On-farm use Public health concerns are changing the way antibiotics can be used in animal agriculture
ATLANTA, Ga. — Common infections killed thousands every year before the age of antibiotics.
Women died of infection after childbirth, pneumonia killed 30 percent of those who contracted it and 70 percent of meningitis patients died. Ear infections caused deafness. Rheumatic fever and heart failure could result from a sore throat.
Bacterial resistance followed as soon as antibiotics were introduced, and today it is considered a major public health issue, said scientists at a conference devoted to antibiotic use and bacterial resistance in Atlanta Nov. 12-14.
The problem was originally considered manageable because the growth of resistance was slow and the pharmaceutical industry continued to create new antibiotics for human and veterinary medicine.
All that has changed.
“This is an emerging crisis internationally, and especially in animal agriculture,” said Lonnie King, dean of the college of veterinary medicine at Ohio State University.
On the agriculture side, the U.S. Food and Drug Administration released a three-year plan to voluntarily eliminate the use of medically important drugs in the feed and water of food-producing animals to increase weight gain or feed efficiency.
A total of 283 products in seven classes of antimicrobials used for growth promotion are commonly available over the counter.
By 2016, these will be available only by prescription.
The response has been mixed, said Dr. Bill Flynn at the FDA’s Centre for Veterinary Medicine.
“There are concerns, and we recognize that,” he said.
However, government agencies want to know what kind of antibiotic use is happening on farms. The information could improve stewardship programs to make better use of available medications, reduce resistance and prevent the spread of resistant infections.
The FDA has tracked trends since 1996 by following resistance patterns in food-borne pathogens, including isolates and residues collected from food-producing animals.
The agency also collects antibiotic sales and distribution information, and two years ago it asked for public comments on other ways to enhance existing sales data and summarize it into useful information.
The U.S. Center for Disease Control has attempted to measure the level of resistance and antibiotic use in the United States, but one veterinarian suspects the true prevalence is under reported.
“Antimicrobial resistance is a real phenomenon, and it is complex and it is incompletely understood,” said Brian Lubbers of the Kansas State University’s veterinary medicine college.
The World Health Organization and World Organization for Animal Health (OIE) have also attempted similar assessments.
He said practitioners welcome the FDA proposal to get a better handle on what is happening on farms by ending over-the-counter sales of antibiotics.
As a veterinarian, he does not want antibiotics eliminated from animal care programs.
“Treatment can make a difference, and it is important we do not lose that ability to make that difference,” he said.
The OIE has a list of antimicrobials that are of veterinary importance. These are rated as critically important, highly important and important.
Critically important antimicrobials include penicillins, phenicols, sulphonamides, tetracylines and cephalosporins.
For example, cephalosporins can be used to treat footrot, mastitis in dairy cattle, metritis in cattle, respiratory disease in cattle, swine and goats and forms of E. coli in chicks and turkey poults.
It has also been known since 2007 that 60 percent of mannheimia haemolytica isolates showed multi-drug resistance to three or more classes of antimicrobials.
This bacterium cause bovine respiratory disease, a leading cause of death among cattle.
- Antimicrobial drugs include all drugs that work against a variety of micro-organisms, such as bacteria, viruses, fungi and parasites.
- An antibiotic drug is effective against bacteria.
- All antibiotics are antimicrobials, but not all antimicrobials are antibiotics.
- Antimicrobial resistance is when bacteria or other microbes become resistant to the effects of a drug after being exposed to it. This means that the drug, and similar drugs, will no longer be effective against those microbes.