Meningitis

Question 1

Bacterial Meningitis
Q. Definition
Q. complicatons if untreated

Answer 1

=> Definition: Inflammatory response to infection of leptomeninges & subarachnoid space

=>Symptoms:
* Fever/headache/Photophobia/Neck stiffness
* Altered GCS
* Seizures- in children

=>Complications if untreated:
* Shock
* DIC
* ARDS
* Metabolic derangement
* Seizures
* ↑ ICP → cerebral oedema → cerebral herniation

Question 2

Pathogenesis

Answer 2

->1. Colonisation & Invasion:
* Pathogenic organisms colonise nasopharynx → → cross BBB
* Can follow middle ear, sinus, or dental infection (haematogenous spread)

->2. Multiplication & Immune Response:
* Bacteria multiply in CSF → release cell wall products / LPS
* Stimulates release of cytokines & chemokines

->3. Vascular & Tissue Injury:
* Vasculitis of CNS vessels, Thrombosis
* Cytotoxic & vasogenic oedema
⬇️
* ↑ ICP
* Altered cerebral blood flow
* Cerebral infarction

Question 3

Lumbar Puncture — Contraindications

Answer 3

• GCS < 12
• Focal neurological deficit
• New onset seizures
• Immunosuppression
• Papilloedema
• Note: CT brain prior to LP if any contraindications present

CTB prior to LP lessens but does not R/O risk of cerebral herniation
(ICP may be ↑ even if CTB is normal)

Question 4

Bacterial Meningitis — Common Pathogens
m/c/c in adults worldwide after the advent of HIB vaccine

Answer 4

Pneumococcus
N. meningitidis

Question 5

Bacterial Meningitis —
Listeria monocytogenes Risk Factors

Answer 5

• Elderly
• Alcoholism
• Malignancy
• Immunosuppression
• DM

MADIE

Question 6

Bacterial Meningitis — Common Nosocomial Pathogens

Answer 6

Pseudomonas
E coli
Acenatobacter
Klebsiella
Staph

PEAKS

Question 7

Bacterial Meningitis —
Pathogens in immunocompromised

Answer 7

• Mycobacteria
• Fungal
• Viral(CMV)

Question 8

Bacterial Meningitis — Common Pathogens post Neurosurg &Trauma

Answer 8

Staph aureus
Staph epidermitis

Question 9

CSF findings

Answer 9

Question 10

Other invx

Answer 10

Other Investigations
* Blood cultures (haematogenous spread)
* CSF Gram stain (positive in ~50–60%)
* Bacterial latex agglutinin (possible non-specific results)
* PCR for bacterial/viral pathogens
* For N. meningitidis:
-Throat swab
-Clotting profile
-examine ears, sinuses, nose for source

Question 11

Emperical Abs

Answer 11

=><60yrs:
* -Ceftriaxone-2gm/iv/bd
* -Vancomycin 25mg/kg loading foll by 20mg/kg /iv/bd or as infusion

=»60yrs:
* Ceftriaxone
* Vancomycin
* Ampicillin/amoxycillin-2gm/iv/4hrly

=>Neurosurgical shunt infection/ Immunosuppressed:
Vancomycin
Meropenem-2g/iv/8hrly

Question 12

Consider admission to ICU if:

Answer 12

1. Rapidly evolving rash
2. Evidence of limb ischaemia
3. ARDS / Respiratory compromise
4. GCS < 12
5. Seizures (treatment / recurrent)
6. Haemodynamic instability

Question 13

Special Considerations in Bacterial Meningitis

Answer 13

=> Early antibiotics

=> Steroids and cultures prior to Abs if possible

=>Imp. to monitor response to therapy

=> Penicillin-Resistant Pneumococcus
* Repeat LP at 24–48 hrs to ensure bacteriological improvement

=>In meningitis, always think about:
* ICP⬆️
* Steroids
* Seizures

⸻

Duration of Antibiotic Therapy
* N. meningitidis: 5 days
* S. pneumoniae: 14 days
* L. monocytogenes: 21 days

Question 14

Steroids in Meningitis

Answer 14

=>Rationale:
Bacterial infection of
meninges->severe inflammation, worsened by bacterial cell lysis–> leading to aggravated CNS damage in animal studies

=>Lower rates of Neurological sequelae and hearing loss
=>Decreased mortality only in pneumococcal meningitis
=>In underdeveloped countries, benefit only in Tuberculous meningitis
=>Concern that steroids may decrease drug penetration not validated in studies

=>Dose- 10mg/iv/6hrly for 4 days–>discontinue if cause other than Strept pneumoniae identified

SEE college ans- Q 11, 2015- paper 1

Question 15

Seizures- in Meningitis

Answer 15

->Uncommon in adults
-> Think of CAT in the Brain:
* Cerebritis
* Abcess
* septic venous Thrombosis
* ⬆️ ICP->ICP monitoring
>ICP control measures
>serial LP

Question 16

Meningococcal meningitis
Special considerations

Answer 16

• Prophylaxis for close contacts (droplet infection / kiss etc.)
  
  • Rifampicin 600 mg BD × 2 days
    OR
• Ciprofloxacin 500 mg PO stat
• Notifiable to Public Health

⸻

Mortality — higher if:
* Delay in treatment (e.g. antibiotics)
* Seizures
* Very young / very old

Question 17

Cryptococcal meningitis
points to consider

Answer 17

->Leptomeningeal inv. common
-> Cryptococcus neoformans — yeast → chronic meningitis similar to TB meningitis

->C gatti— can infect immunocompetent

-> LP: measure opening pressure if suspected
* more Common in immunocompromised

=>Other labs:
->Staining → India Ink
->Antigen testing — helps establish Dx
->culture from CSF = gold standard
->Raised ICP management → may require daily LP or CSF diversion

=>Tx – Flucytosine + Amphotericin-B → consolidation therapy = Fluconazole

Question 18

Viral Meningitis

Common Causative Viruses

Answer 18

• Enteroviruses (e.g., Coxsackievirus)
• HSV-2
• HIV
• Mumps virus
• VZV
• Echovirus
• Endemic regions: West Nile virus, other arboviruses

=> HSV-1: usually causes encephalitis, rarely meningitis

Question 19

Viral Meningitis
Clinical Features

Answer 19

=>Meningeal irritation:
* Headache
* Fever
* Photophobia or
* Retrobulbar pain
* Nausea/vomiting
* Vertigo
* Neck stiffness

=>Brain parenchymal involvement:
* Focal neurological deficits
* Intellectual impairment
* Seizures

Question 20

Viral Meningitis
Invx(specific)

Answer 20

CTB to r/o other causes
* CSF biochemistry, lactate
* Staining for bacteria, mycobacteria, cryptococcus

Question 21

Viral Meningitis
Treatment

Answer 21

=>Cryptococcal: Flucytosine + Amphotericin B → consolidation with fluconazole

=>HSV / VZV: Acyclovir IV

=> HIV: Antiretroviral therapy

=>Others: Supportive — rest, analgesia, antipyretics