RESEARCH OF SENSITIVITY OF CLINICAL STRAINS OF S. AUREUS TO DECAMETHOXIN AND LOCAL ANESTHETICS

The formation of biofilms by pathogenic microorganisms S. aureus increases the risk of infectious lesions of different localization in surgical patients. However, about 65-85% of all infectious diseases caused by bacteria, which have the ability to form biofilms. There was found that large number of complications after the use of catheters, other implantable medical materials and equipment were closely related to the ability of pathogens to form biofilms. Microorganisms included in a biofilm have a higher resistance to antimicrobial agents, than the same bacteria that live outside such structures. Regarding this, the search and study of drugs, which can suppress the formation of biofilms by micro-organisms and destroy them within such microbial com-munities is an integral and relevant part of antimicrobial therapy. Objective. The aim of the research was to study the formation of mono-species biofilms in vitro by S. aureus strains and further determine their sensitivity to local anesthetics separately and in combination with the antiseptic decamethoxin. Materials and methods. The activity of local anesthetics (bupivacaine 0.5%, lidocaine 2%, ropivacaine 0.75%) was studied on clinical strains of S. aureus (n = 31) using a qualitative disco-diffusion method using standard sterile paper disks soaked with ex tempore clinical doses of drugs. An antiseptic decamethoxin 0.01% was used as a control. Zones of growth inhibition of microorganisms around discs with anesthetics and decamethoxin on solid nutrient media were measured after 24 h of incubation of cultures of microorganisms (t 37 ° С). Additionally, the effect of anesthetics on the ability of S. aureus to produce biofilms was studied in the presence of clinical concentrations of local anesthetics on polyurethane catheters and the optical density (OR) of biofilms in a 96-well plate followed by crystal-violet staining (according to Christensen, 1985). Results. Researches have shown the effect of lo-cal anesthetics against staphylococcus, but inferior to the antimicrobial effect of the antiseptic decamethoxin. There was found that in the presence of 1.0% lidocaine and 0.125% bupivacaine, the formation of biofilm by S. aureus was suppressed by 0.778 and 0.776 times, re-spectively, and the average film formation of S. aureus increased in the presence of 0.375% ropivacaine and 0.25% bupivacaine in 1.308 and 1.206 times, respective-ly. It is studied that when using the antiseptic decameth-oxine (1/4 of the minimum bacteriostatic concentration) with anesthetics - there is an increase in the inhibitory effect of anesthetics on the biofilm formation of S. aure-us. Conclusions. The S. aureus culture has an ability to form biofilms on medical devices. Clinical strains of conditionally pathogenic microorganisms S. aureus that colonize the polymer surfaces of medical devices are highly sensitive to the antiseptic decamethoxin. Local anesthetics bupivacaine, lidocaine have pronounced antimicrobial properties for S. aureus isolates, inhibiting their formation of a bacterial biofilm. In the presence of 0.375% ropivacaine strains of S. aureus formed a dense biofilm, which confirmed the resistance of this strain to ropivacaine. Ropivacaine provides a weak bacteriostatic effect only on the planktonic form of Staphylococcus aureus.