[Acute bacterial meningitis in older people].

BACKGROUND

The age distribution of acute bacterial meningitis (ABM) has shifted from children to adults. At the same time, older population is increasing. The aim of this study is to characterize ABM in elderly patients.

METHODS

We reviewed the meningitis cases diagnosed at our hospital (1982-2006), including ABM cases defined by established criteria. Two groups were analyzed: elderly patients (aged > or =60) and young adults (aged 14-59).

RESULTS

Ninety-five of 239 ABM (40%) were diagnosed in elderly patients, while 144 (60%) were found in younger adults. In elderly people, 32% were nosocomial, 49% had postoperative risk factors, and 24% were spontaneous infections. The combination of fever, neck stiffness, and altered mental status was present in 45%. Elderly people presented altered mental status more often (p=0,002), had higher protein level (p=0,023) and higher percentage of positive cerebrospinal fluid culture (p=0,039). The most common pathogens were Streptococcus pneumoniae (20%), coagulase-negative Staphylococcus (14%) and Listeria monocytogenes (8%), whereas meningitis of unknown etiology was less common (p=0,014). Elderly patients had a higher mortality rate (19% vs. 6%, p=0,001), closely related to: age > or =years, altered mental status, absence of headache or vomiting, development of complications and systemic complications, and infection by Staph. aureus. In the multivariate model, age > or =75 years [OR=6,65; p=0,008], absence of headache [OR=0,15; p=0,003], and development of complications [OR=4,55; p=0,015] remained significantly associated with mortality.

CONCLUSIONS

In elderly people, ABM affects patients with risk factors,and is predominantly due to Strep. pneumoniae. This age group has a higher mortality rate, which is associated with advanced age and development of complications.