Médecine et maladies infectieuses
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Bacterial meningitis in adults is a severe disease, with high fatality and morbidity rates. Experimental studies showed that the inflammatory response in the subarachnoid space is associated with unfavorable outcome. In these experiments, corticosteroids, and in particular dexamethasone, were able to reduce the inflammatory cascades in the subarachnoid space. ⋯ A quantitative review showed a consistent beneficial effect of dexamethasone on mortality and a borderline statistical beneficial effect on neurologic sequels. On the basis of available evidence, adjunctive dexamethasone therapy should be initiated before or with the first dose of antibiotics and continued for four days in all adults with suspected or proven community bacterial meningitis in high-income countries, regardless of bacterial etiology. Since prompt use of dexamethasone and appropriate antibiotics improves the prognosis of adults with bacterial meningitis, hospitals will need protocols to include dexamethasone with the initial antibiotic therapy.
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Despite breakthroughs in the diagnosis and treatment of infectious diseases, meningitis still remains an important cause of mortality and morbidity. An accurate and rapid diagnosis of acute bacterial meningitis is essential for a good outcome. The gold-standard test for diagnosis is CSF analysis. ⋯ Furthermore, in the early phases of acute bacterial and viral meningitis, signs and symptoms are often non specific and it is not always possible to make a differential diagnosis. Markers like CRP, procalcitonin, or sTREM-1 may be very useful for the diagnosis and to differentiate between viral and bacterial meningitis. Bacterial meningitis diagnosis and management require various biological tests and a multidisciplinary approach.
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Lumbar puncture is the best way to prove bacterial meningitis. It should be performed without any delay if the diagnosis is suspected. Herniation is a rare complication of LP. ⋯ Patients who do not respond well to treatment or with atypical presentation, persistence of fever, or new neurological signs should undergo brain imaging; MRI and CT may identify subdural effusions, brain abscesses, empyemas, hydrocephaly, or brain parenchymal changes (cerebritis, infarction, hemorrhage). CT and MRI are useful to screen for an ENT cause of bacterial meningitis, and mandatory in case of pneumococcal meningitis. Numerous MRI sequences are useful to identify bacterial meningitis complications: SE T1 without and with gadolinium injection, SE T2, FLAIR, gradient-echo T2, diffusion weighted imaging, MR angiography.
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The potential severity of meningitis in infants and children requires an optimized initial empirical therapy, mainly based on direct cerebro spinal fluid (CSF) examination, and rapid therapeutic adaptation according to bacterial identification and susceptibility. Combination treatment including cefotaxim (300 mg/kg per day) or ceftriaxone (100mg/kg per day) and vancomycine (60 mg/kg per day) remains the standard first line if pneumococcal meningitis cannot be ruled out. A simple treatment with third generation cephalosporin can be used for Neisseria meningitidis or Haemophilus influenzae meningitis, aminoglycosides must be added in case of Enterobacteriacae, mainly before 3 months of age. ⋯ When the minimal inhibitory concentration (MIC) of pneumococcal strain is less than 0.5mg/L, third generation cephalosporin should be continued alone for a total of 10 days. In other cases, a second lumbar puncture is necessary and the initial regimen, with or without rifampicin combination, should be used for 14 days. Amoxicillin during 3 weeks, associated with gentamycin or cotrimoxazole is recommended for listeriosis.
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Clinical diagnosis of acute bacterial meningitis may be delayed, either because off lack of sensitivity of clinical signs, or because of a poor vital prognosis; but over diagnosing is also frequent, leading to useless, expensive, and potentially dangerous hospitalizations. We conducted a comprehensive review of English and French literature from 1997 to 2007 by searching MEDLINE to review the accuracy of clinical examination for the diagnosis of meningitis. Additional references were identified by reviewing reference lists of articles back to 1993. ⋯ Sensitivity for clinical signs such as headache, vomiting, or fever was low, generally less than 30%, neck stiffness could reach 45%, but the absence of two signs among fever, headache, neck stiffness, and altered mental status eliminated meningitis with a negative predictive value of 95%. Given the seriousness of bacterial meningitis, clinicians perform lumbar puncture (or brain imaging) too often, especially in high-risk patients. Further prospective clinical research is needed to improve the accuracy of bacterial meningitis clinical diagnosis.