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Antimicrobial Resistance

Fact Sheet

Antimicrobial resistance occurs as a result of microbes, such as bacteria and viruses, changing in ways that reduce or eliminate the effectiveness of the drugs used to treat the infections they cause.

Antimicrobial resistance can develop from the use of antimicrobials in humans, animals, or plants (antimicrobials include antibacterial drugs, antibiotics, antivirals, antifungals and antiparisitic drugs). However, the overuse and/or inappropriate use of antimicrobials make the development and spread of resistance more likely. This is why the prudent use of antimicrobials is very important.

Once microbes become resistant, the drugs used to cure the infections they cause are less effective and may no longer work. Individuals infected with an antimicrobial resistant organism may be ill for a longer period of time, which also increases the chance for the illness to spread to other people.

What is the difference between antimicrobials, antibiotics and antibacterials and antivirals?

Microbes are living organisms such as bacteria, viruses, fungi and parasites.

Antimicrobials are drugs, chemicals, or other substances that either kill or slow the growth of microbes. Among the antimicrobial agents are antibacterial drugs, antibiotics, antivirals, antifungals, and antiparisitic drugs.

Antibiotics are substances that can kill or inhibit the growth of bacteria. Antibiotics are commonly used to fight bacterial infections, but are not effective against infections caused by viruses.

Antibacterials are substances that kill or inhibit the growth of bacteria on human and environmental surfaces. These include substances that aid in proper hygiene like antibacterial cleansers and hand sanitizers.

Antivirals are substances that kill or inhibit the growth of viruses.

How does antimicrobial resistance occur?

Some organisms are inherently resistant to some drugs. Microbes can also adapt, as a group, to their environment and resist the antimicrobials that are used to try to kill them. The microbes do this by changing their genetic make-up. Once these microbes mutate so they are resistant to an antimicrobial, this new genetic structure is carried on as the microbes grow and replicate.

Why does antimicrobial resistance occur?

Antimicrobial resistant organisms can develop from the use of antimicrobials in humans, animals, or plants. The overuse and/or inappropriate use of antimicrobials make the development and spread of resistance more likely. This is why the prudent use of antimicrobials is very important.

How does antimicrobial resistance affect public health?

When infections are caused by organisms resistant to drugs like antibiotics, it means they are more difficult to treat. Individuals infected with an antimicrobial resistant organism may be ill for a longer period of time, which also increases the chance for the illness to spread to other people.

An infection caused by an antimicrobial resistant organism can be serious because the infection does not respond to conventional antimicrobial treatment. Some infections can cause severe illness leading to complications and even death. In addition, some people are more susceptible to complications from infections than others. The elderly, pregnant women, young children and people with weakened immune systems are groups that often are at higher risk of developing severe illness from an infection.

Where does antimicrobial resistance occur?

Antimicrobial resistance occurs everywhere in the world.

Healthcare facilities often deal with antimicrobial resistance, in part because of the frequent use of antimicrobials. These organisms can easily spread inside these institutions if proper infection prevention and control practices are not followed. Examples of health-care associated infections that are multi-drug resistant are Clostridium difficile (C. difficile) and Methicillin-Resistant Staphylococcus aureus (MRSA).

In the community, antimicrobial resistant infections can also spread from person to person. Examples of community associated infections that could show resistance include sexually transmitted infections (STIs), pneumonia, and skin and soft tissue infections.

What are the treatment options if I am infected with an antimicrobial resistant organism?

If you become infected with an antimicrobial resistant organism, this does not necessarily mean your infection is untreatable. There are usually several types of antimicrobials that may be used to fight an infection. When an infection fails to respond to one type of antimicrobial treatment, another type may successfully fight the infection.

For infections caused by an antimicrobial resistant organism, as with all infections, patients should undergo treatment under the supervision of a physician. If you are infected with an antimicrobial resistant organism, your physician will determine the best treatment option. It is important to closely follow directions provided by your health care professional and to fully complete the course of treatment as prescribed.

The decision to use antimicrobials should be left to your healthcare provider. It is also important to remember that antibiotics are not effective against viral infections.

What types of infections can become resistant to antimicrobials?

The following infections are some important examples of resistance to antimicrobials:

  • Clostridium difficile
  • Community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA)
  • Escherichia coli
  • HIV
  • Influenza
  • Methicillin-resistant Staphylococcus aureus (MRSA)
  • Salmonella
  • Sexually Transmitted Infections (various microbes)
  • Tuberculosis
  • Pneumonia
  • Vancomycin-resistant Enterococci (VRE)

How can people protect themselves against getting an antimicrobial resistant infection?

To prevent antimicrobial resistance, you and your healthcare provider should discuss the appropriate medicine for your illness to avoid overusing or misusing antimicrobials. You should take the full course of medication as prescribed and never take medication that was not prescribed for you.

Proper hand hygiene is one of the most effective ways to reduce the risk of acquiring an infection, including those that are resistant to antimicrobials. To decrease the risk of transmission of bacteria within healthcare settings, it is particularly important that staff and visitors wash their hands frequently with soap and water or use alcohol-based hand cleansers. Personal protective equipment, such as gloves and masks, when appropriately used and disposed of, can help prevent transmission of infections.