Bacterial meningitis

a)common causes

1.neisseria meningitis
2.haemophilus influenzae type b(HIB)
3.Streptococcus pneumoniae(pneumococcal meningitis)

b)mycobacterium tuberculosis(pneumococcal meningitis)

c)less common causes

1.listeria monocytogenes
2.staphylococcus species
3.streptococcus species
4.gram-negative enteric bacilli
5.pseudomonas aeruginosa
6.spirochetes:leptospira interrorgans(weil's diseases),treponema pallidum(syphilitic meningitis in secondary syphilis and neurosyphilis in tertiary syphilis) and borrelia burgdorferi(lyme disease)

d)neonatal meningitis

1.streptococcus agalactiae
2.escherichia coli
3.listeria monocytogenes
4.gram-negative enteric bacilli including k.pneumoniae and citrobacter spp.