Multi-resistant organisms and antibiotics factsheet


Bacteria are tiny living organisms in the body. Some bacteria can live in places like the gut and nose and not cause any issues. Others are harmful and can cause us to get sick.

Usually, harmful bacteria can be treated using medicine called antibiotics. Multi-resistant organisms (MROs) are bacteria that cannot be killed using antibiotics. 

 Things to consider

Bacterial infection

Bacteria spreads from people, animals, and objects through:

  • contaminated foods
  • contaminated liquids
  • sneezing and coughing
  • contact with infected body fluids
  • touching something that has been contaminated before touching the eyes, nose, mouth, penis or vagina
  • cuts in the skin.

Harmful bacteria can grow and cause symptoms in different parts of the body, including:

  • fever
  • headaches
  • sore throat
  • a cough with mucus
  • weakness
  • pain
  • blisters and redness
  • vomiting
  • diarrhea or runny poo.

This is called a bacterial infection.

Some common bacterial infections include:

  • salmonella – a type of food poisoning
  • cellulitis and impetigo –infections in the skin
  • strep throat – an infection that causes a sore throat
  • pneumococcal disease – infection in the ears, sinus, and lungs
  • chlamydia and gonorrhoea – infections of the penis and vagina, spread by sexual contact.


Bacterial infections are treated using antibiotics. Antibiotics are medications that kill bacteria and make it difficult for them to grow.

Broad-spectrum antibiotics are types of antibiotics that work on wide range of bacteria. These antibiotics are the ones that are commonly given by your local doctor to treat an infection.

Some antibiotics are very specific and can only work on certain types of bacteria.

Antibiotics do not work on illness caused by viruses.

Multi-resistant organisms

Multi-resistant organisms (MROs) are bacteria that cannot be killed using common types of antibiotics. They are sometimes called “superbugs”. 

MROs are no more likely to cause a serious infection than other types of harmful bacteria. Illness and infection caused by MROs are much harder to treat.

MROs have very long names that usually include the specific antibiotic they are resistant to. They are often called by their initials. 

Common MROs include:

  • MRSA - methicillin-resistant staphylococcus aurous
  • VRE - vancomycin-resistant enterococci
  • CRE - carbapenem-resistant enterobacteriaceae
  • ESBL - extended spectrum beta lactamase producing organisms.

MROs can grow naturally in our environment and have become resistant to common antibiotics over time. They can continue to grow and cause infection even if you are taking an antibiotic. 

While these MROs can generally live in the body without causing issues, they can spread from person to person easily. When MROs spread, they can grow, change, and become more resistant to different, more specialised antibiotics.

Antibiotic resistance

Antibiotic resistance is a serious public health issue. It means that some bacterial infections are becoming harder and harder to treat.

Antibiotic resistance is when bacteria grow, change, and become able to defeat the medicine that was made to kill them. 

When antibiotics are used to much when they are not needed, bacteria can learn how to fight and survive the treatment.

If you stop taking a full course of antibiotics before it is finished, there is a risk that not all the bacteria have died. The last surviving bacteria can learn how to fight and survive treatment.

If a person gets sick with an MRO infection, doctors will need to start treatment using more powerful and expensive antibiotics which can have side-effects.

The more this happens, the more likely it is that bacteria will start to become resistant to a wider range of antibiotics. This means there are less treatments available for bacterial infections and a higher risk of developing serious or life-threatening illness.

People who are especially at risk of serious illness and death caused by antibiotic resistance and MROs include:

  • babies and young children
  • people with underlying medical conditions
  • people with weak immune systems
  • people undergoing treatment like chemotherapy.

Stopping the growth and spread of MROs

You can stop the growth and spread of MROs by:

  • washing hands regularly with soap and water
  • finishing your full course of antibiotics, even when you start to feel better
  • not “saving” unused antibiotics for later.

While MROs can live in the body without causing issues, they can be easily spread in places like hospitals. 

If your child is a carrier of an MRO, they will need to be separated in their own room and their treating team will need to wear special gowns and masks. This is to avoid the harmful bacteria and MROs spreading to people who are unwell or recovering from surgery or injury. This is called infection control.

Last updated Friday 19th January 2024


This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2024