Date: February 12th, 2021

Guest Skeptic: Dr. Dennis Ren is a paediatric emergency medicine fellow at Children’s National Hospital in Washington, DC.

Reference: Mintegi S et al. Clinical Prediction Rule for Distinguishing Bacterial from Aseptic Meningitis. Pediatrics 2020

Case: A 4-year-old immunized girl presents to the emergency department (ED) with a fever and rhinorrhea for the past four days. Her parents report that she has been complaining of a headache and seems more tired and sleepy in the past day. On exam, she is febrile to 38.5 ºC, appears tired, with meningismus on examination but answers questions appropriately. She does not have any petechiae or purpura on skin exam. You explain that you must obtain some blood for laboratory work and perform a lumbar puncture (LP) because you are concerned that she has meningitis. Her nervous parents agree to the LP. Her cerebrospinal fluid appears clear and preliminary cerebrospinal fluid (CSF) results show a pleocytosis with 16 white blood cells per µL without any red blood cells. Her parents ask you whether or not she will have to stay in the hospital or receive antibiotics.

Background: Vaccines cause adults. Supporting this position is that since the introduction of conjugate vaccines the incidence of life-threatening bacterial meningitis has decreased. The first conjugate vaccine introduced was the haemophilus influenzae type b (Hib) vaccine. This vaccine has a reported efficacy of 98% (Makwana and Riordan 2007).

The success of conjugate vaccines is that most cases of pediatric meningitis are now aseptic (viral cause). It is important to distinguish between bacterial vs aseptic meningitis. This is because bacterial meningitis is associated with serious morbidity and mortality and requires prompt antibiotic treatment; aseptic meningitis is self-limited and requires only supportive care. Patients with suspected bacterial meningitis require hospital admission with empiric antibiotics pending culture results (Sáez-Llorens and McCracken 2003).

There is no single variable that can help discriminate between bacterial vs. aseptic meningitis.  Combinations of variables have been tried in the past as part of clinical scoring systems such as the Bacterial Meningitis Score (BMS) to identify children with CSF pleocytosis at low risk for bacterial meningitis (Nigrovic et al 2002).

However, BMS did not take into account C-reactive protein and procalcitonin levels that have shown promise in risk stratifying febrile children at risk for bacterial infection (Van den Bruel et al 2011).

Additionally, BMS has missed a few cases of bacterial meningitis. Specifically, 2 out of 1714 patients categorized as very low risk for bacterial meningitis had bacterial meningitis (sensitivity 98.3%, NPV 99.9%). Both patients missed were younger than 2 months old (Nigrovic et al 2007).

The study we are reviewing today aimed to develop and validate a more accurate scoring system called the Meningitis Score for Emergencies (MSE) to distinguish between bacterial vs. aseptic meningitis in children 29 days to 14 years old with CSF pleocytosis based on four objective lab criteria.

Clinical Question:  Can a clinical decision tool using laboratory data help distinguish between bacterial from aseptic meningitis in children 29 days to 14 years old with cerebrospinal fluid pleocytosis?

* Pleocytosis- CSF WBC ≥10 cells per µL. Corrected for presence of CSF RBCS (1:500 leukocytes to erythrocytes in peripheral blood) and CSF protein (every 1000-cell increase on CSF RBCs per mm3, CSF protein increased by 1.