A NEW IN-VITRO MODEL TO INVESTIGATE ANTIBIOTIC PENETRATION OF THE INTERVERTEBRAL DISC

We have studied the ability of a range of antibiotics to penetrate int ervertebral disc tissue in vitro, using a mouse disc model, Equilibriu m concentrations of antibiotics incorporated into the entire disc were determined by bioassay using a microbial growth-inhibition method. Up take was significantly higher with positively-charged aminoglycosides compared with negatively-charged penicillins and cephalosporins. Uncha rged ciprofloxacin showed an intermediate degree of uptake. Our result s support the hypothesis that electrostatic interaction between charge d antibiotics and negatively-charged glycosaminoglycans in the disc is an important factor in antibiotic penetration, and may explain their differential uptake.