Written by Ada’s Medical Knowledge Team
What is bacterial meningitis?
Bacterial meningitis is a bacterial infection of the meninges, the membranes around the brain and spinal cord. It is a serious condition and requires urgent medical treatment.
Many different bacteria can cause bacterial meningitis. Typical symptoms are headache, neck stiffness, fever and vomiting. Symptoms can come on very suddenly, and the affected person can become very sick within a few hours.
Bacterial meningitis is treated with antibiotics, though other treatments might be needed to support the person through the illness. Meningitis can occasionally lead to death, but early recognition and treatment give the best chance of a good recovery. If you become concerned that you or someone you know may have meningitis, you can do a free symptom assessment using the Ada app at any time.
Signs and symptoms of bacterial meningitis
Typical symptoms of bacterial meningitis include:
- Neck stiffness
- Sensitivity to light (photophobia)
Other symptoms include drowsiness and confusion. Some types of meningitis can cause a deep purple, blotching rash.
Symptoms can come on very suddenly, and the affected person can become very sick within a few hours. If meningitis is suspected, it is best to seek medical advice as soon as possible.
Symptoms of bacterial meningitis in infants and young children
In children, the symptoms of bacterial meningitis may be different to those in adults. The symptoms of meningitis in children may not always be clear. It is important to remember that infants and very young children often cannot tell caregivers how they feel, so vigilance is important.
- Fast breathing
- Difficulty breathing
- Excessive, high-pitched crying or moaning, or crying that is noticeably different from the baby’s usual cry
- Lethargy or less activity than usual
- Drowsiness, sleepiness or being difficult to wake up
- Refusal to eat and/or vomiting
- Jerky movements and stiffness, or floppiness
- High fever, above 38 C / 100.4 F, or changing body temperature, i.e. being hot and then cold
- Bulging fontanelle, the soft spot on top of a baby’s head
If seizures occur, or if the baby’s fontanelle is bulging, seek emergency medical help immediately. Small babies with a fever may not necessarily appear to be hot and may in fact shiver. Their hands or feet may be cold, and their skin may be pale, mottled or blue. Children younger than one year of age do not usually have a stiff neck.
In young children, early symptoms indicating that meningitis is developing can include:
- Leg pains
- Cold hands or feet
- Rash (see below)
- Blueness, pallor or duskiness around the lips.
Symptoms of bacterial meningitis in older children, teens, and adults
The classic triad of symptoms of meningitis are a stiff neck, headache and fever, but these are not all present in all cases. However, most people with meningitis tend to have two of the four following symptoms:
- A stiff neck
- Altered mental status, for example confusion, disorientation or unusual sleepiness.
- Pale, blotchy or bluish skin
- Photophobia or discomfort around bright light
- Muscle pain or joint pain
- Abdominal pain or diarrhea
- Cranial nerve problems, such as nonreactive pupils
- Shock, the symptoms of which include low blood pressure, rapid heartbeat, difficulty breathing and low urine output
To check whether someone’s pupils are reactive, shine a small light, for example from a penlight, directly into the eye. If the pupil shrinks and then enlarges again when the light is removed, the pupillary reaction is normal. If this does not happen, the pupils may be nonreactive.
If seizures occur, or the affected person is showing signs of altered consciousness, seek emergency medical help immediately. Seizures affect about three in every ten adults with meningitis.
If the person affected has recently been taking antibiotics, some symptoms may be different or absent. People with suppressed or damaged immune systems may also not show clear signs of meningitis.
If it is not certain that the ill person has meningitis, but it is suspected, seek medical care immediately. It is better err on the side of caution. If you are concerned that you or a loved one may have bacterial meningitis, you can do a free symptom assessment with Ada at any time.
Identifying the rash associated with bacterial meningitis
A rash is one of the most distinctive symptoms of bacterial meningitis in children and adults alike. Although the rash is common, it can be absent. The rash is red or purple in color, and can occur anywhere on the body, including on the palms of the hands or soles of the feet. The spots may resemble tiny bruises.
The rash develops as small spots, which can occur in groups. It is another important feature of the rash associated with bacterial meningitis that it does not go away/fade when pressed.
Good to know: The so-called glass test can be carried out to check whether the rash that the affected person has may be a meningitis-related rash. To do this, take a clear glass and press it against an area of skin affected by the rash. If it still visible when pressure is applied, it may indicate a meningeal infection and emergency medical help should be contacted.
Risk factors and causes of bacterial meningitis
Newborn children are the population group at the highest risk of meningitis, although this condition can affect people of all ages. Males may be slightly more at risk than females. People with other medical conditions, including a recent ear infection or throat infection, or who have had a recent skull fracture, are at increased risk of meningitis.
How bacterial meningitis affects the brain and body
Meningitis occurs when bacteria invade the bloodstream, cross the blood-brain barrier and infect the meninges, membranes that cover the brain and the spinal cord. The meninges are filled with a fluid called cerebrospinal fluid, or CSF. Usually, the blood and brain systems are seperate. Healthy CSF is sterile, meaning it is free from bacteria or other microorganisms.
The bacteria that infect the meninges in bacterial meningitis can come from anywhere in the body, and once they are in the CSF, they multiply, releasing toxins. This causes inflammation of the meninges and the brain, which increases intracranial pressure (ICP), i.e. pressure inside the skull. This increase in pressure causes many of the distinctive symptoms of meningitis, including a stiff neck, headache and sensitivity to light.
Because of the blood-brain barrier, the body’s immune system battles to fight the infection, which causes great stress on the body. White blood cells and other elements of the immune system enter the CSF. The flow of blood components into the CSF means that the amount of blood flowing in the body is reduced, which affects the amount of oxygen available to the muscles and organs. The body tries to maintain its oxygen supply to the vital organs by reducing blood flow to the extremities, resulting in cold hands and feet.
The spread of blood components into the CSF, along with the bacterial infection, can cause the brain to swell, a condition known as cerebral edema. Intracranial pressure increases, causing complications and, in some cases, death.
Bacterial meningitis can result in complications that affect cognitive functioning if not treated in time and is often fatal if not treated. Concerned that you or someone you love might have meningitis? Start your free symptom assessment with Ada at any time.
Conditions that increase the risk of developing bacterial meningitis
Some medical conditions can increase the vulnerability of certain people to bacterial meningitis. These include some chronic conditions, recent bacterial infections and some surgical procedures of the skull and head.
Chronic conditions which increase the risk of catching bacterial meningitis include:
- Diabetes mellitus
- Chronic kidney problems
- Cystic fibrosis
- Sickle cell disease
- Thalassemia major
- Congenital malformations of the brain membranes, spinal cord or skull
- Hypoparathyroidism, or an underactive parathyroid gland
- Having an underactive spleen or no spleen
- HIV infection or Acquired Immune Deficiency Syndrome (AIDS)
- Cirrhosis of the liver
Other factors which increase a person’s risk of developing bacterial meningitis include:
- Being very young or very old
- IV drug use
- An infection elsewhere in the body, such as otitis media, mastoiditis, bacterial sinusitis, bacterial endocarditis, or pneumonia
- Recent cranial surgery
- Cranial shunts or stents
- Head injuries that penetrate the scalp, meningeal membranes, and/or skull
- Crowding, for example in a military barracks or student dormitory
- Exposure to someone with bacterial meningitis
Various bacteria can cause meningitis. The ones most often encountered include:
- Haemophilus influenzae
- Staphylococcus aureus or Staphylococcus epidermidis
- Pneumococcus, also known as Streptococcus pneumoniae
- Meningococcus, also known as Neisseria meningitidis
- Mycobacterium tuberculosis, although this is rare
Other bacteria which can cause meningitis include:
- Escherichia coli
- Pseudomonas aeruginosa
- Listeria monocytogenes (see FAQs)
Meningococcal meningitis is caused by a bacteria known as Neisseria meningitidis. Rates of meningococcal meningitis are dropping in the developed world, largely due to the availability of a vaccine against Meningococcus C. Meningococcal infection can cause septicemia or meningitis, or both (see FAQs).
Many people carry meningococcal bacteria in their nose and throat, where they are quite harmless. These bacteria have to breach the immune system in order to cause an infection, and they tend to cause only isolated cases or small outbreaks. These bacteria can be passed on by contact such as kissing, sneezing or coughing.
However, meningococcus is endemic to certain developing countries in Asia and Africa. It is a common cause of meningitis associated with overseas travel. Muslim pilgrims on the Hajj are particularly at risk. Travellers to these regions should ask their physicians about the possibility of getting the meningococcus C vaccine; vaccinations against meningococcus A, W135 and Y may also be useful.
Severe pneumococcal infections are more common in developing countries. Like meningococcus, pneumococcus can cause meningitis and septicemia, but many people carry it harmlessly in their noses and throats, and infections can only happen if the bacteria breach the immune system.
Meningitis caused by pneumococcus can be more severe than that caused by meningococcus, and is associated with somewhat higher mortality. However, vaccines against pneumococcal meningitis are available. If you are worried that your or someone you know may have bacterial meningitis, you can do a free symptom assessment with Ada at any time.
Diagnosing bacterial meningitis
Diagnosis is based on the symptoms, the physical examination and tests which confirm the presence of a severe infection in the body. A sample of cerebrospinal fluid, the fluid in the meninges around the brain and spinal cord is taken and tested for the specific bacteria causing the infection. When bacterial meningitis is suspected, antibiotic therapy should be started right away.
Also known as a spinal tap, a lumbar puncture is a crucial part of the diagnostic process for bacterial meningitis. A lumbar puncture is done to obtain a sample of cerebrospinal fluid, which is then sent for laboratory testing. Lumbar punctures are usually quite safe, though may be a little tender or painful afterwards.
A lumbar puncture is done under local anesthetic, and a needle is inserted into a gap between two lumbar vertebrae in the lower back. A needle is used to draw off a small amount of fluid from around the spinal cord. The spinal cord itself is not touched.
Good to know: Some affected people, especially those who have already had a seizure, are at increased risk of high intracranial pressure. Performing a lumbar puncture on someone with highly elevated intracranial pressure increases the risk of brain herniation (see FAQs). These people will require a CT scan first. The attending physicians will determine who may need a CT scan.
Blood and CSF tests
The CSF sample taken during the lumbar puncture will be analysed to confirm the presence of bacteria, determine what kind of bacteria are causing the infection, and determine how far along the infection is.
Blood tests may also be carried out to check organ function and dehydration. These results will guide the treatment.
Treating bacterial meningitis
Bacterial meningitis is a serious condition and requires urgent medical care. The infection is treated with intravenous (IV) antibiotics, i.e. through a drip. People with bacterial meningitis are often very sick and may need other supportive treatment, such as fluids to increase blood pressure while the antibiotics work to fight the infection. Most people with suspected bacterial meningitis will also be isolated after being admitted to hospital.
Antibiotic treatment of bacterial meningitis
Most cases of bacterial meningitis are treated with intravenous antibiotics administered as soon as possible. Because the treatment often begins before the exact bacteria responsible is identified, the antibiotics used may change. Also, as some of the bacteria that cause bacterial meningitis are becoming drug-resistant, several antibiotics may have to be tried before treatment is successful. Antibiotics commonly used to treat bacterial meningitis include:
Good to know, although it is not an antibiotic, dexamethasone may be used in infants.
Supportive treatment for bacterial meningitis
People with meningitis will be treated as inpatients in hospital, and most will need to be in intensive care for a short time. They will be monitored for seizures, dehydration, coughing or straining (which can increase intracranial pressure), pain, fever and hypotension (low blood pressure). There is some evidence that administering corticosteroids reduces inflammation, which decreases the risk of some complications.
Complications of bacterial meningitis
Because meningitis involves a severe infection of the brain and the spinal cord, and also affects the body as a whole, complications are common. Even with prompt treatment, almost three in ten survivors of meningitis have neurological complications of some kind, with one in seven experiencing serious long-term problems.
The severity of the bacterial infection in meningitis can cause short-term complications such as:
- Cerebral edema
- Pericardial effusion
- Hemolytic anemia
- Septic arthritis
- Peripheral gangrene
- Waterhouse-Friderichsen Syndrome
Severe bacterial infections, such as bacterial meningitis, can cause a rare complication called Waterhouse-Friderichsen Syndrome, a condition in which the adrenal glands fail due to bleeding. The syndrome causes bleeding throughout the body and, because of the damage to the adrenal glands, adrenal insufficiency. Symptoms include:
- A rash, which begins as small, pink patches or pimple-like swellings, which expand into larger, purple patches
- Malaise and weakness
- Joint and muscle pain
- Nausea and vomiting
- Low blood pressure
- Fast heart rate
Good to know: Low blood pressure and fast heart rate are signs of shock. People showing these symptoms should receive prompt medical attention.
Most cases are caused by severe infection with meningococcal bacteria, Group B streptococcus, Streptococcus aeruginosa, Staphylococcus pneumoniae or Staphylococcus aureus.
Waterhouse-Friderichsen Syndrome is a medical emergency and anyone who shows symptoms of the syndrome should receive medical care immediately. Treatment is usually carried out in an intensive care unit (ICU), and is supportive while using antibiotics and glucocorticoids. However, due to the severity of the syndrome, affected people may die of sepsis.
- Hearing loss
- Sight loss or blindness
- Ataxia, loss of coordinated muscle movements
- Seizures or epilepsy
- Learning and motor difficulties
- Cranial nerve dysfunction, which can affect the facial muscles, smell, sight and taste
- Hydrocephalus, or fluid buildup in the brain
- Organ damage, for example kidney damage
- In children, damage to growth plates of the bones leading to impaired growth
Preventing bacterial meningitis
Some common causes of bacterial meningitis are preventable by vaccine. Keeping to the recommended vaccination schedule can help prevent some cases of meningitis. Good hygiene, such as washing hands, can also help to avoid some cases of bacterial meningitis.
In many countries, children are routinely vaccinated against Haemophilus influenzae, meningococcus and pneumococcus. It is possible to be vaccinated as an adult.
Post-exposure prophylactic antibiotics
People who have been in contact with someone with bacterial meningitis, especially meningococcal meningitis and pneumococcal meningitis should be offered a short course of preventative antibiotics. Rifampin or ceftriaxone in prophylactic doses is offered to:
- Housemates and family members living with the affected person
- Classmates or people in the same school dormitory
- People living in the same student accommodation or military barracks
- Paramedics who were in contact with the affected person
Q: How is bacterial meningitis related to septicemia?
A: Some cases of bacterial meningitis are caused by a bacteria called Neisseiria meningitidis, which is also known as meningococcus. Meningococcus can also cause meningococcal septicemia, a blood infection that can be very serious, especially for young children and babies. Meningococcal meningitis and meningococcal septicemia are both types of meningococcal disease; meningococcal septicemia is also sometimes called meningococcemia. Meningitis and septicemia are both medical emergencies, and if you suspect that you or a loved one has meningitis or septicemia, you should seek medical care as soon as possible.
Q: What are the symptoms of septicaemia?
A: The symptoms of meningococcal septicemia, like the symptoms of meningitis, can come on suddenly, and the affected person can become very ill within hours. The symptoms of meningococcal septicemia include:
- Cold hands and feet
- Pale, mottled or blue skin
- Rapid heartbeat
- Vomiting and nausea, sometimes with diarrhea
- Abdominal pain, muscle pain, joint pain and/or chest pain
- Low urine output
- Rapid breathing, labored breathing or grunting while breathing
- Low blood pressure
- A purple rash on the skin that does not fade when pressed
Not all affected people will have all of these symptoms. If the rash is present, or if the affected person has lowered blood pressure, the infection is serious and an ambulance should be called. All cases of septicemia will require urgent medical care, and it is essential that medical care is sought as soon as possible. The chances of a good outcome are improved if the disease is spotted early. Parents of small children or the caregivers of people who are at risk of septicemia should be on the lookout for:
- Vomiting and nausea
- Pain in the legs
- Cold hands and/or feet
- Pale, mottled or bluish skin
These are the earliest symptoms; others may appear as the infection continues. It is possible to have meningococcal septicemia and meningococcal meningitis at the same time. For the symptoms of meningococcal septicemia, see above. If you are concerned that you or a loved one may have meningococcal meningitis or septicemia, start a free Ada symptom assessment now.
Q: What is the difference between viral and bacterial meningitis?
A: Viral meningitis is also known as aseptic meningitis. Viral meningitis is a serious medical problem in itself, and anyone who might have it should seek medical help as soon as they can, but it is usually less serious than bacterial meningitis. It is much more common than bacterial meningitis.
Most cases of viral meningitis in people with healthy immune systems clear up on their own within a week or so, and complications are not common. However, everyone who presents with the symptoms of meningitis should seek urgent medical care, as it is not possible to tell whether meningitis is caused by bacteria or viruses just by looking at the symptoms.
Q: What is the treatment for viral meningitis?
A: Some people with severe viral meningitis may need to be hospitalized for a short period, but generally the treatment is aimed at relieving the symptoms. It is important to stay well-hydrated, and the pain and fever can be managed with acetaminophen/paracetamol or, in adults, aspirin. However, everyone who presents with the symptoms of meningitis should seek urgent medical care, as it is not possible to tell whether meningitis is caused by bacteria or viruses just by looking at the symptoms.
Some kinds of viral meningitis can be prevented by vaccines which prevent the diseases that can lead to viral meningitis. Diseases associated with viral meningitis, which a person can be vaccinated against, include the chickenpox, [measles], mumps and influenza vaccines.
Q: Can meningitis be caused by fungi, parasites or amebas?
A: Yes. Though rarer than viral or bacterial meningitis, fungi, parasites and amebas can all cause meningitis in some instances.
Fungal meningitis is rare in the developed world, but can be caused by Cryptococcus, Histoplasma, Blastomyces, or Coccidioides. Most of these fungal organisms are found in soil contaminated by bird or bat droppings. Candida, another fungus that can cause meningitis, is usually found in hospital settings. Fungal meningitis cannot be passed from person to person.
Parasitic meningitis can be caused by parasitic nematodes (worms) and roundworms. Most cases are found in people who have travelled to Southeast Asia and eaten contaminated meat or fish, seafood, eggs, snails or fresh produce washed in contaminated water. However, a roundworm called Baylisascaris procyonis is found in raccoon droppings in North America. Parasitic meningitis is quite rare.
Amebic meningitis is very rare, but very serious. It is caused by a water-dwelling ameba called Naegleria fowleri, which is found in unchlorinated water, i.e. warm freshwater bodies such as lakes and swimming holes, bodies of water contaminated by warm industrial discharges, poorly-maintained swimming pools, untreated drinking water, or dirty water heaters. The organism requires warm conditions to survive, and cannot survive in saltwater.
Q: Does Haemophilus influenzae cause the flu?
A: No. Despite the name, viruses that cause influenza are not related to Haemophilus influenzae, which is a bacterium. Influenza is a viral disease caused by a type of orthomyxovirus. Haemophilus influenzae was named by its discoverer during an influenza epidemic in the late 1800s; at that time, it was not known that viruses caused influenza, and the disease was thought to be caused by bacteria.
Q: Who is at risk from Listeria monocytogenes infection?
A: Listeria monocytogenes is a bacterium that is often found as a food contaminant, and most cases of infection, also known as listeriosis, are the result of consuming contaminated food. It does not often cause meningitis, but as listeria-related meningitis has a high mortality, it is important to be vigilant about outbreaks of listeria. People at increased risk of developing meningitis after a listeria infection include:
- Pregnant women
- Infants and young children
- People over 60 years of age
- Immunosuppressed individuals
- People with diabetes
- People with chronic kidney or liver disease.
Q: What is a brain herniation?
A: A brain herniation occurs when high pressure or a change in pressure causes the brain, blood vessels within the brain, or cerebrospinal fluid to move out of their usual position. The brain tissue may be pressed out through an injury in the skull or one of the skull’s natural internal openings, for example the foramen magnum, the hole in the base of the skull through which the spinal cord passes from the brain into the spine. Brain herniation is a serious medical condition, and treatment is essential. Neurological damage or death may result from a brain herniation.
Q: How is the risk of brain herniation minimized during the diagnosis of bacterial meningitis?
A: The most common method of keeping the risk of brain herniation to a minimum is to give the affected person at CT scan before the lumbar puncture is carried out. CT scans are not generally considered to be a standard requirement in the diagnosis of meningitis, but they are an important precaution to prevent brain herniation following a lumbar puncture. People who have the following conditions may need to have a CT scan before a lumbar puncture can be carried out:
- A history of stroke or other central nervous system problems
- Seizures within the previous seven days
- Altered or reduced consciousness
- A very severe headache
- A possible neurological deficit, such as nonreactive pupils or gaze palsy, a condition that affects the ability of the eyes to move in the same direction simultaneously.
Minnesota Department of Health. “Normally Sterile Sites: Invasive Bacterial Diseases.”. Accessed 2 August 2018. ↩
Government of South Australia Health. “Viral meningitis - including symptoms, treatment and prevention.”. Accessed 3 August 2018. ↩