—Dr Harris focuses on specific clinical characteristics of our older adult population (age, ≥50 years) and reiterates concerns regarding efficacy of third-generation cephalosporins in the treatment of gramnegative bacillary meningitis.1 It is important to differentiate those patients with microbiologically proved bacterial meningitis from those with presumed bacterial infections treated as such. In the latter group, situations associated with a negative bacterial
culture included prior antibiotic treatment, parameningeal focus of infection, and CSF leak due to prior trauma or neurosurgical procedure. While higher mortality correlated with positive microbiologie diagnosis in our series of patients,1 characteristics (eg, preexisting neurologic disease, previous neurologic surgical procedures, change in sensorium at time of presentation, and community onset vs hospital onset) did not differ significantly between these two subgroups (Table 1). The eight patients with aseptic meningitis had no preexisting neurologic disease or neurologic surgical procedures, and all had community-acquired infection. The mean CSF white blood cell