Antibiotic Use and Public Policy · Antibiotic Use and Public Policy – H. Scott Hurd DVM, PhD College of Veterinary Medicine, Department of Production Animal Medicine Iowa State

Antibiotic Use and Public Policy –

H. Scott Hurd DVM, PhD

College of Veterinary Medicine, Department of Production Animal Medicine

Iowa State University, Ames IA 50011, 515-294-7905.

[email protected]

Former Deputy Undersecretary for Food Safety USDA

Overview of antibiotic resistance

topics

What does the risk-based science say?

What would the future be like?

What is the problem?

Antibiotic RESISTANCE

• Exposure to

antibiotics selects

for some resistance

strains

• Human infections

with resistant strains

may be harder to

treat

Why is there a debate?

• What is acceptable risk?

• Who gains, benefits?

• Precautionary

• Risk-based vs science-based

• Non scientific political agenda

Antibiotics: Why a debate? S. 619/H.R. 1549: Policy or Politics?

What does risk-based science

say?

“Probabilistic risk assessment should be used to

reduce unnecessary conservatism

associated with current regulatory requirements …”

Nuclear Regulatory Commission (1995)

You too can do a risk assessment

• Risk = Pr (injury | wreck) = conditional

– Risk of auto accident = Pr (wreck)

• Traffic

• Road type

• Weather

• Driver skill and alertness (etc)

• Probability = a*b*c*d

Auto accident example (cont)

– Injury if in auto accident

• Speed at impact (continuous var)

• Seat belt = Y/N

• Type of collision (say 5 categories)

– Head on

– Right angles

– Glancing head on (etc)

– Safety of car (H, M, L)

– Series of conditional probabilities

Multidisciplinary

Quantitative risk assessment

Release Assessment: Describes the

probability that factors related to the

antimicrobial use in animals will result in

the emergence of resistant bacteria or

resistance determinates (RzD).

Exposure Assessment: Describes the

likelihood of human exposure to the RzD

through particular exposure pathways.

Consequence Assessment: Describes the

relationship between specified exposures

to the RzD (the hazardous agent) and the

consequences of those exposures (CVM-

defined hazard)

Pathway of Events Leading to the Risk

Risk = 1 in 10 million per year

FDA 152 methods

2. Risk Assessments have shown Risk (High to Low) Yearly Probability Outcome

Comments

Enrofloxicin use in poultry to

treat disease

1 in 30,000 Compromised treatment

By FDA, overestimated attributable

fraction

Enrofloxicin use in poultry to

treat disease

Removal is more

hazardous to health

By Cox and Popken

Being struck by lightning

1 in 550,000 Occurrence

Dying from a bee sting

1 in 6 million Death

All macrolide uses (cattle,

swine, poultry)

1 in 10 million Compromised treatment

By Hurd et al., Alban in Denmark

Streptogramin/Virginiamycin

use

~ 100 in 100 million Impaired treatment

By FDA, still a draft

Penicillin growth promoter ~4 in billion Excess mortality

Cox and Popken

Fluoroquinolone use in dairy

heifers

~1 in 61 billion Compromised treatment

Stop and Ponder Why take additional risk??

WHY? Healthy animals really do

make safer food

• Meat Inspection Act 1906

• Antemortem inspection

Largest meat

recall in U.S.

history due to

slaughter of

downer cows

February, 2008

Animal

Health

Antibiotic

Use

Herd

Management

Disease

Other

Factors

Healthy

Animals

Uncontaminated

Product

Susceptible

Humans

Sick

Humans

Processing

Discard

Trim

Sick

Animals

Contaminated

Product

Inspection

Swine Health Effects Carcass Quality

and Ultimately Human Health

Adhesions increase chance of fecal contamination!!

• “The public health

risk of unhealthy

animals is greater

than antibiotic

resistance

concerns”

SHOW ME

THE DATA!

0

20

40

60

80

100

120

0.00 5.00 10.00 15.00

Peel out percent

Perc

en

t co

nta

min

ate

d

%Campy PL pos

%Ecocc B pos

Linear (%Campy PL pos)

Linear (%Ecocc B pos)

Recent study (in press Amer J. of Vet Med Research)

• 358 carcasses were selected over four replicates

• Lesioned and non-lesioned carcasses were

identified

• Individual carcass swabs cultured for Salmonella

• Logistic regression analysis showed the

probability of Salmonella contamination in

lesioned carcasses was 90% higher than in non-

lesioned (Odds ratio = 1.9, 95% CI = 0.9-4.0)

Lesioned and non-lesioned

Pathologist score ~ 6

90% more likely to be

contaminated with

Salmonella at end of

slaughter

Pathologist score ~ 0 to 1

The Future?

FDA guidance 209

Legislation

“Consumer” groups

GAO report

CDC and public health

The Future

• More veterinary oversight

• Growth promoters?

• Better records will be required

• Legislation (federal) is doubtful

• Nuisance cases with antibiotic

resistance as part of the harm

• Continued demand for food!

• “Sustainability” concerns

FDA Guidance 209

The Judicious Use of Medically Important

Antimicrobial Drugs in Food-Producing

Animals

• Just released, June 28, 2010

• No regulatory authority

• Focus in “medically important”

antimicrobials (human therapeutic use)

• Principles, Limit to uses:

– “necessary for animal health”

– that include “veterinary oversight”

Focus on growth promotion

• In regard to animal use, this document addresses the use of

medically important antimicrobial drugs in food-producing

animals for production or growth-enhancing purposes. These

uses, referred to as production uses in this document, are often

also referred to as “nontherapeutic” or “subtherapeutic” uses.

• Unlike other uses of these drugs in animals (e.g., for the

treatment, control, and prevention of disease), these “production

uses” are not directed at any identified disease, but rather are

expressly indicated and used for the purpose of enhancing the

production of animal-derived products (e.g. increasing rate of

weight gain or improving feed efficiency).

Preserve prevention

• “…the administration of medically important

antimicrobial drugs to entire herds or flocks of

food-producing animals (e.g., for production

purposes) would represent a use that poses a

qualitatively higher risk to public health than

the administration of such drugs to individual

animals or targeted groups of animals (e.g.,

to prevent, control, or treat specific

diseases)”.

FDA guidance 209 focus

• Growth promotion label

– Must have bacteria of action

• Other the counter (OTC)

• Veterinary oversight

Definition of “oversight”

• (1) evidence of effectiveness,

• (2) evidence that such a preventive use is

consistent with accepted veterinary practice,

• (3) evidence that the use is linked to a

specific etiologic agent,

• (4) evidence that the use is appropriately

targeted, and

• (5) evidence that no reasonable alternatives

for intervention exist

What should you do?

• Fight the GOOD fight

• Do everything you can before using

antibiotics

• Use antibiotics

correctly/fully/carefully/prudently, etc

• Keep perfect records

• WHY?

Full utilization of antimicrobials is

a veterinarian’s/producer’s ethical

responsibility

• IF

• There is minimal public health risk from antibiotic use

• Healthy animals make safe food

• The world will need increasing amounts of pork

• Antimicrobials improve efficiency of production

• The government and consumers do NOT always know what is

best for the “common good”

• THEN

• We must fight for risk-based decision making

• We must use the “systems approach” to address risk-risk

concerns

• We must keep our “antibiotic use house” in perfect order

Ethics of food safety

Intensification / recalls

Sustainability

Organic

Antibiotic use Free range

Animal welfare

Local

Hormones

Animal health

Accountability

Feeding the

world