Antimicrobial Resistance

Strep throat and the flu are just two of the diseases that healthcare providers treat with antimicrobial medications. But, sometimes the medicines don’t work. This antimicrobial resistance is, according to the WHO, one of the top 10 global public health threats.

What is antimicrobial resistance?

Antimicrobials are medications that treat diseases caused by microbes. In this context, the word “resistance” means a lack of sensitivity to those medications. To resist an antimicrobial is to stop the medication from working.

This can lead to:

  • More serious infections.
  • Longer recovery times.
  • Increased medical expenses.
  • The use of more expensive drugs or riskier procedures.
  • Possible death.


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What are microbes?

Microbes are tiny organisms that can enter your body. Examples of microbes include:

  • Bacteria.
  • Viruses.
  • Fungi.
  • Parasites.

Microbes have lived on earth for 3.5 billion years in every type of environment, making them the most numerous and adaptable form of life on the planet.

What are examples of antimicrobials?

Scientists have invented many antimicrobials – medications that treat illnesses caused by microbes. A very short list includes:

  • Penicillin (an antibiotic).
  • Valacyclovir (an antiviral agent).
  • Fluconazole (an antifungal medication).
  • Praziquantel (an antiparasite medication).


What illnesses do microbes cause? What illnesses do antimicrobials treat?

Microbes cause a variety of illnesses that antimicrobials treat. Some examples include:

If you have one of these illnesses and it’s caused by a resistant organism, your treatment may not work. Imagine enduring pneumonia and no matter how much penicillin you take, your symptoms never go away. The microbes inside you have evolved in a way that allows them to continue to live and grow inside you, despite the drugs designed to kill them.

This is an international problem – a global threat to public health.

How does antimicrobial resistance happen?

A microbe has five goals once it enters your body:

  • To reach the target site (your lungs, for instance).
  • To attach to the target site.
  • To multiply.
  • To take nutrients from you, the host.
  • To avoid and/or survive any attacks by your immune system.

When you take an antimicrobial, the medication kills most of the microbes. But resistant microbes may survive.


What does the mutated gene or resistant germ do to the antimicrobials?

There are defense strategies a germ can use to resist the antimicrobial medication:

  • Limit the uptake of the medication (the absorption or incorporation).
  • Change the medication’s target.
  • Deactivate the medication (stop it from working).
  • Activate efflux of the medication (kick the medication out of the cells).

Is antimicrobial resistance the same as antibiotic resistance?

Antibiotic resistance refers specifically to resistance to bacteria. Antimicrobial resistance refers to resistance to bacteria, viruses, fungi and parasites.

When was antimicrobial resistance discovered?

Antimicrobial resistance wasn’t discovered all at once. To use penicillin as an example, this antibiotic was invented in 1941 and resistance was identified in:

  • 1942: Penicillin-resistant Staphylococcus aureus.
  • 1967: Penicillin-resistant Streptococcus pneumoniae.
  • 1976: Penicillinase-producing Neisseria gonorrhoeae.

How common is antimicrobial resistance?

According to the Centers for Disease Control (CDC), at least two million people per year in the United States become infected with resistant germs. At least 23,000 people die as a result. Each year, conditions caused by antimicrobial resistance lead to:

  • An estimated $20 billion in additional healthcare costs.
  • $35 billion in other costs to society as a whole.
  • More than eight million additional days of hospital care.

Who is affected by antimicrobial resistance?

Anyone at any age can be affected by antimicrobial resistance, but you’re at a higher risk if you have a weak immune system or have frequent infections requiring antimicrobial therapy. The more you get sick, the greater chance you have of getting an infection with a resistance germ.

Is antimicrobial resistance contagious?

Antimicrobial resistance germs can spread between people, animals, plants and through food. They’re also found in the water, soil and air.

What increases the risk of antimicrobial resistance?

The following have a role in increasing the rate of antimicrobial resistance:

  • Healthcare providers. Healthcare providers sometimes prescribe antimicrobials that are not needed, at the wrong dose or for an inappropriate length of time. Some healthcare providers give in to pressure from patients to “try something” even when the exact cause of symptoms is unknown. For example, viral infections such as the common cold should not be treated with antibiotics, because antibiotics kill only bacteria.
  • Broad-spectrum medications. Sometimes a healthcare provider may treat an infection with a broad-spectrum antimicrobial that works against a variety of microbes instead of one specific germ. This can increase the risk of antimicrobial resistance.
  • Close contact at hospitals. The close contact among hospital workers and sick patients creates a situation that makes it easy for microbes to spread.
  • Using antibiotics in agriculture. The use of antibiotics in agriculture to promote growth in food and animals is viewed by some scientists as a major problem. Meat-producing animals given antibiotics can develop resistant bacteria. These resistant bacteria may contaminate meat or other food products from the animals. The resistant bacteria are then passed along to people who eat these foods.

How is antimicrobial resistance diagnosed? What tests are done?

Diagnostic laboratory tests can find which microbe is causing an infection and determine whether the microbes present are resistant to certain antimicrobial medications. However, these tests can take days or even weeks. This is because microbes must grow in a laboratory before they can be identified.

How is antimicrobial resistance treated?

Anyone with an antimicrobial-resistant infection may need to:

  • Use a different medication.
  • Take a higher dose of an antimicrobial.
  • Take the medication for a longer period.
  • Try multiple medications in combination.
  • Experiment with non-medication treatments.

How can antimicrobial resistance be prevented?

It’s not possible to eliminate antimicrobial resistance, as microbes will always be able to modify themselves and adapt to their environment. However, there are some ways you could limit your exposure:

  • Work closely with a healthcare provider to discuss symptoms and decide on the correct medicine to treat any illness.
  • Follow the directions exactly for any prescription medication.
  • Never take another person’s prescription medication or share yours with them.
  • Never save old prescription drugs for use at a later time.
  • Get vaccinations as recommended.
  • Follow good general health practices such as a proper diet, exercise, getting enough sleep and good hygiene (especially frequent hand-washing) to prevent illness and the need for antimicrobial drugs.

What happens if antimicrobial resistance gets worse?

The World Health Organization (WHO) says that antimicrobial resistance is one of the top ten global public health threats. It threatens to reverse the miracles of modern medicine. If antimicrobial resistance continues to advance at its current pace, there will come a time where healthcare providers will no longer be able to cure infections.

Fortunately, institutions like the WHO and the CDC are working to track, research, prevent and fight antimicrobial resistance.

Medically Reviewed

Last reviewed on 04/27/2021.

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