Antibiotic penetration into the infected knee. A rabbit experiment

Area of Science:

• Pharmacokinetics
• Infectious Diseases
• Orthopedics

Background:

• Bacterial arthritis necessitates effective antibiotic delivery to joint tissues.
• Understanding antibiotic penetration into synovial fluid and membrane is crucial for treatment optimization.

Purpose of the Study:

• To evaluate the intra-articular diffusion of four commonly used antibiotics into infected and normal synovial joints in a rabbit model.
• To compare the penetration capabilities of penicillin-G, cloxacillin, clindamycin, and netilmicin.

Main Methods:

• Purulent arthritis was induced in rabbit knees using Staphylococcus aureus.
• Antibiotic concentrations were measured in serum, synovial fluid, and membrane after intramuscular administration.
• A control group received sterile saline injection into the contralateral knee.

Main Results:

• All tested antibiotics demonstrated ready diffusion into infected joints.
• Concentrations in infected joints were 2-3 times higher than in normal joints.
• Clindamycin exhibited the highest intra-articular penetration, while cloxacillin showed the lowest, correlating with its higher protein binding.

Conclusions:

• Parenteral administration of penicillin-G, cloxacillin, clindamycin, and netilmicin achieves adequate concentrations in infected synovial joints.
• The findings support the efficacy of systemic antibiotic therapy for bacterial arthritis, negating the need for local instillation.