MENINGITIS

✓ Medically ReviewedDISEASEID: MDBT0126🚨 TRIAGE: EMERGENCYICD-10: G03.9

📖

Definition

CLINICAL DEFINITION

Meningitis is inflammation of the meninges (membranes covering brain and cord). It is most often due to infection by bacteria, viruses, fungi or mycobacteria (tuberculosis germs). Classic features are fever, severe headache, neck stiffness and changed alertness. Bacterial forms can progress fast to sepsis (blood infection with organ failure), brain injury and death.

IN PLAIN ENGLISH

Germs swell the covers around the brain. Fever with bad headache often starts it. Neck turns stiff and sore. It needs urgent care as some types worsen fast.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Meningitis is not encephalitis (brain tissue infection with marked confusion or seizures). It is not meningism (stiff neck with fever but no fluid infection). It is not subarachnoid bleeding (blood around brain) though headache with stiffness overlaps. Diagnosis needs exam plus spinal fluid (cord fluid) and germ tests, not symptoms alone.

🔤

Word Breakdown

mening-

=meninges (membranes covering brain and cord)

-itis

=inflammation

Literal Meaning: inflammation of the meninges

🏷️

Abbreviations

CSF=Cerebrospinal fluid - clear fluid around brain and cord tested by spinal tap

LP=Lumbar puncture - spinal tap collecting fluid through lower back needle

PCR=Polymerase chain reaction - DNA-based germ test on blood and fluid

GCS=Glasgow Coma Scale - eye, verbal and motor consciousness score

🔄

Synonyms & Variants

Leptomeningitis›Cerebrospinal Fever›Spinal Meningitis›

🎯

Category-Specific Context

Meningitis is a Disease because it is an inflammatory syndrome (linked swelling pattern) with causes and course. It is not a Symptom (patient complaint) such as headache alone. It is not a Sign (exam finding) such as stiff neck alone. It spans infectious and non-infectious origins (germ and no-germ levels). Care targets cause removal with pressure control rather than symptom cover alone.

🏥

Clinical Context & Usage

CLINICAL SETTINGS

Emergency DepartmentPrimary Care and Urgent CarePaediatrics and NeonatologyInfectious Diseases WardNeurology WardIntensive Care Unit

USAGE & DOCUMENTATION NOTES

Use meningitis when cover inflammation is suspected or proven. Specify cause when known such as bacterial, viral, fungal or tuberculous. Record Kernig sign (knee pain on leg extension) with Brudzinski sign (hip bend on neck bend), fever and rash. Do not label lone headache or neck pain as meningitis without systemic and cover features.

🔬

Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Germs reach the fluid space around brain via blood or nearby infection. Lung or ear germs often seed blood then cross the blood-brain barrier (vessel filter). Wall parts trigger cytokines (immune messengers) with neutrophils (pus-forming white cells). Leak across the barrier causes oedema (brain swelling) and high pressure. Vessel inflammation with clots cuts flow and injures nerve cells.

PRIMARY CAUSES

Neisseria meningitidis (meningococcus)

Colonises throat then invades blood and crosses vessel filter into fluid space causing pus-forming inflammation

Streptococcus pneumoniae (pneumococcus)

Spreads from lung, sinus or ear via blood, capsule (outer coat) resists engulfing and drives intense inflammation

Haemophilus influenzae type B

Airway coloniser causes blood spread with cover seeding, mainly in unvaccinated children

Listeria monocytogenes

Foodborne germ invades gut then blood and brain inside cells, affecting newborns, pregnancy, older adults and weak immunity

Neonatal Group B Streptococcus with Escherichia coli

Acquired at birth through immature defences then infects blood and covers with sepsis plus cover signs

Viruses including enteroviruses, herpes simplex, varicella zoster and mumps

Reach covers via blood or nerves and trigger lymphocytic (non-pus white cell) inflammation that is often milder

Cryptococcus neoformans

Inhaled yeast spreads widely in weak immunity such as advanced HIV, coat blocks fluid drainage and raises pressure

Mycobacterium tuberculosis

Lung focus spreads via blood to tiny deposits that burst into fluid space causing lumpy inflammation with thick base deposits and fluid buildup

💊

Drug-Induced Causes

💊 Nonsteroidal anti-inflammatories including ibuprofen ↗

Mechanism: Allergic-type cover irritation with sterile white cells without germs, often in lupus (autoimmune disease)

→ Stop suspected drug, exclude infection with cultures, give supportive care and avoid repeat exposure

💊 Trimethoprim-sulfamethoxazole ↗

Mechanism: Immune sterile inflammation of covers with fever and stiffness mimicking bacterial disease

→ Withdraw drug promptly, complete infection workup until excluded, give fluids and record allergy

💊 Intravenous immunoglobulin ↗

Mechanism: Infusion-related sterile inflammation within 48 hours from antibody clumps or fluid shifts

→ Pause infusion and seek advice, hydrate and exclude infection, consider slower re-infusion only with specialist guidance

🌍

Epidemiology

Prevalence:Meningitis is uncommon in general practice but remains a key emergency worldwide. Viral forms are more frequent than bacterial forms and are often milder. Bacterial, tuberculous and cryptococcal disease gathers in infants, older adults and weak immunity.

Age Group:All ages can be affected. Highest vulnerability is in newborns under 28 days with infants, teens for meningococcal disease, and older adults. Weak immunity with absent spleen function raises risk at any age.

Geographic Distribution:Meningitis occurs worldwide in all climates. Meningococcal epidemics cluster in the sub-Saharan meningitis belt (dry-season crowding zone) with dormitories and barracks. Tuberculous disease mirrors tuberculosis spread while cryptococcal disease follows advanced HIV burden.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 EMERGENCY

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Meningococcal disease with purple non-fading rash
Pneumococcal disease in older or spleen-free patients
Neonatal disease with poor feeding and irritability
Tuberculous disease with prolonged course
Cryptococcal disease in weak immunity

URGENT EVALUATION TRIGGERS

Fever with stiff neck and headache
Changed consciousness or seizures with fever
Purple spots that do not fade
Light sensitivity with systemic upset
Focal neurology or disc swelling before spinal tap

Contraindications & Precautions

CONTRAINDICATIONS

Do not delay antibiotics for scan or spinal tap when bacterial disease is suspected
Do not perform spinal tap with herniation signs or severe instability
Do not use painkillers alone as sole therapy for suspected bacterial disease
Do not wait for confirmatory tests before isolation when meningococcal disease is suspected

SPECIAL PRECAUTIONS

Use droplet precautions (mask and isolation) for suspected meningococcal or Haemophilus disease
Watch neurology with rash, circulation and pressure signs closely
Adjust starting antibiotics for age, pregnancy and local resistance
Offer preventive antibiotics with vaccines to close contacts per public health advice

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Septicaemia with shock (blood infection with collapse)
Raised pressure with herniation (brain shift)
Seizures with prolonged fits
Nerve deafness (hearing loss)
Thinking and learning difficulty
Hydrocephalus (fluid buildup in brain)
Stroke from vessel inflammation with clots
Clotting failure with purple rash
Death

🔀

Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Encephalitis

Shares fever with confusion but means brain tissue infection with seizures or focal signs, not pure cover inflammation

Meningism

Confused by stiff neck but means cover irritation without fluid infection in febrile illness

Meningococcaemia

Shares prefix and often coexists but means blood infection with sepsis and purple rash, with or without cover infection

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Encephalitis

Key Distinguishing Feature: Marked behaviour change with seizures or focal deficit and temporal lobe changes

Subarachnoid haemorrhage

Key Distinguishing Feature: Thunderclap headache with vomiting and stiff neck but usually no fever with blood on CT

Migraine with light sensitivity

Key Distinguishing Feature: Recurrent headache with aura and light upset but no fever or fluid white cells

Brain abscess

Key Distinguishing Feature: Fever with focal neurology and rim-enhancing lump on imaging rather than diffuse cover signs

Sepsis without meningitis

Key Distinguishing Feature: Fever with fast pulse and source elsewhere with normal fluid when tap is done

Temporal arteritis

Key Distinguishing Feature: Older adult with headache, scalp tenderness and raised markers without cover infection

💎

Clinical Pearls

💎

Treat fever with headache, stiff neck or changed alertness as possible meningitis until proven otherwise. Classic trio (fever, stiffness, changed consciousness) is often incomplete.

💎

Take blood cultures and give first antibiotics within the hour when bacterial disease is possible. Do not wait for spinal tap (fluid test) to give drugs.

💎

Treat non-fading purple rash with fever as blood infection until proven otherwise. Give antibiotics at once with resuscitation and isolation.

💎

Add ampicillin cover for Listeria (foodborne germ) in newborns, older adults, pregnancy and weak immunity. Add aciclovir (virus drug) when brain tissue infection overlaps.

💎

Check ears, sinuses, lungs and immune status in every case. Arrange hearing testing after bacterial disease because nerve deafness is a common after-effect.

📝

Example Usage & SOAP

CLINICAL SENTENCE

""22-year-old with fever, severe headache and stiff neck needs urgent meningitis workup.""

IN A SOAP NOTE

S: 22-year-old with 1-day fever, severe headache, stiff neck, light sensitivity and vomiting. O: Temp 39.4C, HR 118, BP 104/62, RR 22, SpO2 96 percent on air, drowsy but obeying with neck rigidity and leg pain on extension. A: Suspected acute meningitis, query bacterial with systemic upset. P: Blood cultures with urgent antibiotics per protocol, fluids, isolation, neurology review, scan decision before spinal tap and contact prevention planning.

DIFFERENTIAL DIAGNOSIS CONTEXT

Fever with headache and stiff neck favours meningitis over bleed when fever with markers is present. Thunderclap onset without fever with blood on CT favours bleed. Marked confusion with seizures favours brain tissue infection. Check fluid white cells with glucose, germ tests and imaging together.

📊

Classifications & Scoring

SCORING TOOL

Bacterial Meningitis Score

Paediatric rule using fluid stain with protein and cell counts, seizure history and blood counts to separate bacterial from aseptic disease.

📈

Prognosis

SHORT-TERM OUTCOME

Viral disease often settles in days with supportive care and full recovery. Bacterial disease can worsen within hours to shock, seizures or coma. Early antibiotics with fluids improve survival though intensive care is often needed.

LONG-TERM PROGNOSIS

Many recover fully, chiefly with viral disease and prompt bacterial care. Some keep deafness, learning difficulty, fits or limb loss after purple rash. Tuberculous, fungal and late bacterial disease carries higher lasting disability risk.

📚

References & Coding

ICD-10 DIAGNOSTIC CODE

G03.9

LITERATURE CITATIONS & GUIDELINES

[1]WHO ICD-10 G03.9 Meningitis unspecified

[2]NICE guidance on meningitis and meningococcal septicaemia

[3]Harrison's Principles of Internal Medicine central nervous system infections

[4]Davidson's Principles and Practice of Medicine neurology infections

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.