Bacterial meningitis is usually more severe and can cause brain damage, hearing loss, limb amputation, learning disabilities and even death. The most common causes of bacterial meningitis are Streptococcus pneumoniae and Neisseria meningitidis, followed by Group B Streptococcus (GBS), Eschericia coli K1, Listeria monocytogenes, and Haemophilus influenzae type b.