Research Information System
Congress of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), Vienna, Austria, 11 - 15 April 2025, pp.2782, (Summary Text)
Background
Skin infections, caused by various microorganisms, especially multidrug-resistant bacteria, remain a significant global health concern, leading
to increased morbidity, prolonged treatment durations, and the development of resistant strains. The emergence of antibiotic-resistant bacteria
worldwide has highlighted the need for the development of novel antimicrobials and alternative solutions. This study aims to investigate the antimicrobial
activities of novel biopolymers (especially chitosan based) loaded with antibiotic and metal nanoparticles, which are known for their
antimicrobial properties due to their ability to generate reactive oxygen species, against a wide range of bacteria, including multidrug-resistant
strains.
Methods
The antimicrobial effects of the polymers were tested against the American Type Culture Collection (ATCC) standard strains of Pseudomonas
aeruginosa, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and
Staphylococcus epidermidis. The antimicrobial activities of the substances before polymerization were assessed by the microdilution method,
and the effects of the polymers were evaluated by agar diffusion assays, AATCC-100 tests, and time-kill experiments.
Results
The microdilution assay showed that the substances, except for TiO2, were effective against all Gram-positive bacteria, K. pneumoniae, and E.
coli, but not P. aeruginosa. In the agar diffusion test, antibiotic- and ZnO-loaded biopolymers formed inhibition zones ranging from 22 to 33 mm,
while TiO2-loaded polymers exhibited no effect. The AATCC-100 test demonstrated that silk fibroin-based polymers, even without active agents,
reduced bacterial counts by 1-Log10 after 24 hours, while antibiotic- and ZnO-loaded polymers showed a 3-Log10 reduction, indicating strong
bactericidal activity. Additionally, time-kill assays confirmed the persistence of antimicrobial activity in the polymers for up to 72 hours.
Conclusions
Antibiotic- and ZnO-loaded biopolymers demonstrated strong antimicrobial properties, particularly against Gram-positive bacteria, including
MRSA. While TiO2-loaded biopolymers exhibited no significant antimicrobial effect, the biopolymers containing antibiotic and ZnO showed sustained
bactericidal activity over a period, up to 72 hours. These findings suggest that these biopolymers could offer an effective alternative for the
treatment of bacterial skin infections, with the potential for prolonged antimicrobial effects and minimal resistance development.