What should be done to diagnose suspected syphilitic meningitis in a baby?

To diagnose suspected syphilitic meningitis in an infant, performing a lumbar puncture is essential. This procedure allows for the collection of cerebrospinal fluid (CSF), which can then be analyzed for the presence of Treponema pallidum antibodies, the causative agent of syphilis. By examining the CSF, healthcare professionals can assess for signs of infection and inflammation, which are indicative of meningitis. This diagnostic tool provides critical information regarding not only the presence of syphilis but also inflammation levels and other potential pathogens affecting the central nervous system.

In comparison, other diagnostic methods, such as urinalysis, while useful in assessing kidney function or infection, do not provide information directly relevant to meningitis. Blood tests can help identify syphilis infection but are not definitive for meningitis. Chest X-rays are typically used to evaluate respiratory conditions and would not yield the necessary information related to meningitis. Thus, lumbar puncture is the appropriate and most informative procedure for diagnosing suspected syphilitic meningitis in a neonate.