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

Acute bacterial meningitis, which can be caused by gram-negative bacteria, is very serious and should be treated immediately to prevent permanent damage. Bacteria causing gram-negative meningitis include Pseudomonas aeruginosa, Escherichia coli, Enterobacter aerogenes, Proteus morganii, and Klebsiella pneumoniae.

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

Risk factors in adults and children include recent brain surgery and recent injury to the head. The infection is sometimes connected to spinal fluid shunt placement after brain surgery. Spinal abnormalities, urinary tract abnormalities, a local infection, or urinary tract infection may make children vulnerable to this type of meningitis.

• Fever
• Severe headache
• Nausea and vomiting
• Stiff neck
• Sensitivity to light (photophobia)
• Mental status changes
• Symptoms suggesting infection of bladder, kidney, intestines, or lungs, which might be the source of the spinal fluid infection

For any patient with meningitis, it is important to perform a lumbar puncture (spinal tap). In a lumbar puncture, doctors take a sample of the patient's spinal fluid (known as cerebrospinal fluid, or CSF) for testing.

• Low blood pressure
• Fast heart rate
• Stiff neck
• Elevated white blood cell count in blood
• Spinal fluid showing increased white blood cells, low glucose, high protein
• Special stain of the spinal fluid showing white blood cells and sometimes gram-negative bacteria
• CSF culture growing gram-negative bacteria
• Blood culture growing gram-negative bacteria
• CT scan of the brain (usually normal)

It is important to recognize the symptoms of this kind of meningitis, and seek treatment as soon as possible. Early treatment may prevent serious illness or death. Antibiotic treatment through an IV usually starts right away.

Many people recover completely, but a large number of people suffer 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 the patient's age, other medical conditions that may be present, and how quickly the infection is treated.

• Shock with organ damage
• Brain abscess (collection of bacteria in the brain itself)
• Brain damage
• Seizures

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

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