Comparative evaluation of the antibacterial activity of allografts impregnated with various antibiotics

Radical surgical debridement is the most important condition for the successful treatment of patients with chronic osteomyelitis. However, even the most thorough debridement cannot guarantee complete eradication of the pathogen, so local antibacterial therapy is crucial. This underscores the urgent clinical need for the development of a biodegradable osteoplastic material with prolonged antimicrobial activity. The most promising material is a material based on purified allograft bone. The aim of the study was to compare the duration of antibacterial activity of allografts impregnated with various antibiotics against gram-positive and gram-negative bacteria. Materials and methods. Purified and delipidized bone allografts measuring 5 x 5 x 5 mm were prepared according to the procedure described in Russian Patent No. 2722266C. The bone blocks were impregnated with antibacterial agents with varying activity spectra: vancomycin, aztreonam, meropenem, and fosfomycin. The presence and duration of antibacterial activity of the resulting samples were determined against reference bacterial strains depending on the drug's spectrum of activity by applying a 24-hour incubation solution containing the samples to the surface of a bacterial lawn. The data were analyzed using GraphPad Prism 9.0. Results. The standard vacuum impregnation protocol used ensured reproducible saturation of the bone tissue with antibiotics. The maximum increase in block weight was recorded with aztreonam impregnation, while the minimum was with fosfomycin. Vancomycin-impregnated blocks were most active against methicillin-sensitive and methicillin-resistant S. aureus. Meropenem-impregnated blocks were effective for 4 days against K. pneumoniae. Aztreonam impregnation provided antibacterial activity against K. pneumoniae for 6 days. Fosfomycin-impregnated blocks were active against gram-negative pathogens for 6 days. Conclusion. The development of new bone substitute materials based on antibiotic-impregnated bone allografts appears highly promising. The results indicate the need to develop methods for prolonging the release of antibacterial agents from bone substitute materials, as well as testing other potential antimicrobial agents in combination with antibiotics to overcome potential pathogen resistance.