Health Topic

Bacterial Infections

There are many types of bacterial infections. Learn about bacterial infections that can make you sick and how to treat them.

Reviewed Reviewed by a registered pharmacistGeneral information

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

There are many different types of bacteria. Most types don't make you sick. Some types are helpful. For example, "good" bacteria in your digestive system can help your body digest food and absorb vitamins and minerals. They can help protect you from getting sick. Bacteria are also used in making foods like yogurt and cheese.

But some types of bacteria can cause an infection and make you sick. They are called infectious bacteria. These bacteria can reproduce quickly in your body. Many of them give off toxins (poisons) that can damage your cells and make you sick. Other types can move into and damage your tissues. A few examples of bacteria that cause infections include Streptococcus, Staphylococcus, and E. coli.

There are different ways that bacterial infections may spread:

  • Through droplets and particles that are breathed out by someone who has the infection. You might breathe in the droplets or particles, or they could land on your mouth, nose, or eyes.
  • By touching surfaces or objects that have the bacteria on them and then touching your mouth, nose, or eyes.
  • Through cuts, scrapes, and skin-to-skin contact with someone who has the infection.
  • From the pregnant parent to the baby during pregnancy.
  • Through contaminated food or water.
  • By being bitten by an infected insect or animal.
  • Through sexual contact (usually vaginal, anal and oral sex) with someone who has the infection.

Sometimes your immune system may be able to fight off a bacterial infection. But when you do need treatment, it will be with antibiotics.

You can help prevent some bacterial infections by:

  • Getting vaccines that protect against bacterial infections.
  • Having good hygiene habits. These include washing your hands often and covering your mouth and nose when coughing or sneezing.
  • Paying attention to food safety.
  • Cleaning and disinfecting surfaces that your frequently touch.
  • Preventing insect bites by using a U.S. Environmental Protection Agency (EPA)-registered insect repellent. when you go outdoors. If you travel to an area that has a high risk of diseases from insect bites, also wear long pants, shirts, and socks.
  • Practicing safe sex. This means using a latex condom every time you have anal, vaginal, or oral sex. If your or your partner is allergic to latex, you can use polyurethane condoms.
  • Avoiding close contact with people who are sick.

It sits within Infections.

The lead U.S. institute for this subject is the National Institute of Allergy and Infectious Diseases.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Bacterial Infections

8,055 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Diagnosis and Tests

Treatments and Therapies

Prevention and Risk Factors

Related Issues

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Bacterial Infections. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Bacterial Infections, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.