Meningitis and Neiseria Meningitidis

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Meningitis is an inflammation of the meninges.
The brain and spinal cord are covered by connective tissue layers collectively called the meninges which form the blood-brain barrier.

¡ CAUSES
¡ Bacteria
¡ Viruses
¡ Fungi
¡ Protozoa & parasites

¡ Bacterial meningitis
Age of onset
Common
Less common
NEONATES
GNB ( E.coli,Proteus)
Gr.B Streptococci
Listeria monocytogens
PRE- SCHOOL CHILDREN
H. Infuenzae
N. Meningitidis
Str. Pneumoniae
M. tuberculosis
OLDER  CHILDREN & ADULTS
Str. Pneumoniae
L. onocytogens
M. tuberculosis
Staph aureus

¡ Clinical features
Symptom or Sign         Relative Frequency (% )
¡ FEVER                                     >90
¡ HEADACHE                            >90
¡ NUCHAL RIGIDITY                       >85
¡ ALTERED MENTAL STATUS                80
¡ BRUDZINSKI SIGN                                50
¡ KERNIG SIGN                        50
¡ VOMITING                                     ~35
¡ SEIZURES                                       10-30
¡ FOCAL NEURO SIGNS                  10-30
¡ PAPILLEDEMA                               <1
¡ PHOTOPHOBIA
¡ SKIN RASH  (e.g., petechia/purpura in meningococcemia)
¡ Neisseria SpP
¡ Gram
¡ NEISSERIA MENINGITIDIS
¡ NEISSERIA MENINGITIDIS
¡ Meningococcus  or Diplococcus intracellularis        meningitidis
¡  Weichselbaum      1887
¡ Meningitis or Cerebrospinal fever
MORPHOLOGY
Gram negative diplococci 0.6-0.8um
Regular & generally intracellular
Non motile
Fresh isolates capsular
CuLture
 Blood agar
Chocolate agar
Muller-Hinton starch caesin hydrolysate agar
Modified Thayer Martin agar
CuLture Characteristics
Small, trans, round,convex, bluish grey, smooth glistening surface
Lenticular in shape
Butryous consistency
Emulsifiable
Weak haemolysis in BA
 2 types of colonies R & S
Liquid media: Granular turbidity
BiOCHEMICAL REACTIONS
   
Meningococci Vs Gonococci
ANTIGENIC PROPERTIES & CLASSIFICATION
SEROGROUPS
   based on capsular polysaccharide
   13 serogroups
   A, B, C, D,E..... X, Y, W-135
  
SEROTYPES
   based on outer membrane protiens
   20  serotypes
EPIDEMIOLOGY
Human : the only reservoir
Transmission: Airborne droplets / Fomite
Carrier rates
Epidemics
One million cases world wide per year
 200,000 die annually.
PATHOGENICITY
Strict human pathogen
MENINGITIS
MENINGOCOCCAEMIA
        Waterhouse Friderichsen syndrome
Endotoxin LPS released by autolysis
All major cascade triggered and upregulated
Adrenal haemorrhage & shock
Pathogenesis
Nasopharyngeal colonisation
Nasopharyngeal epithelial cell invasion
Blood stream invasion
Bacteremia with  intravascular survival
Transversal across BBB and entry into CSF
Survival & replication within subarachnoid space
LAB DIAGNOSIS
Establish D/D
Sample collection
CSF examination
Blood culture
Nasopharyngeal swab
Petechial lesions
Autopsy
Retrosective evidence
Molecular diagnosis
TREATMENT
Prompt treatment for recovery without sequale
i.v Penicillin G
Chloramphenicol
Cephalosporins ( Ceftriaxone, Ceftazidime)
RESISTANCE
Highly susceptible to heat, dessication, alteration in PH
Uniformly sensitive to penicillins & other antibiotics
PROPHYLAXIS
SULPHONAMIDES & PENICILLLIN
RIFAMPICIN or  CIPROFLOXACIN
Monovalent & Polyvalent vaccines ( capsular polysaccharides of groups A,C,W-135 & Y)
Conjugate vaccines  immunogenic for children below 2 years.

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