[Early lumbar puncture and cutaneous rash: a clear CSF is not always a normal CSF].

The clinical and biological characteristics of adult bacterial meningitis are usually unequivocal, but more subtle clinical presentations can be observed. A 24-year-old woman was admitted with fever and abdominal discomfort, which had been developing for 24 hours. There were no meningeal signs, but a transient cutaneous rash was observed on admission. A clear CSF was obtained showing no cytological or biochemical abnormality. Ceftriaxone 2 g was administrated intravenously. In the following hours of admission, a frank meningeal syndrome with purpura appeared, leading to a second lumbar puncture, which revealed purulent CSF. The culture of the first CSF yielded Neisseria meningitidis, while the second CSF remained sterile. This case showed a probable meningococcal rash. This is a reminder that a normal CSF can be obtained early in the course of a proved bacterial meningitis, and that CSF bacterial eradication can occur very rapidly after a single dose of third-generation cephalosporin.