Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Bacterial Meningitis


The Manual's Editorial Staff

Reviewed/Revised Jan 2022 | Modified Sep 2022
Get the full details
Topic Resources

What is bacterial meningitis?

Meningitis is an infection of the thin layer of tissue that covers your brain and spinal cord. This layer of tissue is called the meninges. In bacterial meningitis, infection of the meninges is caused by bacteria. Without treatment, meningitis can damage your brain and cause death. That's why bacterial meningitis is an emergency. Meningitis caused by viruses (viral meningitis Viral Meningitis Meningitis is an infection of the thin layer of tissue that covers your brain and spinal cord. This layer of tissue is called the meninges. In viral meningitis, the infection is caused by a... read more ) isn't usually as dangerous.

Bacterial meningitis is dangerous and can cause serious complications if it isn't treated. If you think you or someone else might have meningitis, go to the hospital right away.

Tissues Covering the Brain

Within the skull, the brain is covered by three layers of tissue called the meninges.

Tissues Covering the Brain

What causes bacterial meningitis?

Bacterial meningitis happens when bacteria get into the fluid between your brain and the thin layer of tissue covering your brain. You may get the bacteria from:

What raises my risk of getting bacterial meningitis?

Bacterial meningitis isn't common but you're more likely to get it if you:

  • Had contact with someone with meningitis

  • Haven't had all your shots (vaccines)

You also are at higher risk if you:

  • Have a weakened immune system

  • Recently had surgery on your brain or spinal cord

  • Have a birth defect of your skull or spine

What are the symptoms of bacterial meningitis?

Symptoms are different depending on the person's age. At any age, symptoms can get worse quickly. So if you think someone has symptoms of meningitis, take them to a doctor right away.

Symptoms of meningitis in infants and babies

At first, babies may just have a fever and not appear very sick. However, babies may quickly develop other signs, such as:

Unlike older children, babies under 2 usually don't have a stiff neck.

Symptoms of meningitis in older children and adults

Older children and adults usually start with mild symptoms similar to a cold or other viral infection. Soon after that they get:

  • Fever

  • Constant headache

  • Stiff neck

  • Sometimes a rash of tiny purple spots or patches

As meningitis gets worse, older children and adults may:

  • Become confused or less alert

  • Have seizures

  • Go into a coma

What are the complications of bacterial meningitis?

Children who survive bacterial meningitis sometimes have permanent brain and nerve complications such as:

How can doctors tell if I have bacterial meningitis?

Doctors do tests to look for bacteria in the fluid surrounding your brain and spinal cord (spinal fluid). To get the spinal fluid, doctors do a:

How a Spinal Tap Is Done

Spinal fluid flows through a channel between the middle and inner layer of tissues (meninges) that cover the brain and spinal cord. To remove a sample of this fluid, a doctor inserts a small, hollow needle between two bones (vertebrae) in the lower spine, below the point where the spinal cord ends. Usually, people lie on their side with their knees curled to their chest. This position widens the space between the vertebrae, so that the doctor can avoid hitting the bones when the needle is inserted.

Doctors collect spinal fluid in test tubes and send it to a lab for testing.

Spinal Tap

How do doctors treat bacterial meningitis?

If doctors even suspect bacterial meningitis, they'll give you:

  • One or more antibiotics by vein (IV)

Because bacterial meningitis can get worse so fast, they'll give you the antibiotics as soon as possible, sometimes even before they finish doing tests. Because bacterial meningitis may cause many serious problems, you'll need to stay in the hospital, perhaps in the intensive care unit (ICU).

In addition to antibiotics, doctors may give you corticosteroids. Corticosteroids can help prevent complications by lessening the inflammation and swelling in your brain and nerves.

Most people recover completely from bacterial meningitis if they get treated right away. Waiting too long for treatment can be dangerous or even deadly.

How can I prevent acute bacterial meningitis?

Two important measures are:

  • Vaccines

  • Antibiotics

Ask your doctor about which vaccines you and your children should have.

If you've been in close contact with someone who has meningitis, doctors will give you antibiotics to lower your chance of getting it.

quiz link

Test your knowledge

Take a Quiz!