Jean A. Setterstrom

Evaluation of biodegradable ampicillin anhydrate microcapsules for local treatment of experimental staphylococcal osteomyelitis

Successful treatment of chronic osteomyelitis requires sustained high concentrations of antibiotics locally within the infected bone. The efficacy of biodegradable (poly-DL-lactide-co-glycolide) microspheres containing 30.7% ampicillin anhydrate for the local treatment of experimental staphylococcal osteomyelitis was evaluated in rabbits. In the initial experiment, antibiotic therapy was initiated immediately following injection of Staphylococcus aureus into the proximal tibial metaphysis. A single intramedullary injection of microencapsulated ampicillin (100 mg) prevented osteomyelitis in all seven animals tested and was as effective as a two-week course of parenteral ampicillin administration. When antibiotic therapy was delayed for seven days, osteomyelitis developed in four of eight animals treated locally with microencapsulated ampicillin and in six of eight animals that received parenteral ampicillin therapy. When antibiotic therapy was delayed for seven days and was preceded by debridement, all ten animals treated locally with microencapsulated ampicillin had sterile bone cultures. In contrast, seven of ten animals treated locally with unencapsulated ampicillin powder developed osteomyelitis. Biodegradable antibiotic-loaded microspheres may be of clinical benefit for the local treatment of chronic osteomyelitis.

The effects of thermal and electrical injury on pulpal histamine levels

The present investigation was undertaken to determine possible quantitative changes in porcine pulpal histamine levels following thermal and electrical insult. Quantitative spectrophotofluorometric assays revealed a fourfold increase in pulpal histamine levels within 30 minutes of thermal injury. These findings suggest that histamine may play a role in the initial stages of pulpal inflammation. Electrical insult was found to have no significant effect on pulpal histamine contents 30 minutes after insult. The possible implications of these findings are discussed.