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Home Your Health Multimedia Encyclopedia Meningitis - H. influenzae

Meningitis - H. influenzae

Definition

Haemophilus influenzae meningitis is a bacterial infection of the membranes covering the brain and spinal cord (meninges).

See also:

• Aseptic meningitis
• Meningitis
• Meningitis - cryptococcal
• Meningitis - Gram-negative
• Meningitis - meningococcal
• Meningitis - pneumococcal
• Meningitis - staphylococcal
• Meningitis - tuberculous

Alternative Names

H. influenzae meningitis; H. flu meningitis

Causes, incidence, and risk factors

H. influenzae meningitis is caused by Haemophilus influenzae bacteria. These bacteria should not be confused with the disease influenza, an upper respiratory infection caused by the influenza virus.

Before the Hib vaccine became available, H. influenzae was the leading cause of bacterial meningitis in children under age 5. Since the introduction of the vaccine in the U.S., H. influenzae meningitis occurs in less than 2 in 100,000 children. It still causes 5% - 10% of bacterial meningitis cases in adults.

H. influenzae meningitis may occur after an upper respiratory infection. The infection usually spreads from the respiratory tract to the bloodstream, and then to the meninges. At the meninges, the bacteria produce infection and inflammation, causing serious illness and sometimes death.

Risk factors include:

• Ear infection (otitis media)
• Family member with an H. influenzae infection
• Native American race
• Placement in day care
• Sinus infection (sinusitis)
• Sore throat (pharyngitis)
• Upper respiratory infection

Symptoms

Symptoms usually come on quickly, and may include:

• Fever and chills
• Mental status changes
• Nausea and vomiting
• Sensitivity to light (photophobia)
• Severe headache
• Stiff neck (meningismus)

Other symptoms that can occur with this disease:

• Agitation
• Bulging fontanelles
• Decreased consciousness
• Poor feeding and irritability in children
• Rapid breathing
• Unusual posture, with the head and neck arched backwards (opisthotonos)

Signs and tests

Physical examination will usually show:

• Fast heart rate
• Fever
• Mental status changes
• Stiff neck

For a patient who is suspected of having meningitis, it is important to perform a lumbar puncture ("spinal tap"), in which spinal fluid (known as cerebrospinal fluid, or CSF) is collected for testing.

Tests that may be done include:

• Blood culture
• Chest x-ray
• CSF examination for cell count, glucose, and protein
• CT scan of the head
• Gram stain, other special stains, and culture of CSF

Treatment

Treatment with antibiotics should be started as soon as possible. Ceftriaxone is one of the most commonly used antibiotics.

If the antibiotic is not working and the health care provider suspects antibiotic resistance, chloramphenicol with ampicillin may be used. Sometimes corticosteroids may be used, especially in children.

Unvaccinated people who are in close contact with someone who has H. influenzae meningitis should be given antibiotics to prevent infection. Such people include:

• Household members
• Rommates in dormitories
• Those who come into close contact with an infected person

Support Groups

Expectations (prognosis)

Early treatment improves the outcome. However, 3 - 5% of patients do not survive. Young children and adults over 50 have the highest risk of death.

Complications

• Brain damage
• Buildup of fluid between the skull and brain (subdural effusion)
• Hearing loss
• Hydrocephalus
• Seizures

Calling your health care provider

Call the local emergency number (such as 911) or go to an emergency room if you suspect meningitis in a young child who has the following symptoms:

• Feeding problems
• High-pitched cry
• Irritability
• Persistent, unexplained fever

Call the local emergency number if you develop any of the serious symptoms listed above. Meningitis can quickly become a life-threatening illness.

Prevention

To protect infants and young children:

• Hib immunizations for infants and children are recommended by the American Academy of Pediatrics and the Advisory Committee on Immunization Practices.
• Several types of Hib vaccine are available for children ages 2 months and older.

All unvaccinated family members and close contacts (especially in health care or school settings) of people with this type of meningitis should begin antibiotic treatment as soon as possible to prevent spread of the infection. Ask your health care provider about this during the first visit.

Close contacts in the same household, school, or day care center should be watched for early signs of the disease as soon as the first case is diagnosed. If two cases occur in a day care center, preventive antibiotics should be considered. Always use good hygiene habits, such as washing hands before and after changing a diaper, and after using the bathroom.

References

Swartz MN. Meningitis: bacterial, viral, and other. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 437.