Effect of Staphylococcus aureus bacteria and bacterial toxins on meningealpermeability in vitro

Background and Objectives. Epidural catheterization is associated with a si gnificant bacterial colonization rate and occasionally frank infection. Dur ing epidural space infection, decreased analgesia despite increased epidura l opioid doses has been described. One possible explanation for this observ ation is that bacterial infection decreases meningeal permeability. The pur pose of the study was to determine whether Staphylococcus aureus bacteria, the most common organism causing epidural space infection, or S. aureus tox ins alter meningeal permeability. Methods. Spinal meninges of M. nemestrina monkeys were mounted in a previously established in vitro diffusion cell m odel and exposed to S. aureus toxins A, B, and F. Simultaneous transmeninge al fluxes of mannitol and sufentanil were measured before and after toxin e xposure and compared to controls. In a second series of experiments, diffus ion cells were inoculated with live S. aureus bacteria in suspension and th e permeability of sufentanil was investigated. Results. Staphylococcus aure us toxin-a increased the transmeningeal flux of mannitol but not sufentanil . Toxins B and F did not alter the meningeal permeability of either drug. I noculation with live S, aureus bacteria increased the transmeningeal flux o f sufentanil by 115 +/- 21% (P =.032). Conclusions. These data demonstrate that S. aureus alpha-toxin and live S. aureus bacteria can increase meninge al permeability. Thus, clinical observations of decreased epidural analgesi a in the face of bacterial infection cannot be explained by decreased menin geal permeability.