Bacterial meningitis
Bacterial meningitis is defined as "bacterial infections of the leptomeninges and subarachnoid space, frequently involving the cerebral cortex, cranial nerves, cerebral blood vessels, spinal cord, and nerve roots. The type of causative organism varies with age and clinical status (e.g., post-operative, immunodeficient, or post-traumatic states). Clinical manifestations include the acute onset of fever, stiff neck, altered mentation, seizures, and focal neurologic deficits. Death may occur within 24 hours of disease onset. Pathologic features include a purulent exudate in the subarachnoid space, and diffuse inflammation of neural and vascular structures."[1][2]
Diagnosis
A systematic review by the Rational Clinical Examination has reviewed how to diagnose meningitis.[3] A clinical prediction rule is available to help determine which patients may have meningitis.[4]
Lumbar puncture
A systematic review by the Rational Clinical Examination has reviewed how perform and analyze the results of a lumbar puncture. [5] It conclude that the stylet should be re-inserted prior to withdrawal of the needle to reduce the chance of a headache.
Imaging
X-ray computerized tomography is valuable. Chest X-ray may reveal bacterial pneumonia and suggest the pathogen.
Treatment
Antibiotics
Acute meningitis is a medical emergency, for which antibiotics should be administered promptly, either based on a Gram stain of cerebrospinal fluid or using empiric criteria.[6]
| Treatment group | Common organisms | Drugs |
|---|---|---|
| Neonate to 1 month | group B or D streptococci, Enterobacteriaceae (eg, E coli), and Listeria monocytogenes | Ampicillin plus gentamicin; acyclovir |
| 1-3 month infants | group B or D streptococci, Enterobacteriaceae (eg, E coli), and L. monocytogenes, Sreptococcus pneumoniae, Neisseria meningitidis, and Hemophilus influenzae. | cefotaxime or ceftriaxone plus ampicillin; alternative is chloramphenicol plus gentamicin; vancomycin if cephalosporin-resistant S. pneumoniae is prevalent locally; dexamethasone before antibiotics are recommended |
| 3 month-7 year | S. pneumoniae, N. meningitidis, and H. influenzae | cefotaxime or ceftriaxone plus vancomycin; alternatively chloramphenicol plus vancomycin; dexamethasone |
| 7-50 years | S pneumoniae, N meningitidis, and H influenzae. | cefotaxime or ceftriaxone plus vancomycin; alternatively chloramphenicol or clindamycin plus vancomycin; meropenem but not imipenem are other alternatives may add rifampin; ampicillin if Listeria is suspected; dexamethasone value is less clear but supported for S. meningitidis |
| > 50 years, chronic disease, alcoholism | S pneumoniae, N meningitidis, and H influenzae. | cefotaxime or ceftriaxone plus vancomycin; ceftazidine if Gram-negative organisms in CSF; alternatively chloramphenicol or clindamycin plus vancomycin; meropenem but not imipenem,trimethoprim-sulfisoxazole and doxycycline are other alternatives; dexamethasone if S. pneumoniae is suspected and fungi and tuberculosis or not |
| HIV positive | cryptococci, Mycobacterium tuberculosis, syphilis, HIV aseptic meningitis, and Listeria species. | cefotaxime or ceftriaxone plus vancomycin; ceftazidine if Gram-negative organisms in CSF; alternatively chloramphenicol or clindamycin plus vancomycin; meropenem but not imipenem,trimethoprim-sulfisoxazole and doxycycline are other alternatives; dexamethasone if S. pneumoniae is suspected and fungi and tuberculosis or not |
| Trauma or neurosurgery | S pneumoniae (if CSF leak is present), Staphylococcus aureus, coliforms, and P aeruginosa | vancomycin plus ceftazidime; meropenem as alternative |
| infected ventriculoperitoneal (atrial) shunt | Staphylococcus epidermidis, S aureus, coliforms, Propionibacterium acnes, and diphtheroids (rare) | In children, cefotaxime or ceftriaxone plus vancomycin; in adults, vancomycin plus rifampin, or ceftazidine alone if Gram-negative organisms are present |
Aztreonam is especially efficient for passing the blood-brain barrier.
Corticosteroids
Corticosteroids probably benefit patients with meningitis if they are proven to have a bacterial etiology, especially if they have a Glasgow Coma Scale of less than 12 or are infected by streptococcus pneumoniae.
One randomized controlled trial of 301 patients from the United States of America (76 were infected with streptococcus pneumoniae) found benefit when:[7]
- 10 mg of dexamethasone is given every six hours for four days starting 15 to 20 minutes before antibiotics
- patients had either had an initial Glasgow Coma Scale of less than 12 or were infected by streptococcus pneumoniae
However, a subsequent randomized controlled trial of 465 patients from Africa (277 were infected with streptococcus pneumoniae) no benefit was found in any group - including those patients infected with streptococcus pneumoniae. [8] This study did not analyze by Glasgow Coma Scale.
A third randomized controlled trial of 435 patients from Vietnam found benefit when:[9]
- Dexamethasone 0.4 mg per kilogram of body weight every 12 hours for 4 days (about half received this before starting antibiotics)
- Patients with confirmed bacterial meningitis
The underlying prevalence of human immunodeficiency virus may explain the contradicting results. Although none of the studies explicitly excluded patients with HIV, in the American study (which showed benefit) patients were excluded if they "had a history of active tuberculosis or fungal infection". Whereas in the African study (which showed no benefit), 90% of the patients were positive for HIV. In the Vietnamese study, which showed some benefit, only 1% of patients had HIV.
References
- ↑ National Library of Medicine. Bacterial meningitis. Retrieved on 2008-01-04.
- ↑ van de Beek D, de Gans J, Tunkel AR, Wijdicks EF (2006). "Community-acquired bacterial meningitis in adults". N. Engl. J. Med. 354 (1): 44–53. DOI:10.1056/NEJMra052116. PMID 16394301. Research Blogging.
- ↑ Attia J, Hatala R, Cook DJ, Wong JG (1999). "The rational clinical examination. Does this adult patient have acute meningitis?". JAMA 282 (2): 175–81. PMID 10411200. [e]
- ↑ McKinney WP, Heudebert GR, Harper SA, Young MJ, McIntire DD (1994). "Validation of a clinical prediction rule for the differential diagnosis of acute meningitis". J Gen Intern Med 9 (1): 8–12. PMID 8133355. [e]
- ↑ Straus SE, Thorpe KE, Holroyd-Leduc J (2006). "How do I perform a lumbar puncture and analyze the results to diagnose bacterial meningitis?". JAMA 296 (16): 2012–22. DOI:10.1001/jama.296.16.2012. PMID 17062865. Research Blogging.
- ↑ Marjorie Lazoff (2 February 2010), "Meningitis: Treatment & Medication", eMedicine
- ↑ de Gans J, van de Beek D (2002). "Dexamethasone in adults with bacterial meningitis". N. Engl. J. Med. 347 (20): 1549–56. DOI:10.1056/NEJMoa021334. PMID 12432041. Research Blogging.
- ↑ Scarborough M, Gordon SB, Whitty CJ, et al (2007). "Corticosteroids for bacterial meningitis in adults in sub-Saharan Africa". N. Engl. J. Med. 357 (24): 2441–50. DOI:10.1056/NEJMoa065711. PMID 18077809. Research Blogging.
- ↑ Nguyen TH, Tran TH, Thwaites G, et al (2007). "Dexamethasone in Vietnamese adolescents and adults with bacterial meningitis". N. Engl. J. Med. 357 (24): 2431–40. DOI:10.1056/NEJMoa070852. PMID 18077808. Research Blogging.