In vitro study of the antimicrobial activity of hydrogel-based matrices impregnated with antibiotics against the leading microorganisms of bone infection

Purpose To evaluate the results of a comparative analysis of the in vitro antimicrobial activity of polymer hydrogels and PMMA impregnated with antibiotics against test cultures of the leading pathogens of bone infection. Materials and methods A comparative analysis of the antimicrobial activity of the polymer hydrogel and PMMA impregnated with antibiotics was carried out. The bactericidal efficacy and prolongation of action of the following microbe-antibiotic pairs were assessed: MSSA – gentamicin, MSSE – cefazolin, MRSA and MRSE – vancomycin, A. baumannii – tobramycin. The duration of the study is 7 days. Statistical comparison of groups was carried out using the Mann-Whitney and Wilcoxon tests; the median and 95 % CI were used to describe the data. Results The obtained indicators of the zone of inhibition of the growth of microorganisms around the polymer hydrogel were several times higher than the results of PMMA (p < 0.05 for all periods). The antimicrobial activity of hydrogels in all cases lasted more than 7 days. Hydrogels impregnated with vancomycin showed the lowest rate of contraction of the inhibition zone. The best antimicrobial effect was demonstrated by the compared samples with cefazolin in relation to MSSE, the maximum index of the zone of suppression of which, on average, for the hydrogel was 29.3 mm, PMMA – 22.3 mm. Discussion Samples from polymer hydrogel impregnated with antibiotics demonstrated prolonged pronounced effective antimicrobial activity against the leading pathogens of orthopedic infections in comparison with PMMA. The bactericidal efficacy of the polymer hydrogel significantly exceeded the activity of PMMA already from the first day of the study (p = 0.002). The action of the hydrogel throughout the study was uniform without abrupt changes or dips (p > 0.05), in contrast to bone cement, whose activity against all test cultures significantly decreased (p = 0.042) on the 2nd day of the study. Conclusion Polymeric biodegradable hydrogels impregnated with antibiotics have a greater antimicrobial potential compared to PMMA. Uniform, slow and controlled release of the drug and effective inhibition of the growth of microorganisms, as well as prolonged action show that these properties may turn hydrogels into an effective depot system.