Our Expert FAQs panel ranges from members of RUMA’s independent Scientific Group to other veterinary specialists in their field. They are on hand to answer your tricky or pointed questions about use of antibiotics in farming.
Just complete the boxes below and we will put the question to our panel as quickly as possible. When they’ve answered, we will let you know and post the answer on our list of Frequently Asked Questions.
Antibiotic resistance occurs when an antibiotic is no longer able to effectively control or kill bacteria. As the bacteria become resistant, they continue to multiply in the presence of antibiotics, which would normally kill them.
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. A paper published in Nature in 2011 found resistant bacteria in the frozen remains of a woolly mammoth, and demonstrated that the genes that confer resistance to antibiotics were present in bacteria 30,000 years ago. Gerald Wright, who led the study, said: “This isn’t surprising, since that type of bacteria is the source of many antibiotics. These bacteria produce probably 80% of the drugs currently used today – they also make anti-cancer agents, they make immune suppressants, they are 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’. Those bacteria that survive, can then 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 that are found in both human and veterinary medicine 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 (conjugation), or through plasmid transfer that can ‘reprogramme’ other bacteria to be resistant to antibiotics. They can also pick up stray DNA in their environment or can be infected by viruses, which transmit the resistance gene.
Antibiotic resistance spreads as bacteria themselves move from place to place via direct human contact, for example through coughing or contact with unwashed hands, as well as animal contact, or by contaminated materials and housing and in water, food and even in 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, but overuse of antibiotics can result in resistant bacteria. Bacterial populations can also move around via introduction of animals from other farms, or through introduction via carrier species. It does not always mean that it is directly attributable to practices on any one farm.
Among humans, human medicine is currently the main source of resistant bacteria. This has been acknowledged by the European Medicines Agency Committee for Medicinal Products for Veterinary
Use (CVMP) in its draft strategy on antimicrobials: “…the greatest driver of AMR in people is the use of antimicrobials in human medicine.” The UK Department of Health also says: “Increasing scientific evidence suggests that the clinical issues with antimicrobial resistance that we face in human medicine are primarily the result of antibiotic use in people, rather than the use of antibiotics in animals. Nevertheless, use of antibiotics in animals (which includes fish, birds, bees and reptiles) is an important factor contributing to the wider pool of resistance which may have long term consequences.” In farming, spread from other farm animals would be the main source of resistant bacteria. The cross-over between the two is very small at the moment, with recent studies confirming farm animal use could be responsible for as few as one in every 370 clinical cases of E coli infections. However, a risk does remain and people should always wash their hands thoroughly after contact with animals. Resistant bacteria can be found on meat, but good kitchen hygiene, washing hands after handling raw meat and thorough cooking of meat will almost completely prevent the transmission of antimicrobial resistance – or indeed bacteria in general – from meat to man.
Reducing , refining and replacing use of antibiotics reduce selection for resistant strains (see What is the role of the antibiotic in creating resistance?). But reducing use also 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 and there is no single definition. Remember that antibiotics are used to treat and prevent disease in animals in all countries, but also for growth promotion in some countries where that practice is still permitted. All animal farming must abide by strict withdrawal periods after an animal has been treated with antibiotics for any reason, to ensure medicine residues do not enter the food chain. So in this sense, all food should be ‘antibiotic-free’. However, we have seen the term ‘antibiotic-free’ used (rightly or wrongly) in a number of different situations, for example: where antibiotics have not been used for the purposes of growth promotion in countries where it is still permitted (such as in the USA); where highest priority critically important antibiotics haven’t been used to treat or prevent disease in livestock; and where no antibiotics have been used ever for any purpose in that animal. There is no standard meaning, and labelling one food that way does not mean another food has antibiotics in it. See specific questions about whether meat from animals treated with antibiotics has antibiotics in it.
Any move to reduce antibiotic use sustainably, without impacting 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.
In human medicine, MRSA (Methicillin-resistant Staphylococcus aureus) and E-coli resistant to a number of different antibiotics tend to have the highest profile. But resistance can be found anywhere. For example, a recent report found worryingly high levels of resistance to widely used antibiotics such as ampicillin, which is used to treat urinary tract infections (UTIs) in children.
In human medicine, MRSA (Methicillin-resistant Staphylococcus aureus) and E-coli resistant to a number of different antibiotics tend to have the highest profile.
It is not currently common in the UK, nor a high risk, but it is being monitored closely. A risk assessment published in February 2017 by the Food Standards Agency (FSA) assessed the risk associated with the preparation, handling or consumption of foodstuffs which may be contaminated with MRSA, in particular Livestock-Associated LA-MRSA (which is not the same as hospital-acquired or community-acquired MRSA, which are both more frequently discussed in human medicine). It concludes the risk is very low and based on this the FSA’s current advice remains unchanged, i.e. that raw food should be stored appropriately, handled hygienically and cooked thoroughly to ensure any harmful bacteria present are destroyed. LA-MRSA infection is rare in humans in the UK and such organisms are not readily transmitted from person to person. To the FSA’s knowledge, there have been no reported food borne outbreaks of LA-MRSA in humans in either the UK or worldwide. Furthermore, the indication is that prevalence of food contaminated with LA-MRSA is low in the UK. LA-MRSA has been shown to enter the food chain and survive on raw meat up to the point of retail, although thorough heat treatment of raw meat is sufficient to destroy LA-MRSA and other vegetative bacteria.
E coli is a classic marker of faecal contamination in humans and animals. It is likely that exposure to antibiotics from medical or veterinary treatment could give rise to resistance in E coli, and the potential for these organisms to cause UTIs in humans – whether they are originally from human or animal sources – is also not unexpected. As inhabitants of the intestine, this organism can potentially gain access to the urethra and may cause infection – so it is possible. The likelihood and frequency of this occurrence, though, has not been demonstrated.
All antibiotics in the UK require a prescription by a vet and as such are tightly controlled. Online sales of antibiotics are very closely monitored to ensure they are dispensed with a prescription and no fraud is taking place. The Veterinary Medicines Directorate confirms that its enforcement team has succeeded in removing over 824 antibiotic products from the illegal online market since 2014 – this is not counting all the products taken down directly by E-bay (new procedures were put in place by E-bay in 2016).
Therapeutic or curative treatment of a sick animal or group of animals follows the diagnosis of infection and/or clinical disease in those animals. Control treatment (sometimes referred to in veterinary medicine as Metaphylaxis) is the treatment of a group of animals after the diagnosis of infection and/or clinical disease in part of the group, with the aim of preventing the spread of infectious disease to animals in close contact and at considerable risk and which may already be (sub-clinically) infected or incubating the disease. A useful comparison with human medicines would be where a child in a classroom is diagnosed with meningococcal meningitis necessitating urgent treatment of all other in-contact children. Preventive treatment (sometimes referred to as Prophylaxis) is the treatment of an animal or a group of animals, before clinical signs of infectious disease, in order to prevent the occurrence of disease or infection.
RUMA and almost all farming and veterinary organisations in the UK do not support routine preventative treatment, and agree that preventive treatment or prophylaxis with antibiotics:
Thus there sometimes is a strategic or veterinary need for preventative treatment hence preventative treatment should not be banned, but preventative use should not be routine.
Yes. Preventative use of antibiotics (prophylaxis) is the administration of an antibiotic to healthy animals at risk of a specific infection(s) or in a specific situation where a bacteria caused infection or disease is likely to occur if the drug is not administered, with an appropriate dose and for a limited duration. The Veterinary Medicinal Products (VMP) containing antimicrobial agents should only be used on the prescription of a veterinarian. Use of antibiotics for growth promotion is where it is administered with the purpose of increasing the rate of weight gain and/or the efficiency of feed utilisation in animals by other than purely nutritional means. The term does NOT apply to the use of antibiotics for the specific purpose of prophylactic, metaphylactic or therapeutic use, even when an incidental growth response may be obtained. This definition is in line with the definition developed by Codex Alimentarius in CAC/RCP 61-2005.
In the UK, where it is banned, it would be very difficult. For a product to be used at a low, sub-therapeutic dose for the purpose of creating a growth promotion effect would require either the farmer or the vet to breach the rules of use of antibiotics as growth promotion has been banned across the EU since 2006), and this could have a detrimental effect on their careers. It should be noted that for a veterinary medicinal product to be used preventatively, it should be authorised for this indication, as stated in its summary of product characteristics (SPC), thereby limiting which products can be used for this purpose. There is also a shift in the wording of indications listed in SPCs away from prophylactic use to metaphylactic use; which has a defined definition in the EU legislation, thereby providing more of a steer away from using antibiotics unless the consequence of not doing so are detrimental to health and welfare.
In short, no. The use of veterinary medicines – including antibiotics – can sometimes result in low concentrations of the medicine being present within the animal’s system for a period of time. This is usually at a low level – measured in parts per million. Strict withdrawal periods are stipulated for each licensed medicine. These are based on rigorous testing regimes, and give time for medicines to be excreted from the animal or fall to a level that will not cause any adverse reaction in man should they be eaten. This means medicines must have almost entirely left the animal body by the time meat or milk can enter the food chain. In summary, the current debate is not about antibiotics found in food, but whether resistant bacteria are found in food and can they be transmitted to man.
The response we have from the National Action Group on Johne’s is:
Yes . That is correct 60oC and 60 minutes is the correct temperature. Indeed in some studies the overall absorption is improved, despite some immunoglobulins being lost. But pasteurisation is only part of the control process and care must be made to avoid over-relying on pasteurisation and not tackling other areas of greater importance such as García-oral transmission in calving pens. Also very important that there is no cross-contamination post pasteurisation with infectious manure.
There is no ‘one size fits all’ regarding resistance development. Its very much ‘bug/drug’ related, and even more so on the mechanism of resistance i.e. chromosomal vs acquired resistance being a key factor.
On the human side, resistance is definitely a more pressing problem than in animals. This means animal antibiotics currently remain, on balance, more effective at treating animal bacterial disease.
However, if antibiotics are not used responsibly in the veterinary sector, it is estimated that resistance will increase. Numerous publications (e.g. CEESA VetPath publications) are showing increasing upward trends of resistance in disease-causing bacteria in animals, such as the Staphylococcus aureus bacteria which cause mastitis in cows, which is why it is important to use all antibiotics responsibly.
Statistics on the issue of antibiotic resistance in human health can be found from ESPAUR and other publications collated by the devolved governments. Internationally, WHO carried out surveillance. In animal health, the VARSS reports from the Veterinary Medicines Directorate publish annual surveillance. A range of reports from the UK and EU can be found on this website at www.farmantibiotics.org/media-news-updates/useful-documents-links/.
In some countries, they are. In other countries, people don’t even need a prescription to obtain them.
In the UK, a medically qualified doctor or veterinarian must prescribe antibiotics for the general public, pet owners or farmers to be able to obtain them. In farming, the vet has a responsibility to check whether antibiotics are required and the health of the animals involved. In terms of administering antibiotics to any animal, this can be carried out by pet owners or farmers under the direction of the veterinarian. In asking whether antibiotics should be administered only by a vet, this has not been deemed necessary in the UK. However, undertaking additional training on administration of antibiotics is increasingly a requirement under some farm assurance schemes or supply contracts.
No – the animal’s system will eliminate the antibiotic over a period of time. This is why withdrawal periods are stipulated after treatments with any medicines, and milk and meat are tested for residues.
For beef and lamb and dairy – antibiotic usage has to be recorded by product name. Red Tractor has a template for this although some vet practices may be able to provide one: https://assurance.redtractor.org.uk/tools-and-library/templates
For pigs – antibiotic collation recorded on the electronic Medicine Book quarterly, online.
For poultry – Record total antibiotics used per crop in mg/PCU, according to the British Poultry Antibiotic Stewardship guidelines.
The required withdrawal period is different for each medicine, and is determined through testing to see how long it takes for the medicine to leave the animal’s system. This data forms part of the medicine’s application for approval in each country, and will be scrutinised by the regulator. The withdrawal time period will then be stipulated on the product label. Back up checks are routinely carried out by the regulator to make sure no medicine residues are exceeded in meat or milk or other animal food products.
Not at the moment, but the European Council agreed new rules in June 2018 to ‘better frame the use of antimicrobials in animals’ by limiting the use of antibiotics for animals that are not yet sick but may run the risk of falling ill, both in the case of:
Now that the agreement has been confirmed by EU ambassadors on behalf of the Council, the regulation will be submitted to the European Parliament for a vote at first reading, and will subsequently go back to the Council for adoption. The new rules will apply at latest in 2022
Antibiotics are controlled in the UK, and only veterinarians and doctors can prescribe them. All veterinarians must be Members of the Royal College of Veterinary Surgeons (MRCVS) and as such, must adhere to its codes on use of medicines. A guide to the RCVS’s code of professional conduct which outlines how veterinarians should use medicines can be found here.
This would depend on the size of the farm, but antibiotic treatments, where needed, average out to approximately a quarter of one percentage point (0.25%) of the total cost of production for pigs, which comes out at around a third of a penny (0.35p) per kg of pig produced in the UK. This is based on the 2017 antibiotic usage figures for UK pigs (supplied by AHDB’s electronic medicine book) alongside the costed breakdown of products, pig production figures for 2017, and AHDB’s benchmarked pig production costs for the same year.
When treating farm animals against bacterial disease, antibiotics are most commonly administered in the same way as for humans – orally or by injection. Oral administration can include by bolus, tablet or paste, or as a powder or solution in feed or drinking water. The method of administration is usually a matter for the prescribing vet to determine, and will often depend on the species being treated, the numbers needing treatment, and other factors such as the handling facilities available and the risk of stress for the animal. Stress is a major consideration as the animal being treated should be either clinically infected or at high risk of being infected at the time of treatment, and exposure to stress can further impair its immune system.
The situations where antibiotics are administered in feed are usually where there are large numbers that require treatment and when it’s the most practical option available. In this situation the medicine will usually be added to the feed upon receipt of the veterinary surgeon’s prescription at the feed mill.
Some farms have a facility to add a medicine to drinking water. This can result in increased accuracy as while intake of feed can vary between animals, they tend to drink more uniform quantities. However, if animals are outside, they will usually drink from rainwater sources as well as piped sources, risking any treatments being taken in at levels that are below the prescribed dose rate. In these situations, administration via feed can be the only practical option, for example with a herd of outdoor sows.
The most accurate method of application is to individual animals via injection or oral tablet or paste, after weighing to ensure an accurate dose rate is applied. In reality, this happens more often with cattle and sheep as the numbers per farm are generally fewer and they are easier to handle or bring inside for treatment. In pigs and particularly poultry, it is often impractical and counterproductive to treat individual animals although this can sometimes be an option.
It is important to note that routine preventative use of antibiotics is not supported by RUMA or UK veterinary associations. Use of antibiotics as a growth promoter, commonly applied via feed, has also not been permitted in Europe since 2006.
In countries outside Europe where growth promotion in animals is permitted, antibiotics can be given to the animal on an ongoing basis at sub-therapeutic dose levels, which is different from situations where a veterinary surgeon prescribes a defined course of antibiotics at a clinically approved dose level to treat or prevent a specific disease challenge. Hence treatment of animals for disease via in-feed antibiotics should not be confused with use of antibiotics for growth promotion through feed.
The Veterinary Medicine Directorate, a Defra department, is the regulator for the use of all licensed medicines in the UK farm livestock sectors. They collate annual sales data on antibiotics and more recently have been reconciling this with antibiotic usage data submitted by the livestock sectors themselves. Their annual VARSS reports summarise progress and also detail surveillance results monitoring for the emergence of resistance genes in animals and food. The VMD in turn links into European data collected and standardised by EFSA, ESVAC and other bodies. As well as this, the VMD oversees all testing for medicine residues in food. More about their role can be found here.
The use of penicillin in birds has no impact on human health. This is down to two reason: Firstly the UK poultry meat sector uses almost negligible quantities of penicillin (see British Poultry’s antibiotic stewardship report). Secondly, there are strict regulations governing withdrawal period (how much time passes between when any animal is last treated with antibiotics and when it leaves the farm) which ensures that there are no residues in the meat.
Measuring antimicrobial use in livestock can be complex because of the varying weights of animals at point of treatment, different ways of measuring and the different ways in which each livestock sector operates. For a broad picture, overall levels of use are approximated to annual sales data collated by the Veterinary Medicines Directorate, as reported in its Veterinary Antimicrobial Resistance and Sales Surveillance (VARSS) reports. However, because many products are licensed for use in many different species (for example, in both sheep and cattle, or both pigs and poultry), sales data don’t show what each livestock sector is using individually. Hence the different sectors have been collected increasing amounts of usage data annually, and this is now also checked and reconciled by the Veterinary Medicines Directorate and reported annually as well. For example, p27 in the 2017 VARSS report describes how the various datasets are gathered and calculated, and p8 shows a summary of usage per species. Most measurements take the form of mg/kg, or mg/PCU (PCU being a standardised kg) but sometimes they are reported as DDDVet (Defined Daily Dose) or DCDVet (Defined Course Dose. Tools like the antibiotic calculator launched by the University of Nottingham and AHDB help vets and farmers with their calculations as well.