Bacterial Meningitis

Bacterial meningitis is an infection of the protective membranes that cover the brain and spinal cord (the meninges). Though it's a serious condition, it's also relatively rare and early diagnosis and treatment can lead to a full recovery. Understanding the causes, symptoms, and risk factors of bacterial meningitis is important to protect yourself and the people around you.

Bacterial meningitis is a disease that can affect anyone, but with the proper knowledge, you can take the necessary steps to prevent it from happening and seek early treatment if it does. From the early signs to watch out for, to the treatments available and prevention methods, in this article, we will take a closer look at everything you need to know about bacterial meningitis.

• Bacterial Meningitis Symptoms
  • Medical Signs of Bacterial Meningitis
• Causes of Bacterial Meningitis
• Bacteria that Cause Bacterial Meningitis
• Treatment for Bacterial Meningitis
• Vaccine against Bacterial Meningitis
• Precautions against Bacterial Meningitis
• Viral vs Bacterial Meningitis

Bacterial Meningitis Symptoms

Meningitis is a medical term that means "inflammation of the meninges". The meninges are three layers of membranes that cover your brain. Different organisms can lead to irritation, infection, or inflammation of the meninges, such as bacteria, viruses, fungi, and mycobacteria (like tuberculosis), but in this article we will focus on the bacteria that can cause it.

Symptoms of meningitis are essentially the same regardless of the organism that is causing it. There are four such symptoms, which include:

1. Headache
2. Neck stiffness (called nuchal rigidity)
3. Nausea
4. Fever

Some affected people may have vomiting. Often, people may have seizures as well.

Also, people with meningitis may have photophobia or (less commonly) phonophobia. Photophobia means an affected person will avoid light hitting their eyes, and phonophobia means they will avoid or be averse to hearing sounds.

Other symptoms differ by the particular bacterial agent causing this episode of meningitis.

For example, Neisseria meningitis typically also has a rash. The rash is called a petechial rash, which means small reddish or purplish spots are present on the skin. These occur due to breaks of tiny capillaries that course through and around the skin (Fig. 1).

symptoms of meningitis

Medical Signs of Bacterial Meningitis

We've discussed the symptoms of meningitis, so what of the signs? Medically, signs and symptoms differ in terms of who can view them. Symptoms are things that patients and affected people experience or see for themselves. For example, a patient could report to his doctor that he felt nauseous, he could say that he was vomiting, someone else could report that he was witnessed having a seizure, and so on.

Signs refer to doctors' maneuvers or tests to determine if the patient has meningitis. Important signs doctors make a note of in cases of suspected bacterial meningitis include the following:

Kernig sign

Kernig sign is a manoeuvre a doctor might do to a patient who possibly has an episode of acute meningitis. The patient will be asked to lie on their back (in the supine position) and bend their hip so that it's ninety degrees from the medical table they are lying on. When their hip is up in this manner, the patient's knee will be extended to line up straight with the hip. If a person has bacterial meningitis, they will either not be able to straighten their knee or feel a lot of pain while trying to do so. In either case, that is called a positive Kernig sign.

Brudzinski sign

This manoeuvre also starts with a patient lying on their back. However, this time the doctor tries to move the patient's neck. Specifically, a doctor checking the Brudzinski sign will push the patient's head and neck forward in a flexion movement. If flexing the neck forward causes the patient to spontaneously and involuntarily also bend (flex) the knee, this is called a positive Brudzinski sign and is a sign of meningitis.

The fluid that collects throughout and around your brain and spinal cord (the elements of your central nervous system) is called CSF or cerebral spinal fluid. If a bacterial agent is irritating and infecting your meninges, the contents of your CSF will give many hints to demonstrate that. Therefore, specific doctors are licensed to give patients lumbar punctures, also known as spinal taps, where a needle is inserted into the spinal canal and CSF fluid is collected. This fluid is then tested for white blood cells (which will be increased due to the infection), red blood cells (which normally shouldn't be present in CSF but might be with certain head traumas or infections), and other things like proteins and sugars.

Blood test

Usually, blood tests are one of the first tests done when someone goes to the hospital and appears very sick (as they do in bacterial meningitis), and for a good reason. We can see the white blood cell count, check anemia, and even do cultures of the blood itself to test if there are any pesky organisms lying in it that might be causing the person's ill appearance. In bacterial meningitis, the bacteria that are causing the meningeal infection are often present in the blood. When the doctors do blood culture, they find this organism and decide which antibiotics to give based on what the specific bacterium is sensitive to.

Causes of Bacterial Meningitis

The infection is usually spread through the exchange of respiratory and throat secretions, such as when an infected person coughs or sneezes, and the droplets from their nose or mouth are inhaled by someone else. Close personal contact, such as sharing eating utensils or kissing, can also spread the infection.

People who have a weakened immune system, live in close quarters with many people, travel to countries where the disease is more common, have certain medical conditions or have a head injury or ear infection are at increased risk of developing bacterial meningitis.

Bacteria that Cause Bacterial Meningitis

Bacterial meningitis is caused by various types of bacteria, the most common of which are Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. These bacteria can infect the protective membranes that cover the brain and spinal cord, leading to inflammation and the potential for severe complications.

Which strain of bacteria is more likely to cause meningitis on each individual depends on the age of said individual though.

Although this lesson is exclusively about bacterial meningitis, it's important to remember that other causes of meningitis (particularly viral) exist and affect people at even higher rates than most forms of bacterial meningitis. Especially in adults (both young and middle-aged), viral meningitis, like herpes meningitis and coxsackievirus meningitis, are major causes of meningeal signs.

Treatment for Bacterial Meningitis

When someone is rushed to the ER because they are having a seizure, they're vomiting, they suddenly have a very high fever, and their neck is stiff, what do doctors do to treat this presumed case of meningitis?

Well, there are two general styles of treatment—either empiric treatment or specific treatment to the bacterial agent.

Doctors often give empiric treatment for meningitis. Empiric treatment covers most (if not all) of the possible organisms or factors that can lead to the illness or disorder a patient has. Empiric treatment does not require taking blood tests or cultures, MRIs or CT scans, lumbar punctures, or x-rays to find out exactly what is causing a case of meningitis. Instead, three "broad spectrum" antibiotics are given that cover almost all known causes of bacterial meningitis.

Empiric treatment is essential in severe and life-threatening infections like meningitis because taking time to diagnose the specific bacteria causing the infection may be a very dangerous prospect.

Specific treatment can be given and usually is after empiric treatment. Often, doctors give initial empiric treatment while they wait for the results of all their tests to come back. Once they know the specific organism causing meningitis, they can provide the specific treatment.

Vaccine against Bacterial Meningitis

Thankfully, bacterial meningitis can be treated and prevented. The three most common causal agents of bacterial meningitis: S. pneumoniae, N. meningitides, and H. influenzae; all have vaccines against them. These vaccines are given routinely; they are given to every child during their initial years of life. These were one of the many immunization injections given to you at the checkups you had with your pediatrician as a baby and child.

Meningitis is a terrible illness, so everyone needs to complete their vaccination series. If people have not completed them all as children, they are usually advised to do so in adulthood, with adult versions of these vaccines.

Precautions against Bacterial Meningitis

There are preventative and cautionary measures that people can take to reduce their risk of contracting bacterial meningitis.

The first is to complete the vaccine series for all vaccinable meningitis causes. Catch-up vaccines are available if the series' were not completed in childhood. Also, extra vaccines are available to immunodeficient people or at increased risk for some of these bacterial infections (like older people, people with sickle cell disease, people without spleens, etc.).

Other precautions against bacterial meningitis are more non-specific.

Washing hands, covering your nose and mouth during sneezes or coughs, and keeping away from other people who appear ill, are all recommended behaviors to avoid meningitis. People who live or work in crowded environments, like university students in dorms or soldiers in barracks, are at higher risk than others and should take these precautionary measures even more seriously.

Viral vs Bacterial Meningitis

Bacterial meningitis and viral meningitis are both infections of the protective membranes that cover the brain and spinal cord, also known as meninges. However, they are caused by different types of microorganisms and have different symptoms, severity, and treatment.

Table 2. Comparison between bacterial and viral meningitis.

Bacterial meningitis

Bacterial meningitis is caused by different types of bacteria, such as Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae. It is a serious and potentially life-threatening infection that requires prompt diagnosis and treatment. Symptoms include severe headache, stiff neck, fever, nausea, vomiting, sensitivity to light, confusion and drowsiness. Bacterial meningitis can lead to severe complications such as brain damage, hearing loss, and even death. It is treated with antibiotics.

Viral meningitis

Viral meningitis is caused by different types of viruses, such as enteroviruses, herpes simplex virus and mumps virus. It is generally less severe than bacterial meningitis, and most people recover completely without treatment. Symptoms are similar to those of bacterial meningitis but usually less severe and they may include headache, fever, nausea, vomiting, and a stiff neck. In many cases, viral meningitis is self-limiting and the symptoms resolve in a few days. Antiviral medications may be used in some cases, but in most cases, supportive care and rest are the main treatments.

It's important to note that early diagnosis and treatment are crucial for both bacterial and viral meningitis, and it's important to seek medical attention if you experience symptoms of meningitis.