The use of Haemophilus influenzae type b vaccines has eliminated meningitis worldwide except in older patients. Previous studies of meningitis in adults that defined the clinical presenting features of meningitis were limited by being small and retrospective. Van de Beek and colleagues prospectively analyzed adults to identify the clinical features of community-acquired bacterial meningitis.
The authors used the Netherlands Reference Laboratory for Bacterial Meningitis to identify 696 patients admitted with bacterial meningitis between October 1998 and April 2002. The most common causes of meningitis were Streptococcus pneumoniae (51 percent), Neisseria meningitidis (37 percent), and Listeria monocytogenes (4 percent). The estimated annual incidence rate was 2.6 cases per 100,000 persons. Almost one half of the patients (48 percent) had a predisposing condition, with otitis or sinusitis being the most common (25 percent), followed by an immunocompromised state (16 percent) and pneumonia (12 percent).
The common triad of presenting features of fever, neck stiffness, and altered mental state was present in only 44 percent of the patients. Headache was the most common symptom (87 percent) (see accompanying table). When headache was added to the three common presenting features, 95 percent of patients had at least two of the four symptoms. Only 4 percent (n = 28) of the patients had one of these four symptoms, and only 1 percent of the patients (n = 4) had none of the common presenting features. More than one half of the cases with the three common presenting features were caused by Pneumococcus. Rash was present in 26 percent (n = 176) of the patients, and N. meningitidis was the causative agent in 162 of these patients. Focal neurologic changes were common (33 percent), with aphasia accounting for one half of these changes.
|Symptom||Cases of meningitis (%)|
|Altered mental state||69|
|Symptoms lasting less than 24 hours||48|
|Focal neurologic deficit||33|
The authors concluded that there was a low prevalence of the presenting triad of fever, neck stiffness, and altered mental status in adults with community-acquired bacterial meningitis. However, almost all patients presented with at least two of the four symptoms of headache, fever, neck stiffness, and an altered mental status. Focal neurologic changes, particularly aphasia, also are common.