P>This investigation aimed both to delineate the current status of community-acquired acute bacterial meningitis and to produce data on the interrelationships between clinical, laboratory and therapeutic parameters in the elderly. This retrospective cohort study was conducted in 28 Turkish institutions in 159 culture-positive patients over the age of 50 years. Streptococcus pneumoniae was the most common pathogen (69.2%), followed by Listeria monocytogenes (8.8%). For this reason, antilisterial antibiotics such as ampicillin or benzylpenicillin should be added to the therapeutic regimen. Pathogen-specific mortality did not vary between S. pneumoniae and L. monocytogenes. The overall mortality was 2.5% at the third day, 12.6% at the seventh day, 20.1% at the 14th day and 21.4% at the 21st day. The risk factors for fatality were increasing age, the presence of stupor, sepsis and inappropriate antibiotic administration. Cerebrospinal fluid (CSF) leukocyte counts and CSF/blood glucose ratios were lower in patients who died. Fever did not differ between survivors and fatal cases. The mean duration of antibiotic therapy in survivors was 16.3 +/- 6.4 days. One-fifth of the patients had complications, and in 5.7% of the patients sequelae persisted at follow-up.