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Meningitis - gram-negative

Definition

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

See also:

• Aseptic meningitis
• Meningitis - cryptococcal
• Meningitis - H. influenzae
• Meningitis - meningococcal
• Meningitis - pneumococcal
• Meningitis - staphylococcal
• Meningitis - tuberculous

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
• Weakened immune system

Symptoms

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

Signs and tests

A physical examination will usually show:

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

For any 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. Ceftazidime or Cefepime is one of the most commonly used antibiotics for this type of meningitis, but other antibiotics may be used, depending on the type of bacteria.

If you have a shunt, it may be removed to get rid of the infection.

Support Groups

Expectations (prognosis)

Early treatment improves the outcome. Between 40% and 80% of patients with Gram-negative meningitis do not survive. Young children and adults over age 50 have the highest risk of death.

Many people recover completely, but a large number of people have permanent brain damage or die from this type of meningitis. 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 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

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.