Restoring antibiotic sensitivity to lincomycin in compositions with nanosilver and humic substances

Aim. To study the effect of compositions with nanosilver and humic substances on restoration of sensitivity of methicillin-resistant Staphylococcus aureus to lincomycin. Materials and methods. Compositions of humic substances with silver nanoparticles were synthesized from commercial sodium humate Powhumus and silver nitrate in the presence of NaOH (1 M) to modulate alkaline pH. To synthesize one of the two compositions, sodium humate was modified with hydroquinone. To describe the characteristics of the resulting compositions, surface plasmon resonance spectra of silver nanoparticles and their images obtained by transmission electron microscopy were recorded. Sensitivity of a clinical strain of methicillinresistant Staphylococcus aureus was determined by measuring the minimum inhibitory concentration (MIC) with the addition of lincomycin and tetracycline to the compositions. Results. 100% conversion of ionic silver into metallic silver with a characteristic nanoparticle size of 6 nm was shown. The effects of tetracycline and lincomycin on the studied strain of Staphylococcus aureus were compared, and high sensitivity to tetracycline (MIC < 10 μg / ml) and resistance to lincomycin (MIC > 200 μg / ml) were shown. Studying the effect of the composition containing sodium humates with nanosilver with the introduction of lincomycin into it showed that this approach can significantly reduce MIC of lincomycin to 0.1 μg/ml in the presence of compositions with hydroquinone-modified sodium humate at a concentration of 40 μg / ml and compositions with unmodified sodium humate at a concentration of 60 μg / ml. Conclusion. The study demonstrated that the use of compositions with humic substances and nanosilver completely restores sensitivity of methicillin-resistant Staphylococcus aureus to lincomycin.