Like other technologies and practices, dairy producers face increasing pressures regarding antibiotic use from consumers and regulators. Dr. Brian Lubbers, DVM, Ph.D., believes producers must embrace “antibiotic stewardship” to ward off even greater antimicrobial restrictions.

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Editor / Progressive Dairy

Lubbers discussed antibiotic use, resistance and regulation at a Professional Dairy Producers of Wisconsin Food and Policy Summit, held last October.

“Biology and policy are really going to drive how you use antibiotics over the next months and years,” said Lubbers, an assistant professor and director of the Microbial Surveillance Laboratory at Kansas State University.

Boiling down resistance

The chief concern among regulators and some consumers is antibiotic resistance. Lubbers boils down antibiotic resistance into four points:

  • Antibiotics are chemicals that kill bacteria.

  • Bacteria can adapt to survive in the presence of antibiotics; we call that antibiotic resistance.

  • The more “adaptive pressure” (antibiotic use) that is applied, the more resistance is selected for.

  • When bacteria become resistant, the infection is more difficult to treat.

As a clinician, Lubbers sees antibiotic resistance as a treatment failure. As a microbiologist, he sees it from the bacteria perspective – and as a father and as someone who interacts with consumer groups, he sees it from a consumer perspective.

Use of antibiotics in humans is creating its own threats, with resistance beginning to show up in medical reports within a few years of introducing a new antibiotic, Lubbers explained.

While livestock producers are frequently blamed for antibiotic resistance issues, “There is no ‘smoking gun’ study I am aware of that says this use caused this issue,” Lubbers said.

“However, there are some strong associations between agricultural use of antibiotics and human resistance issues.”

Citing the National Antimicrobial Resistance Monitoring System, which monitors resistance in human and food-borne pathogens, Lubbers said a strain of salmonella associated with beef and pork consumption showed a substantial increase in antibiotic resistance between 2011 and 2013.

Resistance in bovine respiratory disease pathogens

Antibiotic resistance is also of concern within the livestock industry. Resistance has been found in Mannheimia haemolytica, the bacteria causing bovine respiratory disease.

Kansas State Veterinary Diagnostic Laboratory test results show half of the M. haemolytica isolates are now resistant to six of the seven antibiotics tested, severely limiting the ability to successfully treat bovine respiratory disease.

A change of thinking and behavior

“The approach we need to be taking is antibiotic stewardship,” Lubbers said. “It’s a change of thinking and behavior before you administer an antibiotic. Antibiotic stewardship needs to be a consideration before you push the plunger on the syringe.”

Steps start with preventing health events requiring antibiotic treatments and cover everything from vaccination programs and nutrition to animal housing and genetics. If a health event occurs, the cause should be investigated.

“Antibiotic stewardship is first about preventing our need to use antibiotics,” Lubbers said. “When you use antibiotics, did you do everything you could to prevent that disease from happening? After it happened, are you evaluating what went wrong?”

Selecting the right antibiotic and administering it in proper dosage are also important to reduce resistance. As part of a stewardship program, veterinarians should also evaluate how an antibiotic was used, and if it is effective.

“Veterinarians have an opportunity to save you money, in some cases by not using antibiotics,” Lubbers said. “You don’t want to risk the animal’s health, but our production systems have advanced enough that some uses of these antibiotics may be more habit than actual effect.”

New drug development can be a tool to combat antibiotic resistance, but agriculture hasn’t had a new class of antibiotics introduced since 1974.

Almost all new antibiotics under development are for humans, and Lubbers doesn’t expect that to change. Instead, animal health technological advancements will have to come in other areas.

Those new technologies will be primarily directed toward disease prevention, including products that boost immunity and genomic tools to select for health traits. Lubbers urged producers to work with their veterinarians to evaluate and implement those technologies.

Stewardship challenges

Establishing and implementing broad antibiotic stewardship programs are full of challenges, Lubbers warned.

“We can’t build antibiotic stewardship programs that meet the needs of the variety of operational systems we have in place,” Lubbers said. “Stewardship programs must be tailored and individualized. There has to be buy-in as producers.”

“There will be measurements; we don’t yet know what measurements, but we have the opportunity to provide some input still,” he added. “It will require accurate records so we know what we’re doing better. We have to come up with those answers fast.”

If the right metrics can be developed, antibiotic stewardship could be as formal as a “check box” on an on-farm animal care audit. To achieve producer buy-in, stewardship programs must also be sustainable, a balance between regulation and profitability.

Resistance in mastitis pathogens

Lubbers said antimicrobial resistance among mastitis pathogens is generally low in published reports. However, resistance isn’t a static situation. Just because it’s low today doesn’t mean it will be low tomorrow.

“If you are looking to refine your antibiotic use, one of the things you should think about is blanket dry cow therapy,” Lubbers told dairy producers. “Treating every quarter of every cow likely accounts for the heaviest use of antibiotics in dairies outside of calf-rearing.

That doesn’t automatically mean that blanket dry cow therapy should go away, but you should consider its role in overall use.”

Regulations: Past and future

Current antibiotic use regulations trace back to 1994, when the Animal Medicine Drug Use Clarification Act gave veterinarians the ability to prescribe extra-label use of drugs.

More recently, in an effort to address the antibiotic resistance issue, the FDA released Guidance 209 and Guidance 213, restricting use of medically important drugs in food-producing animals, and requiring veterinary oversight of those drugs.

The Veterinary Feed Directive is now in effect, restricting use of feed-grade antimicrobial products. All use from here will require a veterinary-client-patient relationship, and producers shouldn’t expect a Veterinary Feed Directive request to be automatic.

“We (producers and veterinarians) are going to be accountable for antibiotic use as we move forward,” Lubbers said.

Transparency takes many forms

Requirements for increased transparency are being driven by the food supply chain as they seek to meet consumer demand and create market differentiation. To do this will require documentation and verification.

Industry transparency also includes benchmarking to compare antibiotic use and as a tool to manage antibiotic reliance and use and strive for continued improvement.

Government transparency will strive for data to identify associations between antibiotic use and antimicrobial resistance as it seeks to identify any relationships between animal and human health.

Follow regulations, even if no one is watching

To prevent burdensome future regulations, or face the potential ban on antibiotic use, Lubbers urged producers to follow current regulations.

“Enforcement of regulations is always a challenge, but if the dairy industry doesn’t adhere to current regulations, they should expect more regulations or even total withdrawal of antibiotics for agricultural use,” he said.

Lubbers foresees the possibility of regulations removing use of antibiotics for routine disease control or prevention.

There are currently state initiatives going forward as well. California will prevent the sale of over-the-counter antibiotics and has requirements for a statewide antimicrobial stewardship program, with veterinarians involved in all antibiotic use decisions.

In the Netherlands, antibiotic stewardship program regulations include limiting livestock operations to a single veterinarian under a veterinary-client-patient relationship, with one backup, to avoid farmers jumping from veterinarian to veterinarian. They also have established three “tiers” of drugs, with specific prescribing requirements for each tier.

Residue avoidance

One area requiring more attention is residue avoidance. Among livestock production categories, dairy and veal industries have the highest incidence of drug residue violations. In many cases, the residues are due to extra-label use.

Common findings in FDA residue investigations are:

  • Failure to maintain adequate treatment records

  • Extra-label use of antibiotics outside the context of a veterinary-client-patient relationship, including improper use or inadequate withdrawal times

Communicate with regulators, consumers

Lubbers said dairy farmers need not become microbiologists, but they should have a foundational knowledge.

“I worry a lot if a non-agricultural reporter shows up on your dairy and starts asking you about antibiotic resistance,” he said.

He urged producers to get involved during FDA regulatory proposal comment periods. “The legislators are making regulations because they’re getting pressure from who they think are the consumers. They need to hear your side of these issues too.”

“Consumers don’t expect perfection, but they do expect improvement,” Lubbers said. “We should also expect that of ourselves.”

“Your specific uses of antibiotics may be very appropriate, so this may not change your behavior, but I do want to change your thinking,” Lubbers said. “Whenever you grab that syringe with an antibiotic in it, I want you to remember that every single dose has the potential to select for antibiotic resistance.”  end mark

PHOTO: Dr. Brian Lubbers, DVM, Ph.D., an assistant professor and director of the Microbial Surveillance Laboratory at Kansas State University, discussed antibiotic use, resistance and regulation at a Professional Dairy Producers of Wisconsin Food and Policy Summit, held last October. Photo by Dave Natzke.

Dave Natzke