Cerebrospinal (CSF) culture results were compared with results of blood cultures and CSF parameters (WBC, glucose, and protein) in 9111 neonates with culture-proven meningitis and a first lumbar puncture at >34 weeks’ gestational age from 150 NICU’s managed by the Pediatrix Medical Group. The concordance of these values was analyzed by researchers at Duke Clinical Research Institute, Durham, NC. Of 92 (1.0%) neonates with meningitis confirmed by CSF culture, only 62% had a concomitant positive blood culture within 3 days of LP; in 38% the blood culture was negative. In 57 with both positive blood and CSF cultures, the organisms were discordant in 2 (3.5%), the CSF pathogens requiring different antimicrobial therapy than the blood pathogen. In neonates with bacterial meningitis, CSF WBCs ranged from 0-15,900/mm3; 5% had 0-1 and 10% had <3 WBCs. Highest sensitivity (97%) and lowest specificity (11%) for prediction of meningitis was any WBCs in the CSF. When 21 WBCs were used as the upper limit of threshold, the sensitivity and specificity were 79% and 81%, respectively. CSF glucose and protein were variable and not of diagnostic value in the absence of a CSF culture. 
COMMENT. A suspected diagnosis of neonatal meningitis should not be dismissed by a negative blood culture or normal CSF cells, glucose or protein. The diagnosis must be established by a timely LP and positive CSF culture. The authors recommend that an LP should be included in the evaluation of sepsis in an infant. For patients pretreated with antibiotics who are asymptomatic and have negative blood and CSF cultures, and elevated CSF WBC count (21 cells per mm3), 48 hours of antibiotics may be warranted, followed by in-hospital observation or outpatient clinic visit at 48-72 hours after discharge.