Tackling the pressing threat of superbugs at the source

Anti-microbial resistant bacteria, or superbugs, are predicted to overtake cancer as the world's number one killer by 2050. This is the sobering warning delivered by Edgar Garcia Manzanilla, head of Teagasc's pig development department. According to Garcia Manzanilla, deaths from cancer are likely to reach 8 million worldwide by 2050 but superbugs will account for 10 million. Putting those figures in context, he notes that 3.7 million had died from Covid-19 by early June 2021.

Anti-microbial resistance (AMR) is generally associated with the misuse or overuse of antibiotics in both humans and animals, but Garcia Manzanilla explains that it is by no means a new phenomenon.

He points out that AMR is how micro-organisms defend themselves against things that normally kill them. “It’s natural for bacteria to acquire immunity. Excavations in Alaska found 30,000-year-old bacteria with genes for anti-microbial resistance.”

The problem arose when humans discovered antibiotics. This created what is known as selection pressure. By killing lots of non-resistant bacteria, antibiotic use allowed resistant strains to multiply in an unnatural way.

The ability of bacteria to transfer genetic material between them only adds to the problem. “They can become resistant to things they haven’t encountered,” says Garcia Manzanilla.

Secondary infections

And this brings us to the superbugs, bacteria which are resistant to multiple antibiotics. He points to their impact during the coronavirus pandemic when 25 per cent of all Covid-19 patients needed antibiotics due to secondary infections. “When they analyse it and test against antibiotics, they very often find the infection is resistant to all but one antibiotic. In many cases, they don’t even have one antibiotic to use and the bacteria will almost certainly kill the patient.”

The questions which scientists like Garcia Manzanilla are trying to answer are where the superbugs are coming from and what can be done to prevent their occurrence. Is it in farms, or hospitals, or water or water treatment plants?

“It is everywhere,” he says. “People in hospital bring bacteria home with them. Animals are treated on the farm, and it goes with them or into the environment in the rivers to the sewage systems and so on. Then you have wildlife so it is not something you can tackle in one particular place or with one particular species.”

The next question relates to how bad the problem is. He uses the analogy of being run over by a sports car or a truck. The sports car is a virus like Covid-19. The truck is a multi-resistant bacteria. While the sports car doesn’t give you much chance to avoid the impact, we can still do things at the last minute like jump to stop it from killing us and we can develop vaccines to protect us against it. On the other hand, when the truck hits us, the results are almost always fatal, and vaccines against bacteria are very difficult to develop. Furthermore, bacteria are so ubiquitous lockdowns tend not to work as a preventative strategy.

In the face of this, the only effective strategy is to find ways of reducing antibiotic usage in order to reduce the development of new resistant bacteria. “Who is using the antibiotics?” he asks. “The numbers tell us that 30 per cent of antibiotic usage is on humans and the remaining 70 per cent is on animals. But that only tells part of the story.

"We don't have a lot of data, but we know that 37 per cent of animal antibiotic usage is in feed – premixes, mainly for pigs," he adds. "A little bit is used in poultry but to be fair to that sector they have been among the best in reducing antibiotic usage and it is very low at the moment. Then there is the use of oral remedies in water, mainly for calves, and then we have injectables for all animals including dogs and cats, and then a very small amount which is used in the treatment of mastitis in cows. That is very important in Ireland. It might be a small amount, but the farmer could be using an antibiotic that is very important for humans. The total amount used is important but not the final point."

Defence

That final point relates to the importance of the particular antibiotic. These are known as critically important antibiotics (CIAs) and tend to be the last line of defence for humans and should therefore be avoided in all other cases.

“When it comes to antibiotics we must use as little as possible and as much as necessary,” he adds while pointing to the six Rs of antibiotic usage – right diagnosis, right animal, right medicine, right dosage, right duration, and right disposal.

Teagasc has already been working with farmers around Ireland to help them reduce their use of antibiotics. "Whenever we have infections on farm, even if we are using anti-microbials, we should be looking for an alternative approach to treat the actual problem of where the infection is coming from and its underlying causes. We must look at biosecurity, controlling the movement of animals; increased vaccination rates; and other methods.

“At the end of the day it comes down to behaviour,” Garcia Manzanilla concludes. “We have to make people conscious of the problem. If they don’t see the threat, they don’t act until it is probably too late. It is a problem that affects humans, animals and the environment and everyone must play their part.”