Clinical Microbiology and Antimicrobial Chemotherapy. 2025; 27(3):406-416
Determination of the antimycobacterial efficacy of a composite material impregnated with silver in relation to M. tuberculosis.
Samples of the outer shell of bulk porous composite materials with antimycobacterial substances included in the structure (silver (Ag) nanoparticles, as well as silver proteinate) were obtained at the Kurchatov Institute. In total, two types of samples with different particle contents were obtained: chitosan Ag and chitosan Ag2. To obtain an outer shell with an impregnated silver proteinate complex from chitosan Primex 43040 with glutaraldehyde: an aqueous solution of silver proteinate with different concentrations («chitosan Pr» and «chitosan Pr2») was added. The control sample was the outer shell without the addition of drugs. To determine the activity of composite material samples containing silver particles, a pure culture of the control strain M. tuberculosis H37Rv was used. The corresponding samples («chitosan Ag», «chitosan Ag2», «chitosan Pr» and «chitosan Pr2») and 100 µl of M. tuberculosis H37Rv suspension were added to the test tubes. The incubation duration is 28 days or upon reaching a growth control tube of 400 growth units.
The study was conducted on 2 concentrations of silver proteinate of 20 and 40 mg/ml, impregnated into chitosan implants and 2 concentrations of silver nanoparticles. In all cases, there was a growth retardation zone (7 mm), regardless of the concentration of the drug, i.e. antimycobacterial activity was weak. In tubes with chitosan implants without the active substance, the onset of growth was recorded on the 6th day, in tubes with chitosan implants impregnated with silver proteinate – on the 11th day, i.e. there is no complete suppression of culture growth. At high concentrations of silver nanoparticles (0.034–0.042 nmol/ml), complete inhibition of the growth of M. tuberculosis H37Rv was observed; at low concentrations, the culture growth point was on day 16. This composition is promising. Tubes with chitosan implants impregnated with silver nanoparticles in high concentration (0.034–0.042 nmol/ml) were left in the automated Bactec MGIT 960 system to assess the time interval of silver activity against M. tuberculosis, a positive result was recorded on the 35th day.
The study demonstrated antimycobacterial activity of various forms of silver. Silver proteinate requires a significant increase in concentration of impregnation in implants, which indicates a weak antimycobacterial activity of this drug, and silver nanoparticles at high concentrations (0.034–0.042 nmol/ml) show bactericidal activity against M. tuberculosis complex, lasting for 35 days.