Facts about antimicrobial resistance

Better nutrition, clean water and disease prevention leads to healthier populations of both people and animals.

Medicines are still needed to treat disease when it occurs. Antimicrobial drugs are used to treat a variety of bacterial, fungal, viral and parasitic diseases.

Below are some facts about antimicrobial resistance:

An antimicrobial is something that either kills or inhibits the growth of micro-organisms (eg bacteria, fungi, parasites). Antimicrobial medicines can be grouped according to the micro-organisms they act primarily against. For example, antibiotics are used against bacteria and antifungals are used against fungi.

Antimicrobials are used to prevent, control and treat disease in humans and animals. When an organism is exposed to an antimicrobial, they can:

  • be killed
  • be weakened, making it easier for the animal’s own natural immune system to kill
  • remain unaffected

Farmers and pet owners do their best to prevent disease in their animals by providing good nutrition, practising good animal husbandry, having decent hygiene practices and by vaccinating their animals to prevent certain diseases.

However, bacteria are everywhere in our environment some good and some that cause disease. So there will always be situations where the use of an antibiotic will be necessary.

Globally antibiotic resistance (AMR) is a major health challenge, particularly in human health.

Using antibiotics can result in the development of resistance. Any use of antibiotics must be balanced to achieve good human and animal health. Everybody who uses antibiotics has a duty to use them responsibly.

AMR is the development of resistance of a microorganism to an antimicrobial medicine to which it was originally sensitive.

Some bacteria have the ability to survive exposure to an antibiotic. This means that the infection does not go away.

This may require administration of a different, more powerful antibiotic to target these resistant bacteria.

Antibiotic resistance can occur in three ways:

  • In any population of bacteria, there are some bacteria that can survive antibiotic treatment and go on to reproduce more of their kind.
  • A small percentage of bacteria may simply be naturally resistant to certain types of antibiotics.
  • Antibiotic resistance can be transferred from one type of bacteria to another through mobile genetic elements such as plasmids, transposons and integons.

It is difficult to predict how quickly resistance will develop as it depends on the:

  • type of antibiotic
  • type of bacteria
  • level of exposure those bacteria have to the antibiotic and
  • ability of the resistant bacteria to survive and replicate.

It is important to use antibiotics at the correct dose rate, as this has been calculated and authorised as the amount being sufficient to ensure that the right amount of the antibiotic reaches the site of infection for a sufficient amount of time to ensure recovery from disease.

If the correct dose is not given, or if the course is not completed, some bacteria may survive and these may be the ones that are less susceptible to treatment. They reproduce and hence the numbers of these less susceptible bacteria increase within the population as a whole.

Antibiotic resistance is a world-wide problem but is worse in some parts of the world than others.

Antibiotic resistance is a concern for both humans and animals. For example Methicillin-resistant Staphylococcus aureus (MRSA) and Tuberculosis (TB).

Surveillance of human and animal populations shows an increasing incidence of antibiotic resistance.

Bacteria have always been able to develop ways to protect themselves from antibiotics, and to share their genes with other bacteria so it is inevitable that resistance will continue to develop.

New therapeutic options are needed world wide to relieve the over-reliance on existing antimicrobial products for people. However, it must be remembered that many of the oldest and most widely used antibiotics are still being effectively used.

To use antimicrobials “responsibly” is to:

  • Take steps to minimise the need to use antimicrobials
  • use them properly, such as for the full length of the prescription, at the prescribed dose
  • only use those antimicrobials when necessary (not as a way to minimise the effects of a dirty or unhealthy environment that should be managed in other ways, for example)

Both veterinarians and animal owners play a crucial role in ensuring antimicrobials are prescribed and used prudently in farm and pet animals.

Responsible antibiotic use: Downloadable resources

Animal Medicines Australia and Australian Veterinary Association released brochures with 10 easy steps to the responsible and judicious use of antibiotics.

These recommendations assist veterinarians, animal medicine suppliers, farmers and pet owners to manage their antibiotic use responsibly:

To investigate if a bacterial infection is the cause of an animal’s illness; a veterinarian might need to collect samples to identify the type of organism and antimicrobial sensitivities. This helps the veterinarian chose the best treatment.

Don’t expect antibiotics.

Yes and no. There are some natural animal health products available that do appear to show antimicrobial tendencies. But they don’t tend to treat or prevent disease for large groups of animals. Researchers are continuously seeking alternatives to antimicrobials. Some new technologies involves genetically modifying organisms to resist disease. While some consider this a brave new world, these types of new technologies will need to be embraced if we wish to find alternatives to our current practices.

Remember antibiotics treat bacterial infections: they do not treat viral infections. If you go to the doctor do not always expect an antibiotic – but if you are prescribed a course then use as directed and complete the course.

Similarly, do not expect an antibiotic from your veterinarian for your pet. Your vet will not prescribe an antibiotic if they believe it is not necessary.

Animal owners (farmers, pet owners) and veterinarians have a joint responsibility to work together to ensure that the outcome of antibiotic treatment is effective. Animal owners may be required to administer treatments. Where this is the case, it is essential that all instructions are followed. The animal owner should report any unexpected delay in recovery or difficulty in administrating the treatment to their veterinarian. If necessary, an alternative form of treatment may be commenced if the animal is not responding as expected.

Antimicrobial resistance programme

Established in 1999, the Antimicrobial Resistance Steering Committee meets regularly to monitor the prudent use of anti-microbial products such as antibiotics used in agriculture. Agcarm is represented on the committee.

Internal parasites are a major cause of lost production in livestock.

Parasite-killing drenches are an effective way of controlling parasites, but experts say some New Zealand farmers are using drenches in a way that will lead to drench-resistant parasites. And once present on a farm, parasite resistance to drench is permanent.

To combat this, Wormwise® – an industry initiative aimed at developing a national worm management strategy – was established.

It provides farmers, vets and rural retailers with information and services to manage internal parasites in sheep and beef.

The Trust includes representatives from Agcarm, Beef + Lamb NZ, Ministry for Primary Industries and the New Zealand Veterinary Association.

Wormwise began in 2005 after a national survey of New Zealand sheep and beef farms revealed significant levels of anthelmintic resistance to internal parasites.

For more information, see the Wormwise website.