Lumbar punctures and meningitis.

Four patients, with an additional seven from the literature, had meningitis following a lumbar puncture (LP) that disclosed normal cerebrospinal fluid (CSF). Animal studies demonstrate that perforation of the meninges in the presence of bacteremia enhances the development of meningitis. Simultaneous blood culture should be obtained with all LPs. Regardless of the results of the initial LP, a second CSF examination is recommended in any patient whose clinical condition is deteriorating. If the initial blood culture is positive, a second LP should be strongly considered in all newborn and very young infants.