Effects of Vancomycin/Tobramycin-Doped Ceramic Composite (PVA-VAN/TOB-PDCPD) in a Rat Femur Model Implanted with Contaminated Porous Titanium Cylinders

Introduction Periprosthetic joint infection (PJI) remains common and problematic. We hypothesized that using a bioceramic that has rapid release of an antibiotic (vancomycin [VAN] or vancomycin/tobramycin [VAN/TOB]) from a polyvinyl alcohol composite (PVA) combined with a delayed and sustained antibiotic release from polymeric dicalcium phosphate dihydrate (P-DCPD) ceramic would inhibit S. aureus-associated implant infection. Methods A total of fifty male Sprague Dawley rats were randomly divided into 5 experimental groups: I-negative control; II-bacteria only; III-bacteria+saline wash; IV-bacteria+PVA-VAN-PDCPD, and V-bacteria+PVA-VAN-TOB-PDCPD. A porous titanium (Ti) implant was press-fit into the rat knee. S. aureus-containing broth was added into the joint space to create a PJI. After one week, the joints from groups III to V were washed with saline and the fluid collected for bacterial quantification. This was followed by saline irrigation treatment (groups III to V) and application of the antibiotic-loaded PVA-PDCPD bioceramic (groups IV and V). On day 21, joint fluid was collected, and the implants were harvested for bacterial quantification. Results No bacteria were isolated from the negative control (group I). The positive control (group II) was positive on both days 7 and 21. Bacteria were still present on day 21 in the fluid and implant in Group III. Groups (IV and V) showed a decrease in the bacterial burden in the fluid and implant on day 21. There were significant differences in bacteria levels in the collected wash fluid and on the implant at day 21 between the saline wash (Group III) and treatment groups (IV and V). Conclusions In this rat model of acute periprosthetic infection, treatment with PVA-VAN-PDCPD and PVA-VAN/TOB-PDCPD reduced the bacterial load in the infected joint and the infected Ti implant. Application of PVA-VAN-PDCPD and/or PVA-VAN/TOB-PDCPD after saline irrigation could be used as an addition to the treatment of PJI.