Definition

Bacterial meningitis is an infection and inflammation of the meninges. The meninges are the membranes that surround the brain [2] and spinal cord. Bacterial meningitis can cause death within hours, so quick diagnosis and treatment is vital.

Causes

Worldwide, three types of bacteria cause the majority of cases of acute bacterial meningitis:

• Streptococcus pneumoniae (the bacteria that causes pneumonia [3] )
• Neisseria meningitidis
• Haemophilus influenzae b (Hib)

Other forms of bacterial meningitis include Listeria monocytogenes meningitis, Escherichia coli meningitis, and Mycobacterium tuberculosis meningitis.

These bacteria first cause an upper respiratory [4] tract infection, and then travel [5] through the blood stream to the brain [2].

In the United States, widespread immunization has almost eliminated meningitis due to Hib. A variety of other bacteria can also cause meningitis, particularly in newborn babies and the elderly.

Some forms of bacterial meningitis are spread by direct contact with discharge from the mouth or throat of an infected person (eg, kissing). In general, meningitis is not spread by casual contact.

Risk Factors

A risk factor increases your chance of getting a disease or condition.

The following factors increase your chances of developing bacterial meningitis. If you have any of these risk factors, tell your doctor:

• Age: infancy and early childhood; over 60 years of age
• People in close and prolonged contact with patients with meningitis due to Hib or Neisseria meningitidis
• A weakened immune [6] system due to HIV [7] infection or other conditions
• Alcoholism [8]
• Smoking (for meningitis due to Neisseria meningitidis )
• Living in proximity to others, such as dormitories and military barracks (for meningitis due to Neisseria meningitidis )

Symptoms

Classic symptoms can develop over several hours, or may take 1 to 2 days:

• High fever
• Headache
• Very stiff, sore neck

Other symptoms may include:

• Red or purple skin rash
• Cyanosis (bluish skin color)
• Nausea
• Vomiting
• Photophobia (sensitivity to bright lights)
• Sleepiness
• Mental confusion

In newborns and infants, classic symptoms are difficult to detect. Because symptoms in newborns and infants are unreliable, infants under three months old with a fever are often evaluated for meningitis. Symptoms in newborns and infants may include:

• Inactivity
• Unexplained high fever or any form of temperature instability, including a low body temperature
• Irritability
• Vomiting
• Jaundice [9] (yellow color to the skin)
• Feeding poorly or refusing to eat
• Tautness or bulging of soft spots between skull bones [10]
• Difficulty awakening

As bacterial meningitis progresses, patients of all ages may experience seizures and/or hearing loss [11] .

Diagnosis

Your doctor will ask about your symptoms and medical [12] history, and perform a physical exam.

Tests may include the following:

• Spinal tap [13] —removal of a small amount of cerebrospinal fluid to check for bacteria
• Other Cultures–testing of samples of blood, urine, mucous, and/or pus from skin infections
• MRI scan [14] —a test that uses magnetic waves to make pictures of structures inside the body (to be sure the inflammation is not from some other cause, such as a tumor)
• CT scan [15] —a type of x-ray that uses a computer to make pictures of structures inside the body

Treatment

When treatment is provided immediately, more than 90% of all people with bacterial meningitis survive. Antibiotics and many times corticosteroids are given together to treat bacterial meningitis. Fluid replacement may also be given. Talk with your doctor about the best treatment plan for you. Treatment options include:

Prevention

To help reduce your chances of getting bacterial meningitis, take the following steps:

• Vaccines against Hib, which are very safe and highly effective, given to young children
• Pneumococcal polysaccharide vaccine against Streptococcus pneumoniae , given to:
  
  • All people over age 65
  • People ages 2 to 64 with certain chronic medical [12] problems
• Pneumococcal conjugate vaccine against Streptococcus pneumoniae , given to:
  
  • Infants
  • All children older than 2years old
• Preventative antibiotics given to healthcare workers or family members in close contact with infected patients
• Pasteurization of milk and milk products to prevent meningitis due to Listeria monocytogenes
• Monitoring for maternal infection during and before labor to prevent meningitis in newborns