Review : Pyogenic Meningitis in Adults
van de Beek D, de Gans J, Tunkel AR, Wijdicks EF. Community-acquired bacterial meningitis in adults. [ N Engl J Med. 2006;354:44-53. The authors provide a review article on current concepts of the management of pyogenic meningitis in adults.
Presentation: Only 44% of patients present with the classic triad of fever, stiff neck, and altered mental status; nearly all have at least 2 of the 4 classic symptoms: headache, fever, stiff neck, and altered mental status defined as a score of less than 14 on the Glasgow Coma Scale.
Diagnostic Evaluation: "Lumbar puncture is mandatory" although the procedure can be hazardous. Cranial imaging (computed tomography [CT] or magnetic resonance imaging [MRI]) should be done before lumbar puncture (LP) under the following conditions: (1) new-onset seizures, (2) immunocompromised patient, (3) signs of a space-occupying lesion, or (4) moderate-severe impairment of consciousness. These indications apply to about 45% of patients. In addition to herniation, the LP may be harmful due to a coagulopathy that may lead to a spinal subdural or epidural hematoma. Delays in treating pyogenic meningitis of over 4-6 hours are associated with an increase in complications or death. Thus, if imaging is performed prior to LP, antibiotic therapy should be initiated first. The expected findings on cerebrospinal fluid analysis are summarized in Table 1 .
Bacteriology:Table 2 summarizes the anticipated pathogens and suggested antibiotic treatment.
Adjunctive Dexamethasone: The indications are: cerebrospinal fluid that is cloudy, has a white blood cell count over 1000/mcL, or has bacteria on gram stain. Support for this is from studies showing a reduction in mortality from 15% to 7%. The authors also recommended the administration of adjunctive dexamethasone in patients with suspected meningitis. The dose is 10 mg; it should be initiated before or with the first dose of antibiotics, and it should be continued for 4 days at a dose of 10 mg every 6 hours. This treatment should be stopped if the diagnosis of pyogenic meningitis is not established. The authors recommended continuation of dexamethasone for 4 days regardless of the microbial pathogen or clinical severity, although efficacy is best established for pneumococcal meningitis. Clinical efficacy of dexamethasone treatment was analyzed, and a meta-analysis of 5 clinical trials showed a mortality relative risk of 0.9 and a relative risk of neurologic sequelae of 0.5.
Intensive Care Management: Recommendations for management in the intensive care unit are:
High risk for brain herniation: monitor intracranial pressure and:
Osmotic diuretics (mannitol 25%) or hypertonic saline (3%) to keep intracranial pressure < 15 mm and perfusion > 60 mm Hg
Initiate repeated LPs, lumbar drain, or ventriculoscopy
Electroencephalogram (EEG) monitoring with history of seizures
Airway: intubate or provide noninvasive ventilatory support
Circulatory support:
Septic shock: low-dose steroids if corticotropin test is positive
Inotropic agents (dopamine or milrinone) to keep blood pressure > 70-100 mm Hg
Crystalloids or 5% albumin to maintain fluid balance
Consider Swan-Ganz catheter
Gastrointestinal care: nasogastric tube plus prophylaxis with a proton pump inhibitor
Other: subcutaneous heparin; maintain normoglycemic, antipyretic agents for temperature > 40°C
Repeat LP: if no improvement within 48 hours.
Outcome: Patients who have a decline in consciousness or fail to improve within 48 hours of appropriate antibiotic therapy should have imaging and a repeat LP. The most common cause of a decline in consciousness is the development of meningoencephalitis leading to cerebral edema and increased intracranial pressure. For patients whose course is complicated by focal cerebral abnormalities, the most common causes are stroke, seizures, or a combination of both. The frequency of these and other complications is summarized in Table 3 .
With regard to microbial pathogens, Table 4 summarizes the mortality rates and frequency of neurologic sequelae for pneumococcal and meningococcal meningitis.