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Evaluation of biodegradable ampicillin anhydrate microcapsules for local treatment of experimental staphylococcal
E Jacob1, J A Setterstrom, D E Bach
1United States Army Institute of Dental Research, Walter Reed Army Medical Center, Washington, DC 20307-5300.
Abstract:
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.
Insights
Biodegradable microspheres delivering ampicillin locally prevented staphylococcal osteomyelitis in rabbits. This local antibiotic delivery showed promise for treating bone infections, even when delayed.
Area of Science:
- Orthopedics
- Infectious Diseases
- Biomaterials Science
Background:
- Chronic osteomyelitis necessitates sustained local antibiotic concentrations for effective treatment.
- Biodegradable microspheres offer a potential delivery system for localized antibiotic therapy.
Purpose of the Study:
- To evaluate the efficacy of poly-DL-lactide-co-glycolide microspheres loaded with ampicillin anhydrate for treating experimental staphylococcal osteomyelitis in rabbits.
Main Methods:
- Rabbits were infected with Staphylococcus aureus in the proximal tibial metaphysis.
- Treatment involved intramedullary injection of microencapsulated ampicillin or parenteral ampicillin.
- Studies included immediate therapy, delayed therapy, and delayed therapy with debridement.
Main Results:
- A single injection of microencapsulated ampicillin prevented osteomyelitis in all animals when administered immediately.
- Delayed local treatment with microspheres was more effective than parenteral therapy.
- Local delivery of microspheres after debridement resulted in sterile bone cultures in all animals.
Conclusions:
- Biodegradable antibiotic-loaded microspheres are effective for local treatment of experimental osteomyelitis.
- This localized delivery system demonstrates potential for managing chronic bone infections.
- Microencapsulated ampicillin offers a promising alternative to conventional antibiotic administration for osteomyelitis.
