With the spread of antibiotic resistance era, the failure of antibiotic treatment of purulent inflammatory processes with bacterial flora as the etiological factor has increased. The ineffectiveness is related to the evolutionary development of microbial resistance to antibiotics (1–4). According to the literature, bacterial resistance to antibiotics can develop due to the ability of certain species of microorganisms to form biofilms. Biofilms allow bacterial cells to become protected from the effects of antibacterial drugs and also have the ability to evade the defense mechanisms of the macro-organism in individuals of different ages and sexes (5–7). A distinctive feature of bacterial infection associated with biofilm formation is not only an increased strong inflammatory response with release of significant amounts of inflammatory mediators, but also the resistance of microorganisms to antibiotics, which in turn influences the choice of these drugs for treatment of the pathological process and plays a significant role in enhancing the pathogenicity factors, namely, the adhesive properties of the pathogen (8–10). It is through bacterial adhesion that the process of microbial-macroorganism interaction begins, involving the attachment of the bacterial agent and its subsequent colonization of macroorganism cells, which in turn can be a starting mechanism for the process of biofilm formation (11, 12). Doctors are now increasingly using antiseptics to treat and prevent infections and inflammatory processes, given that microbial resistance to these drugs is acquired less frequently. In addition, some antiseptics have been shown to reduce bacterial adhesion, or even block it altogether (3, 13).

Alveolitis or dry socket is a local post-extraction complication, the etiological factor of which is the bacterial flora of the extraction site (14–18).

Currently, many scientific studies have appeared regarding the role of viridans group streptococci, in particular Streptococcus mitis (S.mitis), in the development of infectious processes (19). These Gram-positive catalase-negative α-hemolytic oral streptococci belong to the opportunistic resident microbiota of the human oral cavity (20). S.mitis has been identified among the causative agents of various bacterial infections and their complications, such as caries, endocarditis, endophthalmitis, bacteremia, septicemia (21–24). It should be noted that S. mitis has the ability to make a significant contribution to the pathological process by increasing the pathogenicity of representatives of polymicrobial bacterial associations comprising biofilms. In fact, bacteria composing biofilms undergo evolutionary development together, which leads to an increase in metabolic activity and activation of virulence factors of its representatives, i.e., S. mitis participates in the process of co-aggregation and formation of a multispecies microbial biofilm layer (25, 26).

Today, the use of antiseptics in the treatment of inflammatory diseases of the oral cavity is promising on the background of antibiotic resistance. Chlorhexidine bigluconate is the most widely used antiseptic in dentistry recently. However, more and more often there are data on a decrease in its effectiveness. Along with this, antiseptics based on quaternary ammonium compounds (decamethoxine), possessing a wide spectrum of antibacterial action, demonstrate positive results in the prevention and treatment of infectious inflammatory processes, including those of the oral cavity (18).

The aim of the study was to investigate the effect of antiseptics on the adhesive and biofilm-forming properties of clinical S.mitis isolates isolated from the oral cavity of patients with an infectious and inflammatory post-extraction complication.

We found that the studied clinical isolates of S.mitis isolated from the oral cavity of patients with infectious and inflammatory post-extraction complications are classified as highly adherent microorganisms (Table 1). The MIA for the studied isolates was 8.55 ± 0.82. Moreover, isolates of S. mitis that colonized the oral cavity of somatically healthy adults and were used as a control also showed a high ability to adhere. The average MIA for them was 8.16 ± 0.45, and the results had no significant difference compared to the results of MIA of the studied isolates.

After action of sub-bacteriostatic concentration of decamethoxin on clinical isolates, a 1.3-times (p < 0.05) decrease of the MIA of the studied isolates was observed in comparison with the adhesion index of the free-antiseptic culture. Taking into account the results of action of chlorhexidine bigluconate sub-bacteriostatic concentration on S.mitis isolates, we revealed 1.2-times (p < 0.05) increase of MIA parameters of the studied clinical isolates in comparison with MIA parameters of the S.mitis with no antiseptics. When comparing MIA parameters in the presence of sub-bacteriostatic concentrations of decamethoxin and chlorhexidine bigluconate between each other, it was found that MIA parameters after the action of sub-bacteriostatic decamethoxin concentration were 1.5 times (p < 0.05) lower than MIA parameters after sub-bacteriostatic concentration of chlorhexidine bigluconate (Table 2).

The next stage of our study was to determine the effect of sub-bacteriostatic concentrations of the antiseptics decamethoxin and chlorhexidine bigluconate on the biofilm-forming properties of clinical S. mitis isolates. Having evaluated the results of the study it can be stated that the studied clinical isolates of S. mitis according to the methodology of G.D. Christensen referred to microorganisms with medium ability to biofilm formation (Table 3). It should be noted that, on average, the parameters of biofilm-forming properties of the studied isolates did not differ significantly from the given parameters of control isolates from healthy individuals. After the effect of a sub-bacteriostatic concentration of decamethoxin, we found that the optical density of clinical isolates decreased 2.3-times (p < 0.05) considering the optical density results of the S.mitis with no antiseptics, i.e., the biofilm formation capacity of the studied isolates became low (Figure 1).

Our study showed no significant effect of chlorhexidine bigluconate on the biofilm formation of the examined microorganisms compared to S.mitis with no antiseptics. The clinical isolates left an average film-forming capacity even after antiseptic action. By evaluating the effect of sub-bacteriostatic concentrations of the studied antiseptics on the change in optical density, we determined that after the action of sub-bacteriostatic concentration of decamethoxin, the optical density decreased 2.1-times (p < 0.05), compared with the action of sub-bacteriostatic concentration of chlorine. Such results indicate that decamethoxin changes the biofilm formation capacity of clinical isolates from medium to low.

Microbial adhesion starts a process of interaction between the microorganism and the macroorganism, and such contact can cause a pathological process. Sarah E. Whitmore notes in her research that S. mitis possesses a variety of properties that contribute to different forms of co-existence with other microorganisms. The author attributes this existence to the adhesive properties of this group of bacteria (25). In our studies, clinical isolates of S. mitis isolated from patients with infectious and inflammatory post-extraction complications (dry socket) were classified as highly adhesive microorganisms according to the adhesion index by Brillis. In addition, our study found that the antiseptic decamethoxin under study has the ability to reduce the adhesive properties of clinical S.mitis isolates, while the antiseptic chlorhexidine bigluconate not only did not reduce the adhesion of S.mitis isolates, but also even increased it. Such data should be considered in clinical practice when choosing an antiseptic for the treatment and prevention of infectious and inflammatory processes. Ruben Barreto points out in his research that micro-organisms have the ability to acquire resistance to antiseptics, even those of widespread use. Chlorhexidine bigluconate was added to the list of antiseptics investigated and resistance to it was also found by microorganisms (29). It is possible that resistance to bigluconate chlorhexidine is responsible for various mechanisms leading to an increase in the adhesive properties of bacteria. Oleksandr Nazarchuk et al. studied the film-forming ability of Gram-negative bacteria under the action of the antiseptic decamethoxin in their research (30). Their data showed that decamethoxin reduced the biofilm formation ability of the Gram-negative microorganisms studied. At the same time, given the results of our study, the antiseptic decamethoxin was found to have the ability to reduce biofilm formation of Gram-positive bacteria as well. These findings should be considered in the treatment and prevention of infectious and inflammatory processes in which S. mitis is involved. After all, it is the biofilm that protects micro-organisms from the effects of antibacterial drugs, which entails further development of the pathological process, as well as increasing the resistance of bacteria to antibiotics in it. And using the antiseptic decamethoxin can reduce the biofilm-forming properties of S.mitis if this group of streptococci is one of the representatives of the polymicrobial biofilm community of the post-extraction dental extraction site.

Thus, clinical isolates of S.mitis isolated from patients treated for infectious inflammatory post-extraction complications (dry socket) are highly adherent microorganisms. The antiseptic decamethoxin decreases the adhesion index of these bacteria, while chlorhexidine bigluconate conversely increases the adhesion index of clinical S.mitis isolates. Clinical S. mitis isolates have an average biofilm formation capacity index. The antiseptic decamethoxin inhibits the biofilm formation capacity of S.mitis from medium to low.