title: The many causes of meningitis.
abstract: Meningitis should be suspected in a patient who presents with fever, meningism, or severe headache. A careful physical examination should be performed of perimeningeal foci, with emphasis on the sinuses, ears, throat, neck, and lungs. A history of exposure to tuberculosis, viral disease, rodents, or suspicious dairy products or farm animals may give clues to the source of the meningitis. Immunosuppression through the use of corticosteroids or chemotherapy for such conditions as Hodgkin's disease, lymphoma, leukemia, malnutrition, or acquired immunodeficiency syndrome (AIDS) should also be noted and alert the clinician to the possible presence of an unusual pathogen. Meningitis associated with leukemia or most of the non-T-cell lymphomas is likely to be from a common bacterial agent (often Listeria), unless the patient is being treated with a steroid or is receiving other chemotherapy. Patients with Hodgkin's disease or AIDS or who have been treated with a steroid are more likely to have cryptococcal or tuberculous meningitis. Neonates and the very elderly may present with only irritability or lethargy and fever, without any of the other common symptoms. In neonates up to one week of age, group B streptococcal infection should be suspected. Gram-negative organisms should be suspected in elderly patients and those who have had neurosurgery. In patients with CSF shunts, infection with coagulase-negative Staphylococcus should be assumed and these patients are treated empirically until results of cultures are received. Several noninfectious conditions may mimic infectious meningitis, as may some unusual causes of infectious meningitis (eg, syphilis and schistosomiasis), which have not been discussed in this article.
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001424:Bacterial Infections; D003937:Diagnosis, Differential; D006801:Humans; D008581:Meningitis / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*; D008582:Meningitis, Aseptic / Q000175:diagnosis; D008583:Meningitis, Haemophilus / Q000175:diagnosis; D008585:Meningitis, Meningococcal / Q000175:diagnosis; D008587:Meningitis, Viral / Q000175:diagnosis*
chemical_list: D000900:Anti-Bacterial Agents