This document discusses central nervous system infections such as meningitis. It defines meningitis as the infection of the meninges, or membranes covering the brain and spinal cord. The most common causes of bacterial meningitis are Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae. Viral meningitis is more common and usually self-limiting. Diagnosis involves examination of cerebrospinal fluid including cell count, culture, and staining. Proper treatment requires rapid diagnosis and use of antibiotics effective against the infecting organism.

1. CENTRAL NERVOUS SYSTEM
MENINGITIS
•
•Dr. Mahadi H Abdallah

2. CNS infection:
The CNS can be infected by
bacteria, viruses, fungi and protozoa.
Meningitis: infection of meninges
(membranes that cover the brain and
spinal cord).
Encephalitis: infection of brain
matter.
Meningoencephalitis: infection of
both brain and meninges.
Brain abscess: local lesion of brain.

3. ROUTE OF INFECTION
1. Haematogenous:
The meninges infected via respiratory tract
through the blood stream.
2. Direct
From Otitis media, sinusitis (Pneumococci &
Haemophilus) ,(through the nose).
3. Trauma:
• Neurosurgery (predisposing factor).
• Spinal anesthesia.

4. CLINICAL FEATURES
• headache
• irritability or drowsiness, sometimes with alteration of
consciousness
• fever
• neck stiffness
• photophobia
• Positive Kernig's sign (pain in the lumbar region on
straight-leg raising

5. • Most infections are acute and the commonest pathogens
are viruses, especially in children and young adults.
• Bacterial meningitis (pyogenic).
• Viral meningitis aseptic or lymphocytic

6. MENINGITIS
Bacterial meningitis:
Aetiological agents:
It is mainly caused by N. meningitides -S.pneumoniae
- H. influenzae.
And then by L.monocytogenes -
Pseudomonas, S.aureus coagulase -ve staph
Chronic meningitis
Mycobacterium tuberculosis - Actinomyces - Brucella
- Salmonella - Leptospira - T.pallidum.

7. •Neisseria menigitidis:
• cause epidemic meningitis. The important
serotypes A, B, C, Y, and W 135.
•H. Influenzae:
cause meningitis in infants and preschool
age 1month to 4 years between.

8. MENINGITIS
• Streptococcus pneumoniae
• Affect middle age group and elderly, espicially the
patients who are poor in health.
• L. monocytogenes: Elderly patients, pregnant female
and immunosuppressed patients.
• M. tuberculosis:
• affect all age group (children) Haematogenous spread of
the organism through the blood

9. NEONATAL MENINGITIS
• may be classified as early- ( within 7 days of birth) or
late-onset disease(occurring between 1 week and 3
months).
• Early infections are acquired from the mother, whereas
late infections may result from cross-infection after birth.
• The commonest causes of early-onset disease are
Group B (-haemolytic streptococci)
• coliforms such as Escherichia coli.
• Listeria monocytogenes is less common

10. MENINGITIS
• The majority of cases of bacterial meningitis occur in
childhood.
• The commonest cause is now Neisseria meningitidis
(serotype A, B and C).
• Haemophilus influenzae.
• In later life, pneumococci are more likely pathogens.

11. • Listeria monocytogenes is a relatively rare cause
• but should be considered particularly in pregnant and
immunocompromised patients.

12. VIRAL MENINGITIS
It is more common, benign and self
limiting disease.
The most important group of viruses is:
Enteroviruses (coxsackie) - Mumps -
herps simplex , Echoviruses
,Arbovirus.

13. FUNGAL MENINGITIS
Mainly in immunosuppressed patient:
1. Cryptococcus neoformans (capsulated
yeast).
2. Coccidiodes immites (in South
America).
3. Aspirogellus species.
4. Candida.

14. LAB DIAGNOSIS
Specimens:
C.S.F, Blood.
Collection:
C.S.F is collected by experienced health worker,
under aseptic condition(4th & 5th lumber
vertebrate)
Macroscopical examination
Clear - purulent - cloudy - Xanthochromic (red-
yellow, indication to haemorrhage) - clots &
deposit (large number of WBCs).

15. LAB DIAGNOSIS
Cell count:
• Normal count 5 cell/ml.
Centrifugation:
• For culture & staining (if C.S.F clear).

17. LAB DIAGNOSIS
Culture:
• Blood Agar + Chocolate BA (incubation in CO2).
• Add MacConkey if the specimen from neonate.
• L J media: Tuberculous meningitis.
• Saborand's media: fungal meningitis

18. LAB DIAGNOSIS
Direct examination (staining):
• Gram stain: is very important because it help in the
selection of drugs.
• Capsule stain: for fungi (Cryptococcus neoformans).
• Fluorchrome stain: acridine orange.
• Z.N stain.
• Quellung test for detection of capsular Ag.

19. LAB DIAGNOSIS
Ag detection:
• Latex agglutination test.
• ELISA
VDRL for diagnosis of syphilis.

20. CNS INFECTIONS
• Infections occur in the brain (encephalitis and brain
abscess),
• spinal cord (myelitis),
• Nerves (neuritis or polyneuritis.
• nervous tissue has poor repair mechanisms, and tissue
damage leads to long-term sequelae.

21. • Encephalitis is predominantly a viral disease(HSV).
• brain abscesses are predominantly bacterial in origin
and arise because of spread from other sites such as
infected cardiac valves and bones, mastoid sinuses and
chronic middle ear infection

22. • S. aureus, streptococci,
• Gram-negative bacilli, anaerobes and are often mixed..
• Multiple abscesses/cysts may be due to either bacteria
or Echinococcus granulosus (termed hydatid disease),
• Toxocara spp. (toxocariasis) or tapeworm infection
(which are zoonoses