Prognosis

Morbidity

Generally, with prompt and adequate antimicrobial and supportive therapy, the outcome after acute bacterial meningitis is excellent. However, prognosis does depend on multiple factors such as age, presence of comorbidity, causative pathogen, and severity at presentation. In adults with bacterial meningitis, risk factors associated with a poor prognosis include advanced age, presence of osteitis or sinusitis, low Glasgow Coma Scale score on admission (i.e., low level of consciousness), tachycardia, absence of rash, thrombocytopenia, elevated erythrocyte sedimentation rate, low cerebrospinal fluid cell count, and positive blood culture.[16]

Up to one third of adults who have had bacterial meningitis have cognitive impairment.[121]

One recent meta-analysis looking at patients with bacterial meningitis documented cerebral infarcts in 16% of patients.[122]

Mortality

According to the World Health Organization, 1 in 6 patients who contract bacterial meningitis will die from the disease.[123]​ 

In a global meta-analysis that looked at case fatality rates due to bacterial meningitis from 1935 to 2019, the overall case fatality ratio was 18% (95% CI, 16% to 19%), decreasing from 32% (95% CI, 24% to 40%) before 1961 to 15% (95% CI, 12% to 19%) after 2010. The overall fatality rates were 19.3% in both neonates and adults, and 14.8% in children. It was highest in meningitis caused by Listeria monocytogenes at 27% (95% CI, 24% to 31%) and pneumococci at 24% (95% CI, 22% to 26%), compared with meningitis caused by meningococci at 9% (95% CI, 8% to 10%) or H influenzae at 11% (95% CI, 10% to 13%). Meta-regression showed decreasing case fatality ratios overall and stratified by S pneumoniae, Escherichia coli, or Streptococcus agalactiae (P <0.001).[124]

Patients with meningococcal sepsis have a higher fatality rate, with studies ranging from 20% to 80%.[125]

Delayed antibiotic administration increases mortality.[23][31][97]

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