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Clinical guidelines help identify which children at risk of bacterial meningitis

January 03, 2007

A set of guidelines have been developed that can help predict the risk of bacterial meningitis for children with cerebrospinal fluid pleocytosis (presence of greater number of white blood cells than normal), reducing unnecessary hospitalizations and antibiotics, according to a study in the January 3 issue of JAMA.

Although bacterial meningitis is the greatest concern when evaluating and treating children with cerebrospinal fluid (CSF) pleocytosis, the majority of these children have viral rather than bacterial meningitis, according to background information in the article. However, because exclusion of bacterial meningitis requires negative CSF (and blood) cultures after 2 to 3 days of incubation, most children with CSF pleocytosis are admitted to the hospital to receive broad-spectrum antibiotics while awaiting culture test results. A highly accurate decision support tool that could identify which children with CSF pleocytosis had a near-zero risk of bacterial meningitis by using clinical and laboratory measures readily available at the time the child is in the clinic could guide decision making and limit unnecessary hospital admissions and prolonged antibiotic use.

Lise E. Nigrovic, M.D., M.P.H., of Children's Hospital Boston and Harvard Medical School, and colleagues conducted a study to validate in a large population the clinical prediction rule, the Bacterial Meningitis Score, which classifies patients at very low risk of bacterial meningitis if they lack 5 criteria, which include certain CSF measurements and a history of seizure. The multicenter study was conducted in the emergency departments of 20 U.S. academic medical centers between January 2001 and June 2004 and included 3,295 children, age 29 days to 19 years with CSF pleocytosis.

Among these patients, 121 (3.7 percent) had bacterial meningitis and 3,174 (96.3 percent) had aseptic (nonbacterial) meningitis. Of the 1,714 patients categorized as very low risk by the Bacterial Meningitis Score, only 2 had bacterial meningitis (both were younger than 2 months old) and 1,712 had aseptic meningitis. The sensitivity of the Bacterial Meningitis Score (i.e., having 1 or more Bacterial Meningitis Score risk factor) for bacterial meningitis was 98.3 percent and the specificity was 61.5 percent.

The authors write that for patients with at least 1 Bacterial Meningitis Score risk factor or who are younger than 2 months, they suggest admission to the hospital and administration of parenteral (administered intravenously or by injection) antibiotics.

"In the conjugate H influenzae type b and pneumococcal vaccines era, bacterial meningitis has become an uncommon disease in U.S. children. Therefore, the majority of children with CSF pleocytosis have aseptic rather than bacterial meningitis. Furthermore, our study confirms that most children with CSF pleocytosis are admitted to the hospital to receive parenteral antibiotics while awaiting bacterial culture test results. Using the Bacterial Meningitis Score prediction rule to assist with clinical decision making could substantially reduce unnecessary hospital admissions for children with CSF pleocytosis at very low risk of bacterial meningitis. Future investigations should study the clinical implementation of the Bacterial Meningitis Score as a guide to help care for children with CSF pleocytosis," the researchers conclude.

JAMA and Archives Journals