Determination of antimicrobial activity of chlorhexidine-chitosan gel in vitro

Abstract

Introduction. Skin infections are an increasing concern in both human and veterinary medicine due to factors such as antimicrobial resistance, lifestyle changes, and hygiene habits. The frequent and inappropriate use of systemic antibiotics for superficial skin infections has led to multidrug-resistant pathogens, complicating treatment [1]. This highlights the need for alternative therapies, such as topical antiseptics, to reduce antibiotic use and resistance development. Objective. This study aimed to evaluate the in vitro antimicrobial activity of a chitosan gels containing chlorhexidine against Gram-positive and Gram-negative bacteria. Methods. The gel’s antimicrobial properties were assessed in vitro using the agar diffusion method on Mueller-Hinton agar [2]. Tested organisms included reference strains of Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853), along with wild strains of the same species. Results. The antimicrobial effect of the gels was not dependent on chlorhexidine concentration but was influenced by chitosan content. The 1% chitosan gel showed the strongest inhibitory effect on both reference and wild strains. The results emphasized the importance of testing both strain types, as wild strains were generally more resistant than reference strains. This suggests chitosan boosts chlorhexidine’s antimicrobial effect and shows potential for use in skin and wound antisepsis in veterinary medicine. Conclusions. The study confirmed the synergistic action of chlorhexidine and chitosan, with stronger efficacy against Gram-positive bacteria. Further preclinical trials are planned, and it is expected that chitosan, combined with chlorhexidine, will not only enhance antimicrobial activity but also aid wound healing in damaged tissues.