• Meningitis is the infection of the meninges and subarachnoid space that is usually caused by bacteria results in high mortality and morbidity throughout the world

• The introduction of conjugated vaccines against H influenza type B, N meningitidis and S pneumoniae caused decline in the incidence of bacterial meningitis in children thus majority of cases are now present in the adult population
• Causative agents depend on the age of the patient and predisposing factors

Other causes of acute meningitis include the following:

• Spirochetes eg Treponema pallidum
• Mycobacteria eg Mycobacterium tuberculosis
• Fungi eg Cryptococcus, Coccidioides, Sporothrix
• Viruses eg herpes simplex virus (HSV), varicella zoster, cytomegalovirus (CMV), enterovirus
• Protozoa and helminths

• Classic triad: Fever, neck stiffness and an altered level of consciousness
• Other symptoms:
  
  • Chills
  • Myalgia
  • Photophobia
  • Severe headache
  • Focal neurologic symptoms [eg cranial nerve palsies, ataxia, dilated/unequal and poorly reacting pupils (late sign)]
  • Nausea/vomiting
  • Seizures (late sign)
  • Some patients may present with petechial rash