Gram-negative meningitis is an infection in the membrane surrounding your brain and spinal cord.
“Gram-negative” refers to gram staining, a routine laboratory test used to determine the presence of microorganisms like bacteria or fungi in your blood or tissue. During the test, the gram stain will turn pink if gram-negative bacteria are present. These types of bacteria can also cause infections and pneumonia.
According to the Centers for Disease Control and Prevention, gram-negative bacteria are resistant to multiple antibiotic drugs commonly used to treat infection. In addition, they have the capability to become resistant to new drugs. As a result, gram-negative meningitis is harder to treat than other forms of meningitis. An estimated 40 to 80 percent of gram-negative meningitis cases end in death. Moreover, complications are generally higher in survivors of gram-negative meningitis. It’s more common in infants than adults.
Meningitis is often mistaken for the flu because both have similar early signs. Additionally, both develop over a period of several hours to a few days.
Symptoms of meningitis in newborns and infants include:
- bulge in the soft spot on the top of the head
- constant crying
- excessive irritability
- excessive sleepiness
- poor feeding
- stiffness in the body and neck
- fever, sweats, and/or chills
Symptoms of gram-negative meningitis in adults include:
- high fever, sweats, and/or chills
- lack of interest in eating or drinking
- sensitivity to light
- severe headache
- stiff neck
Gram-negative bacteria don’t reach the brain or spinal column easily. Both of these parts of the body are generally well protected from outside invaders. However, certain medical events increase your chances of getting any kind of meningitis. Examples of these events include:
- brain surgery
- injury to the brain or head
- spinal abnormalities, such as spina bifida
- spinal fluid shunt after brain surgery, used to relieve swelling
- weakened immune system from cancer or AIDS
Gram-negative meningitis occurs when the membrane of your brain and spinal cord becomes infected with a strain of gram-negative bacteria. These include:
- Acinetobacter baumannii
- Enterobacter aerogenes
- Escherichia coli, or E. coli
- Klebsiella pneumoniae
- Pseudomonas aeruginosa
- Serratia marsescens
Your doctor will start with a physical exam and will look for signs of a fast heart rate, fever, and stiff neck. They will do a thorough neurological and skin examination. They will also check if you’ve experienced confusion or disorientation.
If your doctor suspects meningitis, they will order a spinal tap, also known as a lumbar puncture. During this procedure, a needle will be used to extract cerebrospinal fluid, the clear liquid that cushions your brain and spinal column. It is not uncommon to have a headache after this procedure.
The fluid is sent to a lab for testing. People with meningitis often show increased levels of proteins and white blood cells in their spinal fluid.
The fluid will also be tested with a gram stain test and a bacterial culture. In addition to a positive or negative result, the test will provide a description of the bacteria in the infection. This will help guide treatment.
Results can take up to a week, and in the meantime your doctor may order other tests to help reach a definitive diagnosis.
Additional tests for meningitis include:
- blood culture
- CT scan
- polymerase chain reaction, PCR, amplification, used to amplify DNA
As soon as meningitis is diagnosed or even suspected, you will be admitted to the hospital and put on IV antibiotics. Most other types of meningitis respond to common antibiotics. However, several different drugs must be used to treat gram-negative meningitis since it is typically resistant to normal antibiotics. Ceftazidime is one of the most common types, and other antibiotics may be used as well.
If your infection was caused by a shunt after brain surgery, the shunt may be removed to prevent further infection.
Prevention aims to identify and treat the disease as quickly as possible. Antibiotics are usually prescribed. Gram-negative meningitis is the most difficult type of meningitis to treat. Even though there is a high mortality rate, as high as 80 percent, a full recovery is possible. Recovery is dependent on:
- age: newborns, infants, and the elderly have the highest risk
- how quickly treatment begins
- complications from other conditions, such as brain damage
To prevent getting an infection, practicing good hygiene habits like washing your hands and covering your mouth when you cough will help stop the spread of bacteria. Maintaining a strong and healthy immune system will also help your body fight any potentially harmful bacteria.