Difficulties in the diagnosis of bacterial meningitis. Evaluation of antibiotic pretreatment and causes of admission to hospital.

In 104 patients with bacterial meningitis admitted to departments of general medicine, the diagnosis before admission and the effect of previous antibiotic treatment were studied. Antibiotic therapy begun before admission in 30 patients did not affect the ability to make a bacteriological diagnosis. The duration of illness before admission was longer in the treated than in the untreated group. About 50% of the patients were admitted with diagnoses other than meningitis, although half these patients had distinct meningeal signs on arrival at hospital. In the whole series, 76% had meningeal signs on arrival. On the other hand, 95% of 108 patients with lymphocytic meningitis were admitted with a diagnosis of meningitis. The only significant clinical finding in the wrongly diagnosed group was a temperature higher than 40 degrees C on admission to hospital. The diagnosis before admission was not related to the treatment given. The findings illustrate the difficulties of diagnosing bacterial meningitis in the home.