Introduction: Acute bacterial meningitis is a medical emergency that causes high morbility and mortality. In Thailand there are few studies in adults. This study was aimed to determine clinical manifestations, predisposing factors, etiology, cerebrospinal fluid finding, empiric antibiotics and mortality rate in community-acquired bacterial meningitis.

Design: Retrospective descriptive study.

Methods: Medical records were reviewed of all patients 15 years of age or older, in whom acute bacterial meningitis was diagnosed in Songklanagarind Hospital from January 1, 1982 to December 31, 2001.

Results: There were 74 episodes in 71 cases of community-acquired bacterial meningitis. Three patients (4.2%) had recurrent meningitis. The incidence of disease significantly increased during the last 10 years of the study period (p = 0.014). The classic triad (fever, neck stiffness and impaired mental status) of acute bacterial meningitis was found in 62.5 percent of cases. The three most common predisposing factors were HIV infection, cerebrospinal fluid leakage and alcoholism. The most common pathogen was Streptococcus pneumoniae (23%), in 17.6 of which percent the strain was penicillin-resistant and occurred in the last 5 years of the study. There was one case of H. influenzae meningitis but N. meningitidis and L. monocytogenes were not found in this study. An appropriate antibiotic was used in 87.5% of cases and in 25 episodes (33.8%) cefotaxime or ceftriaxone alone was used as empiric therapy. Eleven patients died from meningitis giving a mortality rate of 15.5 percent. Mortality rate did not significantly change during the last 10 years of the study (22.7% and 11.5%, p = 0.18).

Conclusions: The incidence of community-acquired bacterial meningitis in adults increased during the study. Streptococcus pneumoniae was the most common organism with increasing occurrence of penicillin-resistant stain.