Antibiotic resistance is a natural phenomenon. Resistant bacteria are found on and in humans, in our environment, on farms, and on animals. They are all around us because resistance happens naturally as bacteria defend themselves against attack; resistant bacteria millions of years old have been found in the ice caps and in the frozen remains of woolly mammoths.
A paper published in Nature in 2011 found resistant bacteria in a mammoth, and demonstrated that the genes that confer resistance to antibiotics were present in bacteria 30,000 years ago, specifically referring to a soil bacteria Actinobacillus.
Gerald Wright, who led the study, said:
“This isn’t surprising, since that type of bacteria is the source of many antibiotics. They make probably 80% of the drugs currently used today – they also make anti-cancer agents, they make immune suppressants, they are remarkable, remarkable little chemists. Scientists don’t yet know why soil bacteria have a tendency to make antibiotics and be resistant to antibiotics, but they speculate it may help them compete with other bacteria in an environment crowded with millions of bacterial species.”
When an antibiotic is used, bacteria that can resist that antibiotic have a greater chance of survival than those that are ‘susceptible’, and those that are not killed quickly multiply. Some resistance occurs without human action, as bacteria can produce and use antibiotics against other bacteria, leading to a low-level of natural selection for resistance to antibiotics. However, the current higher-levels of antibiotic-resistant bacteria are attributed to the overuse and abuse of antibiotics.
Some bacteria are naturally resistant to certain types of antibiotics. However, some mutate to either produce enzymes that ‘deactivate’ antibiotics while other mutations change or close the target area on the bacteria that the antibiotic would normally attack. Some even create mechanisms to push the antibiotic back out of the cell when it attacks. Bacteria can acquire antibiotic resistance genes from other bacteria in several ways. They can transfer genetic material through a simple ‘mating’ process, or through plasmids that ‘reprogramme’ other bacteria to be resistant to antibiotics. They can also pick up stray DNA in their environment or can be infected by viruses.
Antibiotic resistance spreads as bacteria themselves move from place to place via human contact, for example through coughing or contact with unwashed hands, food, as well as animal contact, contaminated materials and in water and the wind.
You find resistant bacteria the same places you find bacteria – it’s just some of them are resistant.
No, resistance can happen naturally and any use of an antibiotic can result in resistant bacteria so it is important that antibiotics are not used unnecessarily. Bacterial populations can also move around via introduction from other farms, or be spread by wildlife such as birds and badgers. It does not mean that it is directly attributable to practices on any one farm.
In humans and farming, the main source of resistant bacteria is the use of antibiotics which is why it is important that antibiotics are not used unnecessarily. Resistant bacteria can also spread between species e.g. other animals or humans, but the cross-over from animals to humans is thought to be very small at the moment ......
Reducing, refining and replacing use of antibiotics reduces selection for resistant strains (see What is the role of the antibiotic in creating resistance?). But reducing use doesn’t necessarily lessen resistance. In some countries, antibiotic use has halved over the past 10 years but levels of resistant bacteria have risen. Bacteria resistant to some medically critically important antibiotics (CIAs) have also been found on farms that have never bought or used that antibiotic.
At the moment, there is lots of confusion over what ‘antibiotic-free’ means. All farmers must abide by strict withdrawal periods after an animal has been treated with antibiotics to ensure antibiotic residues do not enter the food chain, so in this sense, all food should be ‘antibiotic-free’. If the question refers to how the animals are reared, in the US, where antibiotics are still permitted to be used as growth promoters, (banned since 2006 in the EU), this could mean simply that they aren’t used for this purpose. It could also mean that they are not used preventatively. Or it could mean they aren’t used at all.
Any move to reduce antibiotic use sustainably, without impacting on the animals’ welfare, should be welcomed. However, there is some concern that ‘antibiotic-free’ labelling could be misleading or confusing, and have ramifications on animal welfare. Reassurance should be given that such labels don’t lead to treatment being delayed or avoided for sick animals, or that livestock in need of nothing more than a short course of medicine to recuperate will not be destroyed rather than treated.
Yes, but first we need to explain the difference between antimicrobials and antibiotics.
Antimicrobial is a broader, more general term for any compound that destroys or inhibits the growth of (pathogenic) microorganisms. Antimicrobials include anti-bacterials (or antibiotics), anti-fungals, anti-protozoals and anti-virals.
An antibiotic is a type of antimicrobial drug used in the treatment and prevention of bacterial infections.
AMR, therefore, is resistance to any compound that could be used to treat or prevent infection whereas AR is the ability of a bacteria to survive in the presence of an antibiotic that would normally be sufficient to kill or inhibit it. The key focus of the world in animal and public health is on AR, not AMR.
RUMA is aware of the debate on the preventive use of antibiotics and, in particular, the European Parliament’s view that prophylactic use of antibiotics on farm should not be allowed. It is clear from some of the newspapers you read and websites you visit that there is no single understanding of what is meant by prophylactic medicine so in September 2014, RUMA issued a statement to explain. Read more>
Yes it can, for example, vaccinating poultry to protect against salmonella has seen the number of cases in the EU fall by nearly 50% since 2004. But while there are some really effective vaccines out there, there aren’t vaccinations for every disease and not all vaccines are 100% effective, meaning not all infections can be prevented by vaccination.
To ensure food safety, any authorised medicine used in food producing livestock, including antibiotics, has a statutory withdrawal period stating the minimum amount of time that must be observed following treatment before the meat, milk or eggs produced from that animal can enter the food chain. This period ensures that any residue from the medicine reduces to an amount that is safe to eat every day of your life. Europe and the US typically find a rate of positive samples in all these tests of substantially less than 1%. In the UK, each positive result is investigated and the results are published at https://www.gov.uk/government/statistics/residues-of-veterinary-medicines-in-food-2016
No, antibiotic growth promoters are not used in the UK. Use of antibiotics as growth promoters has been banned in the EU since 2006, although they are still permitted in some countries outside the EU, such as the US.
The MRSA found in supermarket pork is Livestock Associated (LA) MRSA which is a different strain of MRSA from that found in human healthcare infections. LA-MRSA can spread to humans from contact with infected animals but it is not easily spread to humans via food or between humans. Read more> http://www.npa-uk.org.uk/hres/LA-MRSA_briefing.pdf