The Changing Face of Bacterial Meningitis

Abstract & Commentary

Synopsis: The mortality associated with bacterial meningitis remains high, and the strongest risk factors for an unfavorable outcome are those that are indicative of systemic compromise, a low level of consciousness, and infection with S. pneumoniae.

Source: van de Beek D, et al. Clinical Features and Prognostic Factors in Adults With Bacterial Meningitis. N Engl J Med. 2004;351:1849-1859.

The present study was a nationwide examination of all patients in the Netherlands from October of 1998 until April 2002 with community-acquired acute bacterial meningitis. This was confirmed by cerebrospinal fluid cultures. All patients were evaluated neurologically on admission and at discharge. van de Beek and colleagues determined predictors of an unfavorable outcome. They evaluated 696 cases of community-acquired bacterial meningitis. The most common pathogens were Streptococcus pneumoniae with 51% of the episodes, and Neisseria meningitis with 37%. Interestingly, the classic triad of fever, neck stiffness, and a change in mental status was only found in 44% of the patients. Ninety-five percent, however, had at least 2 of the 4 symptoms of headache, fever, neck stiffness, and altered mental status. At the time of admission, 14% of the patients were comatose and 33% had focal neurologic abnormalities. The overall mortality rate was 21%. The mortality rate was higher in patients with pneumococcal meningitis than in those with meningococcal meningitis. This was a mortality of 30% in the former and 7% in the latter. An unfavorable outcome, defined as a Glasgow Outcome Scale of 1-4. occurred at 34% of the cases at discharge. Risk factors for an unfavorable outcome were: advantaged stage, the presence of otitis or sinusitis, absence of rash, and a low score on Glasgow Coma Scale on admission. Other risk factors were tachycardia, positive blood culture, elevated erythrocyte sedimentation rate, thrombocytopenia, and a low cerebrospinal fluid white-cell count.

Commentary

These findings show that the classic findings of meningitis seem to be less frequent than previously assumed. The prevalence of the classic triad of fever, neck stiffness, and altered mental status was found in only 44% of adults with community-acquired bacterial meningitis. Nevertheless, a high percentage had 2 out of the 4 signs of fever, headache, neck stiffness, and altered mental status. In addition, a high percentage of patients were admitted with focal neurologic deficits (33%). Overall, these findings suggest that one has to maintain a very high index of suspicion for bacterial meningitis. A lumbar puncture is mandatory in any suspected case of what is potentially a curable condition. — M. Flint Beal

Dr. Beal, Professor and Chairman; Department of Neurology; Cornell University Medical College New York, NY, is Editor of Neurology Alert.