Control of infection classically involves hand and healthcare hygiene, reduction of selective and ineffective chemotherapy, reduction of invasive procedures and achlorhydria and adequate staffing, along with appropriate containment and concentration of patients. Investigation and control of any continuing sources of infection in food and water supplies is important also, as is recognition of individuals carrying high-risk strains and species. The onset of infection may be distant from the time of acquisition and may critically affect epidemiological assessment of control points. Carriage may be prolonged, increasing the likelihood of recurrent infection and exacerbating the difficulty of control. Mortality associated with resistance is difficult to assess retrospectively and may not be high, complicating analysis of the success or failure of control measures.

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The in vitro antimicrobial activity of highly dispersed silica and polyhexamethylene guanidine hydrochloride composite for treating local infections Antimicrobial drug resistance (ADR) is an urgent global problem for all countries; it has a negative effect on the treatment outcome of patients. The problem can be solved by creating and introducing new antimicrobial compounds and complex drugs. Development of the combined antimicrobial agent which would show the expressed antimicrobial action and sorption properties remains relevant. Polyhexamethylenguanidine hydrochloride (PHMG-HC), being a highmolecular cationic surfactant of the guanidine group, was chosen as an antimicrobial component. Aim. To determine the antimicrobial activity of highly dispersed silica (HDS), a composite (code name CMU-211) of HDS and PHMG-HC, and PHMG-HC polymer solution. Materials and methods. 5% suspension of HDS modified by PHMG-HC polymer, 5 % suspension of HDS and 20 % aqueous solution of polyhexamethyleneguanidine hydrochloride were used in the work. The antimicrobial activity of substances was studied using test-strains of such microorganisms as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica, Klebsiella pneumoniae, and Candida albicans. Results. The composite HDS/PHMG-HC has been shown to have a high activity against C. albicans and S. aureus with the minimum inhibitory concentration (MIC) of ~10 μg/mL (calculated with reference to HDS/PHMG-HC), as well as the marked effect against E. coli (MIC of ~20 μg/mL), S. enterica (MIC of MIC ~40 μg/mL) and P. aeruginosa (MIC ~40 μg/mL). The relatively low activity of CMU-211 was reported against K. pneumoniae (MIC ~ 80 μg/mL). The activity of the composite HDS/PHMG-HC was similar to those of PHMG-HC. Conclusions. The composite HDS/PHMG-HC developed exhibits the marked antibacterial activity against gram-positive, gram-negative microorganisms, as well as C. albicans.

The emerging and steady increase of microbes that are resistant to antimicrobial treatments has become a global public health concern that threatens the effective treatment of infectious diseases, therefore, the development of new medicines with antimicrobial properties is one of the priorities of the health systems. Cationic detergents, which, as a result of the combination of their surface activity and bactericidal properties, are promising for use in pharmacy and medicine. One of the representatives of the cationic surfactant group is polyhexamethylene guanidine hydrochloride (PGMG-GC) which was shown to be less toxic compared to some other disinfectants and effective against a wide spectrum of microbes. The aim of the study was to determine the acute toxicity parameters of a highly-dispersive silica (HDS) and PGMG-GC composite in mice after intragastric administration. The study was carried out on 23 BALB/c female mice weighing 18–22 g. To determine the toxicity, the animals were divided into the following groups. The first group was intragastrically injected with a composite of HDS and PGMG-GH, the second group was given a suspension of HDS, the third group was given a solution of PGMG-GC, and the fourth (control) group was treated with water for injection. The mass of the animals was determined before and on the 3rd, 7th, and 14th day after the composite administration. Administration of PGMG-GC or PGMG-GC + HDS composite caused significant decrease in body weight at 3rd and 7th day compared to control with further normalization on day 14. No significant changes of body weight were found in HDS group. No death of mice occurred after a single intragastric injection of the HDS + PGMG-GC composite during 14 days of the study. For the solution of PGMG-GC (without HDS), lethal cases were reported 2 h after the treatment at a dose level of 400 mg/kg. The condition of the animals survived normalized and, by the day 14, it corresponded to that in the control group for the most of the signs of toxicity indicating the reversibility of the toxic effect of PGMG-GC. Therefore, PGMG-GC is less toxic whet it is used as a part of the composite. Since no lethal cases were reported after a single intragastric administration of the composite at a dose of 2 000 mg/kg of body weight, the composite HDS + PGMG-GC appears to be low toxic according to the classification of substances by toxicity.

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