Dr. K V CHAKRADHAR
Department of Microbiology
• Capsulated Gram negative cocci in pairs
• 0.5 – 1 µm in size
• Kidney shaped, flat sides adjacent
• Intracellular, usually
• Non motile
• Non spore forming.
• 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
• Pili – helps in meningeal invasion
• Lipid A part of
• Induces septicemic shock
• IgA protease – cleaves the IgA
antibodies present in the
• Reservoir and habitat
• Upper respiratory tract of humans
• 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
• 5 – 30% of normal persons may harbor
meningococci in nasopharynx
• Meningitis is an inflammation of leptomeninges within the subarachnoid space.
• Bacterial meningitis can be classified as
• 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
Bacterial Causes Related to Age
0 – 4 Weeks
1 – 3 Months
3 Months – 18 Years
18 – 50 Years
> 50 Years
Bacterial Causes Related to
Post Neurosurgical or Post traumatic
Immunosuppressed or older patients
• 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.
• Although dangerous disease, not easily
• Through droplets from mouth and nose.
• Transmission not necessarily gives rise to
• 15% adults carry disease causing strains in
nose and throat.
• Bacteria reach the intracranial structures in one of the
• Hematogenous spread.
• Extension from the juxtacranial structures.
• Iatrogenic source.
Release of bacterial
large amount of
secretory IgA, Ciliary
IgA protease secretion,
ciliostasis, adhesive pili
Blockage of alternative
Blood brain barrier
Passage through tight
Survival within CSF Poor opsonic activity
• 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.
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
-Baby may be floppy, may dislike being handled, be fretful
-Difficult to wake or lethargic
-The fontanelles may be tense or bulging.
In older children and adults:
-High temperature, fever, possibly with cold hands and feet.
-Vomiting, sometimes diarrhoea.
-Joint or muscle pains, sometimes stomach cramps.
-Neck stiffness (unable to touch the chin to the chest)
-Dislike of bright lights.
-The patient may be confused or disorientated. Seizures may
also be seen.
-A rash may develop.
• Neck and back stiffness
• Positive Kernig’s and Brudzinski’s signs
• In infants, there is usually presence of neck rigidity with bulging fontanelle.
• Severe stiffness of the
hamstrings causes an inability
to straighten the leg when the
hip is flexed to 90 degrees.
• Severe neck stiffness causes a
patient's hips and knees to flex
when the neck is flexed.
• 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.
• Cerebrospinal fluid (CSF) and blood
• Nasopharyngeal swab for carrier state
• CSF is collected through lumbar
puncture, subdural tap or ventricular
• Collected preferably before instillation of
Centrifuge Specimen and take deposits for
Incubate 37oC, 24 hours.
(BA & CA @ 5 – 10 % CO2)
Examine colonies, Gram
AST and Final report
Differential Diagnosis of Meningitis based on Cerebrospinal Fluid Findings
• Culture media
• Blood agar
• Chocolate agar
• Selective medium – Modified Thayer-Martin medium with vancomycin, colistin and
nistatin to avoid contamination.
• Oxygen requirement
• Aerobic and facultative anaerobic
• Optimum growth at 370C
• Growth promoted by 5 – 10% CO2
• Colony morphology
• 1 – 2 mm diameter, convex, grey,
translucent, non pigmented and
• After 48 hours, colonies are larger
with opaque raised center and
• Oxidase positive and catalase positive
• Ferments glucose and maltose with production of gas but not sucrose or lactose
• Latex agglutination test
• CSF sample
• Antibodies to meningococcal polysaccharide capsule can be detected
• Results within 20 – 30 minutes
• High sensitivity but lacks specificity
• Empiric therapy
• Ceftriaxone/ cefotaxime
• Vancomycin until S pneumoniae is ruled
• Ampicillin to be added if Listeria is
• If severe penicillin allergies, Meropenem is
• Acyclovir is to be added if viral infection is
• Definitive therapy
• As per antimicrobial sensitivity test pattern.
• 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
• 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.
• Intravascular multiplication of Neisseria
• 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
• Coma and death ensues within hours
• 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.