Antibiotic-resistant illnesses and bacteria

Antibiotic-resistant bacteria cause illnesses that are difficult to treat and possibly fatal. Antibiotic-resistant bacteria spread as easily among people as non-resistant bacteria do.

On this page you will find information about illnesses and bacteria that have been affected by antibiotic use. In some cases, they are resistant to more than one type of antibiotic. This limits treatment options and means it is especially important to prevent the spread of infection.

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Important antibiotic-resistant illnesses


Gonorrhea (Neisseria gonorrhea) is a common sexually transmitted infection. The overall rate gonorrhoea more than doubled between 2011 and 2015.

Certain strains of gonorrhea have become more resistant to antibiotics and more difficult to treat. It is now recommended that gonorrhea be treated with a combination of antibiotics.


Pneumonia is an illness that affects people's lungs. It has many causes, including bacteria and viruses. Symptoms include coughing, chest pain and fever.

Methicillin-resistant Staphylococcus aureus (MRSA) and Legionella pneumophila (Legionnaires' disease) are examples of bacterial infections that can lead to pneumonia. The elderly are particularly vulnerable to antibiotic-resistant pneumonia.


Tuberculosis (TB) is a serious disease that usually attacks people's lungs. It is caused by bacteria that spread through the air. Symptoms include:

  • coughing for more than 2 weeks
  • fever
  • not hungry
  • night sweats
  • feel weak and tired
  • chest pain
  • weight loss
  • chills

Many strains of TB have become resistant to antibiotics. People with resistant TB may need to be treated in the hospital.

Antibiotic-resistant bacteria

Campylobacter jejuni

Campylobacter jejuni (C. jejuni) is a type of bacteria that causes intestinal illness which may resemble the stomach flu. The bacteria are usually spread through:

  • contaminated food or water, or
  • infected animals and people.

Many strains of C. jejuni bacteria are resistant to antibiotics. Antibiotic use in animals is likely a contributing factor to this resistance.

Carbapenem-resistant Enterobacteriaceae

Carbapenem-resistant Enterobacteriaceae (CRE) are a group of bacteria that are resistant to a type of antibiotics called carbapenems. Some of these bacteria produce an enzyme known as New Delhi metallo-beta-Lacatamase (NDM-1) which makes the bacteria resistant to antibiotics.

Alternative treatments can be difficult to find when bacteria, including bacteria with the gene NDM-1, become resistant to the carbapenem type of antibiotics.

E. coli

E. coli (Escherichia coli) is a type of bacteria that causes many types of illness including urinary tract infections, respiratory infections, wound infections and intestinal illness. Symptoms of the latter include stomach cramps, diarrhea and vomiting.

You may become infected with E. coli bacteria by:

  • eating contaminated food,
  • drinking contaminated water, or
  • having direct contact with someone who is sick.

Some E. coli infections are resistant to the antibiotics used to treat them. If infections become resistant to more than one antibiotic, treatment is even more difficult.

Staphylococcus aureus

Staphylococcus aureus (Staph) is a type of bacteria commonly found on the skin and in the noses of healthy people. Staph bacteria can cause infections and illness.

Some Staph strains are resistant to the antibiotic methicillin and are called methicillin-resistant Staphylococcus aureus (MRSA). If left untreated, MRSA infections can lead to serious, life-threatening complications such as infections of the bloodstream, bones and/or lungs (such as pneumonia). MRSA is most often found in healthcare facilities.


Salmonella is a type of bacteria that causes an intestinal illness called salmonellosis. Symptoms include diarrhea, vomiting, stomach cramps and fever. Antibiotics are used to treat severe cases.

Salmonella bacteria can spread when people:

  • eat contaminated meat, poultry, eggs, fruits and vegetables,
  • drink contaminated water, or
  • have direct contact with infected animals.

Some Salmonella bacteria have become resistant to many commonly used antibiotics.

Vancomycin-resistant enterococci

Enterococci are bacteria that live in the human intestine but which can infect other parts of the body. Symptoms vary depending on the site of the infection. Enterococci bacteria often spread in healthcare facilities.

Vancomycin-resistant enterococci (VRE) are resistant to the antibiotic vancomycin. People who have been treated with vancomycin have a higher risk of developing VRE.

Related bacterium

Clostridium difficile

Clostridium difficile (C.difficile) is the type of bacteria that most frequently causes infectious diarrhea among patients in hospitals and residents of long-term care facilities in Canada.

Most cases of C. difficile occur in patients who are taking specific antibiotics in high doses or over a long period. Because antibiotics can change the normal levels of bacteria in the gut, C. difficile bacteria are able to grow and thrive.

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