The resistance of bacteria to the disinfectants used is one of the pressing health problems that need to be addressed in order to prevent the formation and spread of resistant strains. This leads to a sharp decrease in the effectiveness of anti-epidemic measures and contributes to maintaining a high level of morbidity. In the context of the growing incidence of HAIs, their polyetiology, the large adaptive potential of opportunistic microorganisms, and the growing resistance to antimicrobial drugs, it is necessary to search for new or modify the corresponding substances of plant or synthetic origin that have antimicrobial action and are used as antimicrobial agents. One of the representatives of this class of compounds are polyguanidines, characterized by high antimicrobial activity and low toxicity. Due to the high reactivity of the guanidine group, as well as the ease of synthesis and the relative availability of raw materials, N-phenyl- and N-octyl-substituted derivatives of polyhexamethylene guanidine hydrochloride were obtained by melt polycondensation, their molecular weight characteristics were determined, and the structure was investigated by IR spectroscopy. An earlier study of the acute toxicity of polyhexamethylene guanidine hydrochloride derivatives after a single oral intake of drugs into the body of laboratory animals (white mice) made it possible to establish the following LD50 values: polyhexamethylene guanidine hydrochloride - 850.0 ± 112.02 mg / kg; N-phenyl-substituted polyhexamethylene guanidine hydrochloride - 1399.9 ± 120.51 mg / kg; N-octyl-substituted polyhexamethylene guanidine hydrochloride - 1150.0 ± 137.40 mg / kg. The obtained values, according to the tabulation of hazard classes, allow the synthesized derivatives to be classified into the fourth hazard class and open up the possibility of using disinfectants as active components. The evaluation of the antibacterial properties of the samples was carried out by the method of serial dilutions in agar on hospital strains of bacteria and fungi isolated from the biomaterial of patients of the Republican Clinical Hospital named after N.A. Semashko, according to the clinical guidelines "Laboratory diagnosis of community-acquired pneumonia" 2014; "Bacteriological analysis of urine" 2014; "Determination of the susceptibility of microorganisms to antimicrobial drugs" 2015 It was found that N-substituted derivatives exhibit a greater antimicrobial effect in comparison with an unsubstituted polymer. The most sensitive to all the drugs presented are the yeast-like fungi Candida albicans (No. 2495) (complete suppression), as well as methicillin-resistant St. aureus (no. 2544), and the substituted samples almost completely suppress its growth. The most resistant strains are P. aeruginosa (No. 2281), A. Baumannii (No. 2806) and K. Pneumoniae (No. 3023), the percentage of reduction of these bacteria under the action of substituted samples does not exceed 41%, which is explained by their multi-resistance.
In vitro antimicrobial activity of a highly dispersed silica and polyhexamethylene guanidine hydrochloride (PHMG-HC) composite for local infections treatment
