Meningitis is an inflammatory disease in which the membranes surrounding the brain and spinal cord (meninges) get inflamed and swell up, usually because of an infection. This infection can be bacterial, viral or fungal in nature. Meningitis can also be caused by chemical reactions and drug allergies. Viral meningitis is the most common form of meningitis and it is usually not life-threatening. While most people with meningitis do recover, it can cause severe complications such as hearing loss and brain damage.

Bacterial meningitis can be caused by several different strains of bacteria. Streptococcus pneumoniae (pneumococcus) is a type of bacteria, which causes pneumonia as well as ear and sinus infections. It is a common cause of bacterial meningitis in the elderly. Other strains of bacteria that can cause bacterial meningitis in the elderly are Neisseria meningitidis and Listeria monocytogenes. Contaminated foods such as unpasteurised dairy products and processed meats are known sources of Listeria monocytogenes.

Some forms of bacterial meningitis are contagious and can spread from person to person through coughing, sneezing and kissing. It is particularly contagious in communities where there is close contact among members. An important example is that of the meningococcus. Most bacteria are not as contagious as our common cold and flu viruses. You can get Listeria meningitis only from contaminated​ food.

“Some bacteria can enter the upper respiratory tract and travel through the bloodstream to the brain and spinal cord,” says Dr Limin Wijaya​, Senior Consultant, Department of Infectious Diseases, Singapore General Hospital (SGH), a member of the SingHealth​ group. “The bacteria can also directly invade the meninges as a result of an ear or sinus infection, or a skull fracture.”

Adults and the elderly with the following medical conditions are susceptible to bacterial meningitis:

1. Chronic nose and ear infections
2. Pneumococcal pneumonia
3. Diabetes
4. Kidney failure
5. Sickle cell disease
6. Head injury

“You are also at higher risk of bacterial meningitis if you have had your spleen removed,” says Dr Wijaya.

Some forms of bacterial meningitis can be prevented with a vaccination.

Adults can be protected against Streptococcus pneumoniae with the pneumococcal vaccine.​

Read on for the symptoms and treatment of bacterial meningitis.

Ref. Q15