Meningitis has a wide variety of potential causes, either infectious or non-infectious. If bacterial meningitis is not treated promptly and effectively, the disease is likely to be fatal. Early identification of the infecting agent can be of considerable value in providing the patient with appropriate and adequate chemotherapy. Many bacterial species have been implicated in meningitis. Streptococcus agalactiae (Group B) and Escherichia coli (K1) are two of the most common causes of neonatal sepsis whilst in older age groups the commonest isolated are Haemophilus influenzae (Type B), Streptococcus pneumoniae and Neisseria meningitidis (Group A, B, C, Y, and W135)

Results from bacterial antigen testing should be considered presumptive and culture with Gram stain must also be performed. May be negative in early stages of infection. Vaccination may affect results