MeningitisBy: Darya Osman Hussein Daoud

Introduction• Meningitis is an acute

inflammation of the meninges (i.e. the protective membranes covering the brain and spinal cord)

• Can be bacterial, viral or fungal • The causative organism depends

on the age of the individual• May also be caused by some drugs

Bacterial meningitis – causative organisms

1. Birth – 4 wks:• Streptococci group B, E. coli, Listeria

2. 4 – 12 wks:• Streptococci group B, Pneumococcus Salmonella, Listeria, H. influenza type B

3. 3 mths – 3 yrs:• Pneumococcus, Neisseria meningitidis, H. influenza

4. 3yrs – adult:• Pneumococcus, Meningococcus

Viral meningitis

• Most common infection of CNS especially in <1yr• Causative organisms:

• Herpes, influenza, rubella, echo, coxsackie, EBV, adenovirus

• Tretatment is sympromatic• Complcations associated with envephalitis and ICP

TB Meningitis• Usually insidious: difficult to diagnose in early stages (fever 30%,

URTI 20%)• Rare in children in developed countries• If untreated is usally fatal• Meningitis usually occurs 3-6 mnths after primary infection • 1st stage: lasts 1-2 weeks, fever malaise, headache• 2nd stage: +/- suddenly, menigal signs• 3rd stage: worsening neurological condition, death

Meningitis – Pathogenesis• Begins with infection of upper respiratory tract by bacteria, viral of

fungal infection• Infection progresses and invasion of the blood streem occurs• Microbe enters the subarachnoid space in places where the BBB

isvulnerable (e.g. choroid plexus)• The presence of invador is detected by immune cells of the brain

(astrocytes and microglia) which react by releasing large amounts of cytokines stimulating the inflammatory response of the immunesystem

• The BBB becomes more permeable leading to vasogenic cerebral edema

• Large numbers of WBCs enter the CSF causing inflammation and interstitial edema

• Cerebral vasculitis occurs which leads to decreased blood flow and cytotoxic edema

• The three forms of edema all lead to increased intracranial pressure leading to decreased blood entering the brain and hypoxia induced apoptosis

Meningitis – Pathogenesis cont.

Clinical features – Infants• Non specific in newborns and

infants• Fever• Irritability• Lethargy• Poor feeding • High pitched cry• Convulsions

Clinical features – Older children

• Severe headache• Stiff neck• Photophobia• Fever and vomiting• Drowsy and less

responsive/vacant• Rash

Clinical features - Adults• Headache, fever and vomiting • Neck rigidity and photophobia• Pain in posterior thigh or

lumbar region• Rash on skin and joint pain• Lethargy, seizures, confusion,

coma, focal deficits and cranial nerve palsies(if not treated immediately)

Physical exam – Kernig’s sign

• Patient in supine position with leg flexed at hip and knee

• Extension of leg while hip still flexed

• Patient will experience pain and hamstring muscle spasm if meningeal irritiation/inflammation is present

Physical exam – Brudzinski’s neck sign

• Patient is in supine position

• Head is raised towards the chest slowly

• If hips and knees flex in response to the passive neck flexion (as shown) there is menengial irritiation/inflammation

Physical exam – Glass test

• When a rash is present if it does not fade when a glass is pressed to it

• A sign of meningococcal infection and septicaemia

Diagnostic tests – Lumbar Puncture

• CSF from lumbar puncture is used to culture cells, glucose level, protein, cell count and differential and gram test

Diagnostic tests – LP findings

Bacterial Viral Fungal TB Malignant

Cell number

10 – 100,000 <2000 <2000 250 – 500 ---

Cell type Polys Lymphocytes --- Lymphocyte

sLymphocyte

s

Glucose Low Normal Low Very Low Low

Protein High Normal or high High High High

G-Stain G +ve G –ve G –ve G +ve Zn ---

Management and Treatment

• Medical emergency• Early diagnosis essential• Immediate pharmacological

treatement/intervension• Intensive supportive treatment• Prophylaxis for family• Notification to GP and Public

health autority

Management/Treatment cont.

• Mechanical ventilation may beneeded if lowlevelof consciousness orevidence of respiratory failure

• Monitoring intracranial pressure andcerebral perfusion• Hydrocephalus (obstuctedflow of CSF) may require

insertion of temporary or long-term drainage device(e.g. cerebral shunt)

Pharmacological Intervention – Antibiotics

• Empiric antibiotics should be started immediately even before LP results

• Recommended to administer benzylpenicillin before transfter to hospital

• Treatment starts with a 3rd generation Cefalosporin (eg. Cefotaxime) with possible addition of Vancomycin

• Can also use Chloramphenicol as monotherapy or in combination with Ampicillin

Pharmacological

Intervention – Antibiotic treatment

• The drug used depends on susceptibility of causative organism as well as the age of the patient

Organism Age Group AntibioticUnknown Infants <1mths Ampicillin, Cefotaxime,

Gentamicin

Unknown Children >1mths and Adults

Ampicillin, Cefotaxime, Vancomycin

Gram-positive organisms (unidentified) Children and Adults Ceftriaxone, Vancomycin,

AmpicillinGram-negative bacilli (unidentified) Children and Adults Cefazidime, Gentamicin

Haemophilus influenza type b Children and Adults Ceftriaxone

Meningococci Children and Adults Penicillin G plus ceftriaxone

Streptococci Children and Adults Vancomcin, Nafcillin (with or without rifampin)

Listeria sp Children and AdultsAmpicillin, Gentamicin, Trimethoprim-sulfamethoxaxzole

Enteric gram-negative bacteria(Escherichia coli, Proteus sp, Klebsiella sp)

Children and Adults Ceftriaxone, Gentamicin

Pseudomonas Children and AdultsCeftazidime, Cefepime (may be used with the addition of aminoglycoside)

Staphyococci Children and Adults Vancomycin, Nafcillin (with or without rifampin)

Pharmacological Intervension – Other drugs

Other medication may be used to control/relieve symptoms1. Steroids:

i. Used to control alterations of CSF flow

ii.Dexamethasone – decreased subarachnoids space inflammation

2. Antiepileptic agentsi. Used to control seizure activity

3. Mannitoli. Used to decease intracranial

pressure

4. Antiviralsi. Used for viral meningitis

5. Antifungalsi. E.g amphotericin B and

Flucytosineii.Used for fungal meningitis

Pharmacological Intervention- Prophylaxis

• Rifampicin• Children: 5mg/Kg bd x 2/7• Adults:600mg bd x 2/7

• Pregnant contact• Cefuroxime IM x 1 dose

• Vaccine• Available against H. influenza,

Pneumococcal conjugate, and meningicoccus,

Paritally treated meningitis

• 50% of cases have prior antibiotic use which can alter findings

• Acture history is vital• CSF mainly lyphocytic (not usually polys)• Can have normal glucose• +ve cultures reduced by 30%• Gram stain reduced by 20%

Complications

• Septic shock• Verebral oedema• Seizure • Arteritis/venous

thrombosis

• Subdural effusions• Hyrocephalus• Abscess• Brain damange• deafness

Mortality/Morbidity

• Bacterial: overall mortality 5-10%• Neonatal meningitis: 15-20%• Older children: 3-10%• S. pneumonia: 26-30%• H.influenza type B: 7-10%• N. meningitides: 3.5 – 10%• 30% neurological complications• 4% profound b/l hearing loss

Mortality/Morbidity cont.

• Viral meningoencephalitis: Enteroviral fewer complications

• Tuberculous meningitis: related to stage of disease• Stage I - 30%• Stage II - 56% • Stage III - 94%