Pneumococcal Meningitis: An Overview

What Is Bacterial Meningitis?

Meningitis is the inflammation of the two inner layers surrounding (leptomeninges) the brain and spinal cord. When bacteria cause it, we call it bacterial meningitis. This type of infection affects an individual abruptly and turns fatal. If left untreated, meningitis can cause the death of the individual. Sometimes those who recover from meningitis show permanent disabilities, such as stroke (brain damage due to blood supply interruption), brain damage (destruction of brain cells), learning disabilities, loss of hearing, or paralysis.

What Are the Symptoms of Bacterial Meningitis?

The classic bacterial meningitis symptoms are as follows:

• Stiffness of the neck (nuchal rigidity).

• Headaches.

• Fever.

• Discomfort with bright lights (photophobia).

• Discomfort with loud noises (phonophobia).

• Mental confusion due to impaired brain function.

• Reddish bruises on the skin (petechial rashes).

• Altered mental state and seizure (uncontrolled electrical activity in the brain cells) if there is meningoencephalitis (inflammation of the brain, meninges, or membrane).

• Feeling sleepy, lethargic, and irritable.

• Goes to a comma in advanced infection.

• If the brainstem is involved, it may cause cranial nerve paralysis (palsies).

• Weakness in one-half of the body.

What Bacteria Cause Meningitis?

Various bacteria cause different types of bacterial meningitis. For example;

• In newborns, the main causes of bacterial meningitis include bacteria, such as Group B streptococci (Group B streptococcal meningitis), E-coli, and Listeria monocytogenes (Listeria meningitis).

• Among children and teens, it is usually Neisseria meningitis (Meningococcal meningitis) and Streptococcus pneumoniae (Pneumococcal meningitis).

• In adults and the elderly, Streptococcus pneumoniae and Listeria monocytogenes cause meningitis. Sometimes, tubercular meningitis is caused by Mycobacterium tuberculosis bacteria which also causes tuberculosis (contagious bacterial disease of the lungs). Hemophilus influenza, Salmonella, and Gram-negative bacilli, such as Klebsiella pneumoniae, also cause meningitis.

How Does One Catch Bacterial Meningitis?

Bacterial meningitis is caused by the spread from one to another through droplets produced at coughing, sneezing, kissing, or staying in close contact. In addition, some bacteria spread through contaminated food and water. Infection can spread to the CSF (cerebrospinal fluid) through two routes:

1. Direct Spread: When the bacteria get inside the skull or vertebral column first, then penetrate the meninges, eventually ending up in the CSF. Sometimes, the pathogen will come in through the overlying skin or anatomical defects in the skull. This can be due to the following:

• A birth defect like spina bifida.

• Basal skull fracture where CSF might be leaking through the sinuses.

• A cribriform plate defect.

• Middle ear infection (otitis media), sinusitis (inflamed or swollen tissue lining of the sinuses), or mastoiditis (acute otitis media).

2. Indirect Spread: When a pathogen enters the bloodstream and moves through blood vessels crossing the blood-brain barrier layer and getting into the CSF. Example: pneumonia (a lung infection caused by inflamed sir sacs due to fluid or pus buildup) and sepsis (a condition that occurs due to the body’s improper response to infection).

What Are the Risk Factors for Catching Meningitis?

The following category of individuals are at a higher risk of catching meningitis:

• Those who are suffering from HIV (human immunodeficiency virus) infection or some other condition that lowers immunity.

• Those with damaged or missing organs like the spleen.

• Those who have not taken preventive vaccines.

• Those who are born with or acquired structural abnormalities in the skull and vertebral column.

• Newborn babies are at definite risk for meningitis.

• Those who have been exposed to large groups at the time of infectious outbreaks.

• Those who have been exposed to certain parts of the world have a high attack rate of meningitis.

What Are the Causes of Bacterial Meningitis in Newborns?

Newborns develop meningitis at birth from the mother most of the time. A pregnant mother may pass on a Listeria or Group B Streptococcus bacteria to the infant at the time of delivery. If untreated, it turns out to be a life-threatening condition for the baby. The infant may exhibit inactivity, breathing difficulty, high-pitched crying, irritability, unstable body temperature, seizures, poor sucking and feeding, vomiting, abnormal reflexes, and swelling (bulging fontanelle) on top of the head.

What Are the Complications of Bacterial Meningitis?

It normally starts when a foreign-body-like bacteria makes its way inside the leptomeninges, either by direct contact or through the bloodstream (hematogenous spread). There is a fluid known as cerebrospinal fluid (CSF) present between the layers of the leptomeninges, cushioning the brain from physical impacts and providing nutrients. Once the bacteria find a way into the CSF, it starts to multiply. The immune system responds to this invasion by flooding the space with white blood cells. In addition, they release chemicals called cytokines resulting in inflammation. If treatment is delayed, the inflammation build-up will increase the pressure around the brain, causing injury and damage. Sometimes, the infection may pass on to the brain and cause meningoencephalitis. As a result, the individual may suffer a loss of consciousness, progress to a state of unconsciousness, and die.

How Is Bacterial Meningitis Diagnosed?

Diagnosis starts with a thorough review of the medical history and an analysis of the symptoms. A physical examination follows this to look for the features below:

• Kernig’s Sign - The person, lies flat on their back facing upwards, and one of their legs is raised with the knee flexed to a 90-degree angle. Holding the leg, try to straighten the knee slowly. It is observed whether this causes back pain.

• Brudzinski’s Sign - The person lies flat on their back facing upwards and has their neck supported and flexed if this causes them to bend their knee or hips automatically.

• Stiff Neck - Not able to flex the neck by oneself or with the doctor’s help.

• Abnormal stiffness of the body posture.

• Asymmetry between two sides of the body along with reflexes.

The following tests are also confirmatory for bacterial meningitis:

• Spinal Tapping or Lumbar Puncture - A needle is forced into the lower back portion of the vertebral column to enter the spinal cord, and a few milliliters of CSF are taken. This sample is analyzed in the laboratory for the number of white blood cells, protein, glucose, and more.

• The pressure applied by the CSF is compared against the blood pressure to see if there is an increase.

• Other blood tests to check the presence of bacteria.

• The doctor might order a computed tomography scan (CT) of the brain to look for underlying infection causes like fractures and structural abnormalities.

How Is Bacterial Meningitis Treated?

Bacterial meningitis treatment involves reducing the complications associated with meningitis. It mainly depends on the underlying cause. For bacterial meningitis, steroids like Dexamethasone are initially administered, followed by an antibiotic. This is to prevent massive injury to the leptomeninges from inflammation. The most effective antibiotics for bacterial meningitis are Cefotaxime, Ceftriaxone, Vancomycin, Ampicillin, and Benzylpenicillin. In affected communities and households where individuals are not vaccinated, doctors usually administer prophylactic antibiotics to avoid outbreaks of bacterial meningitis. It is highly recommended to people who are aged or immunocompromised as well.

How Is Bacterial Meningitis Prevented?

Prevention with a vaccine is the most appropriate way to safeguard against bacterial meningitis. Currently, there are vaccines like the pneumococcal vaccine, meningococcal vaccine, and Hemophilus influenza vaccines available at predetermined schedules for early prevention.

Conclusion:

Bacterial meningitis is a disease with a sudden onset, rapid progression, and severe complications. But it can be prevented to a large extent by early vaccination and by creating awareness of its ways of spreading. The occurrence of bacterial meningitis has drastically reduced over the past years due to timely vaccinations. Still, this is one disease with high death rates if left untreated. If in doubt that one has symptoms of meningitis, getting the help of a medical professional at the earliest is crucial to avoid long-term complications.