Health Encyclopedia

Gram-negative meningitis

Definition

Meningitis is present when the membranes covering the brain and spinal cord become swollen and inflamed. This covering is called the meninges.

Bacteria are one type of germ that may cause meningitis. Gram-negative bacteria are a type of bacteria that behave in a similar manner in the body. They are called gram-negative because they turn pink when tested in the laboratory with a special stain called Gram stain.

Causes

Acute bacterial meningitis can be caused by different Gram-negative bacteria including meningococcus and H influenzae.

This article covers Gram-negative meningitis caused by the following bacteria:

Escherichia coli
Klebsiella pneumoniae
Pseudomonas aeruginosa
Serratia marcescens

Gram-negative meningitis is more common in infants than adults. But it can also occur in adults, especially those with one or more risk factors. Risk factors in adults and children include:

Infection (especially in the abdomen or urinary tract)
Recent brain surgery
Recent injury to the head
Spinal abnormalities
Spinal fluid shunt placement after brain surgery
Urinary tract abnormalities
Urinary tract infection
Weakened immune system

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)
Symptoms of a bladder, kidney, intestine, or lung infection

Other symptoms that can occur with this disease:

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

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 provider thinks meningitis is possible, a lumbar puncture (spinal tap) will likely be done to remove a sample of spinal fluid for testing.

Other tests that may be done include:

Blood culture
Chest x-ray
CT scan of the head
Gram stain or, other special stains, and culture of the spinal fluid

Treatment

Antibiotics will be started as soon as possible. Ceftriaxone, ceftazidime, and cefepime are the most commonly used antibiotics for this type of meningitis. Other antibiotics may be given, depending on the type of bacteria.

If you have a spinal shunt, it may be removed.

Outlook (Prognosis)

The earlier treatment is started, the better the outcome.

Many people recover completely. But, many people have permanent brain damage or die of this type of meningitis. Young children and adults over age 50 have the higher risk for death. How well you do depends on:

Your age
How soon treatment is started
Your overall health

Possible Complications

Long-term complications may include:

Brain damage
Buildup of fluid between the skull and brain (subdural effusion)
Buildup of fluid inside the skull that leads to brain swelling (hydrocephalus)
Hearing loss
Seizures

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

Prompt treatment of related infections may reduce the severity and complications of meningitis.

References

Centers for Disease Control and Prevention website. Bacterial meningitis. www.cdc.gov/meningitis/bacterial.html. Reviewed July 15, 2021. Accessed November 10, 2022.

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.

Review Date:9/10/2022
Reviewed By:Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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