Epidemiology of meningoencephalitis from 2017 to 2024 in Romagna, Italy, through a molecular integrated surveillance

Meningoencephalitis (ME) is a severe inflammatory condition that affects the central nervous system and poses a complex diagnostic challenge. Timely diagnosis and effective treatment are essential to reduce both mortality and long-term neurological complications. This study analysed data from 1,879 cerebrospinal fluid (CSF) samples collected in seven different hospitals and processed at the Greater Romagna Hub Laboratory, Italy, over eight years. Each CSF sample was analysed for total cell count, polymorphonuclear cells, mononuclear cells, physical appearance, glucose and protein levels, bacterial culture, molecular findings, and blood culture. The majority of CSF appeared turbid when the total cell count was > 5×106 cells/L. Notably, polymorphonuclear cells > 5×106 cells/L can be considered a potential surrogate marker of bacterial ME, and bacterial pathogens showed significantly different glucose level among different species. The integrated diagnostic approach, including culture and molecular testing, identified Streptococcus pneumoniae as the most common bacterial cause of adult meningitis, followed by Listeria monocytogenes and Neisseria meningitidis. Interestingly, blood culture anticipated the detection of the same pathogen that was revealed in CSF only by molecular assay. In conclusion, the findings underscore the essential role of an integrated diagnostic approach to optimize patient management and to better define the local epidemiology.