Background Dental infections, like dental degradation and periodontal diseases, are the most widespread bacterial infections in humans.Due to non-life threatening nature and ubiquity, their significance in healthcare was minimized.Still, they burden the economics of healthcare and the patients.Material and methods The study of SkQ1 (10-(6'-plastoquinoyl) decyltriphenylphosphonium) antibacterial activity against Streptococcus mutans species and dental biofilm bacteria was conducted.Bactericidal and bacteriostatic effect of this substance in micromolar concentrations on pure cultures and in higher concentrations on dental plaque bacteria was established.The compound binding effect with high molecular components of human saliva was identified and quantitatively evaluated.Results The test results showed that acidic media or competing for cation-containing drugs weaken this effect.SkQ1 is potentially applicable for oral cavity infections treatment and its efficiency can be enhanced by the utilization of proper vehicles.Conclusions SkQ1 disturbs bacteria transmembrane potential, so it can be considered as an antibacterial agent that is effective against gram-positive bacteria and can increase gram-negative bacteria sensitivity to the compounds that they are often resistant to.

The use of platinum-based anticancer drugs is limited by both their side effects and their effect on normal microflora's metagenome. Drugs that possess mutagenic and genotoxic properties may cause mutations in microbial genomes that contribute to the emergence of resistance to antimicrobial preparations and the development of complications after chemotherapy. The effects of cisplatin and oxaliplatin on microorganisms were studied using bacterial biosensors-E. coli strains MG1655 pKatG-lux, which reacts to the generation of hydrogen peroxide; MG1655 pSoxS-lux, which reacts to the superoxide anion radical; and the MG1655 pColD-lux strain, which detects DNA damage. The biosensor tests demonstrated high levels of genotoxicity for both drugs and some differences in the spectrum of reactive oxygen species generated. Ascorbate reduced genotoxicity of cisplatin by 41%. Nonlethal doses of cisplatin induced a three- to sevenfold increase in the frequency of the mutations that confer the resistance of E. coli to rifampicin and ciprofloxacin. Ascorbate also reduced frequency of the mutations by 65%. Thus, the effect of these drugs was probably associated with the generation of reactive oxygen species and induction of SOS response. The risk of secondary antibiotic-resistant infections may be decreased by applying antioxidants and antimutagens. At the same time, these increases may also decrease the anti-tumoral action of these compounds.

The capability of the dioxidine drug to cause bacterial resistance to antibiotics was studied. The study was performed with the use of a bioluminescent test and the recombinant E. coli strains MG 1655 (pSoxS-lux), MG1655 (pKatG-lux), MG1655 (pRecA-lux), and MG1655 (pColD-lux). The strains harbored plasmids with the operon luxCDABE from the photobacteria Photorhabdus luminescens under control of the corresponding E. coli stress-inducible promoters. The mutation frequency of the stable mutants was found by conventional methods for nonpathogenic and opportunistic strains of E. coli, Bacillus amyloliquefaciens, and Klebsiella pneumoniae. Dioxidine was shown to induce the promoters PrecA and Pcda in E. coli MG1655, which suggests the induction of the SOS-response in bacterial cells. The Pcda induction was higher than with PrecA. The value of the induction coefficient was highest if the dioxidine concentration was 2.25 × 10–5 M. Moreover, this drug enhanced the induction of the SoxS and KatG promoters responding to the superoxide anion radical and hydrogen peroxide, which suggests possible participation of oxidative mechanisms in dioxidine DNA damage. The maximal value of the induction coefficient was also observed under conditions of 2.25 × 10–5 M. Dioxidine can induce mutations leading to antibiotic resistance in all bacterial strains studied. An increase in mutation frequency was observed for rifampicin (twofold), ciprofloxacin (sixfold), and azithromycin (fourfold). These data show the necessity for an antibiogram for every patient who is taking or has taken dioxidine.

В статье показано, что лекарственные препараты, обладающие мутагенными свойствами: диоксидин, цисплатин, фурацилин, способны повысить уровень мутагенеза у дрожжей Saccharomyces cerevisiae и привести к возникновению штаммов, обладающих резистентностью к флуконазолу.

DNA protective and antioxidant activity of Bacillus amyloliquefaciens B-1895 and Bacillus subtilis KATMIRA1933 were evaluated by Escherichia coli-based Lux biosensors. Two biosensor strains of E. coli, MG1655 (pColD-lux) and MG1655 (pSoxS-lux), which react on DNA damage and superoxide-anion radical activity, were used. SOS-response and Sox-response were stimulated by addition of dioxidine (2,3-Quinoxalinedimethanol, 1,4-dioxide) and paraquat (N, N0-dimethyl-4,4'-bipyridinium dichloride) respectively. Preparations of both Bacillus fermentates demonstrated DNA protective and antioxidant (superoxide scavenging) activity (up to 60.19%). The strain.1933 is, in general, characterized by higher DNA protective activity (28.85%), with parameters of antioxidant activity of both bacilli strains being statistically not significantly different. Sporogenous potential probiotic micro-organisms with antioxidant and DNA protective activities can become an effective tool for compensation of various negative oxidative stress processes in humans.