Antimicrobial resistance

When bacteria, viruses, fungi and parasites become resistant to medicines used to treat infections

Key points about antimicrobial resistance

  • Antimicrobials include different groups of medicines that are used to prevent or treat infections caused by bacteria, viruses, fungi and parasites.
  • Antimicrobial resistance happens when bacteria, viruses, fungi or parasites change so that antimicrobial medicines used to treat these infections no longer work.
  • Antimicrobial resistance leads to higher medical costs, longer hospital stays and, sometimes, death.
  • Preventing infection and using antimicrobials appropriately are key ways of fighting antimicrobial resistance.
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Antimicrobials include different groups of medicines such as antibiotics, antivirals, antifungals and antiparasitics.

  • They're used to prevent and treat infections in humans, animals and plants.
  • Antimicrobials are lifesaving medicines, but only if they work against the organism causing infection.
  • Antibiotics are the most commonly prescribed antimicrobial.


Image credit: ACSQHC

Antimicrobial resistance occurs when bacteria, viruses, fungi and parasites change over time and no longer respond to antimicrobial medicines. Infections become harder to treat and there is increasing risk of disease spreading, causing severe illness and death.

  • Antimicrobial overuse increases the chance of some bacteria, viruses, fungi or parasites becoming resistant, which means when you next need antimicrobials they may no longer work to treat your infection.
  • Resistant bacteria, viruses, fungi or parasites can multiply and spread to other people you have contact with, then these people can also develop antimicrobial-resistant infections.

Antimicrobial resistance is a major concern because it means some infections will become more difficult, and sometimes impossible, to treat.

Antimicrobial resistance is a concern because:

  • it can lead to "harder to treat" or "untreatable'" infections
  • it can lead to longer stays in hospital
  • it can increase the risk of surgery and other life-saving procedures
  • there aren't many new antimicrobials being created to treat resistant germs/bugs.

In Aotearoa New Zealand, the occurrence of antibiotic-resistant bacteria is increasing. Examples of antibiotic-resistant bacteria include:

  • Methicillin-resistant Staphylococcus aureus (MRSA) – a group of bacteria (called Staphylococcus aureus) that are resistant to commonly used penicillin-like antibiotics
  • Extended spectrum beta-lactamases (ESBL) – chemicals produced by some bacteria that prevent certain antibiotics from working.
  • Vancomycin-resistant enterococci (VRE) – a group of bacteria (called enterococci) that are resistant to the antibiotic vancomycin.  

Watch this video on how you can prevent antimicrobial resistance

(World Health Organization, 2021)

Avoid infection in the first place

Avoiding infections in the first place reduces the amount of antimicrobials that have to be used worldwide. This reduces the chance of antimicrobials develop ing resistance during treatment. Avoiding infections also prevents the spread of resistant antimicrobials.

Simple ways to avoid infections include washing your hands and getting vaccinated.

  • Wash your hands regularly: Infections can be avoided by simple measures such as washing your hands or, if that's not possible, using an alcohol-based hand gel. Wash your hands regularly and especially after using the toilet and before preparing food. Many strains of bacteria are spread by person-to-person contact and can survive on surfaces like doorknobs, desktops and benchtops. Read more about handwashing.
  • Get vaccinated: Vaccination is a way of preventing infectious diseases (eg, mumps, measles, chickenpox and whooping cough). Vaccination uses your body’s natural defence mechanism (your immune system) to build resistance to specific infections. If you've been vaccinated and you come into contact with that disease, your immune system will respond and prevent you developing the disease. Vaccination can lessen the chances of you getting sick, which reduces the likelihood that you will be prescribed antibiotics or other medications. Read more about immunisation.

Use antimicrobials correctly

  • Take the right dose of your antimicrobial, at the right time and for the right duration (as recommended by your healthcare provider).
  • Don’t use antimicrobial when you don't need them or when they haven't been prescribed for you.
  • Only use antibiotics for an infection caused by bacteria. Antibiotics are effective against infections caused by bacteria. They don't work against infections caused by viruses such as the common cold and the flu. Having green or yellow-coloured mucous, phlegm or snot isn’t always a sign of a bacterial infection. Read more about snot and sputum
Never share antimicrobials with others

The antimicrobials you are prescribed may not work for your family/whānau member, friend or neighbour’s illness. Using antimicrobials when they are not needed, or taking the wrong antimicrobials, exposes bugs to antimicrobials unnecessarily, which encourages antimicrobial resistance.

Don't use antibiotics left over from a previous prescription
  • The type, dose and amount of antibiotics left over may not be enough to fight a new infection. This creates more opportunity for resistant bacteria to develop and multiply. Different infections may need different treatments, even though you might have similar symptoms.
  • If your condition is caused by bacteria, to treat it effectively you need to get the right antibiotic, at the right dose, for the right period of time. Using antibiotics when they are not needed or taking the wrong antibiotic at the wrong dose or wrong length of time exposes bacteria to antibiotics unnecessarily, which encourages antibiotic resistance.
  • Another thing to keep in mind is that, just like food, antibiotics go off. Keeping leftover antibiotics may lead you to take expired medicines, which means they may not work when you need them or may make you feel more ill. Liquid antibiotics often need to be kept in the fridge and expire quickly, and other antibiotics may not be labelled with a specific expiry date,

Dispose of antibiotics correctly

  • Take unused antibiotics to a pharmacy for safe disposal. If you have leftover antibiotics, dispose of them correctly by returning them to your pharmacy for safe disposal.
  • Don't put them down the toilet or sink. There is a risk that antibiotics poured down the sink or flushed down the toilet may pass through treatment systems and enter rivers, lakes and even drinking water supplies. In homes that use septic tanks, antibiotics flushed down the toilet could leach into the ground and seep into ground water or soil. Read more about medicines and the environment.
  • Antibiotics that get into the environment may drive bacteria to become more resistant. Appropriate disposal of antibiotics by the pharmacy minimises this risk. Unused medicines taken to pharmacies are disposed of by specialist waste disposal companies.

Your family and antibiotics – what you need to know(external link) Pharmac, NZ
Antimicrobial resistance(external link) Ministry of Health, NZ
Drug infections are hard to treat(external link) (te reo Māori(external link)) Royal Society, Te Aparangi, NZ  
Keeping antibiotics effective, with your help(external link) Canterbury District Health Board, NZ
Antibiotics can help, but they can also harm(external link) Canterbury District Health Board, NZ
Your health is very important to us(external link) Canterbury District Health Board, NZ 


Your family & antibiotics – What you need to know(external link) PHARMAC, NZ
Antibiotic amnesty frequently asked questions(external link) Pharmaceutical Society of New Zealand, 2019
5 questions to ask about your medications(external link) Health Quality and Safety Commission, NZ, 2019 English(external link), te reo Māori(external link)
Think twice, seek advice(external link) World Health Organisation, 2017
Everyone has a role to play – you can help prevent antibiotic resistance [JPG, 284 KB] World Health Organisation, 2017
Misusing and overusing antibiotics puts us all at risk(external link) World Health Organisation, 2017
Keeping antibiotics effective, with your help(external link)  Canterbury District Health Board, NZ 
Antibiotics can help, but they can also harm(external link)  Canterbury District Health Board, NZ 
Your health is very important to us(external link)  Canterbury District Health Board, NZ


  1. Antimicrobial resistance – implications for New Zealanders(external link) Royal Society, Te Aparangi, NZ
  2. Antibiotic awareness week – a time to reflect on how we prescribe(external link) BPAC, NZ, 2017
  3. Antibiotic resistance questions and answers(external link) Centers for Disease Control and Prevention, US
  4. Keeping antibiotics working(external link) Pharmaceutical Society, NZ 


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Credits: Healthify He Puna Waiora editorial team. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Waitematā

Last reviewed: