Infections in neurosurgery: using laboratory data to plan optimal treatment strategies.

Laboratory services contribute to the management of patients with neurosurgical infections in a variety of ways and, in so doing, increase the likelihood of a favourable outcome. Microbiology laboratories and clinical microbiologists are able to confirm the diagnosis, identify the causative agents and facilitate optimal antimicrobial therapy. Other pathology specialties perform investigations which help neurosurgeons to differentiate between postoperative aseptic and bacterial meningitis, these disease processes being indistinguishable on clinical grounds. A broad range of variables have been evaluated to date, but only the lactate and interleukin-1beta concentrations in cerebrospinal fluid have been shown to have sufficiently high sensitivities and specificities to be useful for this purpose. In preliminary studies measurement of the serum C-reactive protein concentration has been shown to be an effective criterion for monitoring the response to antibacterial therapy in patients with spinal extradural abscesses, postoperative discitis, brain abscesses and subdural empyemas, thereby enabling patients to be treated successfully with courses of these drugs that are markedly shorter than those currently recommended.