Bacterial Meningitis

Español: Meningitis bacteriana

Bacterial meningitis is very serious and can be deadly. Death can occur in as little as a few hours. Most people recover from meningitis. However, permanent disabilities (such as brain damage, hearing loss, and learning disabilities) can result from the infection.

There are several types of bacteria that can cause meningitis. Leading causes in the United States include

• Streptococcus pneumoniae
• Group B Streptococcus
• Neisseria meningitidis
• Haemophilus influenzae
• Listeria monocytogenes

On average, bacterial meningitis caused about 4,100 cases and 500 deaths in the United States each year between 2003 and 2007.* [1]

These bacteria can also be associated with another serious illness, sepsis. Sepsis is the body’s overwhelming and life-threatening response to infection that can cause tissue damage, organ failure, and death.

Causes

Common causes of bacterial meningitis vary by age group:

• Newborns: Group B Streptococcus, Streptococcus pneumoniae, Listeria monocytogenes, Escherichia coli
• Babies and children: Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae type b (Hib), group B Streptococcus
• Teens and young adults: Neisseria meningitidis, Streptococcus pneumoniae
• Older adults: Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae type b (Hib), group B Streptococcus, Listeria monocytogenes

 

Risk Factors

Certain people are at increased risk for bacterial meningitis. Some risk factors include:

• Age
  • Babies are at increased risk for bacterial meningitis compared to people in other age groups. However, people of any age can develop bacterial meningitis. See section above for which bacteria more commonly affect which age groups.
• Community setting
  • Infectious diseases tend to spread where large groups of people gather together. College campuses have reported outbreaks of meningococcal disease, caused by N. meningitidis.
• Certain medical conditions
  • There are certain medical conditions, medications, and surgical procedures that put people at increased risk for meningitis.
• Working with meningitis-causing pathogens
  • Microbiologists routinely exposed to meningitis-causing bacteria are at increased risk for meningitis.
• Travel
  • Travelers may be at increased risk for meningococcal disease, caused by N. meningitidis, if they travel to certain places, such as:
    • The meningitis belt in sub-Saharan Africa, particularly during the dry season
    • Mecca during the annual Hajj and Umrah pilgrimage

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How it Spreads

Generally, the germs that cause bacterial meningitis spread from one person to another. Certain germs, such as Listeria monocytogenes, can spread through food.

How people spread the germs often depends on the type of bacteria. It is also important to know that people can carry these bacteria in or on their bodies without being sick. These people are “carriers.” Most carriers never become sick, but can still spread the bacteria to others.

Here are some of the most common examples of how people spread each type of bacteria to each other:

• Mothers can pass group B Streptococcus and Escherichia coli to their babies during labor and birth.
• People spread Hib and Streptococcus pneumoniae by coughing or sneezing while in close contact with others, who breathe in the bacteria.
• People spread Neisseria meningitidis by sharing respiratory or throat secretions (saliva or spit). This typically occurs during close (coughing or kissing) or lengthy (living in the same household) contact.
• People can get Escherichia coli by eating food prepared by people who did not wash their hands well after using the toilet.

People usually get sick from Escherichia coli and Listeria monocytogenes by eating contaminated food.

Signs and Symptoms

Meningitis symptoms include sudden onset of fever, headache, and stiff neck. There are often other symptoms, such as

• Nausea
• Vomiting
• Photophobia (increased sensitivity to light)
• Altered mental status (confusion)

In newborns and babies, the meningitis symptoms of fever, headache, and neck stiffness may be absent or difficult to notice. The baby may be irritable, vomit, feed poorly, or appear to be slow or inactive. In young babies, doctors may also look for a bulging fontanelle (soft spot on infant’s head) or abnormal reflexes. If you think your baby or child has any of these symptoms, call the doctor right away.

Symptoms of bacterial meningitis can appear quickly or over several days. Typically they develop within 3 to 7 days after exposure

Later symptoms of bacterial meningitis can be very serious (e.g., seizures, coma). For this reason, anyone who thinks they may have meningitis should see a doctor as soon as possible.

Diagnosis

If a doctor thinks you have meningitis, they will collect samples of blood or cerebrospinal fluid (fluid near the spinal cord). A laboratory will test the samples to see what is causing the infection. It is important to know the specific cause of meningitis so the doctors know how to treat it.

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Treatment

Doctors treat bacterial meningitis with a number of antibiotics. It is important to start treatment as soon as possible.

Prevention

The most effective way to protect you and your child against certain types of bacterial meningitis is to get vaccinated. There are vaccines for three types of bacteria that can cause meningitis:

• Neisseria meningitidis
• Streptococcus pneumoniae
• Hib

Make sure you and your child are vaccinated on schedule.

Like with any vaccine, the vaccines that protect against these bacteria are not 100% effective. The vaccines also do not protect against all the types (strains) of each bacteria. For these reasons, there is still a chance you can develop bacterial meningitis even if you were vaccinated.

Pregnant women should talk to their doctor or midwife about getting tested for group B Streptococcus. Women receive the test when they are 35 to 37 weeks pregnant. Doctors give antibiotics (during labor) to women who test positive in order to prevent passing group B Strep to their newborns.

Pregnant women can also reduce their risk of meningitis caused by Listeria monocytogenes. Women should avoid certain foods during pregnancy and safely prepare others.

If someone has bacterial meningitis, a doctor may recommend antibiotics to help prevent other people from getting sick. Doctors call this prophylaxis.  CDC recommends prophylaxis for:

• Close contacts of someone with meningitis caused by Neisseria meningitidis
• Family members, especially if they are at increased risk, of someone with a serious Hib infection

Your doctor or local health department will tell you if you or someone in your house needs prophylaxis.

You can also help protect yourself and others from bacterial meningitis by maintaining healthy habits:

• Don’t smoke and avoid cigarette smoke
• Get plenty of rest
• Avoid close contact with people who are sick

This is especially important for people at increased risk for disease, including:

• Young babies
• Older adults
• People with weak immune systems
• People without a spleen or a spleen that doesn’t work the way it should (functional asplenia)

 

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Reference

1. Thigpen MC, Whitney CG, Messonnier NE, Zell ER, Lynfield R, Hadler JL, et al. Emerging Infections Programs Network. Bacterial meningitis in the United States, 1998-2007. N Engl J Med. 2011;364:2016-25.

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Footnote

*This is the most recent data to date.

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