NEISSERIANEISSERIA

Pavithra G. Palan.

INTRODUCTION:INTRODUCTION:

Gram negative aerobic cocci arranged Gram negative aerobic cocci arranged in pairs.in pairs.

Nonsporulating & nonmotile.Nonsporulating & nonmotile.

Oxidase positive.Oxidase positive.

CLASSIFICATIONCLASSIFICATION: : Based on Based on pathogenicitypathogenicity

1. Pathogenic-1. Pathogenic-

a) Neisseria meningitidis( Meningococcus a) Neisseria meningitidis( Meningococcus ))

b) Neisseria gonorrhoeae( Gonococcus)b) Neisseria gonorrhoeae( Gonococcus)

2. Commensals- 2. Commensals-

a) Neisseria flavaa) Neisseria flava

b) Neisseria subflavab) Neisseria subflava

c) Neisseria flavisansc) Neisseria flavisans

Neisseria meningitidisNeisseria meningitidis

MORPHOLOGY:MORPHOLOGY: Gram negative cocciGram negative cocciarranged in pairs, with arranged in pairs, with

thetheadjacent sides flattened.adjacent sides flattened. Each coccus is aboutEach coccus is about0.6-0.8 0.6-0.8 μμm in diameter.m in diameter. They may be intra orThey may be intra orextracellular.extracellular. They are nonmotile,They are nonmotile,nonsporing & most of nonsporing & most of

the the strains are capsulated.strains are capsulated.

Intracellular

Extracelluar

Pus cell

CULTURE & CULTURAL CULTURE & CULTURAL CHARACTERISTICS:CHARACTERISTICS:

Meningococci are fastidious organisms do Meningococci are fastidious organisms do not grow on ordinary culture media.not grow on ordinary culture media.

They are strict aerobes, no growth occur They are strict aerobes, no growth occur anaerobically.anaerobically.

The optimum temperature for growth is 35-The optimum temperature for growth is 35-36°C & optimum pH is 7.4-7.6.36°C & optimum pH is 7.4-7.6.

Growth is facilitated by 5-10% CO2.Growth is facilitated by 5-10% CO2.

Media usedMedia used::

a) Non selective media: Blood agar, a) Non selective media: Blood agar,

Chocolate agar,Chocolate agar,

Muller-Hinton Muller-Hinton agar.agar.

b) Selective media: Modified Thayer b) Selective media: Modified Thayer Martin medium,Martin medium,

New-York City New-York City medium.medium.

Colony morphologyColony morphology: On chocolate agar : On chocolate agar the colonies arethe colonies are small, round, convex, mall, round, convex, translucent, bluish grey, smooth with translucent, bluish grey, smooth with entire edges.entire edges.

BIOCHEMICAL REACTIONSBIOCHEMICAL REACTIONS::

1. Catalase test- Positive1. Catalase test- Positive

2. Oxidase test- Positive2. Oxidase test- Positive

2. Glucose & maltose is fermented, but 2. Glucose & maltose is fermented, but not sucrose, producing acid but no gas.not sucrose, producing acid but no gas.

PATHOGENICITY:PATHOGENICITY:

Source of infectionSource of infection::

1.1. Asymptomatic nasopharyngeal carriersAsymptomatic nasopharyngeal carriers

2.2. PatientsPatients

Mode of infectionMode of infection: Inhalation of : Inhalation of respiratory respiratory

dropletsdroplets

Antigenic structure & Virulence factorsAntigenic structure & Virulence factors::

1. 1. CapsuleCapsule::

- Carbohydrate in nature.- Carbohydrate in nature.

- Based on their capsular antigens, - Based on their capsular antigens, meningococci aremeningococci are

classified into 13 serogroups, of which classified into 13 serogroups, of which Groups A, BGroups A, B

& C are the most important.& C are the most important.

- It is antiphagocytic.- It is antiphagocytic.

2. 2. Endotoxin (LPS)Endotoxin (LPS): It damages vascular : It damages vascular endothelium.endothelium.

Antigenic structure & virulence factors of Meningococcus

Mechanism of pathogenesisMechanism of pathogenesis::

Entry of meningococci into nasopharynx by Entry of meningococci into nasopharynx by inhalation inhalation

Adherence to nasophayngeal mucosaAdherence to nasophayngeal mucosa

Colonization of nasopharynxColonization of nasopharynx

It reaches meninges through blood( bacteremia) or It reaches meninges through blood( bacteremia) or throughthrough

the olfactory nerve or through cribriform plate to the olfactory nerve or through cribriform plate to thethe

subarachnoid spacesubarachnoid space

On reaching the CNS, suppurative lesions of the On reaching the CNS, suppurative lesions of the meningesmeninges

will be set upwill be set up

(Meningococcemia)

DISEASES:

1. 1. Meningitis:Meningitis:

Meningococci causes purulent Meningococci causes purulent meningitis.meningitis.

Clinical symptoms- Fever, head ache, Clinical symptoms- Fever, head ache, stiff neck & blurred vision.stiff neck & blurred vision.

Some cases develop chronic or Some cases develop chronic or recurrent meningitis. recurrent meningitis.

2. 2. Meningococcal septicemia:Meningococcal septicemia:

PresencePresence of meningococci & its toxin of meningococci & its toxin in blood.in blood.

Clinical symptoms- Acute fever, chills, Clinical symptoms- Acute fever, chills, malaise, prostration & typical petechial malaise, prostration & typical petechial skin rash occurs early in the disease.skin rash occurs early in the disease.

Metastatic involvement of joints, ears, Metastatic involvement of joints, ears, eyes, lungs & adrenals may occur.eyes, lungs & adrenals may occur.

Purpura

Petechial skin rashes

A few develop fulminant A few develop fulminant meningococcemia (Waterhouse-meningococcemia (Waterhouse-Friderichsen syndrome) characterized by Friderichsen syndrome) characterized by shock, disseminated intravascular shock, disseminated intravascular coagulation & multisystem failure.coagulation & multisystem failure.

Rarely chronic meningococcemia may be Rarely chronic meningococcemia may be seen.seen.

LABORATORY DIAGNOSIS:LABORATORY DIAGNOSIS:

Specimens to be collected:Specimens to be collected:

CSF,CSF,

Blood,Blood,

Material from petechial skin lesion,Material from petechial skin lesion,

Nasopharyngeal swab.Nasopharyngeal swab.

MethodsMethods of of examinationsexaminations

1. 1. Examination of CSF:Examination of CSF:

A) Macroscopic examination: The CSF will A) Macroscopic examination: The CSF will be turbid.be turbid.

B) Biochemical examination:B) Biochemical examination: Glucose level - decreased Glucose level - decreased Protein level - increasedProtein level - increased Lactic acid level - increasedLactic acid level - increasedC) Cytological examination: Shows C) Cytological examination: Shows

polymorphs.polymorphs.D) Bacteriological examination: The CSF is D) Bacteriological examination: The CSF is

divided into 3 portions.divided into 3 portions.

a) a) One portion of CSFOne portion of CSF: is centrifuged.: is centrifuged.

i) From deposit: Gram stained smears are i) From deposit: Gram stained smears are prepared.prepared.

Gram negative diplococciGram negative diplococci

will be seen mainly inside will be seen mainly inside

polymorphs but often polymorphs but often

extracellularly also. extracellularly also.

ii) From supernatant: antigen may be ii) From supernatant: antigen may be demonstrated bydemonstrated by

- Latex agglutination Latex agglutination - Counter immunoelectrophoresis.Counter immunoelectrophoresis.

b) b) Second portion of CSFSecond portion of CSF: : used for culture.used for culture.

Media used:Media used:

Colony morphology:Colony morphology:

Gram’s smear: Gram’s smear: Reveals Gram negative cocci in pairs. Reveals Gram negative cocci in pairs.

Biochemical reactions:Biochemical reactions:

Slide agglutination: The isolated Slide agglutination: The isolated meningococcus is grouped bymeningococcus is grouped by

using antisera.using antisera.

c) c) Third portion of CSFThird portion of CSF: is incubated : is incubated overnight as it is or after adding equal overnight as it is or after adding equal volume of glucose broth & subculture in volume of glucose broth & subculture in chocolate agar or blood agar.chocolate agar or blood agar.

2. 2. Blood culture:Blood culture: in meningococcemia & in meningococcemia & in early cases of meningitis, Blood in early cases of meningitis, Blood culture is positive.culture is positive.

3. 3. Nasopharyngeal swab:Nasopharyngeal swab: useful for useful for detection of carriers. The swab should detection of carriers. The swab should be held in a transport medium (Stuart’s) be held in a transport medium (Stuart’s) till it is plated.till it is plated.

4. 4. Material from petechial lesionMaterial from petechial lesion: used : used for microscopy & culture.for microscopy & culture.

5. 5. Autopsy specimens:Autopsy specimens: used for used for microscopy & culture.microscopy & culture.

6. 6. SerologySerology: Antibodies to capsular : Antibodies to capsular polysaccharide may be demonstrated polysaccharide may be demonstrated by haemagglutination test.by haemagglutination test.

TREATMENT:TREATMENT: Penicillin G is the drug of choice.Penicillin G is the drug of choice. Chloramphenicol is used for penicillin Chloramphenicol is used for penicillin

allergic persons.allergic persons. Ceftriaxone or Ceftazidime may be used Ceftriaxone or Ceftazidime may be used

for the initiation of treatment before the for the initiation of treatment before the etiology of meningitis is known.etiology of meningitis is known.

After the initial course of treatment, After the initial course of treatment, eradicative therapy is to be given with eradicative therapy is to be given with Rifampicin or Ciprofloxacin to free the Rifampicin or Ciprofloxacin to free the nasopharynx from the cocci & to nasopharynx from the cocci & to prevent carrier state.prevent carrier state.

EPIDEMIOLOGY:EPIDEMIOLOGY:

Humans are the only reservoir of the Humans are the only reservoir of the meningococcus.meningococcus.

The asymptomatic nasopharyngeal The asymptomatic nasopharyngeal carriers serve to infect their contacts.carriers serve to infect their contacts.

Meningitis is more common in children Meningitis is more common in children below the age of 5.below the age of 5.

PREVENTION:PREVENTION:

1.1. Chemoprophylaxis:Chemoprophylaxis: Rifampicin or Rifampicin or Ciprofloxacin is recommended.Ciprofloxacin is recommended.

2.2. ImmunoprophylaxisImmunoprophylaxis: : Monovalent & Monovalent & polyvalent vaccines containing the polyvalent vaccines containing the capsular polysaccharides groups A, C, capsular polysaccharides groups A, C, W-135 & Y are available.W-135 & Y are available.

Thank you