Episodes of patients with bacterial meningitis had a median NfL level of 576 pg/ml (IQR 278–2777) compared to 603 pg/ml (IQR 248–1557; P = 0.99) in all other episodes, and compared to 303 pg/ml (IQR 156–1041; P = 0.22) in viral CNS infections. Here, NEFL is linked to bacterial meningitis.