Backgroundand study aim:The differential diagnosis between bacterial meningitis and aseptic meningitis is a critical clinical issue and ‎searching for reliable and valid markers is required. This work aimed to assess the role of the combined ‎measuring of CSF lactate and serum procalcitonin in the diagnosis of acute bacterial meningitis‎‎‎.
Patients and Method:‎A cross-sectional study including 42 meningitis patients was conducted at Zagazig Fever Hospital and Zagazig ‎University Hospitals in the period from November 2018 to June 2019, Patients were divided according to their ‎final diagnosis into two groups; group I included 13 patients with bacterial meningitis ( positive CSF bacterial ‎culture and/or  Gram stain ), group II included 29 patients with aseptic meningitis (negative CSF  bacterial ‎culture and Gram stain), The data collection sheet included clinical assessments, lumbar puncture with CSF ‎analysis, CSF lactate level testing, and  Serum procalcitonin level testing‎‎.‎
Results: One hundred five of house officer participated Serum procalcitonin and CSF lactate levels were significantly higher in the bacterial meningitis group (1.16 ‎‎±1.24, 7.5 ± 6.6, respectively) than patients with aseptic meningitis (0.059 ± 0.04, 3.98 ± 2.1, respectively). ‎The measuring of both serum procalcitonin and CSF lactate levels had got a higher sensitivity, specificity, and ‎accuracy (96.6%, 76.9%, 90.9% respectively) for the diagnosis of bacterial meningitis more than measuring ‎either of them only‎‎‎.
Conclusion: The combined measuring of both serum procalcitonin and CSF lactate levels is highly accurate in the diagnosis ‎of bacterial meningitis cases and helps to differentiate bacterial meningitis from aseptic meningitis‎‎‎‎.