Purpose of review: Distinguishing between bacterial and aseptic meningitis in children is sometimes difficult. Guidelines recommend that patients with acute meningitis be systematically hospitalized and treated with antibiotics until the cerebrospinal fluid culture results are available. This strategy ensures rapid treatment for bacterial meningitis, but also involves unnecessary admissions and antibiotics for aseptic meningitis. Some authors have, therefore, proposed different combinations of predictors in clinical decision rules to distinguish as early as possible between bacterial and aseptic meningitis. To be useful, these rules must have near-100% sensitivity for bacterial meningitis, good specificity (to reduce unnecessary antibiotics and admissions), and easy bedside application.
Recent findings: The present review examines the performance and level of validation of decision rules proposed after the Haemophilus influenzae vaccination entered widespread use. Most of these rules have been validated incompletely, if at all. Only one rule incorporates the best single validated predictive marker for distinguishing between bacterial and aseptic meningitis in children: serum procalcitonin level.
Summary: Two rules are highly promising, meeting the three major conditions after a retrospective validation process in large samples. These rules can be applied cautiously to patients with the same inclusion and exclusion criteria as those in the derivation sets, while awaiting prospective multicenter validation studies.