Bacterial meningitis
Bacterial meningitis is a serious infection that affects the protective layers surrounding the brain and spinal cord, known as the meninges. It is primarily caused by three types of bacteria: Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type B (Hib), with incidence rates significantly reduced in areas with widespread vaccination. The infection often begins as an upper respiratory tract infection before bacteria enter the bloodstream and reach the central nervous system. Symptoms can escalate rapidly and typically include high fever, severe headache, and a stiff neck, while infants may exhibit subtle signs such as irritability and feeding difficulties. Diagnosis involves a thorough medical history, physical examination, and tests like a spinal tap to identify the bacterial cause. Immediate treatment with antibiotics and corticosteroids is critical to improve survival rates and mitigate complications. Prevention strategies include vaccination and proper food safety practices, especially for vulnerable populations such as infants and the elderly. Understanding bacterial meningitis is essential for timely intervention and effective prevention.
Bacterial meningitis
Anatomy or system affected: Brain, central nervous system, respiratory system, spinal cord, tissue
Also known as: Spinal meningitis
Definition
The brain and spinal cord are encased by layers of tissue. These layers are called the meninges. Certain bacteria can cause an infection in these layers called bacterial meningitis, a serious infection that can cause death within hours. A quick diagnosis and treatment are vital.
Causes
Many times, the bacteria first cause an upper respiratory tract infection. Then the bacteria travel through the bloodstream to the brain. Worldwide, three types of bacteria cause the majority of cases of acute bacterial meningitis: Streptococcus pneumoniae (the bacterium that causes pneumonia); Neisseria meningitidis ; and Haemophilus influenzae type B (Hib). In the United States, widespread immunization has almost eliminated meningitis caused by Hib. Other forms of bacterial meningitis include Listeria monocytogenes meningitis, Escherichia coli meningitis, Mycobacterium tuberculosis meningitis, and group B Streptococcus meningitis.
Newborn babies and the elderly are more prone to get sick. Some forms are spread by direct contact with fluid from the mouth or throat of an infected person. This can happen during a kiss or by sharing eating utensils. In general, meningitis is not spread by casual contact.
Risk Factors
Risk factors for bacterial meningitis are close and prolonged contact with persons with meningitis caused by Hib or N. meningitidis; a weakened immune system caused by human immunodeficiency virus (HIV) infection or other conditions; alcoholism; smoking (for meningitis caused by N. meningitidis); and living in proximity to others, such as in dormitories and military barracks (for meningitis caused by N. meningitidis). At higher risk are infants, young children, and persons sixty years and older. Rates of bacterial meningitis have declined since the 1990s, with the Centers for Disease Control and Prevention reporting 371 cases in 2019. The World Health Organization estimated, as of 2021, 1.2 million people worldwide contract bacterial meningitis each year. Despite access to treatment, one in ten will die.
Symptoms
Classic symptoms can develop over several hours or may take one to two days. These symptoms are a high fever, headache, and a stiff, sore neck. Other symptoms may include red or purple skin rash, cyanosis (bluish skin), nausea, vomiting, photophobia (sensitivity to bright lights), sleepiness, and mental confusion.
In newborns and infants, symptoms are hard to see. As a result, infants younger than three months of age with a fever are often checked for meningitis. Symptoms in newborns and infants may include inactivity; unexplained high fever or any form of temperature instability, including a low body temperature; irritability; vomiting; jaundice (yellow color to the skin); feeding poorly or refusing to eat; tautness or bulging of soft spots between skull bones; and difficulty awakening. As the illness progresses, seizures or hearing loss, or both, can occur. This can happen to patients of all ages.
Screening and Diagnosis
A doctor will ask about symptoms and medical history and will conduct a physical exam. Tests may include a spinal tap (removal of a small amount of cerebrospinal fluid to check for bacteria); other cultures (testing of samples of blood, urine, mucus, and pus from skin infections); magnetic resonance imaging (a scan that uses radio waves and a powerful magnet to produce detailed computer images) to be sure the inflammation is not from some other cause, such as a tumor; and a computed tomography scan (a detailed X-ray picture that identifies abnormalities of fine tissue structure).
Treatment and Therapy
More than 90 percent of all people with this infection survive when they receive immediate care that includes antibiotics and corticosteroids, which are often given together, and fluids. Options include antibiotics, which are given intravenously (IV). This is started as soon as the infection is suspected. The antibiotics may be changed once tests name the exact bacterial cause. The patient usually stays in the hospital until their fever has fallen. The fluid around the spine and the brain must also be clear of infection.
Another treatment option is corticosteroids. These are usually given by IV early in treatment. They control brain pressure and swelling and reduce the body’s production of inflammatory substances. This treatment can prevent further damage. Also, fluids can be lost because of fever, sweating, or vomiting. They may be replaced through an IV, but replaced carefully to avoid complications of fluid overloading. The doctor might prescribe pain medications and sedatives, and also anticonvulsants to prevent seizures.
Prevention and Outcomes
To help reduce the chances of infection with bacterial meningitis, one should consider getting the recommended vaccines (for oneself and one’s child). The vaccines include Hib vaccine (for babies), pneumococcal vaccine (for children younger than two years of age, for adults older than age sixty-five years, and for others with certain medical conditions), and meningococcal vaccine (for children aged eleven to twelve years and for others at high risk; people in the high-risk group may need to be vaccinated every five years).
Persons such as healthcare workers, who have close contact with someone who is infected, should take preventive antibiotics. Another preventive measure is to use only pasteurized milk and milk products, which can prevent meningitis caused by L. monocytogenes. Persons who are pregnant will be monitored by a doctor to ensure the infection is not passed to the fetus.
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