1. CNS INFECTIONS

2. Classification of CNS Infections
Diffuse
Meningitis
encephalitis
Focal
Brain abscess
Epidural abscess
Subdural empyema
Herpes simplex encephalitis

3. Etiology of CNS Infection
Syndrome
Usual Causes
Meningitis
Bacterial
Bacterial meningitis
TB meningitis
Viral
Fungal
Encephalitis
Mainly viral
Brain abscess
Mainly bacterial, TB
Others
Protozoal, rickettsia, nematodes, cestodes

4. Meningeal Anatomy

5. Routes of Entry into the CNS
Hematogenous spread
Contiguous (bacterial)
Sinus, ear, face
Direct inoculation (bacterial)
trauma
Iatrogenic
Surgery
VP shunting
Lumbar puncture
Via nerves
Herpes, Varicella, Rabies

6. Pathogenesis: Bacterial meningitis
Bloodstream
CNS seeding
*Virulence factor: Bacterial capsule
(H. influenzae, N. meningitides, S. pneumoniae, E. coli)

7. Pathogenesis: Tuberculous meningitis
Pulmonary infection
bacteremia
CNS seeding in the meninges
(Rich focus)
Rupture of Rich focus

8. Pathogenesis: Viral Infection pathways
Respiratory passages: mumps, measles, varicella
Oro-intestinal route: poliovirus, enterovirus
Oral/genital mucosa route: herpes
Inoculation: rabies
Maternal-fetal transfer: rubella, CMV, HIV

9. Viral Invasion Enters the body multiplies locally
and in secondary sites
Massive viremia
Reticuloendothelial system
Blood Brain Barrier
CNS invasion
cerebral capillaries
choroid plexus

10. Viral Invasion via Peripheral nerves
Inoculation
(HSV, VZV, rabies)
Local infection
Centripetal movement
(retrograde axoplasmic transport system)
CNS invasion
cerebral capillaries
choroid plexus

11. Pathogenesis: Fungal infection
May arise without obvious predisposing cause
But usually due to opportunistic/ inadequate defenses
AIDS
Organ transplantation
Diabetes
Leukemia, lymphoma, malignancy
Prolonged steroid therapy

12. Cardinal Manifestations of CNS Infections
Fever
Headache
Alteration of Sensorium
Focal neurologic signs
Seizure
Meningeal signs

13. Identifying the Organism
Age of the patient
Clinical setting
Community-acquired
Post-surgical
nosocomial
Immune status of the patient
Evidence of systemic and local cranial disease

14. CNS Infection Syndromes according to length of symptoms
DAYS
Acute Meningitis
Bacterial meningitis
Viral meningitis
DAYS TO WEEKS
Subacute meningitis
Tuberculous meningitis
Cryptococcal meningitis
Acute encephalitis
Mumps
Measles
Rabies

15. CNS Infection Syndromes according to length of symptoms
WEEKS TO MONTHS
Space-Occupying Lesions
Brain/ Spinal Abscess
Subdural empyema
Cysticercosis
Toxin-Mediated
Tetanus
Botulism
Post-Infectious
Guillain-Barre Syndrome
Acute Demyelinating Encephalomyelitis (ADEM)

16. CNS Infection Syndromes according to length of symptoms
MONTHS TO YEARS
Chronic meningitis
Neurosyphilis
Chronic Encephalitis
Subacute Sclerosing Panencephalitis (SSPE)
HIV Encephalitis
Prion Disease
Creutzfeldt-Jacob disease
Kuru
PML

17. Bacteria which invade the CNS

18. Viruses which invade the CNS
HIV-1 & HIV-2 (human Immunodeficiency viruses)
HSV-1 (Herpes simplex virus)
HSV-2 (Herpes zoster virus)
EBV (Epstein-Barr virus)
CMV (Cytomegalovirus)
Poliovirus
rabies

19. Fungi which invade the CNS
Cryptococcosis
Candidiasis
Aspergillosis
Mucormycosis
Coccidioidomycosis
Histoplasmosis

20. Bacterial meningitis Suppurative meningitis

21. Bacterial meningitis Suppurative meningitis

22. Bacterial meningitis

23. Bacterial meningitis Suppurative Meningitis
Gram stain: PMNs and intracellular bacteria

24. Meningococcemia

25. Neisseria meningitidis

26. Early TB Meningitis

27. Late TB Meningitis

28. Cryptococcal Meningitis

29. Cryptococcus: India Ink Stain

30. Brain Abscess DAY STAGE 1-3 Early cerebritis 4-9 Late cerebritis 10-13
Early Capsule Formation
14 onwards
Late Capsule Formation

33. Diagnostics in CNS Infection
CSF analysis
Lumbar puncture
Cisternal puncture
Ventricular tap
Q/Q, GS/CS,AFB, CALAS
Neuroimaging
CT scan
MRI

34. CSF Profiles Profile Common Causes Purulent (acute) ↑PMNs, ↓glucose
Bacterial
Lymphocytic (subacute)
↑Lymph ↓glucose
TB, fungal, CA
Syphilis
Lymphocytic
Normal glucose
viral

35. Bacterial meningitis – therapy according to Gram stain
Probable organism
Provisional antibiotics
G(+) diplococci
S pneumoniae
Cefotaxime or ceftriaxone
G(+) cocci
S aureus or epidermidis
Streptococci
oxacillin
G(-) intracellular diplococci
N meningitidis
Pen G or ampicillin
G(-) bacilli
E coli & other G(-)

36. Recommended Treatment for Fungal Meningitis
Organism
Treatment
Cryptococcus neoformans
Amphotericin B
Flucytosine
Candida
Aspergillus
Mucorales
Coccidioides imitis

37. Recommended Treatment for Viral Meningitis
Virus
Treatment
HSV-1 (Herpes simplex virus)
Acyclovir
HSV-2 (Herpes zoster virus)
Rabies
Human rabies immune globulin
Human diploid cell line vaccine

38. Thank you and Good Day!