H influenzae meningitis
H. influenzae meningitis; H. flu meningitis; Haemophilus influenzae type b meningitisMeningitis is an infection of the membranes covering the brain and spinal cord. This covering is called the meninges.
Meningitis
Meningitis is an infection of the membranes covering the brain and spinal cord. This covering is called the meninges.

Bacteria are one type of germ that can cause meningitis. Haemophilus influenzae type b is one kind of bacteria that causes meningitis.
Causes
H influenzae meningitis is caused by Haemophilus influenzae type b bacteria. This illness is not the same as the flu (influenza), which is caused by a virus.
Influenza
The flu is an infection of the nose, throat, and lungs. It spreads easily. This article discusses influenza types A and B. Another type of the flu ...

Before the Hib vaccine, H influenzae was the leading cause of bacterial meningitis in children under age 5. Since the vaccine became available in the United States, this type of meningitis occurs much less often in children.
H influenzae meningitis may occur after an upper respiratory infection. The infection usually spreads from the lungs and airways to the blood, then to the brain area.
Risk factors include:
- Attending day care
- Cancer
- Ear infection (otitis media) with H influenzae infection
Otitis media
Ear infections are one of the most common reasons parents take their children to the health care provider. The most common type of ear infection is ...
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- Native American race
- Pregnancy
- Older age
- Sinus infection (sinusitis)
Sinusitis
Sinusitis is present when the tissue lining the sinuses become swollen or inflamed. It occurs as the result of an inflammatory reaction or an infect...
ImageRead Article Now Book Mark Article - Sore throat (pharyngitis)
Pharyngitis
Pharyngitis, or sore throat, is discomfort, pain, or scratchiness in the throat. It often makes it painful to swallow.
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- Weakened immune system
Symptoms
Symptoms usually come on quickly, and may include:
- Fever and chills
- Mental status changes
Mental status changes
Unconsciousness is when a person is unable to respond to people and activities. Doctors often call this a coma or being in a comatose state. Other c...
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- Sensitivity to light (photophobia)
- Severe headache
- Stiff neck (meningismus)
Other symptoms that can occur include:
- Agitation
- Bulging fontanelles in infants
Bulging fontanelles
A bulging fontanelle is an outward curving of an infant's soft spot (fontanelle).
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- Poor feeding and irritability in children
- Rapid breathing
- Unusual posture, with the head and neck arched backwards (opisthotonos)
Opisthotonos
Opisthotonos is a condition in which a person holds their body in an abnormal position. The person is usually rigid and arches their back, with thei...
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Exams and Tests
The health care provider will perform a physical exam. Questions will focus on symptoms and possible exposure to someone who might have the same symptoms, such as a stiff neck and fever.
If the doctor thinks meningitis is possible, a lumbar puncture (spinal tap) is done to take a sample of spinal fluid (cerebrospinal fluid, or CSF) for testing.
Spinal tap
Cerebrospinal fluid (CSF) collection is a test to look at the fluid that surrounds the brain and spinal cord. CSF acts as a cushion, protecting the b...

Other tests that may be done include:
- Blood culture
Blood culture
A blood culture is a laboratory test to check for bacteria or other germs in a blood sample.
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Chest x-ray
A chest x-ray is an x-ray of the chest, lungs, heart, large arteries, ribs, and diaphragm.
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CT scan of the head
A head computed tomography (CT) scan uses many x-rays to create pictures of the head, including the skull, brain, eye sockets, and sinuses.
ImageRead Article Now Book Mark Article - Gram stain, other special stains, and culture of CSF
Culture of CSF
A cerebrospinal fluid (CSF) culture is a laboratory test to look for bacteria, fungi, and viruses in the fluid that moves in the space around the spi...
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Treatment
Antibiotics will be given as soon as possible. Ceftriaxone is one of the most commonly used antibiotics. Ampicillin may sometimes be used.
Corticosteroids may be used to fight inflammation, 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
- Roommates in dormitories
- Those who come into close contact with an infected person
Outlook (Prognosis)
Meningitis is a dangerous infection and it can be deadly. The sooner it is treated, the better the chance for recovery. Young children and adults over age 50 have the highest risk for death.
Possible Complications
Long-term complications may include:
- Brain damage
- Buildup of fluid between the skull and brain (subdural effusion)
Subdural effusion
A subdural effusion is a collection of cerebrospinal fluid (CSF) trapped between the surface of the brain and the outer lining of the brain (the dura...
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Hydrocephalus
Hydrocephalus is a buildup of fluid inside the skull that leads to brain swelling. Hydrocephalus means "water on the brain. "
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- Seizures
Seizures
A seizure is the physical changes in behavior that occurs after an episode of abnormal electrical activity in the brain. The term "seizure" is often ...
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When to Contact a Medical Professional
Call 911 or the local emergency number 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
Meningitis can quickly become a life-threatening illness.
Prevention
Infants and young children can be protected with the Hib vaccine.
Hib vaccine
All content below is taken in its entirety from the CDC Hib (Haemophilus Influenzae Type b) Vaccine Information Statement (VIS): www. cdc. gov/vaccin...

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 person is diagnosed. All unvaccinated family members and close contacts of this person should begin antibiotic treatment as soon as possible to prevent spread of the infection. Ask your provider about antibiotics during the first visit.
Always use good hygiene habits, such as washing hands before and after changing a diaper, and after using the bathroom.
References
Centers for Disease Control and Prevention website. Bacterial meningitis. www.cdc.gov/meningitis/bacterial.html. Updated August 6, 2019. Accessed December 1, 2020.
Nath A. Meningitis: bacterial, viral, and other. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 384.
Hasbun R, Van de Beek D, Brouwer MC, Tunkel AR. Acute meningitis. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 87.
Central nervous system and peripheral nervous system - illustration
The central nervous system comprises the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.
Central nervous system and peripheral nervous system
illustration
CSF cell count - illustration
CSF (cerebrospinal fluid) is a clear fluid that circulates in the space surrounding the spinal cord and brain. A CSF cell count is a test to measure the number of red and white blood cells that are in CSF.
CSF cell count
illustration
Haemophilus influenzae organism - illustration
This is a Gram stain of spinal fluid from a person with meningitis. The rod-like organisms seen in the fluid are Haemophilus influenzae, one of the most common causes of childhood meningitis (prior to the widespread use of the H influenzae vaccine). The large red-colored objects are cells in the spinal fluid. A vaccine to prevent infection by Haemophilus influenzae (type B) is available as one of the routine childhood immunizations (Hib), typically given at 2, 4, and 12 months.
Haemophilus influenzae organism
illustration
Central nervous system and peripheral nervous system - illustration
The central nervous system comprises the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.
Central nervous system and peripheral nervous system
illustration
CSF cell count - illustration
CSF (cerebrospinal fluid) is a clear fluid that circulates in the space surrounding the spinal cord and brain. A CSF cell count is a test to measure the number of red and white blood cells that are in CSF.
CSF cell count
illustration
Haemophilus influenzae organism - illustration
This is a Gram stain of spinal fluid from a person with meningitis. The rod-like organisms seen in the fluid are Haemophilus influenzae, one of the most common causes of childhood meningitis (prior to the widespread use of the H influenzae vaccine). The large red-colored objects are cells in the spinal fluid. A vaccine to prevent infection by Haemophilus influenzae (type B) is available as one of the routine childhood immunizations (Hib), typically given at 2, 4, and 12 months.
Haemophilus influenzae organism
illustration
Review Date: 10/25/2020
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.