Microbes are showing increased resistance because of:
More than 80 percent of antimicrobials in distribution are used to treat animals.
From a consumer’s point of view that is an alarming statistic but it needs to be taken in context, said Cheryl Gow of the Public Health Agency of Canada.
The numbers are misleading because the statistics are measured in kilograms and do not consider the number or weight of animals when looking at the proportion of use, she said at the recent University of Calgary beef health conference.
Still there are ongoing concerns over the volume used in animal agriculture and the complex connections to human health and antimicrobial resistance.
“It is really difficult sometimes to figure out where that antimicrobial resistance is originating and where it is ending up,” Gow said.
“The use of antimicrobial agents are increasing the amount of resistance we are seeing in humans and animals.”
Organisms typically become resistant to multiple drugs and they are unlikely to spontaneously disappear.
There are serious consequences to antimicrobial resistance as current drugs become less effective and few may be left to treat certain infectious diseases or superbugs.
The United Nation’s World Health Organization wants countries to collect information and create a global database on use in humans and animal agriculture.
The WHO is also looking at antimicrobial exposure in food-producing animals to get specific information on usage patterns in specific animal species, agents used and administration.
Gow is part of the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS). It is collecting data on antimicrobial use and resistance to assist in development of evidence-based policies.
CIPARS looks at human and animal data including on-farm programs. It examines beef, pork and poultry production and also checks meats in retail stores for antibiotic resistant bacteria.
She most products used in food animal production are not medically important to humans.
CIPARS has found that four times more flouroquinolones are used to treat people than animals and 11 times more cephalosporins are given to people than animals. More tetracycline is used in animals and five times more macrolides treat animals than people.
CIPARS is expanding surveillance on turkey production, injectable products in water and antimicrobial use in baby pigs.
The organization is also working to expand surveillance in the beef industry.
In addition, WHO asked the University of Calgary’s faculty of veterinary medicine to summarize the literature evaluating the relationship between restrictions in the use of antibiotics in food animals and antibiotic resistance in production animals and humans.
“The misuse of antibiotics in treating humans is most likely the most important cause of antimicrobial resistance but that doesn’t let us off the hook,” said Herman Barkema of the University of Calgary.
He is part of the team that has reviewed more than 9,000 manuscripts that were eventually narrowed down to less than 200 reports.
The team found considerable studies on the issue from the United States and northern Europe, but developing countries had almost no research available.
Many studies showed a reduction in antimicrobial resistant bacteria in herds where antibiotic use was voluntarily reduced.
“If you stop using antibiotics, there will be between a 10 to 20 percent reduction in antimicrobial resistance,” Barkema said.
“Very likely if you start using them again, it will pop up again because of the selection that takes place.”
WHO also wanted to know the unintended consequences if antimicrobial use is stopped in animal production, including growth-promoting products.
“If you take away fluroquinolone or ceftiofur, it may have an effect on resistance against one bug but it won’t have an effect on the whole gamut of bacteria and resistance to antibiotics,” he said.
Analysis of studies showed no predicted adverse effects on human health but some studies indicated more animals got sick so microbial use increased.
Food safety studies were included in the analysis because bacteria are being detected more often in food products.
When one growth promoter was banned, there was increased use of other permitted products on farms.
More antibiotics were given to individual animals for therapeutic purposes but there was not a large increase in sick animals suffering from diarrhea or respiratory disease.
“There will be an effect on growth when you take away growth promotion. There may be an effect that more animals get sick but then it is never enormous,” he said.
Agriculture needs to be proactive about antibiotic use, he said.
“We want to maintain the right to use antibiotics and have the license to do so in animals that are sick.”
All commodities need to figure out how this should be handled rather than waiting for government intervention, he warned.
“They will take measures and if we do not get our act together they will come with measures whether we like it or not.”
- overall increase in use
- prescriptions incorrectly taken
- antibiotics sold without medical supervision
- prophylactic use of antibiotics before surgery
- improper use to treat viral infections
- patients do not complete full prescriptions
- use of antibiotics in animals