Approximately 18,000 cases of bacterial meningitis are identified in children under the age of 5 years in the United States annually. In this age group, Haemophilus influenzae type b, Diplococcus pneumoniae, and Neisseria meningitidis are responsible for 87% of those cases in which the etiologic agent is demonstrable.1 A total of 43% to 50% of these patients receive some form of antimicrobial therapy before a diagnostic lumbar puncture is performed.2-6 The question is frequently asked: does pretreatment with small doses of antimicrobials significantly alter cerebrospinal fluid (CSF) findings in bacterial meningitis? A related problem is the differentiation of aseptic from bacterial meningitis when clinical and CSF findings do not clearly distinguish the two.
Effects of Antecedent Therapy
Several studies have suggested that prior treatment with antimicrobials may alter CSF findings, leading to an erroneous diagnosis of aseptic meningitis.2,7,8 More recently, other investigators3-6 have presented data