Acute bacterial meningitis in adults: a clinical and developmental analysis of 100 cases

BACKGROUND: Characterize clinical findings and outcome of acute bacterial meningitis (ABM) in adults, with special emphasis on nosocomial meningitis and meningitis in the elderly. METHODS: We reviewed the charts of all persons 14 years of age or older in whom ABM was diagnosed in our hospital during a 12 and a half-year period. RESULTS: Ninety-seven patients were treated for 100 episodes of ABM, of which 23 percent were nosocomial and 27 percent occurred in elderly persons. Predisposing factors were present in 59 percent of the episodes. Fifty-four percent had the classic triad of fever, nuchal rigidity, and change in mental status. Cerebrospinal fluid pleocytosis with a neutrophilic predominance, hypoglycorrhachia, and elevated protein levels were present in 62 percent of the episodes. A pathogen was identified in 62 percent of the cases, in a higher frequency in elderly persons (p < 0.05) and in patients who had not received antibiotics before the lumbar puncture (p < 0.05). Causal agents more frequently identified were: Streptococcus pneumoniae (27 percent) in community-acquired meningitis, coagulase-negative Staphylococci (35 percent) in nosocomial meningitis, and Strep. pneumoniae (33 percent) in elderly persons. Central nervous system (CNS) complications occurred in 18 percent of episodes, and 15 percent developed systemic complications. The overall mortality rate was 9 percent, higher among patients in whom CNS complications began within 24 hours of admission (p < 0.05). CONCLUSIONS: A high proportion of cases of ABM in adults are nosocomial, or affect elderly persons. The fatality rate is high, particularly among those who develop CNS complications at the onset of the disease.