STUDY OF THE COMBINED ACTIVITY OF POLYHEXAMETHYLENE GUANIDINE HYDROCHLORIDE AND TETRAMETHYLENEDIAMINETETRAMINE AGAINST CLINICAL ISOLATES

520 Volume 5, Issue 10: Special Issue (EJAR) ISSN: 2181-2020 MPHAPP THE 6TH INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE “MODERN PHARMACEUTICS: ACTUAL PROBLEMS AND PROSPECTS” TASHKENT, OCTOBER 17, 2025 in-academy.uz STUDY OF THE COMBINED ACTIVITY OF POLYHEXAMETHYLENE GUANIDINE HYDROCHLORIDE AND TETRAMETHYLENEDIAMINETETRAMINE AGAINST CLINICAL ISOLATES D.D. Kurlovich R.V. Kravchenko Vitebsk State Order of the Friendship of Peoples Medical University, Vitebsk, Republic of Belarus e-mail: [email protected], tel.: +375 29 815-41-90 https://doi.org/10.5281/zenodo.17343817 Background: The widespread availability and use of antibacterial and antiseptic agents have led to the emergence of antimicrobial resistance among many strains of pathogenic and conditionally pathogenic microorganisms. Antibiotic resistance poses a particular challenge in the treatment of nosocomial infections in hospital settings, especially in intensive care units (ICUs). Addressing the pharmacotherapy of nosocomial infections in ICUs remains one of the most pressing issues in modern medicine. To tackle this problem, novel antimicrobial agents as well as their combined activity are being investigated. Synergistic interactions between antimicrobials can facilitate therapy and enhance efficacy at lower doses, thereby reducing adverse and toxic effects on the human body. Objective: To evaluate the combined antimicrobial activity of two antiseptic agents against clinical strains of Escherichia coli and Staphylococcus aureus using the checkerboard method. Materials and Methods: Six clinical isolates obtained from the Vitebsk Regional Clinical Center were included in the study: E. coli (strains №778, №779, №809) and S. aureus (strains №767, №765, №975). Additionally, reference strains from the American Type Culture Collection (ATCC) were tested: E. coli ATCC №25922 and S. aureus ATCC №25923. The combined activity of two antimicrobial agents—belonging to the classes of quaternary ammonium compounds (QACs) and biguanides—was assessed. Results: Minimum inhibitory concentrations (MICs) of the individual compounds against the reference strains (E. coli ATCC №25922 and S. aureus ATCC №25923) and the clinical isolates (E. coli №778, №779, №809; S. aureus №767, №765, №975) had been previously determined. Based on these data, the combined antimicrobial activity was evaluated in duplicate experiments. The combination demonstrated synergistic activity against the reference strain E. coli ATCC №25922. Neutral (indifferent) interactions were observed for the clinical isolates E. coli №778, S. aureus №767, and S. aureus №975. Additive effects were found for E. coli №779 and №809, S. aureus №765, and S. aureus ATCC №25923. Notably, against certain multidrug-resistant isolates, the combination exhibited additive or synergistic activity, highlighting its potential for the pharmaceutical development of topical antimicrobial formulations. Conclusions: The observed synergistic and additive interactions enable the use of lower concentrations of each active substance compared to monotherapy. Reduced concentrations may decrease the incidence of adverse effects and slow the development of microbial resistance, thereby significantly improving the management of multidrug-resistant microorganisms.