Bacterial Meningitis

What bacterial meningitis is

The brain and spinal cord are wrapped in three thin membranes, the meninges, with cerebrospinal fluid (CSF) between them. In bacterial meningitis, bacteria reach this space, usually from the bloodstream or from nearby infections such as the sinuses or ears. The immune response causes intense inflammation, swelling of the brain, raised pressure inside the skull and reduced blood flow.

This is why bacterial meningitis is far more dangerous than viral meningitis. Without treatment it is usually fatal. Even with prompt treatment, about 1 in 10 people die and up to 1 in 5 survivors have lasting effects.

Symptoms

In adults and older children

• fever
• severe headache
• stiff neck: pain and difficulty bending the chin to the chest
• sensitivity to light (photophobia)
• nausea and vomiting
• confusion, drowsiness or difficulty waking
• seizures
• in meningococcal disease, a rash of tiny red or purple spots (petechiae) or larger bruise-like areas that do not fade under pressure

The classic triad of fever, neck stiffness and altered mental state is present in fewer than half of adults, so the absence of one sign does not rule it out.

In babies and young children

Babies often do not have a stiff neck. Look for:

• fever, or a low temperature in newborns
• irritability, especially when handled, or a high-pitched cry
• unusual sleepiness, floppiness or stiffness
• poor feeding and vomiting
• a bulging soft spot (fontanelle) on the head
• pale, blotchy or mottled skin, and cold hands and feet
• seizures

The glass test

Press the side of a clear drinking glass firmly against a rash. If the spots do not fade and remain visible through the glass, this is a sign of meningococcal sepsis. Get emergency help immediately. On darker skin, check paler areas such as the palms, soles and inside the eyelids. Do not wait for a rash: it can appear late or not at all.

Causes

Tuberculosis causes a slower, more insidious meningitis over weeks.

Risk factors

• age under 1, teens and young adults, and over 65
• living in close quarters such as college dorms and military barracks
• weakened immunity, HIV, cancer treatment, alcohol use disorder or diabetes
• no spleen or a non-working spleen (for example in sickle cell disease)
• cochlear implants, CSF leaks, skull fractures and recent neurosurgery
• complement deficiencies and treatment with complement inhibitors
• travel to the "meningitis belt" of sub-Saharan Africa or for Hajj

Diagnosis

Doctors do not wait for test results before giving antibiotics if bacterial meningitis is likely.

• Blood cultures taken immediately.
• Lumbar puncture (spinal tap): CSF in bacterial meningitis is cloudy, with high pressure, many white cells (mostly neutrophils), high protein and low glucose. Gram stain, culture and PCR identify the organism.
• CT scan of the head before the lumbar puncture in some people, such as those with seizures, reduced consciousness, focal weakness, papilledema or a weak immune system.
• Blood tests: blood count, inflammatory markers, clotting tests and kidney function.

Bacterial vs viral meningitis

Treatment

• IV antibiotics within the first hour of suspicion. Adults typically receive ceftriaxone or cefotaxime plus vancomycin. Ampicillin is added for people at risk of Listeria. Treatment is narrowed once the bacterium is known and continues for 7 to 21 days.
• Dexamethasone (a steroid), given just before or with the first antibiotic dose, reduces hearing loss and deaths in pneumococcal meningitis.
• Intensive care for sepsis, seizures, breathing support and raised brain pressure.
• Public health notification for meningococcal and Hib disease.

Protecting close contacts

Household members, intimate contacts and others with prolonged close exposure to someone with meningococcal meningitis should receive preventive antibiotics (such as ciprofloxacin, rifampin or ceftriaxone) as soon as possible, ideally within 24 hours of the diagnosis.

Complications

• hearing loss, the most common long-term effect, so every survivor should have a hearing test
• brain damage, memory and learning problems
• seizures and epilepsy
• hydrocephalus
• vision loss and weakness
• in meningococcal sepsis: loss of fingers, toes or limbs, skin scarring and kidney damage

Prevention

• Pneumococcal vaccines: for infants, adults 50 and older, and people with risk conditions.
• Meningococcal ACWY vaccine (MenACWY): routinely at 11 to 12 years with a booster at 16 in the US, and for high-risk groups and travelers.
• Meningococcal B vaccine (MenB): for high-risk groups and, by shared decision, for people aged 16 to 23.
• Hib vaccine: part of routine infant immunization.
• Group B strep screening in late pregnancy, with antibiotics during labor for carriers.
• Food safety in pregnancy: avoid unpasteurized dairy, soft cheeses and cold deli meats unless heated until steaming.

Frequently asked questions

What are the first symptoms of bacterial meningitis?

Early symptoms often include fever, headache, vomiting and feeling very unwell. These can quickly progress to a stiff neck, light sensitivity, confusion and drowsiness. In meningococcal disease, leg pain, cold hands and feet, and a non-fading rash can appear early.

How quickly does bacterial meningitis progress?

Very quickly. Bacterial meningitis can go from first symptoms to life-threatening illness within hours, especially meningococcal disease. That is why anyone with suspected meningitis should call 911 or go to the ER immediately rather than wait to see if it improves.

Is bacterial meningitis contagious?

Some types are. Meningococcal and Hib meningitis spread through close contact with respiratory and throat secretions, such as kissing or living together. Pneumococcal meningitis is not usually spread person to person. Close contacts of meningococcal cases need preventive antibiotics.

What is the difference between bacterial and viral meningitis?

Bacterial meningitis is a medical emergency that can kill or cause permanent damage within hours and needs immediate IV antibiotics. Viral meningitis is more common and usually milder, with most people recovering in 7 to 10 days. A lumbar puncture tells them apart.

Can vaccines prevent bacterial meningitis?

Yes. Vaccines against pneumococcus, meningococcus (MenACWY and MenB) and Hib have greatly reduced bacterial meningitis. They do not cover every strain, so recognizing symptoms and getting urgent care remains essential even after vaccination.