​Pathology-Meningitis

​Pathology-Meningitis 
Pyogenic meningitis is caused by different bacteria depending on the age group: Group B streptococci, Escherichia coli, and Listeria in neonates and infants; Haemophilus influenzae and Neisseria meningitidis in children and young adults; and pneumococcus, Listeria, and gram-negative rods in older individuals.

Causes of viral meningitis include HSY virus, Coxsackievirus, echoviruses, and arboviruses.


Pyogenic meningitis is characterized by a purulent discharge in the leptomeninges, engorged meningeal arteries, and the presence of neutrophils in the subarachnoid space.
Viral meningitis may show either no abnormalities or a slight lymphocytic infiltration in the subarachnoid space, with moderate edema perhaps occurring.

Pyogenic meningitis presents with symptoms such as headache, photophobia, neck stiffness, fever, and altered mental status.
Laboratory results indicate that the cerebrospinal fluid obtained from a lumbar puncture appears cloudy, contains neutrophils, has elevated protein levels, reduced glucose levels, and demonstrates increased opening pressure.
Symptoms of viral meningitis include headache, photophobia, neck stiffness, fever, and altered mental status. Lab results: Lumbar puncture indicates an increase in lymphocytes, slightly raised protein levels, and normal glucose levels.

Pyogenic meningitis is treated with antibiotics and supportive care. Steroids may be considered for H influenzae infection.
Viral meningitis is a self-limiting condition. Acyclovir is used for herpes simplex virus (HSY) meningitis.

Viral encephalitis is an infection that affects the brain and/or meninges.
It can be caused by several organisms such as arboviruses, herpes, CMY, rabies, and poliovirus.
Glial nodules, neuronal inclusion bodies, and perivascular mononuclear cell infiltrates are observed histopathologically.