What are the other Names for this Condition? (Also known as/Synonyms)

• Acute Bacterial Meningitis
• Bacterial Arachnoiditis
• Bacterial Leptomeningitis

What is Bacterial Meningitis? (Definition/Background Information)

• Bacterial Meningitis is a bacterial infection of the meninges, a protective tissue layer surrounding the brain and spinal cord
• The condition can be contagious (transmitted from one individual to another). It can also be transmitted through germs within the individual’s own body, when the immune system is weak or from surgical procedures, especially involving the brain or spinal cord
• Meningitis can also be caused by a virus, fungus, parasites, and also by other non-infectious causes
• Infection of the meninges leads to an inflammatory response by the immune system of the body that can cause brain swelling, impaired consciousness, seizures, stroke, and even permanent neurological impairment (such as paralysis)
• Bacterial Meningitis is a potentially life-threatening condition and is treated as a medical emergency. The condition is fatal in approximately 3-20% of the cases

Who gets Bacterial Meningitis? (Age and Sex Distribution)

• Bacterial Meningitis can develop very quickly in, otherwise healthy individuals, as well  as in those who are immunocompromised (having a weakened immune system)
• Individuals of all ages can be affected, but certain age groups are more susceptible to infection by specific bacterial types (explained below)
  • Infants less than 2 months old may develop meningitis due to infection by group B streptococcus (GBS), Escherichia coli, or Listeria monocytogenes
  • Infants over 2 months old, children, and adults tend be more affected by Streptococcus pneumonia, Neisseria meningitides, or Haemophilus influenza type B
  • Older adults are also susceptible to Listeria monocytogenes in addition to the microorganisms (mentioned above)
• Both males and females are equally affected

Bacterial Meningitis is seen all over the world, and there is no particular geographical restriction. There is no ethnic or racial preference is observed. An exception to this is Neisseria meningitides infection, which is noted in higher numbers in sub-Saharan Africa, especially in Mecca and Saudi Arabia, during Hajj and Umrah pilgrimage season

What are the Risk Factors for Bacterial Meningitis? (Predisposing Factors)

Individuals with an increased risk for Acute Bacterial Meningitis include:

• Newborns and children who have not received all of their scheduled vaccines
• Immunocompromised individuals
• Those who live or work in close quarters with many others such as in childcare facilities, college dormitories, military bases, etc.
• Pregnant women who consume non-pasteurized dairy products
• Individuals who work with animals
• Individuals with recent pneumonia, sinusitis, or otitis media (ear infection) caused by Streptococcus pneumoniae infection
• Individuals with diabetes, alcoholism, or even a recent head trauma, may be at risk for Bacterial Meningitis

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Bacterial Meningitis? (Etiology)

• Acute Bacterial Meningitis is usually caused by bacteria entering the bloodstream and traveling to the brain or spinal cord. This can occur in many ways such as by an injury to the skull, close contact with individuals having meningitis, or even an ear or sinus infection
• There are many different types of bacteria that cause meningitis. Community-Acquired Bacterial Meningitis is often caused by:
  • Streptococcus pneumoniae
  • Neisseria meningitides
  • Haemophilus influenzae type B
• Some of these bacteria may live in the nose or throat of healthy individuals without causing any illness, but could inadvertently spread to young or susceptible individuals with poor immunity
• Other bacteria, such group B streptococcus, Listeria monocytogenes, or Escherichia coli, and other, can also cause Acute Bacterial Meningitis depending factors such as the age of the individual, existing medical conditions, living conditions, immune status, eating habits, or vaccination history

Prolonged close contact among individuals increases the likelihood of bacteria spread. Outbreaks have been identified on college campuses, military bases, and installations with large populations living in small confined areas.

What are the Signs and Symptoms of Bacterial Meningitis?

Signs and symptoms of Bacterial Meningitis may appear rapidly over a few hours or worsen over a few days. These may include:

• High fever, headache, and stiff neck (in about 90% of the individuals)
• Nausea, vomiting, and sensitivity to light
• Confusion and lethargy
• Seizure (in 40% of the infected individuals)
• Skin rash that spreads over the trunk, legs and feet, palms and soles

In Infants, the symptoms may be non-specific such as fever, decreased activity, increased irritability, vomiting, or poor feeding.

How is Bacterial Meningitis Diagnosed?

Bacterial Meningitis may be diagnosed as follows:

• A thorough evaluation of medical history with a complete physical exam
• Bacterial Meningitis is diagnosed by examining cerebral spinal fluid (CSF) obtained by a spinal tap (lumbar puncture) procedure
  • Typically, CSF will have elevated levels of white blood cells (leukocytes) and protein, and decreased levels of glucose
  • Bacteria may be identified in the CSF, through culture methods or serological tests
  • These tests may help detect the particular type of bacteria so that the proper antibiotics may be administered
• Individuals may also undergo a blood test before a lumbar puncture so that empirical antibiotics (initial treatment) can be started
• Some individuals may need a head MRI or CT scan, especially those with impaired consciousness, to determine if it would be safe to perform a lumbar puncture procedure

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Bacterial Meningitis?

The complications of Bacterial Meningitis include:

• Deafness (may be an immediate or delayed complication in approximately 14% of the cases)
• Paralysis of limbs or eye movements
• Visual impairment
• Depression, fatigue, and sleep disorders
• Memory impairment
• Epilepsy
• Hydrocephalus
• Stroke and coma

How is Bacterial Meningitis Treated?

Acute Bacterial Meningitis is a medical emergency. Individuals should be admitted to a hospital for treatment as soon as possible. Early treatment can help prevent more serious complications from developing in the individual.

• Antibiotic therapy is given as soon as a diagnosis of Bacterial Meningitis is known or even suspected
• Dexamethasone (steroid/corticosteroid) may be given to decrease inflammation and brain swelling and to help prevent permanent brain damage and hearing loss

How can Bacterial Meningitis be Prevented?

Getting vaccinated, as per the recommended vaccination schedule may increase the chances of preventing Bacterial Meningitis.

• Over the last two decades, administration of the Hib vaccine to children has significantly decreased the incidence of Bacterial Meningitis caused by H. influenzae type b
• Vaccines are also available for N. meningitidis and S. pneumoniae bacterium
• Avoiding contact with the infected individuals will help prevent individuals from contracting the condition
• Family members or others who have had close contact with an individual diagnosed with meningitis due to H. influenzae or N. meningitidis may be given antibiotics, such as rifampin, to prevent the spread of the disease

What is the Prognosis of Bacterial Meningitis? (Outcomes/Resolutions)

• Most individuals recover from Bacterial Meningitis with appropriate treatment, but there is also a fairly high death rate (3-20%)
• Permanent brain damage or deficits may result in approximately 25% of the survivors
• Bacterial Meningitis caused by S. pneumoniae and L. monocytogenes have the highest death rates

The likelihood of death increases with several of the following factors:

• Decreased consciousness on admission
• Early seizures after admission
• Signs of increased intracranial pressure
• Very young age or age greater than 50 years
• Presence of other serious medical conditions
• Delay in getting treatment

Additional and Relevant Useful Information for Bacterial Meningitis:

• The annual incidence of Acute Bacterial Meningitis in the United States is approximately 2.5 individuals per 100,000 population
• Information on vaccines to help prevent the condition is available via the U.S. Centers for Disease Control and Prevention (CDC)