Meningitis is the inflammation of the meninges and is caused by viral or bacterial infections. The terminology pyogenic meningitis describes bacterial meningitis, while viral infections usually presents as meningoencephalitis. However, clinically it is difficult to differentiate one from the other and a Cerebrospinal fluid analysis is mandatory to make the diagnosis.
Etiology
Viral - Enterovirus (Coxsackie, echovirus), mumps virus and Herpes Simplex virus.
Bacterial
Neonates: Group B Streptococcus, Listeria Monocytogenes, Enterococcus, Staphylo-coccus, and Gram negative Organisms.
2 months to 2 years - Hemophilus Influenza, Streptococcus Pneumonia, Staphylococcus
2 years: Streptococcus Pneumonia, Neisseria Meningitis and Salmonella
Immunocompromised individuals at all ages: Staphylococcus, Pseudomonas, and Listeria monocytogenes along with the regular group of organisms causing meningitis in the immunocompetent group.