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Pathology of Meningococcal Infection

 Dr Sampurna Roy MD

 

                                                                                                                      

 

Neisseria meningitides are Gram negative, diplococci with capsule.  

 

In addition to antiphagocytic factor in capsule, bacteria produce powerful endotoxin, which are responsible for disease.

Transmission of infection is from healthy carrier or recently recovered patients, by airborne droplets, particularly in crowded environment.

2-5% healthy persons harbour menigococci in their nasopharynx.

The disease is not highly contagious and infection rate, rarely exceeds 1 in 1000, even during epidemic.

Infection may be Sporadic, Endemic or Epidemic:

Meningococci causes two distinct, fatal diseases:

1. Meningococcal meningitis ; 

2. Fulminant meningococcemia.

 

1. Meningococcal meningitis:

           

The disease may be described under three stages:

Stage-I:   Local infection at the site of entry i.e. nasopharynx.
Most people become carrier & develop no symptoms, except occasional pharyngitis.

Stage-II:   Characterized by septicemia.
There is fever with skin rashes (spotted fever), which may extend to erythema.

Occasionally, there may be massive purpuric hemorrhage & involved area becomes  gangrenous.

Stage-III:   Localization, mainly in the meninges.

This is associated with headache, vomiting & stiff-neck, followed by delirium & coma.

Due to blood-brain barrier bacteria cannot enter to brain tissue.

It causes acute inflammation of the leptomeninges (Pia and arachnoid matter).

Meningeal vessels are congested with exudates in the subarachnoid space and minute areas of hemorrhage.

In advanced stage thick purulent exudates is seen, mainly  in the base of the brain.

Inflammation and degenerative changes are present in the superficial layer of brain due to diffusion of toxin.

In chronic form, internal hydrocephalus may develop.

2. Fulminant Meningococcemia:

           

- Sudden onset of fever, tachycardia & hypotension are the early symptoms.

- Sudden toxemia kills the patient within 6-26 hours.

- Evidence of meningitis is uncommon due to rapid course.

- Meningococcemia is the main cause of Waterhouse-Friderichsen Syndrome in children, which is characterized by:

(i) Purpura (ii) Circulatory collapse and (iii) Adrenal hemorrhage.

- Patients surviving early phase of meningococcemia develop allergic manifestations:

(i) Polyarthritis (ii) Cutaneous vasculitis leading to ulceration. (iii) Gangrene of distal portion of limbs.

Cutaneous Lesions :

  

The cutaneous lesions in meningococcal septicemia show an acute vasculitis with fibrin thrombi in the small blood vessels of the dermis and extravasation of fibrin.

There are neutrophils in and around the vessels.

Leukocytoclasis is not a conspicuous feature.

In pustular lesions of chronic meningococcemia there are intraepidermal and subepidermal collections of neutrophils.

Vasculitis is present in the dermis. The infiltrate contains some lymphocytes in addition to neutrophils.

 

Further reading:

-Epidemiology and prevention of meningococcal disease.

-Gangrene associated with meningococcemia.  

-Pathophysiology, treatment and outcome of meningococcemia: a review and recent experience.

-Diagnostic Microbiology -Fourth Edition. JB Lippincott Company,1992, pp.370-398

-Meningococcal Disease-Journal of Medical Microbiology.1993;39(1):3-25.

-Infectious Diseases -Fourth Edition. Churchill Livingstone, 1995, p1896-1906

 

 

 

Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)


 

 

 

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