Update on Characteristics and Prognosis in Bacterial Meningitis

Abstract & Commentary

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.

This prospective study from the Netherlands evaluated 696 episodes of community-acquired acute bacterial meningitis from October 1998 to April 2002. The diagnosis was confirmed by cerebrospinal fluid (CSF) cultures, and all patients underwent a neurologic examination on admission and at discharge and were evaluated using the Glasgow Outcome Scale. The most common pathogens were Streptococcus pneumoniae (51%) and Neisseria meningitidis (37%).

The authors found that the classic triad of fever, neck stiffness, and a change in mental status was present in only half of the episodes; nearly everyone had at least two of the four symptoms of headache, fever, neck stiffness, and altered mental status. The mortality rate was markedly higher among patients with pneumococcal meningitis compared with those with meningococcal meningitis (30% vs 7%, P < 0.001). Risk factors for an unfavorable outcome were advanced age, presence of otitis or sinusitis, absence of rash, a low score on the Glasgow Outcome Scale on admission, tachycardia, a positive blood culture, an elevated erythrocyte sedimentation rate, thrombocytopenia, and a low CSF white blood cell count. The mean opening pressures were similar among patients with and without papilledema.

Most patients had at least one individual CSF predictor of bacterial meningitis (glucose less than 34 mg/dL, a CSF/blood glucose ratio less than 0.23, a protein level greater than 220 mg/dL, or a white-cell count of more than 2000/mm3). A small percentage of patients received corticosteroids and were more likely to have an unfavorable outcome. However, patients who received corticosteroids before antibiotics were more likely to have a favorable outcome than patients who received corticosteroids after antibiotics. The authors conclude that in adults presenting with community-acquired acute bacterial meningitis, the mortality remains high; the strongest risk factors for an unfavorable outcome are: systemic compromise, a low level of consciousness, and pneumococcal infection.

Commentary by Richard Hamilton, MD, FAAEM, ABMT

This is a must-read article for all emergency medicine physicians, and I would not be surprised to see it as one of the continuing board certification articles at some point. The study is full of information and is worthy of a detailed read. Highlights of the information presented here and supported by other studies include: 1) papilledema does not predict elevated opening pressure; 2) corticosteroids before antibiotics improve outcome; 3) a weak immune response to infection (e.g., low peripheral white blood cell count, no rash) bodes a poor outcome; 4) clinical suspicion remains important because the classic triad is present as often as it is not; and 5) mortality remains high despite our armament of therapeutic tools. The article’s accompanying editorial discusses the latter point in detail. In fact, the mortality from meningitis has changed only modestly in the past 50 years.1 There is one weakness in the study: The authors excluded anyone who did not have a positive CSF culture, and experience suggests that those patients are either too ill for lumbar puncture or have contraindications (e.g., space-occupying lesions). Excluding those patients makes for a well-defined study population, but as a result, the data probably underestimated the mortality of this disease.

Dr. Hamilton, Associate Professor of Emergency Medicine, Residency Program Director, Department of Emergency Medicine, Drexel University College of Medicine, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.

Reference

1. Swartz MN. Bacterial meningitis — A view of the past 90 years. N Engl J Med 2004;351:1826-1828.