U.S. Food and Drug Administration

1. U.S. Food and Drug Administration Notice: Archived Document The content in this document is provided on the FDA’s website for reference purposes only. It was current when produced, but is no longer maintained and may be outdated.

2. Introduction to Cefquinome (CEQ) and Overview of Microbial Safety Assessment Veterinary Medicine Advisory Committee Public Hearing, 25 September 2006 Carl K. Johnson, D.V.M. Director, Product Development and Regulatory Affairs Intervet Inc.

3. Agenda • An introduction to cefquinome, a 4th generation cephalosporin for use in veterinary medicine • Overview of the Microbial Safety Assessment of cefquinome (CEQ), following FDA/CVM Guidance for Industry #152 • Experience with 4th generation cephalosporin use in human and veterinary medicine in Europe since 1993 (Prof. André Bryskier)

4. Cephalosporins Used in Veterinary Medicine Cefapirin, 1st Generation Cephalosporin core syn-Methoxyimino group: β-Lactamase stability Ceftiofur, 3rd Generation 2-Aminothiazolegroup: activity spectrum Cyclohexenopyridine group: activity spectrum Cefquinome, 4th Generation

5. Cefquinome • Molecular structure of 4GC: zwitter-ionic Beta-lactam nucleus beta-lactam nucleus quaternary ammonium C3' aminothiazolyl moeity zwitter-ionic

6. Description of Cefquinome (CEQ) • Innovative β-lactam antimicrobial (4th generation cephalosporin, 4GC): • Characterized by zwitter-ionic molecular structure • faster penetration of outer cell membrane (gram-negatives) • lower affinity to β-lactamases • higher affinity to target penicillin binding proteins ► Enhanced antimicrobial activity

7. Description of Cefquinome (CEQ) • Exclusively for veterinary medicine: • Europe (EU): since 1994 for prescription only use in cattle, followed by swine (1999), and horses (2005) • US: pending applications for treatment of bovine respiratory disease with two injectable formulations (by prescription only) • Not for use in feed and water

8. Mode of Action (4GC) Porin tunnel β-lactamases Penicillin Binding Proteins (PBP) Binding of CEQ to PBP disrupts synthesis of peptidoglycan layer Integrity of cell wall is compromised Net result: cell death (bactericidal)

9. Overview of Microbial Safety Assessment for Cefquinome (Guidance for Industry #152) Description of hazard and conditions that influence its occurrence HAZARD CHARACTERIZATION RELEASE • Probability of emergence of resistance • resulting from use of the drug in animals EXPOSURE • Probability of human exposure to bacteria of concern • via food-borne transmission • Potential that human exposure to resistant bacteria results in adverse health consequence • estimated by medical importance of the drug class CONSEQUENCE • Integration of the above assessments to estimate the relative potential of an adverse human health impact • resulting from the proposed veterinary use RISK ESTIMATE

10. Food-borne Pathogens of Concern • GI #152: “…antimicrobial-resistant bacteria attributable to an animal-derived food commodity and treated with the human antimicrobial drug of interest” • Non-typhoidal Salmonella spp. are the relevant food-borne pathogens of interest • NARMS survey data • Enteric salmonellae are susceptible to CEQ • E. coli is also considered in the release assessment • E. coli is usually not associated with food-borne infections, except E. coli O157:H7 (for which there is zero tolerance in food) • Other food-borne pathogens - Campylobacter spp., and Enterococcus spp. - are not considered • CEQ is not active against these pathogens

11. Hazard Characterization Risk Assessment Hypotheses • The use of CEQ may cause resistance in Salmonella spp. (E. coli) present in the intestinal tract of the target animal, and • Resistant Salmonella spp. may contaminate the carcass at slaughter and may transfer to humans via food, and • Resistant Salmonella spp. may cause infections in humans, and when treated with a 4 GC, effectiveness may be compromised

12. Outcome of CEQ Microbial Risk Assessment Using Guidance for Industry #152 (“Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to Their Microbiological Effects on Bacteria of Human Health Concern”), it is shown that : • The overall risk estimate is MEDIUM for the proposed veterinary therapeutic use of CEQ in cattle • The proposed risk management measures minimize this risk and are consistent with antimicrobial prudent use guidelines • There is reasonable certainty of no harm to public health with regard to the proposed use

13. RELEASE: Emergence of CEQ resistance in Salmonella and E. coli Probability is MEDIUM as determined by: • Conditions of use are limited (therapeutic, parenteral, individual animal use only, for short duration) • 4GCs are active against bacteria carrying the AmpC-type β-lactamase resistance mechanism • 4GC resistance is very rare (must have either non-transferable Outer Membrane Protein mutation plus enhanced β-lactamase activity or Extended Spectrum β-Lactamases [ESBLs] that confer resistance to 4GCs); furthermore, ESBLs have not been identified in isolates from US livestock • Susceptibility surveillance data for 4GCs for both human and veterinary 4GCs indicates no change in resistance patterns of relevant food-borne pathogens (ongoing surveillance in the US and EU since late 1990’s: sustained high level of susceptibility)

14. RELEASE: Emergence of CEQ resistance in Salmonella and E. coli 1. Conditions of use of the two injectable formulations: • Individual parenteral therapy of bovine respiratory disease data on CEQ-related residues demonstrate that • only very small amounts present in the intestinal tract of treated cattle, and • gastro-intestinal inactivation of CEQ • Short duration of treatment (daily injection for <1 week; single injection) • Use controlled by prescription only status ► Only limited exposure of enteric pathogens to CEQ possible

15. RELEASE:Emergence of CEQ resistance in Salmonella and E. coli 2. 4GC activity against existing β-lactam resistance mechanisms • The plasmid-encoded AmpC-like ß-lactamase CMY-2 is the most important β-lactamase in Salmonella spp. and E. coli isolated from food-producing animals • CMY-2 confers resistance to most β-lactams (including 3GCs), but not for carbapenems and 4GCs • CEQ does not induce Amp C-type β-lactamases in Salmonella spp., or E. coli • Extended Spectrum β-Lactamases (ESBLs) have not been found in Salmonella spp. and E. coli isolatedfrom US livestock • 4GCs (incl. CEQ) do not select for most common β-lactam resistance mechanisms

16. RELEASE: Emergence of CEQ resistance in Salmonella and E. coli 3. Resistance mechanism relevant for 4GCs • High level 4GC resistance requires: • A combination of both • changes in outer membrane protein (non-transferable chromosomal mutation) which decreases permeability and/or increases efflux, and • simultaneous enhanced β-lactamase activity • Specific ESBLs that confer resistance to 4GC ► Low risk of emergence of resistance to 4GCs (as confirmed by susceptibility surveillance data)

17. RELEASE: Emergence of CEQ resistance in Salmonella and E. coli 4. Surveillance data (animal isolates) • Sustained high level of susceptibility to CEQ post- approval(EU): • in Salmonella and E. coli (EASSA survey, 1999-01) • Sustained high susceptibility to CEQ pre-approval (US): • in bovine Salmonella (NARMS slaughter isolates, since 2000) • in bovine E. coli (Intervet feedlot survey, 2002) ► No change observed in high level of susceptibility to CEQ

18. RELEASE: Emergence of CEQ resistance in Salmonella and E. coli Susceptibility surveillance data (animal isolates) Sustained high susceptibility to CEQ pre-approval (US) in bovine Salmonella (NARMS slaughter isolates, 2000-2003)

19. RELEASE: Emergence of CEQ resistance in Salmonella and E. coli Susceptibility surveillance data (human isolates) • Susceptibility to the 4GC cefepime: • nearly 100% in US isolates of Salmonella spp. and E. coli (SENTRY, 1997-1999). • consistently above 98% from 1997 to 2003 in E. coli and Salmonella spp. obtained from US hospitals (TSN, Focus Bio-Inova) ► Sustained high level of susceptibility to 4GC

20. RELEASE: Emergence of CEQ resistance in Salmonella and E. coli Release Assessment Summary • Exposure of Salmonella spp. and E. coli to CEQ is limited • CEQ does not select for the most prevalent beta-lactam resistance mechanisms (Amp C); ESBLs have not been found in food producing animals • Selective pressure leading to resistance emergence to 4GCs (incl. CEQ) is minimal • No change observed in high level of susceptibility to 4GCs (incl. CEQ) ►The probability of the emergence of CEQ-resistant Salmonella (and E. coli) in cattle is MEDIUM

21. RELEASE: Emergence of CEQ-resistant Salmonella, E. coli MEDIUM Probability of human exposure to Salmonella spp.via food-borne transmission EXPOSURE: Human exposure to Salmonella spp. • Contamination of beef (USDA/FSIS) and milk (pasteurization) with Salmonella spp. is low: • However, US per capita beef consumption is high

22. RELEASE: Emergence of CEQ-resistant Salmonella MEDIUM Exposure Assessment Summary Probability of human exposure to Salmonella spp. from applicable food animal source EXPOSURE: Human exposure to Salmonella MEDIUM ► Default values provided in FDA/CVM GI #152 for beef result in MEDIUM human exposure

23. RELEASE: Emergence of CEQ-resistant Salmonella MEDIUM Consequence Assessment Summary EXPOSURE: Human exposure to Salmonella MEDIUM CONSEQUENCE: Human health consequences of R-salmonella infection Qualitative estimate of human medical importance of drug class • Potential human health consequences are assessed according to the relative importance of 4GCs in human medicine (Appendix A, GI #152) • Only 4GC approved in US for human use is Maxipime®(cefepime HCl) • Cefepime’s primary use in human medicine • sole agent approved for empiric monotherapy for neutropenic fever • used to treat enteric pathogens of non-food-borne disease

24. ► 4GCs are classified as HIGHLY IMPORTANT

25. RELEASE: Emergence of CEQ-resistant Salmonella MEDIUM EXPOSURE: Human exposure to Salmonella MEDIUM CONSEQUENCE: Human health consequences of R-salmonella infection HIGH

26. RELEASE: Emergence of CEQ-resistant Salmonella MEDIUM Overall Risk Estimation • Consistent with GI #152 the overall risk estimate is MEDIUM (Category 2) • This estimate is conservative: • Design of GI #152 is conservative • Release Assessment ranking of MEDIUM is related to resistance mechanism that is not prevalent • While 4GCs are important for human medicine, there is a range of treatment alternatives to 4GCs EXPOSURE: Human exposure to Salmonella MEDIUM CONSEQUENCE: Human health consequences of R-salmonella infection HIGH Overall Risk Estimate MEDIUM (Category 2)

27. RISK Management Considerations Risk management for CEQ (GI #152) a Prescription (Rx), Veterinary Feed Directive (VFD), over-the-counter (OTC) b 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.

28. RISK Management Considerations Conditions of use for the two injectable formulations of CEQ limit the risk of the emergence of resistance • Both parenterally administered products will be used in individual animals for short duration, by prescription only • The extent of use is ranked LOW in accordance with FDA/CVM GI #152 • CEQ will continue to be tested against isolates from the NARMS susceptibility surveillance program • The microbial safety of CEQ has been reviewed by FDA/CVM and by VMAC • Consistent with GI #152 no extra-label use limitations are deemed appropriate

29. Conclusions • The overall microbial food safety risk estimate is MEDIUM • The conditions of use and proposed risk management measures are appropriate to minimize this risk and are consistent with prudent use guidelines • There is reasonable certainty of no harm to public health with regard to microbial food safety for the proposed veterinary therapeutic use of CEQ