Meningitis is an inflammation of the meninges that can be caused by bacterial, viral, fungal or non-infectious etiologies. The most common bacterial causes are Streptococcus pneumoniae, Neisseria meningitidis, and group B streptococci. Clinical presentation includes fever, headache, neck stiffness, and altered mental status. Diagnosis involves examination of cerebrospinal fluid which shows pleocytosis and elevated proteins. Treatment depends on the identified cause but commonly includes antibiotics and steroids. Complications can include brain abscesses, hydrocephalus, and neurological deficits if not treated promptly.

1. 7 March 2023 MENINGITIS 1
MENINGITIS

2. OUTLINE
• Definition
• Epidemiology & aetiology
• Pathogenesis & pathophysiology
• Clinical presentation
• Diagnostic evaluation
• Treatment
• Complications/prognosis
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3. DEFINITION
Clinical syndrome (Infectious dse) xterised by
inflammation of the meninges.
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Meningitis
Bacterial
(Septic)
Aseptic
Tuberculous
·Viral
·Fungal
·Non-infectious

4. EPIDEMIOLOGY
IMPORTANCE
• Common cause of morbidity and
mortality
• CNS immune priviledged site
• Treatment leads to bacteriolysis &
release of more toxins
>>inflammation&edema
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5. EPIDEMIOLOGY
RISKS
• Systemic (resp) infxn
• Head trauma
• Splenectomy
• Anatomic meningeal defects
• Prior neurosurgery
• Ca, alcoholism, other ISS
• overcrowding>pharyngitis
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6. EPIDEMIOLOGY
DISTRIBUTION
• 80% H. influneza, N.meningitidis & S.
pneumoniae-US
• Bacterial meningitis-Streptococcus
pneumoniae (~50%), N. meningitidis
(~25%), group B streptococci (~15%),
and Listeria monocytogenes (~10%).
• The young and the elderly more
affected
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7. EPIDEMIOLOGY
Meningitis belt
• Sub-Saharan Africa
• Senegal to Ethiopia
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8. EPIDEMIOLOGY
PREVALENCE
• 0.6-4 cases per 100,000 population- US
• Kenya figures more on epidemics e.g2005/06
western kenya (CDC)
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9. AETIOLOGY
Infectious:
• Bacterial- meningococcal, pneumococcal, haemophilus
• Mycobacterial (TBM)
• Viral (aseptic)- Herpesviridae, measles, influenza,
mumps
• Fungal- Cryptococcus, Candida (prematures),
Histoplasma
Non-infectious:
Cancers, Systemic lupus erythematosus, Drugs, Head
injury, Neurosurgery
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10. AETIOLOGY-causative bacteria.
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11. AETIOLOGY-transmission
• Droplet effect- coughing, sneezing
• During birth (MTCT)-bacteria&viruses
can be transmitted
• Stool- enteroviruses or certain types of
bacteria- more children than adults
• Kissing, sex, contact with infected
blood-viral
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12. PATHOGENESIS
Hematogenous seeding of brain from the lungs-
S.pneumoniae
Contigous invasion for H.influenza and N.
meningitidis (nasopharynx)
Entry via compound skull fractures
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13. PATHOGENESIS
• Nasopharyngeal colonization- sIgA proteolysis
• Nasopharyngeal epithelial cell invasion-
Nisseria -trans cellular endocytosis
Haemophilus- tight jxn separation & intracellular
penetration
• Blood stream invasion
• Bacteremia with intravascular survival
• Crossing BBB and entry into CSF (?choroid plexus
receptors)
• Survival and replication in the CSF (capsule)
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14. PATHOGENESIS
• Meningeal entry >acute inflammatory
response to:
– Lipopolysacharides (endotoxins )- haemophilus &
nisseria
– cell wall peptidoglycans & teichoic acid
(streptococcal)
• Inflam’ mediators: IL-1, IL-6 & TNF-α,
metalloproteinases (1-3hrs)
• 20 mediators IL-6,IL-8,NO,PGE2,PAF
• Astrocytes, monocytes, endothelial cells, CSF
leukocytes, microglia responsible.
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15. PATHOGENESIS
• CSF invasion>BBB permeability>release of
albumin into SA space
• Infxn & meningeal irritation increases
complement, opsonization & phagocytosis but
still low to clear the infxn due to:
– Low WBCs
– Low complement factors and Igs
– Fluid nature of the CSF unconducive fo phagocytosis
• SA space low in complement, immune factors
(SA: serum ratio of IgG 800:1)
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16. PATHOGENESIS
Neurotropic Stage Host Defense Strategy of Pathogen
1. Colonization or
mucosal invasion
1. Secretory IgA
2. Ciliary activity
3. Mucosal epithelium
1. IgA protease secretion
2. Ciliostasis
3. Adhesive pili
2. Intravascular
survival
Complement Evasion of alternative
pathway by polysaccharide
capsule
3. Crossing of blood-
brain barrier
Cerebral endothelium Adhesive pili
4. Survival within CSF Poor opsonic activity Bacterial replication
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17. PATHOPHYSIOLOGY
Cytokine & proteolytic enzyme release>membrane
permeability>edema
• Vasogenic edema- BBB permeability
• Cytotoxic edema- cellular swelling d2 toxic prdts frm
bacteria* & neutrophils.
• Interstitial cerebral edema – obstn to CSF flow. O2 free radical
& NO mediate cerebral edema
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18. PATHOPHYSIOLOGY
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19. PATHOLOGY
• An exudate of varying thickness may be distributed widely
around the brain
• Spinal cord may be encased in pus .
• Vascular changes - arteritis & thrombosis of vessels
• Damage of the cerebral cortex occurs
secondary to thrombosis of blood vessels , hypoxia , bacterial
invasion , toxic encephalopathy.
• Meningococcal=basilar, pneumococcal & haemophilus
vertex
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20. DIAGNOSTIC EVALUATION
HISTORY
• Fever, headache, neck stiffness, photophobia,
nausea/vomiting (worse in the morning) , rigors,
profuse sweating and myalgias
• Symptoms of cerebral dysfunction (lethargy,
confusion, coma)
• Presence of VP shunts, past neurosx, skull #s,
URTI
• Atypical presentation- ISS, neonates, elderly
• Seizures (focal-ischemia, generalsd-metabolic)
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21. DIAGNOSTIC EVALUATION
EXAMINATION
Septicemia vs raised ICP vs meningism vs others
 Sick looking, comatose, confused, anxious, fever,
tachycardia, tachypnoea
 cushings reflex, papilloedema, dilated pupils,
decorticate/decerebrate
 Stiff neck, kerning’s, brudzinski (neck to leg,
leg to leg), photophobia, exacerbation of
headache by horizontal mvt of head
• Focal neurological signs-cortical, brainstem,CNs
• Systemic findings depending on cause
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22. MENINGEAL SIGNS
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23. DIAGNOSTIC EVALUATION
DIFFERENTIALS
• Meningeal carcinomatosis
• CNS vasculitis, Stroke, SAH, sinus thrombosis
• Encephalitis,CNS tumor
• Intracerebral abscess, epidural abscess,
• Sinusitis, mastoiditis,
• Intoxication, seizure disorder
• Medication induced,
• Hypoglycemia
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24. DIAGNOSTIC EVALUATION
INVESTGATION
 CSF (R/O SOL-CT, clinically, fundoscopy)
-microscopy, biochemistry, PCR, serology
 Blood cultures
 U/E/Cs, LFT- complicated dse
 CT/MRI (Prolonged coma, Persistent irritability, Persistent
(>4d) or focal seizures, focal neurological deficits, Persistent
↑ in CSF proteins & WBCs,Recurrent disease
Sputum, CXR- ?TBM
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25. DIAGNOSTIC EVALUATION
NORMAL BACTERIAL TBM VIRAL FUNGAL
APPEARANCE CLEAR CLOUDY CLOUDY CLEAR ………..
PRESSURE 5-18cmH2O N/↑ (10-30) N/↑ N/↑ ↑
WBC 0-4/mm3 >1000
(neutrophils)
500-5000
(Lymphocytes)
500-1000
(lymphocytes)
25-500
Neutrophils &
lymhpcytes
PROTEIN
(mg/dl)
15-45 ↑↑ (100-500) ↑↑ (100-500) N/↑ (50-200) ↑(20-500)
GLUCOSE ≥ 2/3 of RBS DECREASED DECREASED DECREASED DECREASED
MICROBIOLOGY STERILE GRAM STAIN
CULTURE +VE
??AFB
CULTURE
PCR CULTURE
CrAg
Indian ink
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26. DIAGNOSTIC EVALUATION
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GRAM STAIN- MENINGOCOCCI

27. TREATMENT-septic meningitis
SUPPORTIVE
Antipyretics
Oxygen
!!!Fluids(ICP, SIADH)
SPECIFIC
Empirical ceftriaxone 2gm bd OR
x-pen 4MU QID +
 CAF 1gm QID x10-14days
Treat according to M/C/S results
ADJUNCTS
*Dexamethasone 0.15mg/kg QID x 2-4days
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28. PREVENTION
Vaccines
– Pneumovax
– Meningicoccal vaccine
– Both should be administered to any asplenic
patient
Exposure to meningococcus
– Rifampin 600 mg PO BID x 4 doses
– Only for intimate contacts: spouse,
boyfriend/girlfriend, household contacts
– Not needed for: classmates, co-workers, HCWs (ER
personnel, EMTs, etc)
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29. TREATMENT- VIRAL
Conservative
Acyclovir if HSV
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30. TREATMENT- TBM
PRESENTATION:
Prodromal phase- fever, malaise, headache,
lassitude
Meningitic phase- meningeal features,
vomiting, CN palsies
Paralytic phase- stupor, coma,seizures,
hemiparesis
TREATMENT :
• 2RHZE + 4RH/6HE, ARVs
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31. TREATMENT- FUNGAL
• Mostly cryptococcal
• Indian ink, CrAg, culture +ve
• Chronic recurrent course
• Treatment:
– Induction: Ampho B 0.5-1 mg/kg IV 2 wks( may add
5flucytosine 25mg/kg q 6hrs PO)
– (can use 800mg/d fluconazole for 6 wks)
– Consolidation: oral fluconazole 400mg/d for 10wks
– Maintenance: fluconazole 200mg/d for life (stop if
CD4 >200/mm3)
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32. CRYPTOCOCCAL MENINGITIS
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INDIAN INK STAIN- Cryptococcus neoformans

33. COMPLICATIONS
• Brain abscess
• Hydrocephalus
• Altered mental
status
• Increased ICP
• Seizures
• Focal neurological
deficits
• Cranial nerve
palsies
• Hemiparesis
• Sensorineural
hearing loss
• Intellectual
impairment
• Subdural effusion
• Waterhouse-
Friderichsen
syndrome
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