Background Meningitis causes substantial morbidity and mortality in neonates. Clinicians frequently use the presence of positive blood cultures to determine whether neonates should undergo lumbar puncture. Abnormal cerebrospinal fluid (CSF) parameters are often used to predict neonatal meningitis and determine length and type of antibiotic therapy in neonates with a positive blood culture and negative CSF culture.

Methods We evaluated 500 lumbar punctures of neonates admitted to the Neonatal intensive care unit of a tertiary referral maternity and neonatal centre between January 2001 and March 2008. CSF culture results were compared with results of blood cultures and CSF leukocyte counts to establish the concordance of these values in culture-proven meningitis.

Results 121 samples (24.2%) were unsuitable for analysis. Twenty samples (5.3%) had a positive CSF culture. Three culture positive samples were considered contaminants. Of the 17 patients with culture-positive meningitis, 10 had CSF WCC >21 cells per mm3 and 15 had CSF WCC>5 mm3. Only 8 infants of 42 with CSF WCC >21 cells per mm3 were CSF culture positive.

Conclusions Neonatal meningitis frequently occurs in the presence of normal CSF parameters. Absence of CSF leukocytosis cannot reliably exclude the presence of meningitis in neonates. The CSF culture is critical to establishing the diagnosis of neonatal meningitis but may be not be available due to the large number of samples unsuitable for analysis