Prognosis

Morbidity

Generally, with prompt and adequate antimicrobial and supportive therapy, the outcome after acute bacterial meningitis is excellent. However, prognosis depends 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.[27] Up to one third of adults who have had bacterial meningitis have cognitive impairment.[99]

About 10% to 20% of children who survive bacterial meningitis develop severe sequelae such as sensorineural hearing loss, motor problems, seizures, and significant cognitive impairment.[100][101][102]​ From 20% to 30% of children have more subtle adverse outcomes such as cognitive, academic, and behavioral problems.[103]

Mortality

The case-fatality rates for bacterial meningitis are 4% to 10% in the pediatric population and 25% in adults.[39][104] The case-fatality rates are 3% to 7% for Haemophilus influenzae and Streptococcus agalactiae; 20% to 25% for Streptococcus pneumoniae; and 30% to 40% for Listeria monocytogenes.[17][105] Fatality rates are high among patients at the extremes of age (i.e., neonates and older people).[9]

The overall mortality of meningococcal infections is 10% to 15%.[106]

Patients with meningitis have a lower mortality (5%) than those with meningococcal sepsis (5% to 40%). Most deaths occur in the first 24 hours of illness. Mortality is higher in adolescents than in younger children, and higher during outbreaks than in sporadic disease.[107] Delayed antibiotic administration increases mortality.​[38][66][67]

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