What Is Staphylococcal Meningitis?
Staphylococcal meningitis (SM) is a bacterial infection affecting the meninges—the protective covering around the spinal cord and brain. The condition is rare and can be deadly. SM is defined as either community- or hospital-acquired. Both are dangerous; the only difference is where they were obtained. According to the National Institutes of Health, when Staphylococcal meningitis is caused by S. aureus or S. epidermidis bacteria, it is usually a complication of a surgical procedure. (PubMed Health)
Early symptoms of SM are vague and may not be taken seriously because they resemble a cold or flu. They grow more serious as the infection worsens. Diagnosis requires a positive finding of S. aureus or S. epidermidis bacteria. Your doctor may do blood tests and take imaging scans of the brain to aid in diagnosis.
Treatment is difficult because the condition is so rare. Many patients are given the wrong antibiotics upon hospital arrival. Even with correct antibiotics, the risk of death is very high. Those with underlying chronic conditions have a higher risk of mortality.
Risk Factors for Staphylococcal Meningitis
Knowing the risk factors for SM is very important. Risk factors include:
- history of inflammation in your organs
- diabetes (periods of high blood sugar may cause a problem in the blood-brain barrier, making it easier for bacteria to enter the brain)
- history of hospital stays and surgical procedures
- taking immunosuppressant drugs
Causes of Staphylococcal Meningitis
There are two ways a person can contract Staphylococcal meningitis. Hospital-acquired means that you got the infection while being treated at a hospital or nursing home. Community-acquired means that you got the infection outside of the hospital or a healthcare setting. Both infections are treated in the same way.
Once you get the infection, germs must cross the blood-brain barrier in order to infect the brain. The blood-brain barrier is supposed to stop most germs from crossing from the blood into the brain. Once inside the brain, the bacteria infect the meninges.
Diagnosing Staphylococcal Meningitis
Diagnosis is based on clinical tests with positive cultures for the germs that cause the disease. It is necessary to determine which specific type of germ is causing the meningitis in order to treat it properly. According to the Mayo Clinic, the most common causes of meningitis are viruses and bacteria, such as Streptococcus pneumoniae, Neisseria meningitides, Haemophilus influenzae, and Listeria monocytogenes. (Mayo) Staphylococcal meningitis is rare.
In order to correctly identify the type of germ causing the meningitis, your doctor will usually perform the following tests:
- bacterial culture: A swab from the nose or throat is taken. The bacteria are put on a special laboratory culture plate and left to grow. Doctors are then able to identify the type of bacteria present.
- magnetic resonance imaging (MRI): to look for signs of inflammation in the brain
- lumbar puncture (spinal tap): to look for signs of infection in the cerebrospinal fluid (CSF)
- complete blood count (CBC): to look for signs of infection in your blood
Symptoms of Staphylococcal Meningitis
Because the symptoms of SM are common to many other diseases, it can be difficult to use them to diagnose Staphylococcal meningitis.
Common symptoms of SM include:
Less common symptoms of SM include:
- very low blood pressure
- decreased consciousness
Treatment for Staphylococcal Meningitis
Treatment with the correct antibiotics must be given quickly. Blood cultures should let doctors know which medications to prescribe. Most are given intravenously to reach the infection as quickly as possible.
Inappropriate antibiotics that should not be prescribed include ampicillin, erythromycin, and penicillin. Correct antibiotics for treatment include methicillin (unfortunately, most cases of SM are now resistant to this antibiotic), cefuroxime, and dicloxacillin.
Treatment for worsening cases of SM may include mechanical ventilation by mask or throat tube (the brain may not be receiving enough oxygen) and dialysis (the kidneys may begin shutting down).
Outlook for Staphylococcal Meningitis
SM has a very high mortality rate. Many patients receive the wrong antibiotics upon hospital arrival. The rarity of the disease means that physicians do not always suspect its presence.
Even with proper antibiotics, the condition is affecting the most sensitive organ in the body—the brain. Survivors have a high chance of suffering permanent brain damage. Those with underlying conditions (e.g. diabetes, heart disease) have a much higher risk of dying.