, MD 20852. All comments should be identified with the Docket No.98D-1146.
Submit electronic comments to http://www.regulations.gov.
Direct questions regarding this document to Jeffrey M. Gilbert, (HFV-157), Center for
Veterinary Medicine, Food and Drug Administration, 7500 Standish Place, Rockville, MD
20855, 240-276-8174, e-mail: jeff.gilbert@fda.hhs.gov.
Additional copies of this guidance document may be requested from the Communications Staff
(HFV-12), Center for Veterinary Medicine, Food and Drug Administration, 7519 Standish Place,
Rockville, MD 20855 and may be viewed on the Internet at
http://www.fda.gov/AnimalVeterinary/GuidanceComplianceEnforcement/GuidanceforIndustry/d
efault.htm.
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U.S. Department of Health and Human Services
Food and Drug Administration
Center for Veterinary Medicine
October 23, 2003

Table of Contents
I. Introduction................................................................................................................................2
II. Scope of Guidance .....................................................................................................................3
III. Risk Analysis Methodology.......................................................................................................5
IV. Hazard Characterization.............................................................................................................8
V. Qualitative Antimicrobial Resistance Risk Assessment ............................................................9
A. Release Assessment ...........................................................................................................10
B. Exposure Assessment.........................................................................................................14
C. Consequence Assessment ..................................................................................................20
D. Risk Estimation ..................................................................................................................20
VI. Antimicrobial Resistance Risk Management Considerations .................................................22
VII. Application of Risk Management Strategies ..........................................................................24
VIII. Summary of Microbial Food Safety Assessment Process .....................................................26
Glossary ...................................................................................................................................27
Appendix A: Ranking of antimicrobial drugs according to their importance in
human medicine ...............................................................................................28
References................................................................................................................................34

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Evaluating the Safety of Antimicrobial New Animal Drugs With Regard to
Their Microbiological Effects on Bacteria of Human Health Concern 1

This guidance represents the Food and Drug Administration’s (FDA’s) current
thinking on this topic. It does not create or confer any rights for or on any person
and does not operate to bind FDA or the public. You can use an alternative
approach if the approach satisfies the requirements of the applicable statute and
regulations. If you want to discuss an alternative approach, contact the FDA staff
responsible for implementing the guidance. If you cannot identify the appropriate
staff, call the appropriate number listed on the title page of this guidance.

I. INTRODUCTION
Prior to approving an antimicrobial new animal drug application, FDA must determine that
the drug is safe and effective for its intended use in the animal. The Agency must also
determine that the antimicrobial new animal drug intended for use in food-producing animals
is safe with regard to human health (21 CFR 514.1(b)(8)). FDA considers an antimicrobial
new animal drug to be “safe” if it concludes that there is reasonable certainty of no harm to
human health from the proposed use of the drug in food-producing animals. This document
provides guidance for industry on a possible process for evaluating the potential effects of
antimicrobial new animal drugs on non-target bacteria as part of the new animal drug
application process.
This guidance document outlines a risk assessment approach for evaluating the microbial food
safety of antimicrobial new animal drugs. Within the context of risk assessment, many
possible mechanisms to address the development of antimicrobial resistance resulting from
the use of antimicrobial new animal drugs in food-producing animals are available to the
sponsor. Alternative processes that may be more appropriate to a sponsor’s drug and its
intended conditions of use, may be used to characterize the microbial food safety of that drug.
FDA’s guidance documents, including this guidance, do not establish legally enforceable
responsibilities. Instead, guidances describe the Agency’s current thinking on a topic and
should be viewed only as guidance, unless specific regulatory or statutory requirements are
cited. The use of the word “should” in Agency guidances means that something is suggested
or recommended, but not required.
1

This guidance has been prepared by the Division of Human Food Safety, Office of New Animal Drug Evaluation,
Center for Veterinary Medicine (CVM), at the Food and Drug Administration.

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II. SCOPE OF GUIDANCE DOCUMENT
As part of the pre-approval safety evaluation process, FDA intends to consider the potential
impact on human health of all uses of all classes of antimicrobial new animal drugs intended for
use in food-producing animals. The scope of this document is an assessment of the effect of the
transmission of foodborne bacteria of human health concern through the consumption of animal
derived food products. Although FDA’s primary focus will be foodborne pathogens, other
(enteric/gastrointestinal) bacteria may be considered when deemed necessary.
Further clarification is provided regarding microbial food safety considerations that should
be addressed, and the investigational new animal drugs (INADs) or new animal drug
applications (NADAs) covered by the guidance described herein. This document focuses on
the concern that the use of antimicrobial new animal drugs in food-producing animals will
result in the emergence and selection of antimicrobial resistant food-borne bacteria which
impact human health adversely.
Note: Effects of drug residues on human intestinal microflora: Antimicrobial drug
residues present in food from food-producing animals may cause adverse effects on the
ecology of the intestinal microflora of consumers.1, 2 For further information on
requirements regarding these effects, refer to FDA Guidance for Industry #159 entitled
“Studies to Evaluate the Safety of Residues in Veterinary Drugs in Human Food:
General Approach to Establish a Microbiological ADI, VICH GL36(R).”
The FDA believes that human exposure through the ingestion of antimicrobial resistant
bacteria from animal-derived foods represents the most significant pathway for human
exposure to bacteria that have emerged or been selected as a consequence of antimicrobial
drug use in animals.
This risk assessment approach is recommended for all uses of all antimicrobial new animal
drugs in food-producing animals; however, sponsors of applications described below are
encouraged to consult with FDA to decide if the risk assessment approach is recommended
for their application.
1. Certain supplemental NADAs: Microbial food safety information is not typically
needed for Category I supplemental NADAs (21 CFR 514.106(b)(1)). These

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supplements ordinarily do not require a reevaluation of any of the safety or
effectiveness data in the parent application. However, information may be needed for
certain Category II supplemental NADAs (21 CFR 514.106(b)(2)). These
supplements may require a re-evaluation of certain safety or effectiveness data in the
parent application.
2. NADAs for antimicrobial drug combinations: Microbial food safety information
would ordinarily not be needed for antimicrobial drug combinations as defined in
Section 512(d) of the Act (21 U. S. C. 360b(d)), as amended by the Animal Drug
Availability Act (ADAA) of 1996. Microbial food safety would typically be
addressed as part of the NADAs for the individual antimicrobial drugs that comprise
the combination. However, in certain circumstances information may be requested
for drug applications for antimicrobial drug combinations.
3. Abbreviated (generic) NADAs: Microbial food safety information would not be
needed for abbreviated new animal drug applications (ANADAs) filed under section
512(b)(2) of the Act for generic copies of approved antimicrobial new animal drugs.
Microbial food safety information would be needed for supplements to add claims to
approved ANADAs.

III. RISK ANALYSIS METHODOLOGY
This guidance document outlines a risk analysis method, and describes its application as a
process for evaluating human food safety with respect to the potential microbiological effects
of antimicrobial new animal drugs on food-borne bacteria of human health concern. The
sponsor of an antimicrobial new animal drug may use this guidance and the methodology
described herein to conduct a qualitative risk assessment as part of the pre-approval safety
evaluation of a new animal drug. It is important to note that the sponsor is free to demonstrate
the safety of their proposed drug product in other ways.

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FDA’s current thinking on a qualitative approach for risk assessment, especially where there
may be a lack of substantial data, is described in this guidance. FDA does not intend to
exclude quantitative risk assessment in favor of a qualitative process. Further, FDA
encourages sponsors to seek data and modeling approaches that can best refine and improve
the approach and assumptions incorporated in this risk assessment process.
If the sponsor elects to use this or a similar process, FDA recommends the assessment be
submitted to the INAD file with supporting data as a component of the Human Food Safety
technical section, or should be included in the NADA as part of the sponsor’s submission
under 21 CFR 514.1(b)(8). The results of this risk assessment can help to estimate the overall
risk, allowing an informed risk management decision. Evaluation of all available information
submitted in support of the NADA may result in actions ranging from approval of the new
animal drug to denial of the new animal drug application. The remainder of the document
provides guidance on this risk analysis method.
A. Background:
The risk analysis process outlined in this document is based on the process described by
the Office International des Epizooties (OIE) Ad Hoc Group on Antimicrobial
Resistance.3 The OIE risk analysis methodology is tailored to address antimicrobial
resistance in animals and includes hazard identification, risk assessment, risk
management, and risk communication. Although the OIE approach differs
organizationally from the risk analysis paradigm described by the National Academy of
Science/National Research Council (NAS/NRC), the OIE process includes similar steps
to describe the risk assessment.4
The risk assessment process described in this guidance is comprised of a hazard
characterization, a release assessment, an exposure assessment, a consequence
assessment, and a risk estimation (See Figure 1). The risk estimation integrates the
components of the risk assessment into an overall conclusion, providing a qualitative
indication of the potential risk to human health of the proposed use of the antimicrobial
new animal drug. FDA then uses the overall risk estimation ranking, along with other
relevant data and information submitted in support of the NADA, to determine whether
the drug is approvable under specific risk management conditions.

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Hazard Characterization

Qualitative Risk Assessment

Release
Assessment

probability that resistant bacteria are present in
target animal as a consequence of drug use
(rank as High , Medium , or Low )

Exposure
Assessment

probability for humans to ingest bacteria in question
from the relevant food commodity
(rank as High, Medium, or Low )

Consequence
Assessment

probability that human exposure to resistant
bacteria results in an adverse health consequence
(rank Important, Highly Important, or Critically Important)

Integration of
Overall Risk Estimate:
release, exposure and consequence
assessments.
(rank as High , Medium , or Low )

Risk Estimation

Figure 1: Components of a qualitative antimicrobial resistance risk assessment

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B. Definitions:
1. Hazard: Human illness, caused by an antimicrobial-resistant bacteria, attributable to
an animal-derived food commodity, and treated with the human antimicrobial drug of
interest.
2. Hazardous agent: Antimicrobial-resistant food-borne bacteria of human health
concern that are in or on a food-producing animal as a consequence of the proposed
use of the antimicrobial new animal drug.
3. Risk: The probability that human food-borne illness is caused by an antimicrobialresistant bacteria, is attributable to an animal-derived food commodity, and is treated
with the human antimicrobial drug of interest.
FDA’s overriding concern is the decreased or lost effectiveness of antimicrobial
drugs in humans as a consequence of human exposure to resistant bacteria through
ingestion of animal derived food products. FDA is concerned about a range of
deleterious effects that antimicrobial resistant bacteria may have on human health.
These effects include but are not limited to increased duration of illness, treatment
failure, and loss of therapeutic options. Due to the difficulties associated with
measuring loss of effectiveness, the risk assessment process described in this
guidance document estimates the probability of the occurrence of the hazard.
C. Data sources/data quality:
A variety of materials may be used to support a microbial food safety assessment. These
materials should meet FDA standards for data used to support an approval. Sponsors
may consider:
1) Generating necessary data through the conduct of prospective studies. FDA
recommends that drug sponsors refer to 21 CFR Part 58 for requirements related to
Good Laboratory Practices for conducting non-clinical laboratory studies.
2) Submission of current and relevant literature (including peer reviewed, published
literature). FDA recommends that sponsors refer to Guidance for Industry #106,

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IV. HAZARD CHARACTERIZATION
Note: Prior to initiating and submitting the risk assessment, FDA recommends that
sponsors electing to use this process characterize the hazard, and the conditions that
influence the occurrence of that hazard. CVM envisions hazard characterization as
distinct and separate from the qualitative risk assessment and it is recommended that
the hazard characterization be submitted to the FDA as a stand alone document. This
submission will enable the sponsor and the FDA to determine the information that
should be included in the risk assessment. In addition, based on the hazard
characterization, it may be determined in certain cases that completion of a risk
assessment is not recommended.
The hazard has been defined as human illness, caused by an antimicrobial-resistant bacteria,
attributable to an animal-derived food commodity, and treated with the human antimicrobial
drug of interest.
FDA recommends that sponsors address the hazard characterization step of the risk
assessment by submitting information regarding the chemical, biochemical, microbiological,
and physical properties of the antimicrobial new animal drug that bear on characterizing the
downstream effects of the drug. This information may include, but should not be limited to:
A. Drug-specific information:
Chemical name and structure
1. Class of antimicrobial drug (e.g., macrolide)
2. Mechanism (e.g., protein synthesis inhibitor) and type of action (i.e., bactericidal vs.
bacteriostatic)
3. Spectrum of activity (e.g., Gram-positive, Gram-negative, broad, or narrow spectrum, etc.)
4. Standardized antimicrobial susceptibility testing methodology and specific
susceptibility data (i.e., minimum inhibitory concentration (MIC) and minimum
bactericidal concentration (MBC) data pertinent to the appropriate bacteria of human
health concern). FDA recommends that if the sponsor does not use standardized
susceptibility test methods, the sponsor should include a detailed description of the
antimicrobial susceptibility testing method(s) used for determining the susceptibility

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of the bacterial isolates of concern and the reason(s) for the needed change. The
methods should include the quality control organism(s), the dilution scheme used, and
the source for the interpretive criteria for human or veterinary isolates. The methods
may include citations, if available, of relevant laboratory standards such as the
National Committee on Clinical Laboratory Standards (NCCLS). Additional
guidance on susceptibility testing may be obtained from recognized sources such as
NCCLS documents.
5. Relative importance of the drug in human medicine (see Appendix A).
B. Bacterial resistance information:
Taking into account the target animal species to be treated with the drug, the conditions
of intended animal use of the drug in animals, and the antimicrobial properties of the drug
in question, FDA recommends that the sponsor identify:
1. Bacterial species and strains for which resistance acquisition has potential human
health consequence.
2. Known resistance determinants or mechanisms associated with the antimicrobial
drug(s) of interest. FDA recommends that information describing phenotypic and
genotypic similarities with resistance determinants in other food-borne bacteria of
human concern be identified.
C. Data gaps and emerging science: T
he sponsor or FDA may identify data gaps and areas
of emerging science that may be relevant to the microbial food safety assessment for the
proposed conditions of use.
V. QUALITATIVE RISK ASSESSMENT
Note: After submission and review of the hazard characterization, and prior to
completing the risk assessment, the sponsor may wish to consult with FDA regarding
recommendations on additional information to complete the risk assessment.
The OIE method is described below in a simplified format. The risk assessment approach is
comprised of a release assessment, an exposure assessment, a consequence assessment, and
a risk estimation (refer to Figure 1).
FDA recommends that sponsors adapt and expand their risk assessment to accommodate the
unique relationships that may exist among an antimicrobial new animal drug, affected
microbe(s), proposed condition(s) of use, and other parameters that potentially affect human
health. The assessment process outlined below will result in an overall estimate of the level
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of concern (risk estimation) associated with the emergence or selection of resistant bacteria
as a consequence of the proposed use of the drug in animals. This process may help guide
the selection of appropriate risk management steps.
Note: FDA intends to determine the appropriate use conditions or other risk
management steps based on its review and consideration of the new animal drug
application as a whole, including any risk assessment submitted by the sponsor as part
of the application.
A. Release Assessment:
The release assessment estimates the probability that the proposed use of the
antimicrobial new animal drug in food-producing animals will result in the emergence or
selection of resistant bacteria in the animal.
1. Defining the boundaries of the release assessment:
The boundaries of the release assessment span from the point the antimicrobial new
animal drug is administered to the food-producing animal, to the point the animal is
presented for slaughter or the animal-derived food is collected.
For the purposes of this guidance, FDA is focusing on the food-producing animal as
the source of human exposure to the hazardous agent. Human exposure to the
hazardous agent should be addressed in the exposure assessment.
2. Factors that may be considered in release assessment:
A number of relevant factors are suggested for consideration in completing the release
assessment. These factors include items that are also considered as part of the hazard
characterization step described earlier.
Note: Following submission of the hazard characterization, the sponsor may wish
to consult with FDA to determine the specific factors most relevant to the
proposed conditions of use of the antimicrobial new animal drug in question.
In order to address specific considerations pertinent to the drug and its proposed
conditions of use, the sponsor or FDA may consider factors not listed below. The
relative significance of any particular factor may vary depending on the specific
antimicrobial new animal drug application under consideration. Therefore, when
determining the overall release assessment ranking, certain factors may carry greater
weight than other factors. FDA recommends that the factors considered in the release
assessment include the following. Other factors may also be relevant. FDA
recommends these be clearly defined and supported.
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a. Product description:
• Product formulation (active and inactive ingredients)
• Information regarding proposed conditions of use including:
− Route of administration (i.e., injection, water, feed)
− Dosing regimen
− Proposed product indication
− Intended target animal species
− Proposed withdrawal time
b. Drug substance description:
• Class of antimicrobial drug (e.g., macrolide)
• Chemical name, CAS number, and structure
c. Mechanism and type of antimicrobial action:
• Specifics regarding antimicrobial mechanisms (e.g., protein synthesis
inhibitor)
• Type of action (e.g., bactericidal action vs. bacteriostatic)
d. Spectrum of activity:
• General information (e.g., is active against Gram-positive, Gram-negative,
broad, or narrow spectrum, etc.)
• Specific susceptibility data (e.g., minimum inhibitory concentration (MIC)
and minimum bactericidal concentration (MBC) data pertinent to the foodborne bacteria of human concern in question)
e. The pharmacokinetics/pharmacodynamics of the drug:
• absorption, distribution, metabolism, and elimination of the drug in the target
animal
• data on, or an estimation of, the active antimicrobial drug in colonic contents

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• additional effects such as first-exposure effects, post-antibiotic effects, subMIC effects, etc.
• Pharmacodynamics, such as concentration and/or time dependent effects, etc.
f. Resistance mechanisms and genetics: FDA recommends that the sponsor provide
information regarding the mechanism(s) and genetic basis of resistance
development that includes:
• Known mechanism(s) of resistance in animal and human pathogens (e.g.,
antimicrobial inactivation, alteration of the drug target, reduced uptake, efflux
of the antimicrobial drug, etc.)
• Location of resistance determinants (e.g., plasmid-mediated vs. chromosomal;
present on transposon, integron, or phage)
g. Occurrence and rate of transfer of resistance determinants: FDA recommends
that the sponsor provide information regarding whether resistance determinants
are transferable and, if so, at what rate. Relevant questions may include, but are
not limited to:
• Can resistance determinants be transferred among bacteria by transformation,
transduction, conjugation, or transposition? If so, at what rate?
• If resistance occurs by point mutation, at what rate do the point mutations
occur?
h. Resistance selection pressures: FDA recommends that the sponsor provide
information to help characterize the relative magnitude of selection pressure for
resistance that may exist for the particular drug use in question. Pertinent
information may include:
• Information regarding other antimicrobials that may co-select for resistance
• Information regarding cross resistance to other antimicrobial drugs approved
in veterinary and human medicine
• Consideration of the extent of use of the proposed product (e.g., duration of
administration; individual vs. small groups vs. flocks/herds)
i. Baseline prevalence of resistance: FDA recommends that the sponsor provide
available epidemiological data outlining the existing prevalence of resistance to
the drug and/or related drugs in target pathogens and commensal gut flora. This

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may be obtained from newly generated data, or existing sources of data, such as
the National Antimicrobial Resistance Monitoring System (NARMS) data,
current literature, or other reliable surveillance sources. If baseline data is not
available for the proposed antimicrobial drug, sponsors may wish to consult with
FDA regarding collection or generation of such data.
j. Other information relevant to the release assessment:
• Relevant information relating to the rate of resistance development and
decline after treatment
• Information or studies to characterize the rate of resistance development in
food-borne bacteria of human health concern following use of the drug under
the proposed conditions of use.
• Information or studies to characterize the decline of resistance in food-borne
bacteria of human health concern following cessation of therapy. Of
particular interest is information relative to the interval up to the earliest time
point (post-drug administration) at which animals would be presented for
slaughter.
3. Summarizing the Release Assessment:
FDA recommends that the sponsor qualitatively characterize all factors relevant to the
release assessment based on supporting information. We recommend that this
characterization include an estimate of whether each factor would have a high,
medium, or low likelihood of favoring resistance emergence. For example, the
spectrum of activity of the drug might be ranked high for favoring resistance
emergence or selection if the new animal drug in question readily selects for
mutations conferring resistance; in contrast, pharmacodynamics might be ranked low
with regard to impact on resistance if the drug did not enter the target animal
intestinal tract at concentrations shown to have an effect on resistance development,
etc. These rankings would then be integrated into an overall release assessment
ranking of high, medium, or low. FDA recommends that the sponsor provide a
detailed discussion of the conclusions as well as present the conclusions in summary
format (see Table 1).
Note: If sufficient information regarding a factor is not available or has not
been generated for the assessment, the most conservative estimate (high) of the
particular factor should be assumed.

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Table 1: Sample table for collating and summarizing interpretation of relevant
factors considered in completing the release assessment
Relevant parameters

Extent to which relevant factors favor
emergence of resistance

Release2
(H, M, L)

Comments/conclusions regarding factors
Mechanism of activity
Spectrum of activity
Pharmacokinetics
Pharmacodynamics
Resistance
mechanism(s)
Resistance transfer
Selection pressure
Other factors1
1

Other factors may be identified that are thought to be of importance to the evaluation.
After submission of the hazard characterization, the sponsor may wish to consult with
FDA regarding additional factors prior to completing the assessment.

2

Potential for favoring the release of resistant bacteria.

4. Release Assessment conclusion:
The outcome of the release assessment is intended to estimate the probability that
resistant bacteria will emerge or be selected for as a consequence of the proposed
drug use in animals. FDA recommends that the sponsor use the conclusions obtained
from assessing all relevant factors to derive an overall qualitative ranking for the
release assessment. This overall conclusion may be expressed in terms of a high,
medium, or low probability that resistant food-borne bacteria will occur in animals as
a consequence of the proposed drug use.
B. Exposure Assessment:
The exposure assessment describes the likelihood of human exposure to food-borne
bacteria of human health concern through particular exposure pathways, in this case
animal derived food products. The exposure assessment should provide a qualitative
estimate of the probability of this exposure occurring.
The division of the qualitative risk assessment into “release” and “exposure”
components effectively produces a natural placement of animal and animal treatment

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factors into the “release assessment component” and food-chain and human factors
within the “exposure assessment component.” FDA recognizes that there are many
factors that may affect the bacteria of interest between the time animals are presented
for slaughter (or the animal-derived food is collected) and the time the final food
product is consumed.
Note: For the purposes of this qualitative risk assessment, FDA assumes that the
probability that bacteria in or on the animal at slaughter may be used as an
estimate of the probability of human exposure to that bacterial species in the
food commodity derived from that animal.
FDA recognizes that food-borne human exposure to antimicrobial resistant bacteria is
complex and often involves the contributions from other sources of exposure (e.g.,
direct contact between animals and humans, introduction of resistant bacteria and
resistance determinants into the environment). However, FDA believes that evaluating
antimicrobial new animal drug safety relative to the most significant exposure pathway
(i.e., food-borne pathway) is the best way to qualitatively assess the risk of
antimicrobial drug use in food-producing animals. Uncertainties regarding the
contribution of other exposure pathways may be considered during the development of
appropriate risk management strategies.
1. Factors to consider in the exposure assessment:
The exposure assessment is independent of the use of the antimicrobial drug under
review and may be estimated by considering the relative amount of relevant bacterial
contamination of the food product and the relative quantity of the food product
consumed by humans. While it is acknowledged that other factors such as food
preparation practices can affect exposure, the two prior considerations are intended to
provide a qualitative indication of the probability of human exposure to the foodborne bacteria of human health concern. Appropriate current survey data of both
food commodity contamination and consumption may be submitted to support a
qualitative ranking of the probability of human exposure to the given bacteria via a
particular food commodity.
FDA recommends that the sponsor derive the exposure assessment ranking by
integrating the ranking of the probability of human exposure (through food) to the
bacteria in question with the ranking of consumption of the animal derived food
commodity. The qualitative probability should be expressed in terms of high,
medium, or low as discussed below.

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2. Example process for the estimation of exposure to the hazardous agent:
Note: The specific information provided in the tables in this section is for
illustrative purposes only. Sponsors may reference a variety of data sources
which best characterize human exposure to bacteria of human health concern
via animal-derived foods. FDA recommends that sponsors reference the most
reliable, current data available at the time that the assessment for their product
is conducted.
FDA believes that the concept of qualitatively ranking bacterial contamination in the
manner described is consistent with the overall risk assessment process outlined. In
addition, FDA believes that the incidence of carcass contamination is a relevant factor
in estimating the probability of human exposure to foodborne bacteria. For the
purposes of this risk assessment, FDA assumes that a high incidence of carcass
contamination is more likely to lead to human exposure through food than a low
incidence of carcass contamination. Based on this assumption, FDA believes that it is
appropriate to rank contamination qualitatively as high, medium, or low.
Food commodity consumption: As an example of food commodity consumption
data, per capita meat consumption data are provided in Table 2. The data presented
are for the year 2001 and are published by the USDA Economic Research Service.
FDA recommends that the sponsor reference this type of information when
completing the risk assessment for their product. The most recent available
information should be used for the assessment. The qualitative rankings provided in
Table 2 are illustrative, and represent relative rankings of consumption of the
commodities listed for the year 2001.

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Table 2: Per capita consumption data for red meats, poultry, fish and
shellfish for the year 2001.
Commodity

Per capita consumption*
(pounds per capita per
year)

Qualitative ranking**

Beef

62.9

High

Chicken

53.9

High

Pork

46.7

High

Fish and shellfish

15.2

Medium

Turkey

13.7

Medium

Lamb and mutton

0.8

Low

Veal

0.5

Low

Total meat

193.7

*From USDA Economic Research Service5; Boneless, trimmed
(edible) weight.
**Qualitative ranking based on relative proportion of the total per capita
consumption of meat that is attributable to each of the individual meat
commodities.
Food commodity contamination: FDA recommends that the sponsor reference food
commodity contamination data when completing the risk assessment for their
product. The most recent information should be used for the assessment. The
relative qualitative ranking of the level of contamination among various food
commodities, High (> 25%), Medium (5–25%), Low (< 5%), is a general ranking,
proposed here for illustrative purposes only, and may be subject to modification to
more appropriately reflect the most current data.
For illustrative purposes, Tables 3 and 4 present Salmonella and Campylobacter
contamination rates in various animal-derived food commodities.

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Table 3. Prevalence of Salmonella contamination of various animal-derived food
commodities and qualitative contamination rankings.
Calendar Year 2001
Baseline
Commodity
Qualitative ranking3
1
Prevalence (%)1,2
prevalence (%)
Ground Turkey

49.9

26.2

High

Ground Chicken

44.6

19.5

Medium

Broilers

20.0

11.9

Medium

Market hog

8.7

3.8

Low

Ground Beef

7.5

2.8

Low

Cows/bulls

2.7

2.4

Low

Steer/Heifer

1.0

0.6

Low

1

As reported in the USDA/FSIS “Progress Report on Salmonella Testing of Raw Meat
and Poultry Products, 1998-2001”6
2
Prevalence data for CY 2001 for all size slaughter establishments and establishments
that produce raw ground product
3
Relative qualitative ranking of the level of contamination among various food
commodities, Low (< 5%), Medium (5 – 25%), High (> 25%), is a general ranking,
proposed here for illustrative purposes only, and may be subject to modification to more
appropriately reflect the most current data.

Table 4. Prevalence of Campylobacter contamination of various
animal-derived food commodities and provisional qualitative
contamination rankings.
Commodity
Prevalence (%)1
Qualitative
ranking2
Turkeys

90

High

Broilers

88

High

Ground Chicken

60

High

Market hog

32

High

Ground Turkey

25

Medium

Steer/Heifer

4

Low

Cows/bulls

1

Low

Ground Beef

0

Low

1

Data from national surveys conducted between 1992 – 1997.7-14
2
Relative qualitative ranking of the level of contamination among various food
commodities; Low (< 5%), Medium (5–25%), High (> 25%) is a general ranking,

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CONTAINS NON-BINDING RECOMMENDATIONS

proposed here for illustrative purposes only, and may be subject to modification
to more appropriately reflect the most current data.

FDA acknowledges that the calendar year 2001 contamination data listed in Table 3
indicate that all listed food commodities are below their respective Salmonella
performance standards (i.e., baseline prevalence). For the purposes of the assessment
outlined here, FDA has decided to base the criterion for “high” contamination upon the
highest level of contamination reported for Salmonella in 2001. Therefore, for the year
2001, a prevalence of contamination of greater than 25 percent is considered a “high”
level of contamination. The medium and low rankings of contamination are bracketed
at 5 to 25 percent and less than 5 percent, respectively. For consistency, as described in
Table 4, the same ranking criteria may be applied to other bacteria such as
Campylobacter. Sponsors may propose alternative criteria and rankings, if data are
available to support their position.
3. Summarizing exposure assessment: Ranking human exposure to foodborne bacteria.
Table 5 describes a possible process for estimating the probability of human exposure
to the hazardous agent through consumption of animal derived food commodities.
Table 5: Possible process for ranking qualitatively the probability of
human exposure to a given bacteria in a given food commodity
Probability of human exposure to a given bacteria
Amount of food commodity being consumed
Amount of food
commodity
contamination

High

Medium

Low

High

H

H

M

Medium

H

M

L

Low

M

L

L

4. Exposure assessment conclusion
The outcome of the exposure assessment is intended to estimate the probability that
humans will be exposed to the hazardous agent through consumption of animal
derived food commodities. FDA recommends that the sponsor use the outcome of the
integration process described in Table 5 to reach an overall qualitative rank of a high,
medium, or low probability of human exposure to the hazardous agent.

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CONTAINS NON-BINDING RECOMMENDATIONS

C. Consequence Assessment
FDA believes that the potential human health consequences of exposure to the
defined hazardous agent may be qualitatively estimated by considering the human
medical importance of the antimicrobial drug in question.
While antimicrobial agents are important for the treatment of infectious disease in
humans, certain antimicrobial agents are believed to be of greater importance to the
therapy of infectious diseases in humans than are others. Therefore, it is assumed that the
human health consequences associated with bacteria that are resistant to drugs of greater
importance are more significant than the consequences associated with bacteria that are
resistant to drugs of lesser importance.
FDA recommends the sponsor refer to Appendix A of this document to assess the
importance of the drug or antimicrobial class in question for human medicine. FDA
recommends that the sponsor base the consequence assessment conclusion on the human
medical importance ranking and be expressed as critically important, highly important or
important. This ranking will be integrated along with the outcomes of the release and
exposure assessments to derive an overall risk estimation as described below.
D. Risk estimation:
The risk estimation integrates the results from the release, exposure, and consequence
assessments into an overall risk estimation associated with the proposed conditions of use
of the drug. FDA recommends that the risk estimation rank drugs as high, medium, or
low risk. The risk rankings represent the potential for human health to be adversely
impacted by the selection or emergence of antimicrobial resistant food-borne bacteria
associated with the use of the drug in food-producing animals.
Table 6 provides a possible method for integrating the outcomes of the release,
exposure, and consequence assessments into a single risk estimation ranking. The
distribution of risk estimation rankings listed in Table 6 provides an initial indication
as to the integration of rankings. Refinement of the risk estimation ranking may be
appropriate for specific cases based on available information.

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CONTAINS NON-BINDING RECOMMENDATIONS

Table 6. Possible risk estimation outcomes based on the integration of the
release, exposure, and consequence assessment rankings
Release

Exposure

Consequence

Risk Estimation

low

low

important

low

low

medium

important

low

medium

low

important

low

low

low

highly important

low

low

high

important

medium

high

low

important

medium

medium

medium

important

medium

medium

high

important

medium

high

medium

important

medium

high

high

important

medium

low

medium

highly important

medium

low

high

highly important

medium

medium

medium

highly important

medium

medium

low

highly important

medium

medium

high

highly important

medium

high

low

highly important

medium

high

medium

highly important

medium

low

low

critically important

high

high

high

highly important

high

low

medium

critically important

high

medium

low

critically important

high

low

high

critically important

high

high

low

critically important

high

medium

medium

critically important

high

medium

high

critically important

high

high

medium

critically important

high

high

high

critically important

high

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CONTAINS NON-BINDING RECOMMENDATIONS

VI. RISK MANAGEMENT CONSIDERATIONS
Possible risk management steps range from denying the approval of a drug application (i.e.,
the drug is unsafe or not shown to be safe) to approving the application under various use
conditions that assure the safe use of the product.
A. Denying approval of a drug application: The Federal Food, Drug, and Cosmetic Act
(FFDCA), Sec. 512(d), and regulations promulgated thereunder (see 21 CFR 514.111),
provides possible grounds for denying the approval of a new animal drug application.
The statutory grounds for denying approval include the results of tests that show the drug
is unsafe or the determination that there is insufficient information as to whether the drug
is safe. Consequently, denying the approval of an antimicrobial drug application is one
possible outcome of an overall safety evaluation which could include the qualitative
antimicrobial resistance risk assessment process described above.
B. Drug approval under safe conditions of use: Approval of the use of the drug under those
conditions for which safety and effectiveness has been demonstrated is another possible
outcome of an overall safety evaluation that could include the qualitative antimicrobial
resistance risk assessment process described above.
Drugs considered to be of high concern (with regard to potential human health impact)
would typically be associated with more restricted use conditions. Drugs considered to
be of lower concern would typically be associated with less restricted use conditions in
food-producing animals.
C. The following represent relevant risk management steps or conditions that may be
appropriate based on the outcome of the qualitative antimicrobial resistance risk
assessment process.
1. Marketing status limitations: Antimicrobial drugs approved for use in animals may
be marketed as prescription (Rx), over-the-counter (OTC), or veterinary feed
directive (VFD) products. FDA believes that for certain antimicrobial drugs
veterinary supervision is critical to assuring the judicious and safe use of the
antimicrobial drug. Therefore, such drugs might be approved for limited use by, or
under the supervision of, a veterinarian. For other antimicrobial drugs, the
requirement for this level of veterinary supervision may not be warranted.
2. Extra-label use prohibition: As provided under 21 CFR 530.21(a)(2), FDA may
prohibit the extralabel use of an approved new animal drug or class of drugs in foodproducing animals if FDA determines that “the extralabel use of the drug or class of
drugs presents a risk to the public health.” If significant concerns exist regarding
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CONTAINS NON-BINDING RECOMMENDATIONS

assurance of drug safety in light of potential extralabel use, extralabel use may be
prohibited according to the procedures described in 21 CFR 530.
3. Extent-of-use limitations: FDA believes that “extent of use” is an important factor to
consider when determining safe conditions of use for an antimicrobial new animal
drug. Table 7 presents a possible process for integration of administration and
duration of administration of an antimicrobial drug into a qualitative ranking for
“extent of use”.
Table 7: Possible process for ranking (High, Medium, Low) of extent of
antimicrobial drug use in animals based on duration and method of
administration.
Intended administration to:
Duration of
use

1

individual
animals

select groups or
pens of animals

flocks or herds
of animals

Short
(<6 days)

L1

M2

H3

Medium
(6-21 days)

L

M

H

Long
(>21 days)

M

H

H

Low, 2Medium, and 3High extent of use

In general, administration to groups or pens of animals is defined as administration to
a segregated group of animals within a building, house or feedlot, whereas
administration to flocks or herds of animals is defined as administration to all animals
within a building, house, feedlot. The sponsor may use another definition of these
terms that is more reflective of relevant, current animal husbandry practices.
D. The following are examples of additional risk management steps that may be associated with
the approval of antimicrobial new animal drugs in food-producing animals.
1. Post-approval monitoring: Antimicrobial new animal drugs intended for use in foodproducing animals may be subject to monitoring through a post-approval process, such
as the National Antimicrobial Resistance Monitoring System (NARMS).
2. Advisory committee review: When making an approval decision regarding a Category
1 or select Category 2 drugs, FDA may choose to convene an advisory committee to
discuss the application.

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CONTAINS NON-BINDING RECOMMENDATIONS

FDA believes that antimicrobial drugs ranked as high risk may be approvable if, after evaluating
all supporting information, FDA can conclude that there is a reasonable certainty of no harm to
human health when the drug is approved under specific use restrictions. Such a determination
would be made on a case-by-case basis and based on a review of the entire application. FDA’s
concerns associated with drugs estimated to pose high risk may be mitigated through the
introduction of risk management steps that minimize resistance emergence or selection
associated with any adverse impact on human health.
FDA believes that antimicrobial drugs ranked as medium risk may be approvable if, after
evaluating all supporting information, FDA can conclude that there is a reasonable certainty of no
harm to human health when the drug is approved under specific use restrictions. Interpreting the
medium risk category of drugs is more complex than the other categories, since the conclusions for
the various risk assessment components are potentially more disparate (i.e., ranging from low to
high). However, FDA believes it is appropriate to conclude that drugs in this category are
associated with a level of risk that is intermediate between the high and low risk category drugs.
Therefore, it is consistent to conclude that a finding of reasonable certainty of no harm might be
reached for such drugs when use conditions are intermediately restrictive. Such a determination
would be made on a case-by-case basis and based on a review of the entire application.
FDA believes that antimicrobial drugs ranked as low risk may be considered approvable if, after
evaluating all supporting information, FDA can conclude that there is a reasonable certainty of
no harm to human health when the drug is approved under specific use restrictions. Such a
determination would be made on a case-by-case basis and based on a review of the entire
application. For a drug to be ranked as low risk overall, two of three major components of the
risk assessment would have been ranked as low and the third component ranked moderate. FDA
believes that a single medium ranking when the other two risk assessment components are
ranked low should not substantially increase the overall level of risk. Therefore, combinations
involving two low ranks and one medium are consistent with an overall risk estimation ranking
of low.
VII. Application of Risk Management Strategies:
The integration process outlined above (Table 6) results in an estimation of the risk that the use
of an antimicrobial new animal drug will adversely impact human health. The outcome of the
risk estimation (high, medium or low) can be used to help identify steps necessary to manage the
risks associated with the proposed conditions of use for an antimicrobial new animal drug.
Examples of risk management steps and how these steps might be applied to manage the
estimated level of risk are described below. Table 8 contains three categories (1, 2, and 3) which
associate the overall drug risk estimation (i.e., high, medium, or low risk) with a set of possible

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CONTAINS NON-BINDING RECOMMENDATIONS

risk management strategies. In general, Category 1 includes those drugs ranked “high” in the
risk estimation, Category 2 includes those ranked “medium”, and Category 3 includes those
ranked as “low.” However, certain cases may warrant alternative categorization.
Table 8. Examples of potential risk management steps associated with the approval of
antimicrobial new animal drugs in food-producing animals based on the level of risk
(high, medium, or low).
Approval
Category 1 (High) Category 2(Medium) Category 3 (Low)
conditions
Marketing Status1

Rx

Rx/VFD

Rx/VFD/OTC

Extra-label use
(ELU)

ELU Restrictions

Restricted in some
cases3

ELU permitted

Extent of use2

Low

Low, medium

Low, medium,
high

Post-approval
monitoring
(e.g., NARMS)

Yes

Yes

In certain cases

Advisory
committee review
Yes
In certain cases3
No
considered
1
Prescription (Rx), Veterinary Feed Directive (VFD), Over-the-counter (OTC)
2
See Table 7 for characterization of extent of use
3
These risk management steps may be appropriate for certain Category 2 drugs that were
ranked critically important for consequence assessment and ranked “high” for release or
exposure assessment
As illustrated in Table 8, drugs in Category 1 are associated with a high risk ranking and
would typically be subject to the most restrictive use conditions. Category 3 drugs have
the lowest risk ranking and would typically be subject to the least limitations. Category 2
drugs, ranked intermediate for risk to human health, would typically be subject to
limitations that are intermediate between those of Categories 1 and 3. Category 2 drugs
(as described in Table 8) include several approval conditions that may or may not be
applied to all drugs in the category. For example, the table indicates that restrictions
limiting extra-label use may be considered for certain Category 2 drugs.
The conditions listed for a given drug category in Table 8 are intended to provide an
example of the conditions of use or limitations that FDA might expect to be associated with
a drug product in that category. However, FDA’s final determination of the approvability
of antimicrobial new animal drug applications will depend on a consideration of all
information available for the drug application in question. FDA may determine that a
proposed drug product can be approved under alternative use conditions/limitations

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CONTAINS NON-BINDING RECOMMENDATIONS

proposed by the sponsor, if the sponsor provides adequate information to support the safety
of the drug under those conditions.
VIII. Summary of Microbial Food Safety Assessment Process
FDA recommends that sponsors choosing to use this process:
• Prepare a hazard characterization (described in pages 7 through 8) and submit the
characterization to the FDA for review.
• After review of the hazard characterization, FDA and the sponsor may discuss
whether a risk assessment needs to be completed and, if so, what information is
recommended for completion of the risk assessment.
• Prepare the risk assessment and submit the assessment to the FDA for review.
• Following review of the safety package as a whole, including the risk assessment,
FDA will determine the risk estimation and associated risk management steps
applicable to the proposed conditions of use for the antimicrobial new animal drug.

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CONTAINS NON-BINDING RECOMMENDATIONS

Glossary
Consequence assessment: The consequence assessment describes the relationship between
specified exposures to a biological agent (the hazardous agent) and the consequences of those
exposures. For the purposes of this risk assessment, FDA has decided that the potential human
health consequences of exposure to the defined hazardous agent may be estimated qualitatively by
considering the human medical importance of the antimicrobial drug in question.
Exposure assessment: The exposure assessment describes the likelihood of human exposure to
the hazardous agent through food-borne exposure pathways. The exposure assessment should
estimate qualitatively the probability of this exposure to bacteria of human health concern through
food-related pathways.
Hazard: Human illness, caused by an antimicrobial-resistant bacteria, attributable to an animalderived food commodity, and treated with the human antimicrobial drug of interest.
Hazardous agent: Antimicrobial-resistant food-borne bacteria of human health concern that are
in or on a food-producing animal as a consequence of the proposed use of the antimicrobial new
animal drug.
Hazard characterization: The process by which one may identify the hazard and the conditions
that influence the occurrence of that hazard. This is based upon drug-specific information,
bacteria/resistance determinant information, and the methodology for the determination of
“resistant” or “susceptible” bacteria.
Release assessment: The release assessment should describe those factors related to the
antimicrobial new animal drug and its use in animals that contribute to the emergence of resistant
bacteria or resistance determinants (i.e., release of the hazardous agent) in the animal. The
release assessment should also estimate qualitatively the probability that release of the hazardous
agent would occur. For the purposes of this assessment process, the boundaries of the release
assessment span from the point the antimicrobial new animal drug is administered to the foodproducing animal, to the point the animal is presented for slaughter or the animal-derived food is
collected.
Risk: The probability that human food-borne illness is caused by a specified antimicrobial
resistant bacteria, is attributable to a specified animal-derived food commodity, and is treated with
the human antimicrobial drug of interest.
Risk estimation: The overall estimate of the risk associated with the proposed use of the drug in
the target food-producing animals following the integration of the release assessment, exposure
assessment and consequence assessment. The risk rankings represent the relative potential for
human health to be adversely impacted by the emergence of antimicrobial resistance associated in
a food-borne pathogen with the use of the drug in food-producing animals.
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CONTAINS NON-BINDING RECOMMENDATIONS

Appendix A
Ranking of antimicrobial drugs according to their importance in human medicine
Objective: This appendix describes a process for ranking antimicrobial drugs with regard to their
relative importance in human medicine. FDA recommends this ranking be considered when
completing the hazard identification and the consequence assessment portions of the qualitative risk
assessment outlined in this guidance document. The general criteria for determining the importance
ranking are outlined and a preliminary listing of various antimicrobial drugs and assigned rankings
is provided.
Ranking process: Based on a consideration of the factors described below, specific antimicrobial
drugs or classes of antimicrobials should be ranked as to whether they are critically important,
highly important, or important to human medical therapy. The assignment of a ranking to a given
antimicrobial or class of antimicrobials is dependent upon the degree to which any one or more of
the factors described below is applicable to the drug in question. Table A1 provides a ranking
based on a consideration of the criteria described below.
The possible importance rankings are defined as follows:
Critically Important: Antimicrobial drugs which meet BOTH criteria 1 and 2 below.
Highly Important: Antimicrobial drugs which meet EITHER criteria 1 or 2 below.
Important: Antimicrobial drugs which meet EITHER criterion 3 and/or 4 and/or 5.
Note: Table A1 does not necessarily include all antimicrobial drugs or drug classes. The
development of new antimicrobials for human therapy, the emergence of diseases in
humans, or changes in prescribing practices, etc., are among the factors that may cause the
rankings to change over time. Therefore, it is the intent of the Agency to reassess the
rankings provided in Table A1 periodically to confirm that the ranking is consistent with
current circumstances. The rankings of drugs in Appendix A may be subject to change at
any time when information becomes available that would impact those rankings. The
sponsor may wish to consult with FDA regarding the ranking relevant to their proposed
drug at the time the assessment is made.
Criteria considered in ranking process: In developing criteria for ranking antimicrobial drugs
with regard to their importance in human medicine, the FDA considered broad issues associated
with the efficacy of drugs in human medicine and factors influencing the development of
antimicrobial resistance. Specific factors include the usefulness of the drug in food-borne
infections, the types of infections treated, the availability of alternative therapies, the uniqueness
of the mechanism of action, and the ease with which resistance develops and is transferred
between organisms. Note that multiple factors may be applicable to some products, illustrating
their considerable importance to human medicine. We recommend that drug sponsors use the

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CONTAINS NON-BINDING RECOMMENDATIONS

following criteria to rank the importance of drugs in human medicine. The criteria are ranked
from most to least important, e.g. criterion 1 is the most important.
1. Antimicrobial drugs used to treat enteric pathogens that cause food-borne disease
The Infectious Disease Society of America (IDSA) guidelines on the treatment of diarrhea and
other sources such as the Sanford Guide provide the drugs typically used in the treatment of
food-borne diseases.
2. Sole therapy or one of few alternatives to treat serious human disease or drug is essential
component among many antimicrobials in treatment of human disease.
A. Includes antimicrobials like vancomycin and linezolid for MRSA infections. Although
they are not the “sole” therapy, they are one of only a few alternatives.
B. This would also include a drug like polymyxin where it is one of few alternatives for
multi-drug resistant Pseudomonas aeruginosa infections.
C. Rifampin is not only a drug used to treat TB but also it is an essential part of the treatment
regimen as the cure rate is lower without it.
D. Serious diseases are defined as those with high morbidity or mortality without proper
treatment regardless of the relationship of animal transmission to humans. For example,
rifampin is an essential drug to treat disease caused by Mycobacterium tuberculosis (high
morbidity and mortality if untreated) even though this is a human pathogen. Gonorrhea
occurs only in humans and is not lethal but can result in sterility if left untreated (high
morbidity).
3. Antimicrobials used to treat enteric pathogens in non-food-borne disease
Enteric pathogens may cause disease other than food-borne illness. For instance, E. coli,
which causes food-borne disease, is also capable of causing diseases as diverse as urinary tract
infections and neonatal meningitis.
4. No cross-resistance within drug class and absence of linked resistance with other drug
classes
A. Absence of resistance linked to other antimicrobials makes antimicrobials more valuable.
An example is quinolone resistance in pneumococci, which currently does not appear
linked to penicillin resistance. On the other hand, penicillin resistance appears to be linked
to macrolide, tetracycline, and trimethoprim-sulfamethoxazole resistance in pneumococci.
B. Cross-resistance within antimicrobial classes and absence of linked resistance may change
over time and will need to be updated periodically.
C. In this context, “cross-resistance” refers to the transmission of resistant determinants
between bacterial species or genera and does not refer to transmission of resistant
organisms between animals and humans. This is addressed in the release assessment part
of the guidance.
5. Difficulty in transmitting resistance elements within or across genera and species of
organisms
A. Antimicrobials to which organisms have chromosomal resistance would be more valuable
compared to those antimicrobials whose resistance mechanisms are present on plasmids
and transposons.
B. This does not refer to “ease of transmissibility” from animals to humans of the resistant
pathogen as this is addressed elsewhere in the guidance in the release assessment.
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CONTAINS NON-BINDING RECOMMENDATIONS

Natural penicillins

5) Limited risk of
transmission of
resistance elements
within/across species
of organisms

4) No cross-resistance
within class/no linked
cross-resistance with
other classes

3) Used to treat enteric
pathogens in nonfood-borne disease

2) Sole/limited therapy
or essential therapy
for serious disease
(See "Comments" for
examples)

1) Enteric pathogen
responsible for foodborn disease

Classification

Table A1: Potential ranking of antimicrobial drugs/drug classes based on the identified relevant
factors. C- Critically important; H- Highly important; I – Important.

H

X

Comments
Neurosyphilis: Serious
infection due to Group A
streptococci

H

X

Serious infections due to
Staphylococcus aureus

H

X

X

Serious infections due to
Pseudomonas aeruginosa

H

X

X

Infections due to Listeria
monocytogenes

Benzathine pen G
Penicillin G
Penicillin V
Penase Resistant Pens
Cloxacillin
Dicloxacillin
Nafcillin
Oxacillin
Antipseudomonal Pens
Mezlocillin
Pipercillin
Pipercillin/tazo
Ticarcillin
Ticarcillin/Clav
Carbenicillin
Aminopenicillins
Amoxicillin
Ampicillin
Ampicillin/Sulbacta
1st Gen Ceph

I

X

I

X

Cefazolin
Cafadroxil
Cephalexin
Cephradine
2nd Gen Ceph
Cefaclor
Cefaclor-CD
Cefamandole
Cefonacid
Cefprozil
Cefuroxime
Lorcacarbef

- 30 -

X

5) Limited risk of
transmission of
resistance elements
within/across species
of organisms

X

4) No crossresistance within
class/no linked
cross-resistance with
other classes

2) Sole/limited
therapy or essential
therapy for serious
disease (See
"Comments" for
examples)

C

3) Used to treat
enteric pathogens in
non-food-borne
disease

1) Enteric pathogen
responsible for foodborn disease

3rd Gen Ceph

Classification

CONTAINS NON-BINDING RECOMMENDATIONS

X

Comments
Meningitis: Necrotizing
enterocolitis

X

Sole agent approved for use as
empiric monotherapy for
neutropenic fever

Cefdinir
Cefixime
Cefoperazone
Cefotaxime
Cefpodoxime
Ceftazidime
Ceftibuten
Ceftizoxme
Ceftriaxone
4th Gen Ceph

H

X

Cefepime
Cephamycins

I

X

Cefotetan
Cefoxitin
Carbapenems

H

X

Infections due to multidrug
resistant gram negative rods

X

Imipenem
Meropenem
Ertapenem
Monobactams

I

Aztreonam
Quinolones

I

X
X

X

X

X

Nalidixic Acid
Cinoxacin
Oxolinic Acid
Pipemidic Acid
Flouroquinolones

C

X

X

Norfloxacin
Ciprofloxacin
Ofloxacin
Enoxacin
Levofloxacin
Lomefloxacin
Sparfloxacin
Grepafloxacin
Gatifloxacin
Moxifloxacin

- 31 -

X

Infections due to multidrug
resistant gram negative rods

Aminoglycosides

H

X

5) Limited risk of
transmission of
resistance elements
within/across species
of organisms

4) No cross-resistance
within class/no linked
cross-resistance with
other classes

3) Used to treat enteric
pathogens in non-foodborne disease

2) Sole/limited therapy
or essential therapy for
serious disease (See
"Comments" for
examples)

1) Enteric pathogen
responsible for foodborn disease

Classification

CONTAINS NON-BINDING RECOMMENDATIONS

Comments

X

Amikacin
Gentamicin

Enterococcal endocarditis
Sole antimicrobial approved for
aerosolized therapy in cystic
fibrosis

Tobramycin
Kanamycin

Infections due to
Mycobacterium tuberculosis

Streptomycin
Neomycin
Netilmicin
Spectinomycin

Infections due to Neisseria
gonorrhoeae in pregnancy

Macrolides

Legionnaire's disease:
MAC/MAI prophylaxis and
therapy

C

X

X

Erythromycin
Azithromycin
Clarithromycin

Clindamycin

H

X

Tetracyclines

H

X

Serious infections due to
Group A streptococci:
Alternative therapy of
infections due to
Staphylococcus aureus in
patients with serious beta
lactam allergy
Rickettsial disease: Anthrax
therapy/prophylaxis

H

X

Infections due to methicillin
resistant Staphylococcus
aureus

H

X

Infections due to vancomycin
resistant Enterococcus faecium

Tetracycline
Chlorteracycline
Demeclocycline
Doxycycline
Minocycline
Glycopeptides
Vancomycin
Streptogramins
Dalfopristin/quinupristin

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Oxazolidones

H

X

Pyrazinamide

H

X

Isoniazid

H

X

Rifamycins

H

X

X

5) Limited risk of
transmission of
resistance elements
within/across species
of organisms

4) No crossresistance within
class/no linked
cross-resistance with
other classes

3) Used to treat
enteric pathogens in
non-food-borne
disease

2) Sole/limited
therapy or essential
therapy for serious
disease (See
"Comments" for
examples)

1) Enteric pathogen
responsible for foodborn disease

Classification

CONTAINS NON-BINDING RECOMMENDATIONS

Comments
Infections due to methicillin
resistant Staphylococcus
aureus and vancomycin
resistant Enterococcus

Linezolid

Rifampin
Rifabutin
Chloramphenicol

H

Metronidazole

H

Trimeth/Sulfameth

C

Polymyxin B

H

X

X
Infection due to Clostridium
difficile

X

X

X

X

Infection due to Pneumocystis
carinii

X

X

Infections due to multidrug
resistant gram negative rods

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CONTAINS NON-BINDING RECOMMENDATIONS

References
1. Woodward. K.N. 1998. The use of microbiological end-points in the safety evaluation and
elaboration of maximum residue limits for veterinary drugs intended for use in food
producing animals. J. Vet. Pharmacol. Ther. 21:47-53.
2. Paige, J.C., L. Tollefson, M.A. Miller. 1999. Health implications of residues of veterinary
drugs and chemicals in animal tissues. Vet. Clin. North Am. Food Anim. Pract. 15:31-43.
3. Vose, et al. Antimicrobial resistance: risk analysis methodology for the potential impact on
public health of antimicrobial resistant bacteria of animal origin. In: Review of Science and
Technology. Vol. 20(3), 811-827. Office of International Epizootics. Paris, 2001
4. Committee on the Institutional Means for Assessment of Risks to Public Health,
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