Assessment of tuberculocidal efficiency of disinfectants according to manufacturers’ 'instructions and results of experimental studies using reference test strain mycobacterium terrae

Objective. The aim of the study was to investigate the tuberculocidal efficacy of disinfectants according to the manufacturers instructions and the results of experimental studies using a test strain of Mycobacterium terrae. Materials and methods. The instructions for 150 disinfectants (DS) were studied. An experimental evaluation of the tuberculocidal efficacy of 6 DS was carried out using the reference strain M. terrae. Results. A study of the documentation for the DS showed that from the number of DS produced before 2010, only 38.2 % of the drugs were recertified after 2010. Of these, only in 50.0 % of cases it was noted in the instructions that the recertification was carried out using the test microorganism M. terrae. From the number of DS produced after 2010, only 49.2 % of the drugs were certified using the M. terrae test strain. According to the results of laboratory assessment of DS, it was shown that drugs that did not pass re-certification using M. terrae have low tuberculocidal efficacy. Conclusions. It has been established that many manufacturers of DS during certification and recertification of drugs do not test the modes of their tuberculocidal efficacy on the regulated microorganism M. terrae. In the course of laboratory assessment of the tuberculocidal effect of DS, it was confirmed that the least effective drug was the one that did not pass re-certification using M. terrae.

Comparative evaluation of hydrolysates as a basis for the construction of a nutrient medium for the cultivation of Listeria monocytogenes

The objective is to perform a comparative evaluation of the pancreatic hydrolysates prepared from fish and squid to determine the optimal culture medium for Listeria monocytogenes.Materials and methods. The following raw materials were used in the study: Pacific Herring (Clupea pallasii), Alaska Pollock (Gadus chalcogrammus), Common Roach (Rutilus rutilus lacustris), European Squid (Loligo vulgaris). The raw materials were subjected to enzymatic hydrolysis using the pancreas (according to Hottinger). A study of the physicochemical properties of pancreatic hydrolysates (content of free amino nitrogen (FAN), acidity of fish hydrolysates, the amino acid composition) was carried out.. The specific activity of nutrient media during the cultivation of the test strain L. monocytogenes 766 was assessed by a complex of microbiological methods.Results and discussion. The highest content of FAN at the end of enzymatic hydrolysis was observed in the pancreatic hydrolysate of the common roach (6%), the acidity of the hydrolysate remained stable from 6th to 13th day of the hydrolysis process (pH 7.2). Pancreatic hydrolysate of the common roach contained a number of amino acids that are most essential for the growth of Listeria. An assessment of the biological properties of nutrient media prepared on the basis of the obtained hydrolysates demonstrated that the best results in terms of sensitivity and germination of L. monocytogenes 766 showed a nutrient medium based on the pancreatic hydrolysate of the common roach. During the cultivation of L. monocytogenes 766 the test strain retained its morphological and cultural properties and did not show signs of dissociation.Conclusion. The research results have shown that the pancreatic hydrolysate of the common roach is a promising protein basis for the construction of an experimental environment for listeria.

The Destructive Effects of Extremely Halophilic Archaeal Strains on Sheepskins, and Proposals for Remedial Curing Processes : Use of sterile brine or direct electric current to prevent red heat damage on salted sheepskins

Proteolytic and lipolytic extremely halophilic archaea found in curing salt may contaminate skins during the brine curing process and damage skin structure. In the present study, three proteolytic and lipolytic extremely halophilic archaea were isolated from deteriorated salted sheepskins and characterised using conventional and molecular methods. Each test strain (Haloarcula salaria AT1, Halobacterium salinarum 22T6, Haloarcula tradensis 7T3), a mixed culture of these strains and the mixed culture treated with 1.5 A direct current (DC) were used for brine curing processes of fresh sheepskins and examined during 47 days of storage to evaluate the degree of destruction wreaked by these microorganisms. Both organoleptic properties and scanning electron microscopy (SEM) images of sheepskins proved that each separate test strain and the mixed culture caused serious damage. However, the mixed culture of strains treated with electric current did not damage sheepskin structure. Therefore, we highly recommend sterilisation of brine using DC to prevent archaeal damage on cured hides and skins in the leather industry.

Assessment of the applicability of primarily identified natural luminescent bacteria, isolated from the azov and the black seas, to determine the antimicrobial activity of antibiotics

Five isolates of luminous bacteria from aquatic organisms of the Azov and the Black Seas were isolated. The study of morphological, cultural, physiological and biochemical properties showed that isolates M1 and M4 were the representatives of the species harveyi, and isolates Fb, Sh1, and B were the representatives of the species P. leiognathi. It was found that the strain P. leiognathi Sh1 was the most sensitive to zinc sulfate when studying its effect on allocated luminescent bacteria. The effective concentration that reduced the bioluminescent index (BLI) by 50% (EC50) for zinc sulfate, when exposed to the test strain, was 4,0 0,1 g/ml. Experimental data allowed to consider the strain P. leiognathi Sh1 to be the test-object for determining the antimicrobial activity of benzylpenicillin, gentamicin, streptomycin, tetracycline and ceftriaxone. The results of evaluating the effect of antibiotics on the test object, revealed that after 15 minutes of incubation, the BLI values decreased by 50% only in samples containing benzylpenicillin, gentamicin, and tetracycline. Their EC50 were 500.0, 283.0 and 28.5 g/ml respectively. It was found that the exposure of test-strain to all antibacterial agents demonstrated resulted in decrease in BLI by 100% as compared to the control values. Strain P. leiognathi Sh1 can be used as a test-object for determining the antimicrobial activity of antibiotics.

Study of the Effect of a Biologically Active Compound Tris(2-hydroxyethyl)ammonium 4-Chlorophenylsulfanylacetate on the Growth of Listeria monocytogenes and Staphylococcus aureus

Background. Development of nutrient media ensuring the maximum growth rate of pathogens of dangerous infectious diseases while preserving their biological properties is extremely important. A promising direction in this area seems to be the use of synthetic microbial growth biostimulants.The aim of the work is to study the possibility of improving nutrient media for the cultivation of Listeria and Staphylococcus using a biologically active compound tris(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate.Materials and methods. The object of the study was experimental nutrient medium for the cultivation of Listeria used for the culturing of the test strain Listeria monocytogenes 766. As a comparison medium, commercial medium Fraser broth to which agar was added at a concentration of 1.5 %, was used. The test strain Staphylococcus aureus ATCC 6538-P (FDA 209-P) was cultivated on meat-peptone agar with 1% glucose. The compound tris(2-hydroxyethyl) ammonium (4-chlorophenyl)sulfanylacetate at a concentration of 10–4 wt. % was studied as a growth stimulator. A nutrient medium without a stimulant served as a control. The specific activity of nutrient media (germination rate, medium sensitivity, growth rate and stability of the main biological properties of microorganisms) was evaluated by the microbiological method.Results. Studies have shown that the addition of a growth stimulator to nutrient media contributes to the growth of colonies (by 10–50 %) and a decrease in the time of their development. When growth stimulator was added to the nutrient medium for the cultivation of Listeria, the initial growth of colonies of the L. monocytogenes 766 test strain after 12 hours of cultivation and growth of colonies of the test strain S. aureus ATCC 6538-P after 6 hours of cultivation on the meat-peptone agar with 1% glucose was observed.Conclusion. Thus, the addition of a growth biostimulator tris(2-hydroxyethyl)ammonium 4-chlorophenylsulfanyl acetate at a concentration of 10–4 wt. % in the nutrient medium accelerates the growth of Listeria and Staphylococcus, allows to reduce the time of issuance of the analysis result in half.

A comparative study of the bacteriotropic effect of metabiotics

Objective of the study: comparative evaluation of the bacteriotropic activity of Actoflor-S metabiotic and the exometabolic bifidobacteria complex.Materials and methods: in our work we used Actoflor-S dietary supplement as oral solution in 2 ml drop tubes (Solopharm). As a comparator drug, we used an exometabolite complex from the culture fluid of strain Bifidobacterium bifidum 1 obtained by method of ultrafiltration using separation apparatus with HOMM 15 kDa. We studied the stimulating effect of metabolite compositions on the acid forming activity and dynamics of the accumulation of lactobacilli Lactobacillus plantarum 8P-A3. Antagonistic activity against enterobacteria was determined in the test of inhibition of bioluminescence of the indicator strain Escherichia coli lum+ and quantified as an index of antibacterial activityResults and discussions. A comparative study of the effects of metabiotics on the acid forming activity of lactobacilli showed that both drugs have a pronounced stimulating effect on the probiotic strain L. plantarum. A comparative study of the effects of metabiotics on the model test strain of enterobacteria showed that whole preparations quickly and significantly (by more than 90%) inhibit the bioluminescence of E.coli lum+. Preparation dilutions 1:10 and 1:100 discovered significant differences in their activity. Given equal pH values (5.8 ± 0.1), Actoflor-S (dilution 1:10) inhibited the luminescence of E. coli lum + to a greater degree, exceeding almost 2 times the indicators of the metabolite bifidobacteria complex. It is revealing that Actoflor-S diluted 1:10 is not inferior to the whole preparation in terms of the level of effect on the test strain culture. What calls attention to itself is that large dilutions of UFLC of bifidobacteria after a short period of inhibition of luminescence of E. coli lum + have a stimulating effect. There is evidence that effect of inhibition of the luminescence of the control culture is dose-dependent.Conclusion. The results of a comparative examination of the bacterial action profile of the native exometabolites complex and Actoflor-S preparation confirm the presence of combination of the necessary inhibitory and stimulating activity against various agents of the microbiota. Creation of the metabiotics line based on Actoflor-S preparation with variability of biological properties and specialized for the management of various dysbiotic conditions show promise. An additional inclusion of native exometabolites of bifidobacteria and/or lactobacilli into the formula of artificial compositions will make it possible to expand the spectrum of the positive effect of probiotic preparations on the microorganism.

Study of gentamicin deposition in cellulose with albumin

Methods of binding antibacterial drugs to the surface of cellulose without the use of oxidizing agents to prevent the occurrence of wound infections have been studied. The immobilization of gentamicin in the complex of partially denatured albumin in the composition with bacterial cellulose has been analyzed. The study was carried out on samples of cellulose synthesized by Gluconacetobacter hansenii. Albumin served as a binding agent, which was used to impregnate cellulose samples, which were then denatured. Using PCR amplifi cation CFX (BioRad), the optimal denaturation temperature was selected. The effectiveness of the immobilization of albumin in the thickness of the cellulose was assessed by staining it with the luminescent dye SYPRO® Ruby Protein Gel Stain, followed by transilluminator detection. Bacterial cellulose impregnated with undenatured albumin was used as a control. Albumin immobilization in bacterial cellulose was observed at temperatures of 65– 95 °C. The antibacterial activity of the complex “cellulose + albumin + gentamicin” was evaluated using a test strain of bacteria Staphylococcus aureus ATCC 25923. The growth inhibition of the test strain of bacteria was observed in all tests with bacterial cellulose in combination with partially denatured albumin and gentamicin. In control samples, in which gentamicin was not immobilized as part of partially denatured albumin, growth inhibition zones of Staphylococcus aureus ATCC 25923 were not noted. It was concluded that by partial denaturation of albumin it is possible to delay antibacterial drugs in the thickness of bacterial cellulose for their further release. A new version of the material suitable for the production of implants and bandages based on bacterial cellulose gel with antibacterial properties is proposed. Dressings based on a composite of bacterial cellulose, albumin and gentamicin are most relevant for the treatment of burns. The presence of gentamicin in their composition is also relevant for the prevention of bacterial infections.

A method for predicting the blasting pressure of balloons using the surface strain in low pressure

Balloons made by cut fabric pieces are widely used in space research. To predict the blasting pressure of a balloon, we propose a novel method based on the non-contact test strain at a low internal pressure. The three-dimensional digital image correlation technique is introduced to measure the surface strain of the balloon. Representative regions of the balloon are selected as the test regions. A correction factor is proposed that accounts for the relationship between the internal pressure and the surface strain for the actual and the ideal balloon. By combining the maximum surface strain at a given internal pressure and the correction factor, we can predict the blasting pressure of the balloon. A blasting test is carried out to verify the feasibility of the predictive method. When the value of the ratio of the maximum test strain to the limiting strain reaches about a reference value, the absolute value of the deviation percentage between the predicted blasting pressure and the actual blasting pressure is less than 10%. The blasting pressure for balloon can be predicted accurately. This method does not require the balloon to be inflated to a high internal pressure, which improves the practicality of the prediction.

Ways to Improve Quality Control of Culture Medium Used for Mycoplasma Detection

An urgent safety concern associated with biological products is contamination with mycoplasmas, which may originate from donor tissues and organs, virus harvests, culture medium components, trypsin, animal blood serum, as well as be transmitted by personnel involved in the manufacture of medicines. Currently, due to an increase in the range of biologicals available, there is a need for more sensitive and specific test methods. In the Russian practice, microbiological (culture-based) testing of finished pharmaceutical products for mycoplasma contamination is performed using complex culture media whose sensitivity depends on the quality of proteins, ingredients, and reagents used. Growth promotion properties of the media are determined according to the State Pharmacopoeia of the Russian Federation, 14th ed., using a single test strain — Mycoplasma arginini G230 (M. arginini G230 industry reference material). The aim of the study was to analyse current Russian and foreign requirements for the quality control of culture media that are used for mycoplasma detection, in order to update and improve the quality control procedure in Russia. It was demonstrated that a compelling advantage of the State Pharmacopoeia of the Russian Federation is the possibility of using a semi-liquid culture medium which does not require special aerobic or anaerobic incubation conditions and allows for quantification of mycoplasma colonies and determination of mycoplasma titre in culture medium while testing its growth promotion properties using reference М. arginini G230 test strain. The analysis revealed some differences in Russian and foreign requirements for quality evaluation of culture media. These differences were taken into account when developing recommendations for improvement of the Russian test procedure, i.e. enlarging the range of test strains used and development of respective reference standards.