• Disease Overview
  • Synonyms
  • Signs & Symptoms
  • Causes
  • Affected Populations
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  • Standard Therapies
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Meningitis, Bacterial


Last updated: May 11, 2009
Years published: 1990, 1991, 1993, 1997, 1998, 2000, 2009

Disease Overview

Bacterial Meningitis is a central nervous system disease caused by certain types of bacteria. Meningitis is characterized by inflammation of the membranes (meninges) around the brain or spinal cord. Inflammation can begin suddenly (acute) or develop gradually (subacute). Major symptoms may include fever, headache, and a stiff neck, sometimes with aching muscles. Nausea, vomiting and other symptoms may occur.

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  • Bacterial Meningitis
  • Pyogenic Meningitis
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Signs & Symptoms

Bacterial Meningitis in adults and children is often preceded by respiratory illness or a sore throat. Most forms of bacterial meningitis are acute. In its acute form, the disorder is characterized by sudden fever, headache, a stiff neck, and vomiting. Adults may become seriously ill within 24 hours. In children, the course of the infection may be even shorter.

Symptoms among older children and adults may progress from irritability through confusion, drowsiness, and stupor, possibly leading to coma. Dehydration is common. Other symptoms may include chills, sweating, weakness, loss of appetite, or inability to tolerate bright light (photophobia). Later symptoms may include hydrocephalus (accumulation of fluid in the brain cavity), paralysis of one side of the body (hemiparesis), hearing loss, or other neurological abnormalities.

Among infants between 3 months and 2 years of age, fever, refusal of feedings, vomiting, irritability, and convulsions usually occur. A high- pitched cry, and a bulging or tight soft spot (fontanel) on the crown of the head (where the parts of the still unhardened bones join) may also occur. Since the incidence of Meningitis is highest among this age group, any unexplained fever needs to be investigated. Cerebral fluid may accumulate just inside the tough outer membrane covering the brain (subdural effusions) after several days. Typical signs of Meningitis include seizures, a persistent fever, and an enlarging head size. A brain abscess or subdural pus accumulation may also occur. Water accumulating in the brain (hydrocephalus), deafness and slowed mental and physical development are possible effects of Bacterial Meningitis on the central nervous system.

A neonatal form of Bacterial Meningitis in newborn babies up to 4 weeks old may be caused by infections in parts of the body other than the brain or spine. Some cases may arise from complications occurring at birth. The disorder is characterized by subtle and nonspecific signs such as jitteriness, interrupted breathing (apnea), vomiting, diarrhea, and a yellowish skin color (jaundice). Usually signs of infection elsewhere in the body (e.g. middle ear infection) are also present. The cerebrospinal fluid can be tested for a definite diagnosis.

Bacterial Meningitis due to Group B pneumococcus bacteria may be present in the first 10 days of life, when it frequently accompanies a lung illness. Usually, however, this form of Meningitis occurs after 10 days of age as an isolated illness. Other symptoms such as fever, drowsiness, and seizures may occur.

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Bacterial Meningitis is the most common type of meningitis. Three types of bacteria are responsible for 80% of all Bacterial Meningitis. These are: 1) Hemophilus influenzae (type B), 2) Streptococcus pneumoniae (Pneumococcus), and 3) Neisseria meningitidis (Meningococcus). (For more information on Meningococcal Meningitis, choose “meningococcal” as your search term in the Rare Disease Database). All three types occur most often in winter.

Gram-negative bacteria such as Escherichia coli, Klebsiella-Entero, or Pseudomonas often cause Bacterial Meningitis in newborn infants. Other types of bacteria that may cause the disorder are Streptococci, Staphylococci (Staphylococcus aureus) or listeria monocytogenes.

Bacterial Meningitis due to hemophilus influenza type B bacteria occurs most often in infants over 1 month old and young children. It usually does not occur in adults except in relation to another condition such as head trauma or impaired immunity. Bacterial Meningitis caused by pneumococcus occurs most often in adults, especially those with alcoholism, chronic otitis (inflammation of the ear), sinusitus (inflammation of the mucous membranes lining the sinuses that open into the nose), mastoiditis (infection of the bone located behind the ear), closed head injury, recurrent meningitis, pneumococcal pneumonia, or sickle cell anemia. (For more information choose “meningitis,” or “sickle” as your search terms in the Rare Disease Database).

Bacterial Meningitis from gram-negative organisms such as Escherichia coli and Klebsiella-Enterobacter is called Gram-negative Meningitis and frequently occurs after central nervous system trauma or surgery, or from blood poisoning). Newborns or people who have impaired immunity may also become infected.

Staphylococcal Meningitis (from Staphylococcus bacteria), another form of Bacterial Meningitis, occurs after blood poisoning (e.g., from endocarditis which is inflammation of the inner lining of the heart), open head trauma, or neurosurgery.

Listeria Meningitis is another form of meningitis that occurs in newborns, in patients who have chronic renal (kidney) failure, or adults taking immunosuppressive drugs (e.g. organ transplant patients). (For more information on Listeria, choose “Listeria” as your search term in the Rare Disease Database).

Intravenous drug use from unsterilized needles can cause blood poisoning that may lead to Bacterial Meningitis.

Of all bacteria causing Bacterial Meningitis, Hemophilus influenza type B is the most common and represents almost half of all Bacterial Meningitis cases. Meningococcal Meningitis represents about 27 per cent, and Pneumococcal Meningitis represents about 11 per cent.

Bacteria that cause Bacterial Meningitis are thought to be carried by approimately ten percent of the population in their throats. It is not clear why only a very small percentage of people get this disease.

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Affected populations

In the United States, approximately 2,600 sporadic cases of Bacterial Meningitis are reported each year. Meningitis caused by pneumococcal infections affects about 1.1 in 100,000 individuals. Meningitis caused by haemophilus influenza affects about .2 in 100,000 individuals. About 70 percent of all Bacterial Meningitis occurs in children aged 5 and under. Children under age 2 are at highest risk for infection, and males are affected more often than females. Bacterial Meningitis in general occurs most often during the first month of a newborn’s life and is usually caused by gram-negative bacteria such as Escherichia coli or by group B streptococcus. Bacterial Meningitis caused by Hemophilus influenzae type B occurs most often in infants over 1 month old and young children. However, in the United States, this type of Bacterial Meningitis occurs more often in adults as a result of a vaccine that has led to a decline in the number of affected infants and children. Bacterial Meningitis caused by pneumococcus bacteria occurs most often in adults, but there are an estimated 1,400 cases of pneumococcal meningitis each year among children under age five.

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Testing for Bacterial Meningitis may include imaging techniques such as CT scans or MR imaging. Other testing may include examination of the patient's blood and/or skin. Diagnosis is made by examination of the cerebrospinal fluid.

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Standard Therapies


Bacterial Meningitis is usually treated with different types of antibiotics used against the specific bacteria causing the infection. These may include ampicillin, chloramphenicol, gentamicin, penicillin, moxalactam, nafcillin, cefuroxime, cefotaxime, ceftizoxime, oxacillin, vancomycin, or rifampin. The addition of dexamethasone to the antibiotic treatment is also being used and is helpful in reducing meningeal inflammation. Research has shown that the use of dexamethasone in children may be beneficial when administered within the first two days of the illness.

For children under 5 who have come in close contact with a person having Meningitis caused by Hemophilus influenzae, the drug rifampin may be prescribed as a preventative measure.

For children under the age of 2, a vaccine approved in February, 2000, helps protect against invasive pneumococcal diseases, including meningitis. Called the Prevnar Pneumococcal 7-valent Conjugate Vaccine, it is marketed by Wyeth-Ayerst Laboratories and is to be given to infants at two, four, and six months and again between 12 and 15 months of age.

Children over 2 years of age can be immunized against Meningitis with the Hemophilus influenzae type b polysaccharide vaccine. A vaccine composed of attenuated bacteria with added protein, has been approved for use in children under two years of age to protect them against Hemophilus influenzae type B Meningitis.

The Centers for Disease Control (CDC) in Atlanta, GA, have advised that an outbreak of three or more cases of Bacterial Meningitis in a well-defined geographical area (i.e., school, county) be considered a risk factor for contracting this disease. The CDC advises local officials to define the immediate population that is at risk (i.e., day care center, university) and vaccinate those at risk once the disease occurs at a rate of 10 patients per 100,000.

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Clinical Trials and Studies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:


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Cecil Textbook of Medicine, 18th Ed.: James B. Wyngaarden, and Lloyd H. Smith, Jr., Editors; W.B. Saunders Co., 1988. Pp. 57, 65, 1604-1610, 1888.

Internal Medicine, 2nd Ed.: Jay H. Stein, ed.-in-chief; Little, Brown and Co., 1987. Pp. 1494-1502.

Principles of Neurology, 6th Ed.: Raymond D. Adams, Maurice Victor, and Allan A. Ropper, Editors; McGraw-Hill, Inc., 1997. P. 735.

Harrison’s Principles of Internal Medicine, 14th Ed.: Kurt J. Isselbacher, M.D. et al., Editors; McGraw-Hill, Inc., 1998. P. 1179.

Mandell, Douglas and Bennett’s Principles and Practice of Infectious Diseases, 4th Ed.: Gerald L. Mandell, M.D. et al., Editors; Churchill Livingstone Inc., 1995. P. 2410.


Bacterial Meningitis in Older Children. W. A. Bonadio et al.; Am J Dis Child (Apr 1990; 144 (4)). Pp. 463-65.

Ceftriaxone Alone Compared to Ampicillin and Chloramphenicol in the Treatment of Bacterial Meningitis. N. I. Girgis; Chemotherapy (1988; 34 (Suppl 1)). Pp. 16-20.

Gd-Dtpa-Enhanced MR Imaging of the Brain in Patients with Meningitis: Comparison with CT. K. H. Chang et al.; AJR Am J Roentgenol (Apr 1990; 154(4)). Pp. 809-16.

Treatment of Bacterial Meningitis. V.J. Quagliarello et al.; New Eng J Med (Mar 6 1997; 336(10)). Pp. 708-16.

Dexamethasone As Adjunctive Therapy in Bacterial Meningitis. P.B. McIntyre et al.; JAMA (Sept 17 1997; 278). Pp. 925-31.

Bacterial Meningitis in the United States in 1995. A. Schucat et al.; New Eng J Med (Oct 2 1997; 337(14)). Pp. 970-76.

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