7 Scary Diseases Caused by Bacteria

Bacteria are fascinating organisms. They are all around us and many bacteria are helpful to us. Bacteria aid in food digestionnutrient absorption, vitamin production, and protect against other harmful microbes. Conversely, a number of diseases that impact humans are caused by bacteria. Bacteria that cause disease are called pathogenic bacteria, and they do so by producing poisonous substances called endotoxins and exotoxins. These substances are responsible for the symptoms that occur with bacteria related diseases. The symptoms may range from mild to serious, and some can be deadly.

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Necrotizing Fasciitis (Flesh-eating Disease)

A scanning electron micrograph of Group A Streptococcus (Streptococcus pyogenes), the bacteria that causes strep throat, impetigo, and necrotizing fasciitis (flesh-eating disease).
National Institute of Allergy and Infectious Diseases (NIAID) / CC BY 2.0

Necrotizing fasciitis is a serious infection most often caused by Streptococcus pyogenes bacteria. S. pyogenes are cocci shaped bacteria that typically colonize the skin and throat areas of the body. S. pyogenes are flesh-eating bacteria, producing toxins that destroy body cells, specifically red blood cells and white blood cells. This results in death of the infected tissue or necrotizing fasciitis. Other types of bacteria that can also cause necrotizing fasciitis include Escherichia coli, Staphylococcus aureus, Klebsiella, and Clostridium.

People develop this type of infection most commonly by the entrance of bacteria into the body through a cut or other open wound in the skin. Necrotizing fasciitis is not typically spread from person to person and occurrences are random. Healthy individuals with properly functioning immune systems, and who practice good wound care hygiene are at low risk for developing the disease.

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Staph Infection

Commonly known as MRSA, the bacteria seen here in yellow is an antibiotic resistant strain of Staphylococcus aureus bacteria.
National Institutes of Health / Stocktrek Images / Getty Images

Methicillin-resistant Staphylococcus aureus (MRSA) are bacteria that can cause serious health issues. MRSA is a strain of Staphylococcus aureus bacteria or Staph bacteria, that have developed a resistance to penicillin and penicillin-related antibiotics, including methicillin. MRSA is typically spread through physical contact and must breach the skin—through a cut, for example—to cause an infection. MRSA is most commonly acquired as a result of hospital stays. These bacteria can adhere to various types of instruments, including medical equipment. If MRSA bacteria gain access to internal body systems and cause a staph infection, the consequences could be fatal. These bacteria can infect bones, joints, heart valves, and the lungs.


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Neisseria meningitidis bacteria cause meningococcal meningitis.
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Bacterial meningitis is an inflammation of the protective covering of the brain and spinal cord, known as the meninges. This is a serious infection that can lead to brain damage and even death. A severe headache is the most common symptom of meningitis. Other symptoms include neck stiffness and high fever. Meningitis is treated with antibiotics. It is very important that the antibiotics start as soon as possible after infection to help reduce the risk of death. A meningococcal vaccine can help prevent it for those who are most at risk of developing this disease.

Bacteria, viruses, fungi, and parasites can all cause meningitis. Bacterial meningitis can be caused by a number of bacteria. The specific bacteria that cause bacterial meningitis vary based on the age of the infected person. For adults and adolescents, Neisseria meningitidis and Streptococcus pneumoniae are the most common causes of the disease. In newborns, the most common causes of bacterial meningitis are Group B Streptococcus, Escherichia coli, and Listeria monocytogenes.

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Pneumococcus (Streptococcus pneumoniae) bacteria. Pneumococcus is the bacterium that causes pneumonia, bronchial pneumonia, purulent pleurisy, bacterial meningitis, ear infections, sinusitis and conjunctivitis.
BSIP / UIG / Getty Images

Pneumonia is an infection of the lungs. Symptoms include a high fever, coughing, and difficulty breathing. While a number of bacteria can cause pneumonia, the most common cause is Streptococcus pneumoniae. S. pneumoniae typically reside in the respiratory tract and don't normally cause infection in healthy individuals. In some cases, the bacteria become pathogenic and cause pneumonia. The infection typically begins after the bacteria are inhaled and reproduce at a rapid rate in the lungs. S. pneumoniae can also cause ear infections, sinus infections, and meningitis. If needed, most pneumonia has a high probability of cure with antibiotic treatment. A pneumococcal vaccine can help protect those who are most at risk of developing this disease. Streptococcus pneumoniae are cocci shaped bacteria.

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This scanning electron micrograph (SEM) depicts a number of Gram-positive Mycobacterium tuberculosis bacteria. TB bacteria become active, and begin to multiply, if the immune system can't stop them from growing. The bacteria attack the body and destroy tissue. If in the lungs, the bacteria can actually create a hole in the lung tissue.
CDC / Janice Haney Carr

Tuberculosis (TB) is an infectious disease of the lungs. It is typically caused by bacteria called Mycobacterium tuberculosis. Tuberculosis can be deadly without proper treatment. The disease is spread through the air when an infected person coughs, sneezes, or even talks. In a number of developed countries, TB has increased with the rise of HIV infections due to HIV's weakening of the immune systems of infected persons. Antibiotics are used to treat tuberculosis. Isolation to help prevent the spread of an active infection is also typical of treating this disease. Treatment can be long, lasting from six months to a year, depending on the severity of the infection.

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These are cholera bacillus or vibrion (Vibrio cholerae).
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Cholera is an intestinal infection caused by the bacteria Vibrio cholerae. Cholera is a food-borne disease typically spread by food and water contaminated with Vibrio cholerae. Around the world, approximately 3 to 5 million cases per year with approximately 100,000 plus deaths occur. Most instances of infection occur in areas with poor water and food sanitation. Cholera can range from mild to severe. Symptoms of the severe form include diarrhea, vomiting, and cramps. Cholera is typically treated by hydrating the infected individual. In more severe cases, antibiotics may be used to help the person recover.

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This illustration depicts a three-dimensional (3D) computer-generated image of a number of rod-shaped, drug-resistant Shigella bacteria.
CDC / James Archer

Bacillary dysentery is an intestinal inflammation caused by bacteria in the genus Shigella. Similar to cholera, it is spread by contaminated food and water. Dysentery is also spread by individuals who do not wash their hands after using the toilet. Dysentery symptoms can range from mild to severe. Severe symptoms include bloody diarrhea, high fever, and pain. Like cholera, dysentery is typically treated by hydration. It can also be treated with antibiotics based on severity. The best way to prevent the spread of Shigella is to wash and dry your hands properly before handling food and avoid drinking local water in areas where there may be a high risk of getting dysentery.


  • "Necrotizing Fasciitis: A Rare Disease, Especially for the Healthy." National Center for Immunization and Respiratory Diseases, Division of Bacterial Diseases. Centers for Disease Control and Prevention. Updated 17 April 2015. (http://www.cdc.gov/features/necrotizingfasciitis/).
  • "Bacterial Meningitis." National Center for Immunization and Respiratory Diseases. Centers for Disease Control and Prevention. Updated 1 April 2014. (http://www.cdc.gov/meningitis/bacterial.html).
  • "Pneumococcal Disease." Centers for Disease Control and Prevention. Updated 10 June 2015 (http://www.cdc.gov/pneumococcal/index.html).
  • "Tuberculosis (TB)." Centers for Disease Control and Prevention. Updated 28 April. 2015 (http://www.cdc.gov/tb/default.htm).
  • "Dysentery." National Health Service. Reviewed 18 Feb. 2015 (http://www.nhs.uk/Conditions/Dysentery/Pages/introduction.aspx).
  • "Cholera - Vibrio cholerae infection." Centers for Disease Control and Prevention. Updated 27 October 2014. (http://www.cdc.gov/cholera/index.html).