[The determination of biofilm composition of gram-positive bacteria.]

[Colonization activity of conditionally pathogenic microorganisms and features of biofilm formation on the surface of thermoplastic polymer material]

THE PURPOSE OF THE STUDY

Was to assess the microbial colonization and biofilm-forming activity of conditionally pathogenic microorganisms in vitro to samples of acrylic-free thermoplastic polymer material and to assess the possibility of its use for the manufacture of removable tooth splinting structures by injection method.

MATERIALS AND METHODS

The reference strains S. aureus, S. epidermidis, S. pyogenes, E. faecalis, E. coli, and C. albicans. Biofilm-forming activity was assessed by the level of ethanol extraction of a 0.1% aqueous solution of gentian violet by measuring on a PowerWave X microplate reader (USA).

RESULTS

A low degree of severity of microbial colonization and sufficient colonization resistance to the formation of a microbial biofilm of E. coli (0.374±0.056 cu opt. Pl.), S. aureus (0.272±0.039 cu. Opt. Pl.), S. epidermdis (0.299±0.028 cu opt. Pl.), S. ryogenes (0.399±0.069 cu opt. Pl.), E. faecalis (0.401±0.089 cu opt. Pl.). Moreover, C. albicans strains form a more pronounced biofilm (0.425±0.104 cu opt. Pl.) in comparison with other strains studied in the experiment.

CONCLUSION

Samples from a thermoplastic polymer based on polyoxymethylene have satisfactory biomedical characteristics and can be used at the stages of dental orthopedic treatment of patients without oral candidiasis.

A new approach for the study of the morphological structure of microbal biofilms

Microbial biofilms are heterogeneous, moving and constantly changing communities of microorganisms, often of various taxons. Approaches to study and assessment anti-biofilm drugs widely available today do not adequately assess their effects, while the results of studying the interaction of drugs with components of the film composition can provide them the right choice. The aim of investigation was to test a new method of morphological evaluation of biofilms. To form biofilms, we used an approach when the slide was placed at an angle of 30o-45o relatively to the Petri dish, and a suspension of test strains S. epidermidis in peptone broth was poured into the space between the Petri dish and the slide. A sterile cotton swab moistened with distilled water was placed next to the glass slide to create optimal humidity. The system was placed in a thermostat for 24 hours. The formed films were examined under a microscope using the DCM 310 video eyepiece and the Scope photo x86,3.1.312 program that allowed to conduct a complete morphometric study of the film: select layers, channels, cavities and make measurements, and then save the results on electronic media in jpg file format. Microscopy of the stained slides revealed that the biofilm has a layered structure. In each image obtained using a video eyepiece, it was possible to differentiate 4 layers. From the border of the two media to the inside: the fragmentation layer, the dense layer, the matrix substance layer, and the last one - the persistence layer. Channels of different diameters (from 10 to 24 microns) are observed across the entire thickness of the biofilm. Thus, used approach allows us to visualize and evaluate the structure of microbial biofilm, measure the thickness of layers and channel diameters. In addition, this method can be used to study the effect of antimicrobial drugs on bacterial films.

[The determination of biofilm composition of gram-positive bacteria.]

Current methods of biofilm imaging do not support a differentiated assessment of its composition, since it is not possible to establish a substrate stained with crystal violet, as this dye can form complexes with both intracellular and extracellular structures. This approach does not adequately assess the anti-biofilm effects of drugs, while the results of studying the interaction of drugs with biofilm components can ensure their most correct choice. The aim of investigation was to study the possibility of applying the original modification of the current method to determine the ratio of the cellular part and the matrix of biofilms of gram-positive microorganisms. The biofilm components were analyzed using a two-step approach, when prepared biofilms of gram-positive microorganisms were stained with crystal violet for 5 minutes, followed by fixing the dye in bacterial cells with iodine solution, and then the colored products were dissolved with 95% alcohol: matrix components for 1 minute, total biofilm for 15 minutes, after which the composition of biofilms was estimated by the formula: M=(OP1/OP15)×100, Kb=100-M, where M is the proportion of the matrix,%; Kb - the proportion of the cellular component,%; OP1 - optical density of samples, when alcohol was allowed to dissolve the colored product for no more than 1 minute; OP15 - was the optical density of samples, when alcohol is allowed to dissolve the colored product for 15 minutes. It was shown that in the composition of the biofilm formed by the collection strain, the proportion of the matrix was 13.2%, and the cellular component accounted for 86.8%. When the same strain cultivated in the presence of an antibiotic, an increase in the biofilm matrix was observed, which is probably due to the compensatory response of the microorganism to the action of the antibiotic. The proposed approach to the study of biofilms makes it possible to evaluate its component composition. Obtaining additional information in this way can provide, inter alia, an increase in the effectiveness of antimicrobial therapy while reducing the study time.