2. Morphology
• Capsulated Gram negative cocci in pairs
(diplococci)
• 0.5 – 1 µm in size
• Kidney shaped, flat sides adjacent
• Intracellular, usually
• Non motile
• Non spore forming.
3. Virulence factors
• Antigens
• Capsular polysaccharide
• 13 serogroups (A, B, C, D, W 135, X, Y, Z,
H, K & L)
• Used in vaccine
• Serogroups A, B, C, Y, W 135 for about
90% of the epidemics
• Antiphagocytic in nature
• Outer membrane proteins
• 5 classes
• Serogroups further subdivided into 20
serotypes
4. • Pili – helps in meningeal invasion
• Toxin
• Endotoxin
• Lipid A part of
lipopolysaccharide
• Induces septicemic shock
• Enzyme
• IgA protease – cleaves the IgA
antibodies present in the
respiratory mucosa.
5. Epidemiology
• Reservoir and habitat
• Upper respiratory tract of humans
• Transmission
• Direct contact and air borne droplets
• Close contact with infectious person
• Family members
• Day care centers
• Military barracks
• Prisons and
• Other institutional settings
• Incubation period – 1 to 7 days
• Carriage
• 5 – 30% of normal persons may harbor
meningococci in nasopharynx
10. Bacterial Meningitis
• Bacterial meningitis can be classified as
• Acute
• Chronic
• Acute meningitis: Onset of meningeal symptoms over the course of hours to days.
• Chronic meningitis: Onset in weeks to months.
• Acute Pyogenic Meningitis: Infectious inflammatory infiltration of leptomeninges
caused by bacteria
11. Bacterial Causes Related to Age
Age Group
Pathogen
0 – 4 Weeks
Streptococcus agalactiae
Escherichia coli
Listeria monocytogenes
Streptococcus pneumoniae
1 – 3 Months
Haemophilus influenzae
Listeria monocytogenes
Neisseria meningitidis
Streptococcus pneumoniae
3 Months – 18 Years
Haemophilus influenzae
Neisseria meningitidis
Streptococcus pneumoniae
18 – 50 Years
Neisseria meningitidis
Streptococcus pneumoniae
> 50 Years
Listeria monocytogenes
Streptococcus pneumoniae
12. Bacterial Causes Related to
Clinical Condition
Clinical Condition
Pathogen
Healthy, Immunocompetent
(Community Acquired)
Neisseria meningitidis
Streptococcus pneumoniae
Post Neurosurgical or Post traumatic
(Nosocomial)
Staphylococcus aureus
Enterobacteriaceae
Pseudomonas aeruginosa
Immunosuppressed or older patients
Listeria monocytogenes
Enterobacteriaceae
Pseudomonas aeruginosa
Streptococcus pneumoniae
14. Epidemiology
• Accounts for an estimated annual 1,70,000 deaths worldwide.
• S pneumoniae and N meningitidis causes approximately 6.5 and 4 cases per 1,00,000
children aged 1-23 months respectively.
• In 1996, the biggest meningococcal meningitis outbreaks recorded in West Africa. An
estimated 250,000 cases and 25,000 deaths occurred.
• In 1985, in Delhi 6133 cases with 799 deaths (13%) were reported. All the isolates of N.
meningitidis belonged to subgroup A.
15. Transmission
• Although dangerous disease, not easily
spread.
• Through droplets from mouth and nose.
• Transmission not necessarily gives rise to
disease.
• 15% adults carry disease causing strains in
nose and throat.
16. Pathogenesis
• Bacteria reach the intracranial structures in one of the
3 ways
• Hematogenous spread.
• Extension from the juxtacranial structures.
• Iatrogenic source.
20. Immune Response
Pathogenic Event
Host factors
Bacterial evasion
mechanism
Mucosal
Colonization
Mucosal epithelium,
large amount of
secretory IgA, Ciliary
activity
IgA protease secretion,
ciliostasis, adhesive pili
Intravascular
survival
Complement system
Blockage of alternative
pathway
Meningeal
invasion
Blood brain barrier
Passage through tight
junctions
Survival within CSF Poor opsonic activity
Rapid replication
21. Clinical features
• Meningitis and meningococcal septicaemia may not always be easy to detect, in
early stages the symptoms can be similar to flu.
• They may develop over one or two days, but sometimes develop in a matter of hours.
• It is important to remember that symptoms do not appear in any particular order and
some may not appear at all.
22. In infants and young children:
-High temperature, fever, possibly with cold hands and feet
-Vomiting or refusing feeds
-High pitched moaning, whimpering cry
-Blank, staring expression
-Pale, blotchy complexion
-Stiff neck
-Arched back
-Baby may be floppy, may dislike being handled, be fretful
-Difficult to wake or lethargic
-The fontanelles may be tense or bulging.
23.
24. In older children and adults:
-High temperature, fever, possibly with cold hands and feet.
-Vomiting, sometimes diarrhoea.
-Severe headache.
-Joint or muscle pains, sometimes stomach cramps.
-Neck stiffness (unable to touch the chin to the chest)
-Dislike of bright lights.
-Drowsiness.
-The patient may be confused or disorientated. Seizures may
also be seen.
-A rash may develop.
25.
26. Signs
• Neck and back stiffness
• Positive Kernig’s and Brudzinski’s signs
• In infants, there is usually presence of neck rigidity with bulging fontanelle.
27. • Severe stiffness of the
hamstrings causes an inability
to straighten the leg when the
hip is flexed to 90 degrees.
28. • Severe neck stiffness causes a
patient's hips and knees to flex
when the neck is flexed.
29. • One sign of meningococcal septicaemia is a rash that does not fade under pressure
(see ‘Glass test’)
• This rash is caused by blood leaking under the skin. It starts anywhere on the body. It
can spread quickly to look like fresh bruises.
• This rash is more difficult to see on darker skin. Look on the paler areas of the skin and
under the eyelids.
30. Laboratory diagnosis
• Specimen
• Cerebrospinal fluid (CSF) and blood
• Nasopharyngeal swab for carrier state
• CSF is collected through lumbar
puncture, subdural tap or ventricular
aspiration
• Collected preferably before instillation of
antibiotics
31. CSF
Macroscopy
Centrifuge Specimen and take deposits for
bacteriological analysis
Direct
examination
Gram Stain
Initial Report
Culture
Examination
Rapid
Diagnostic Test
Inoculate
BA
CA
MA
Incubate 37oC, 24 hours.
(BA & CA @ 5 – 10 % CO2)
Examine colonies, Gram
stain, biochemical,
Serology.
AST and Final report
•
•
•
•
•
Latex agglutination
Quellung test
Limulus amoebocyte
lysate assay
Coagglutination test
PCR
32. Differential Diagnosis of Meningitis based on Cerebrospinal Fluid Findings
Diagnosis
CSF Pressure
(mm H2O)
(WBC /mm3)
Neutrophils(%)
Glucose
(Ratio)
Protein (g/l)
Normal
<200
1-2
<1
>0.5
<0.45
Acute
Bacterial
>200
>1000
>50
<0.4
>1
Chronic
Bacterial (TB)
Variable
>1000
Variable
<0.4
>0.45
Aseptic (Viral)
<200
<1000
<50
>0.4
Variable
33. • Culture media
• Blood agar
• Chocolate agar
• Selective medium – Modified Thayer-Martin medium with vancomycin, colistin and
nistatin to avoid contamination.
34. Growth characteristics
• Oxygen requirement
• Aerobic and facultative anaerobic
• Temperature
• Optimum growth at 370C
• Growth promoted by 5 – 10% CO2
• Colony morphology
• 1 – 2 mm diameter, convex, grey,
translucent, non pigmented and
non hemolytic
• After 48 hours, colonies are larger
with opaque raised center and
transparent margins.
35. Biochemical reactions
• Oxidase positive and catalase positive
• Ferments glucose and maltose with production of gas but not sucrose or lactose
36. Serology
• Latex agglutination test
• CSF sample
• Antibodies to meningococcal polysaccharide capsule can be detected
• Results within 20 – 30 minutes
• High sensitivity but lacks specificity
37. Treatment
• Empiric therapy
• Ceftriaxone/ cefotaxime
• Vancomycin until S pneumoniae is ruled
out
• Ampicillin to be added if Listeria is
suspected
• If severe penicillin allergies, Meropenem is
used instead
• Acyclovir is to be added if viral infection is
suspected.
• Definitive therapy
• As per antimicrobial sensitivity test pattern.
38. Chemoprophylaxis
• Rifampicin is the drug of choice for 2 days
• A single dose of oral ciprofloxacin or iv ceftriaxone is also effective
• Given to close contacts of suspected patients
39. Immunization
• Infants – passive immunity from mothers
• Under 2 years of age – no reliable antibody production
• Quadrivalent meningococcal polysaccharide vaccine (A, C, Y and W 135)
• Use of vaccine is strongly advised during outbreaks.
40. Meningococcemia
• Intravascular multiplication of Neisseria
meningitidis
• Abrupt onset of spiking fever, chills, arthralgia
and muscle pains
• Abrupt onset of hypotension and tachycardia
• Rapidly enlarging petechial lesions
• Wide spread purpura coalesce into
hemorrhagic bullae
• Shock
• DIC
• Coma and death ensues within hours
41. Fulminant meningococcemia
• The most severe form of meningococcemia is the life threatening
WATERHOUSE FRIDERICHSEN SYNDROME
• Septic shock with vascular collapse and multisystem failure
• Bilateral hemorrhages into the adrenal glands leading to adrenal insufficiency
• Increased prothrombin time, raised fibrin dimers, reduced fibrinogen levels and low
platelet count indicating disseminated intravascular coagulation
• Commonly seen in individuals with C5, C6 and C7 deficiency disorders.
