Ringer s

The drugs used were Human Urotensin II (Servier, Australia), L-phenylephrine HCl (Sigma Company, Australia), and clonidine HCl (Boehringer Ingelheim Pty Ltd, Australia). The doses of drugs were expressed in μg of the base. Drugs administered into the lateral ventricle or fourth ventricle were dissolved in Ringer's (Baxter, Old Toongabbie, NSW, Australia) solution while drugs given i.v. were dissolved in normal saline (Baxter, Old Toongabbie, NSW, Australia).

Gentamicin solutions in Ringer’s (Baxter) were prepared at concentrations of 200 μg/ml and 400 μg/ml. The solutions were filtered with a 0.2-μm sterile filter (Thermo Fisher Scientific). Control samples were loaded with Ringer solution only. Three different bacteria strains were tested: Pharmacopeia US and EU standard for Staphylococcus aureus (SA, ATCC 6538) and Staphylococcus epidermidis (SE, ATCC 14990), and a SA strain derived from a clinical case of postoperative infection including empyema after revision cranioplasty with custom made calcium phosphate implant (OssDsign AB). Subsequent revision with an identical implant was uneventful. Gentamicin soaking of the implant was performed at both surgical procedures, but postoperative images after initial surgery revealed significant dead space beneath the cranioplasty.
Bacteria were seeded at a concentration of 10⁶ CFU on agar (ISO-SENSITEST AGAR, Oxoid) plates. The plates were incubated at 32.5 ± 2.5 °C for 20 h. The inhibition zones were calculated and compared with the performance standards for antimicrobial susceptibility testing according to the Clinical and Laboratory Standard Institute (2013).