Understanding the Activity of Antibiotics in Cerebrospinal Fluid in vitro.

BACKGROUND In vitro studies suggest that antimicrobial activity of antibiotics meant to treat central nervous system infections such as meningitis or ventriculitis may be altered by cerebrospinal fluid (CSF). This could explain the reason behind the often observed discrepancies between the activity of antibiotics determined in artificial growth media in vitro, and their sometimes reduced clinical efficacy in CSF in vivo. If conducted in CSF, in vitro microbiological investigations might predict the ability of antibiotic drugs to treat CSF infections better than experiments in artificial growth media. In addition, they are less expensive, critical and time consuming than animal studies, and might potentially be appreciated in drug development as a rapid and cost-effective means to gain valuable information on drugs meant to treat infections residing in CSF. SUMMARY Data from microbiological in vitro experiments performed in CSF were compiled for fosfomycin, rifampicin, cefepime, cefotaxime, ceftriaxone, ciprofloxacin, gentamicin and vancomycin. Where possible, correlations between in vitro data and evidence from in vivo studies were established. KEY MESSAGES As discussed in the text, no clear correlations between in vitro studies in CSF and clinical outcomes could be identified. Methodological recommendations derived from the collected studies are summarized in order to optimize future research on the topic.