Health Encyclopedia

Meningitis - gram-negative

Definition

Gram-negative meningitis is an infection of the membranes covering the brain and spinal cord (meninges) caused by bacteria that turn pink when exposed to a special stain (gram-negative bacteria).

Alternative Names

Gram-negative meningitis

Causes, incidence, and risk factors

Acute bacterial meningitis can be caused by gram-negative bacteria. Bacteria causing gram-negative meningitis include:

Acinetobacter baumannii
Enterobacter aerogenes
Escherichia coli
Klebsiella pneumoniae
Pseudomonas aeruginosa

Gram-negative meningitis is much more common in infants than adults.

Risk factors in adults and children include:

Local infection
Recent brain surgery
Recent injury to the head
Spinal abnormalities
Spinal fluid shunt placement after brain surgery
Urinary tract abnormalities
Urinary tract infection

Symptoms

Fever
Mental status changes
Nausea and vomiting
Sensitivity to light (photophobia)
Severe headache
Stiff neck
Symptoms of a bladder, kidney, intestine, or lung infection

Signs and tests

A physical examination may show:

Fast heart rate
Low blood pressure
Stiff neck

For any patient with 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 include:

Blood culture
CSF culture
CT scan of the brain
White blood cell count
Spinal fluid tests for white blood cells, glucose, protein
Special stain of the spinal fluid

Treatment

Antibiotic treatment through a vein (IV) usually starts right away. If you have a shunt, it may be removed to get rid of the infection.

Expectations (prognosis)

It is important to recognize the symptoms of this meningitis, and seek treatment as soon as possible. Early treatment may prevent serious illness or death.

Many people recover completely, but a large number of people have permanent brain damage or die from this type of meningitis. Between 40% and 80% of patients with gram-negative meningitis do not survive, although these numbers may be improving. The likelihood of survival depends on:

How quickly the infection is treated
Other medical conditions that may be present
The patient's age

Complications

Brain abscess
Brain damage
Seizures
Shock with organ damage

Calling your health care provider

Go to the emergency room or call the local emergency number (such as 911) if you notice symptoms of meningitis. This condition can be very serious and needs immediate treatment.

Prevention

Prompt treatment of related infections may reduce the risk of meningitis.

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.

Review Date:9/28/2008
Reviewed By:David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, PhD, MD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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