Meningitis is an inflammation of the meninges, the membranes covering the brain and spinal cord. It can be caused by bacteria, viruses, fungi or protozoa. The main types are pyogenic (bacterial) meningitis and aseptic (viral or nonbacterial) meningitis. Pyogenic meningitis is life-threatening and requires immediate treatment. Common causative bacteria in children and adults include Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae. Aseptic meningitis is usually caused by viruses like enteroviruses, mumps virus or herpes simplex virus. Diagnosis involves examination of cerebrospinal fluid for

1. Meningitis
By Dr. Rakesh Prasad Sah
Assistant Professor

2. Introduction
Definition: It is an inflammation of meninges, the
membrane covering of the brain and spinal cord.
• May be caused by
– Bacteria
– Viruses
– Fungi
– Protozoa
• Types
– Pyogenic Meningitis
– Aseptic Meningitis
– Tuberculous Meningitis

3. Pyogenic Meningitis
Bacteria
Bacterial Meningitis
CSF  PML
Polymorphonuclear
meningitis
Aseptic Meningitis
Viruses
Viral Meningitis
CSF 
Lymphocytes
Lymphocytic
meningitis
Acute Bacterial Meningitis  Life threatening infection, more severe but less
common than viral meningitis and needs immediate specific treatment.

4. Pyogenic Meningitis (Causative Organisms)
• In Children and adults
– Neisseria meningitidis (meningococcus)
– Streptococcus pneumoniae (pneumococcus)
– Haemophilus influenzae
– Staphylococcus aureus
– Listeria monocytogenes
– E. coli
– Proteus spp.
– Klebsiella species
– Citrobacter spp.
– Enterobacter spp.
– Serratia
Organisms occasionally
encountered

5. • In Neonates and infants
– E. coli
– Group B streptococci
– Staph aureus
– H. influenzae
– Listeria monocytogenes
– Streptococcus pneumoniae
– Klebsiella spp.
Important cause in first
few months
Meningococcal & Pneumococcal  any age
H. Influenzae  3 months to 5 yrs
Listeria monocytogens  immunocompromised hosts.

6. Lab Diagnosis
CSF
Cell count
Biochemical
analysis
Bacteriological
examination
3 sterile
container
Examined immediately after collection or placed in incubator at 370C.

7. Characteristics Normal
CSF
CSF in
APM TM VM
Pressure Normal Highly increased Mod. increased Slightly incresed
Direct examination (Cell count)
Total cell (per cu.mm) 1-3 1000-20000 50-500 10-500
Predominant cell L Neutrophils (90-
95%)
Lymphocytes
(90%)
Lymphocytes
Biochemical analysis
Total proteins (mg%) 30-45 100-600 (H.I.) 80-120 (M.I.) 60-80 (S.I.)
Sugars (mg%) 40-80 Diminished or
absent (10-20)
Diminished (30-
50)
Normal
Bacteriological examination
Microscopy
Gram Staining Nil GNC, GPC, GNB,
GPB
- -
AFB Nil - AFB seen -
Culture Nil Causative agent
on appropriate
Media
M. Tb on LJ
media
Viruses grown on
cell cultures

8. Bacterilogical Examination
CSF
Centrifuged
Microscopy Ag detection
Culture media
Mix with equal
volume of
glucose broth

9. Aseptic Meningitis
• Mostly caused by viruses and a few cases are caused by bacteria,
fungi and protozoa.
• Mostly in immunocompromised patients e.g. leukaemia,
lymphoma, AIDS or on immunosuppressive drugs. E.g. C.
neoformans.
• Causative Agents of Aseptic Meningitis
• Viruses
– Enteroviruses (echo, coxsackie and polioviruses)
– Mumps virus
– Herpes simplex virus
– Varicella zoster virus
– Measles virus
– Adenoviruses
– Arboviruses

10. • Bacteria
– M. tuberculosis
– Leptospira interrogans
– Treponema pallidum
• Fungi
– Cryptococcus neoformans
– Candida albicans
• Protozoa
– Acanthaoeba
– Naegleria
– Toxoplasma gondii