Decrease in serum procalcitonin levels over time during treatment of acute bacterial meningitis

The aim of this study was to describe the change in serum procalcitonin levels during treatment for community-acquired acute bacterial meningitis. Out of 50 consecutive patients presenting with bacterial meningitis and infection at no other site, and who had received no prior antibiotic treatment, 48 had a serum procalcitonin level above 0.5 ng/ml on admission and were enrolled in the study. The mean age of the patients was 55 years, and mean Glasgow Coma Scale score on admission was 13. The time from symptom onset to admission was less than 24 hours in 40% of the patients, 24-48 hours in 20%, and more than 48 hours in 40%. The median (interquartile) interval between admission and initial antibiotic treatment was 160 min (60-280 min). Bacterial infection was documented in 45 patients. Causative agents included Streptococcus pneumoniae (n = 21), Neisseria meningitidis (n = 9), Listeria monocytogenes (n = 6), other streptococci (n = 5), Haemophilus influenzae (n = 2) and other bacteria (n = 2). The initial antibiotic treatment was effective in all patients. A lumbar puncture performed 48-72 hours after admission in 34 patients showed sterilization of cerebrospinal fluid. Median (interquartile) serum procalcitonin levels on admission and at day 2 were 4.5 (2.8-10.8) mg/ml and 2 (0.9-5.0) mg/ml, respectively (P < 0.0001). The corresponding values for C-reactive protein were 120 (21-241) mg/ml and 156 (121-240) mg/ml, respectively. Five patients (10%) died from noninfectious causes during their hospitalization. Serum procalcitonin levels decrease rapidly with appropriate antibiotic treatment, diminishing the value of lumbar puncture performed 48-72 hours after admission to assess treatment efficacy.