| The first 20% of the full text of this article appears below. |
To the Editor.
Mazor et al1 have attempted to clarify an age-old dilemma concerning traumatic lumbar punctures. The use of the white blood cells (WBC)/red blood cells ratio and the observed/predicted ratio seem to be helpful in determining who doesnt have a positive cerebrospinal fluid (CSF) culture. Unfortunately, the authors fail to point out an underlying confound in the literature and in their data. Patients with a positive culture from blood CSF may not necessarily have meningitis but rather may have bacteremia. I see no easy way to determine in those cases where the WBC count is not clearly markedly different from the peripheral WBC count (and the glucose and protein arent equally different) that the positive CSF culture doesnt reflect bacteria introduced from the peripheral blood. It would be reassuring to know whether the peripheral blood culture was negative (assuming an adequate sample was drawn) before determining whether a positive CSF culture represented meningitis, but even this is not foolproof. The final word is not in yet!