Researchers in emergency medicine and pediatric neurology at Children’s Hospital Boston, MA, assessed the rate of acute bacterial meningitis (ABM) among 526 children (56% male) aged 6 to 60 months (median age 17 months) who were evaluated in the ED between 1995 and 2008 for a first complex febrile seizure (CFS). Ninety patients (17%) had a previous simple febrile seizure. Of the total with CFS, 340 (64%) had a lumbar puncture; 14 (2.7%) had CSF pleocytosis. Three patients (0.9%) had ABM; 2 had csf pleocytosis, diplococci, and a positive culture for Streptococcus pneumoniae. Of the 2 with confirmed ABM, 1 aged 4 years was found unresponsive at presentation and had posturing of one arm and anisocoria; the other aged 11 months was sleepy and on examination, appeared flaccid, toxic, with bulging fontanel, nuchal rigidity and apnea. The third child had failed the LP test (no csf cell count), she appeared well at presentation, but her blood culture grew S pneumoniae and she was treated as suspected ABM. None of the patients discharged without LP returned with a diagnosis of ABM. The decision to perform LP with a first CFS should be based on clinical suspicion and additional signs and symptoms suggestive of meningitis. ABM in a child presenting with CFS is uncommon (<1%), and the risk is particularly low with CFSs manifested by 2 brief nonfocal seizures in 24 hours. 
COMMENT. The rate of seizure among children with acute bacterial meningitis is reported at 12% (Rosman NP et al. 1985) to 27% (Rosenberg NM et al. 1992). In the above series of patients diagnosed with a first complex febrile seizure, the rate of bacterial meningitis among those having an LP was quoted at 0.9% (0.6% in the total group). Routine LP is obviously inappropriate in all children with a complex febrile seizure, especially in those with short nonfocal seizures repeated in 24 hours. The 2 patients with confirmed ABM (0.5%) in the Boston series had symptoms and signs of meningitis other than seizure. Furthermore, the description of presenting features was not convincing for a diagnosis of seizure.
Investigation of infections causing febrile seizures. In a study of 100 consecutive febrile seizures, LP was performed in 14 patients (11 complex seizures and 3 simple). Clinical suspicion and complex seizures were the principal indications for LP, and not age. Viral infection was the most common cause of fever, and bacterial infection was infrequent. Bacterial cultures performed in all 100 patients were positive in only 5%, none from cerebrospinal fluid. Rapid viral testing and diagnosis would result in less emphasis on need for LP and a reduction in empiric antibacterial treatment. Complex febrile seizure as an indication for lumbar puncture should be reexamined. Patients who recover consciousness rapidly should be observed, and the tap deferred . In this study, 23% of febrile seizures were complex, and of these 50% received LP, a slightly lower percentage than that reported in the Boston study.