[Evaluation of the influence of culturing on the intensity of biofilm formation by Klebsiella pneumoniae strains.] / Влияние условий культивирования на интенсивность биоплёнокообразования штаммами Klebsiella pneumoniaе.

Due to the prevalence of biofilm infections caused by Klebsiella pneumoniae, in laboratory diagnostic practice it has a great importance to obtain a standard model of Klebsiella biofilm for evaluating the bactericidal effect and effectiveness of antimicrobial drugs. Describes the method of Klebsiella biofilms formation in vitro. The intensity of biofilm formation was evaluated by the ability of bacteria to bind the crystal violet. The degree of film formation was measured by optical density. The presence of an intercellular matrix was confirmed by staining of Congo-red solution followed by light microscopy. The effect of exogenous and endogenous factors on biofilm formation by K. pneumoniae strains was investigated. The influence of the nutrient composition, the age of the culture («daily¼, «weekly¼), the presence of oxygen and the temperature conditions were studied. The nutrient composition of the medium significantly influenced on biofilm formation of K. pneumoniae: DMEM stimulated biofilm formation in most strains in vitro compared to TSB. The age of the culture (daily, weekly) did not significantly affect the biofilm formation of Klebsiella. At the same time, the temperature of culturing and the presence of oxygen can both stimulate and inhibit biofilm formation, depending on the strain under study. Most strains of Klebsiella better form a biofilm under aerobic conditions at 37º C.

Expression of toll-like and adhesive receptors on epithelial cells of the oral mucosa in periodontitis.

The expression of toll-like and adhesive receptors on epithelial cells of the oral mucosa changes in different pathological conditions, both local and systemic levels, in particular, in chronic periodontitis. The long-term presence of periodontal pathogenic microorganisms in the gingival furrow stimulates and supports the inflammatory process. The interaction of periodontal pathogens with epithelial cells of the oral mucosa is the first stage of the development of periodontitis. The pathological process affects the function of epithelial cells, in particular their ability to interact with representatives of microbiocenosis. Therefore, the natural colonization of normal oral microbiota on buccal epitheliocytes, reflecting the ability of epithelial cells to microbial adhesion, is a sensitive indicator of various destabilizing processes. Determining the level of expression of toll-like TLR2 and TLR4 receptors on epithelial cells also allows us to assess the functional state of cells and the severity of the inflammatory process at the level of the oral mucosa, in particular, in chronic periodontitis. In this paper, we studied the receptor-dependent reactions of buccal epithelial cells in chronic periodontitis using flow cytofluorometry and by determining the level of natural (microbial) colonization. The authors also compared these methods for determining the functional state of mucosal cells in chronic periodontitis. The results showed that in patients with periodontitis, the activity of receptors involved in adhesive reactions with the oral microbiota changed slightly and was little higher than in healthy donors. At the same time, the expression of TLRs on epithelial cells in periodontitis changed significantly. Thus, the percentage of cells expressing TLR2 significantly increased, while TLR4 decreased. Concurrently, the percentage of mucosal cells that do not have TLRs increased significantly in oral pathology. Thus, the study of TLR2 - and TLR4-expression on buccal epithelial cells is a more representative test in assessing the severity of the inflammatory process in chronic periodontitis than determining the level of natural colonization.

[Evaluation of anti-candida activity of metabolites of enterococcal clinical isolates.]

When studying the effect of the metabolic products of clinical isolates of enterococci on the viability of Candida albicans, it was found that metabolites of all tested strains of Enterococcus faecium, E. faecalis had a fungistatic effect. At the same time a reliable fungicidal effect is a strain-specific feature. It is better to use the method of delayed antagonism on double-layer agar to assess the antifungal effect of enterococcal metabolism products.

Humoral and Cellular Responses to a Single Dose of Fendrix in Renal Transplant Recipients with Non-response to Previous Hepatitis B Vaccination.

Approximately 70% of kidney transplant recipients are non-responders to conventional hepatitis B virus (HBV) vaccines. We examined whether Fendrix™, an HBV vaccine containing 3-O-desacyl-4'-monophosphoryl lipid A (MPL) as adjuvant, could induce HBV immunity in these patients and compared their vaccination efficacy with healthy controls tested previously by the same assays. We selected 35 kidney transplant recipients who had been vaccinated at least thrice against HBV but had never displayed anti-HBs antibodies. We re-assessed their anti-HBs antibody titres and further determined cellular HBV immunity by proliferation assay and interferon (IFN)-γ ELISpot. Seventeen recipients did neither display humoral nor cellular immunity and could be tested prior to and at month 1 after vaccination. Of note, HLA antigens associated with non-response to HBV vaccination (HLA-DRB1*03 and HLA-DQB1*02) were over-represented in these 17 recipients. At month 1 after a single vaccination with Fendrix™, we observed a significant increase in anti-HBs antibodies (P = 0.02). In seven of 17 recipients, we detected anti-HBs antibodies ≥10 IU/l (10-264), in four HBV-specific lymphocyte proliferation (stimulation index of 2.6-8.7) and in one specific IFN-γ responses (12 spots increment). The vaccination response to Fendrix™ was significantly higher (P = 0.035) than the response to HBVaxPro™ in young healthy controls. In summary, the results show that a single vaccination with Fendrix™ could already induce HBV-specific humoral and/or cellular responses in ten of 17 kidney transplant patients. Thus, Fendrix™ appears as an efficient vaccine in this patient cohort.