Antimicrobial Preparations Research Articles

Sensitivity to antibacterial preparations Campylobacter jejuni isolated from poultry products

Along with salmonellosis and Escherichiosis, intestinal campylobacteriosis caused by thermophilic campylobacter, primarily Campylobacter jejuni, is widespread. When studying the biological properties of isolated pathogens, great importance is attached to determining their sensitivity to antibacterial preparations and identifying preparation resistance. Livestock products, including poultry, are one of the most common sources of pathogenic campylobacter. Since antibiotics are often used in the process of growing and obtaining poultry meat, the acquired resistance of the campylobacter bacteria that colonize poultry products to the drugs used in veterinary medicine is likely. The spread of antibiotic-resistant strains in future can lead to decrease of the therapeutic effect in the treatment of severe forms of campylobacteriosis. In this article we present the results of determining the antibiotic resistance of C. jejuni cultures isolated from group samples of poultry products purchased in St. Petersburg in comparison with the antibiotic resistance of C. jejuni cultures isolated from group samples of chickens of the control groups, hatched without use of any antimicrobial preparations. Based on the results of our studies, we found that C. jejuni cultures isolated from group samples of poultry products purchased in St. Petersburg retail network have broad antibiotic resistance and are resistant to the effects of amoxicillin, ampicillin, carbenicillin, erythromycin, azithromycin, cephalothin, gentamycin, kanamycin, tetracycline, doxycycline, lincomycin, ciprofloxacin and co-trimoxazole, but are sensitive to the action of nalidixic acid, imipenem, meropenem, chloramphenicol and furazolidone. Cultures of C. jejuni isolated from group samples of poultry products purchased in St. Petersburg retail network have a broader antibiotic resistance to antimicrobial drugs of various pharmacological groups compared to cultures of C. jejuni isolated from group samples of chickens from the control group. Broader antibiotic resistance of C. jejuni cultures isolated from group samples of poultry products purchased in St. Petersburg retail network is most likely associated with the use of various antimicrobial drugs when growing poultry in industrial poultry farming.

The Silkworm as a Source of Natural Antimicrobial Preparations: Efficacy on Various Bacterial Strains.

The global spread of multi-resistant pathogens responsible for infections, which cannot be treated with existing drugs such as antibiotics, is of particular concern. Antibiotics are becoming increasingly ineffective and drug resistance is leading to more difficult-to-treat infections; therefore, new bioactive compounds with antimicrobial activity are needed and new alternative sources should be found. Antimicrobial peptides (AMPs) are synthesized by processes typical of the innate immune system and are present in almost all organisms. Insects are extremely resistant to bacterial infections as they can produce a wide range of AMPs, providing an effective first line of defense. The AMPs produced by insects therefore represent a possible source of natural antimicrobial molecules. In this paper, the possibility of using plasma preparations from silkworm (Bombyx mori) larvae as a source of antimicrobials was evaluated. After simple purification steps, insect plasma was analyzed and tested on different Gram-positive and Gram-negative bacterial strains. The results obtained are encouraging as the assays on Escherichia coli and Enterobacter cloacae showed significant decrease in the growth of these Gram-negative bacteria. Similar results were obtained on Gram-positive bacteria, such as Micrococcus luteus and Bacillus subtilis, which showed strong susceptibility to the silkworm AMPs pool. In contrast, Staphylococcus aureus displayed high resistance to Bombyx mori plasma. Finally, the tested plasma formulations were assessed for possible storage not only at 4 °C, but also above room temperature. In conclusion, partially purified plasma from silkworm could be a promising source of AMPs which could be used in formulations for topical applications, without additional and expensive purification steps.

135 YEARS OF HISTORY AND MODERNITY OF THE STATE INSTITUTION «I. I. MECHNIKOV INSTITUTE OF MICROBIOLOGY AND IMMUNOLOGY OF THE NATIONAL ACADEMY OF MEDICAL SCIENCES OF UKRAINE»

The article is devoted to the results of a retrospective study of the historical path of formation and development of scientific research in State Institution «I. I. Mechnikov Institute of Microbiology and Immunology of the NAMS of Ukraine». The Institute as a scientific institution of anti-epidemic profile was founded in May 1886. At the beginning of the last century, the Institute turned into a major scientific and practical center of pre-revolutionary Russia for the fight against infectious diseases. Already in 1913-1914 the Institute produced 6 types of sera and 7 vaccines. In 1920 the Institute was nationalized, became a state institution and received the name of the Bacteriological Institute, and in 1922 – the First Ukrainian Sanitary-Bacteriological Institute. The Institute was the first in the Soviet Union to begin the production of BCG and became one of the pioneers of the introduction of bacteriophage in the treatment and prevention of intestinal infections: dysentery, typhoid fever, cholera. From 1921 to 1940, the Institute produced more than 40 names of various drugs in an amount exceeding the previous 20 years by more than thirty times. In addition, the Institute currently produces the following serum: diphtheria, scarlet fever, dysentery, meningococcal, pneumococcal, streptococcal, staphylococcal, tetanus, botulinum and 4 gangrenous sera. Since the beginning of the war, the Institute has been evacuated first to Stalingrad and then to Chkalov. During the evacuation, the Institute continues to produce bacteriological preparations. From 1941 to 1945 the release of vaccines and serums amounted to 400% of the pre-war level, only in 1942 110 thousand wounded soldiers received serum against gas gangrene, more than 120 thousand soldiers received tetanus serum. After re-evacuation to Kharkiv, the Institute continued to work on the production of vaccines and serums and, starting in 1944, began the production of smallpox detritus, measles serum and typhus vaccine. At that time, in the laboratory of V. S. Derkach, the antibiotic pyocyanin (or sanazine) was studied and a method for its biosynthesis was developed, and together with the Academy of Sciences of the Ukrainian SSR, its new homologues were synthesized. Also in the laboratory after the war, neocide a drug against cancer was created. The problems of epidemiology at the Institute were developed by the outstanding microbiologist V. M. Zhdanov. From 1946 to 1950 V. M. Zhdanov headed the virological laboratory, and since 1948 – the Kharkov Institute of Microbiology and Epidemiology named I. I. Mechnikov. In 1950, a laboratory for the production of anti-influenza drugs was organized, and a year later, the study and improvement of dry polytype therapeutic and prophylactic anti-influenza serum began. The collection of mycobacterial phages, collected by Professor L. A. Kosobutsky, Doctor of Medical Sciences, was one of the three largest in the world. At the Institute, on the basis of fish oil, the drug «ektericide» was developed. V. L. Nadtoka became the founder of a new scientific direction for the development and use of antimicrobial preparations of plant origin. Under the leadership of V. L. Nadtoka developed dosage forms of the drug chlorophyllipt, which are introduced into production and clinical practice in Ukraine. Now the Institute is a methodological center for the development of theoretical provisions and practical use of laboratory diagnostic methods, anti-epidemic measures, treatment and prevention of infectious diseases, advanced training of bacteriologists, virologists, epidemiologists and other specialists. Currently, on the basis of the Institute, there are a number of divisions of industry-wide importance that coordinate scientific and methodological work in important areas of infection control: the Center for Specific Indication of Biological Pathogenic Agents, the Republican Reference Laboratory of Pathogens of Anaerobic Infections, the Laboratory of New and Little-Studied Infectious Diseases. In general, the staff of the Institute over the years of its existence has developed and introduced into production about 60 different vaccines, sera and other therapeutic and diagnostic immunobiological preparations. The Institute has developed drugs against 21 infections. In addition to immunobiological drugs, the Institute has developed and introduced a number of antimicrobial drugs, among which the most famous are chlorophyllipt, decamethoxin, ektericide, eucavan and others. Keywords: history of science, I.Mechnikov Institute of Microbiology and Immunology, bacteriological preparations, vaccines, serums, bacteriophages, antimicrobial agents, chlorophylipt

Pharmaceutical Approaches on Antimicrobial Resistance: Prospects and Challenges.

The rapid increase in pathogenic microorganisms with antimicrobial resistant profiles has become a significant public health problem globally. The management of this issue using conventional antimicrobial preparations frequently results in an increase in pathogen resistance and a shortage of effective antimicrobials for future use against the same pathogens. In this review, we discuss the emergence of AMR and argue for the importance of addressing this issue by discovering novel synthetic or naturally occurring antibacterial compounds and providing insights into the application of various drug delivery approaches, delivered through numerous routes, in comparison with conventional delivery systems. In addition, we discuss the effectiveness of these delivery systems in different types of infectious diseases associated with antimicrobial resistance. Finally, future considerations in the development of highly effective antimicrobial delivery systems to combat antimicrobial resistance are presented.

Study of the efficiency of the inhibitory effect of antimicrobial preparations in the production of sugar substances

This article presents the relevance of the issue of inhibition of microbiological processes at different stages of processing of sugar-containing raw materials, in particular ensuring the microbiological purity of juices and syrups in the production of sugar substances. Information on the composition of microbiota contaminating raw materials in the production of beet sugar, raw cane sugar, food syrups from sugar sorghum is analyzed.
 Experimental data on the evaluation of the effectiveness of a number of antimicrobial preparations in terms of growth retardation of pure cultures of microorganisms and the effect of disinfection during the introduction of preparations are presented.
 The greatest danger in production is caused by the development of spore-forming and mucus-forming bacteria, which led to the choice of research objects.
 Thus, the effect of antimicrobial preparations on microorganisms: mesophilic bacteria Bacillus subtilis, B. megatherium, thermophilic bacteria B. stearothermophilus, mucus-forming bacteria of the genus Leuconostos, was investigated. In addition, the effect of antimicrobials on mycelial fungi of the genus Aspergillus was studied.
 Based on the conducted experimental studies, the range of costs of the studied antimicrobial preparation for the suppression of contaminating microflora in the production of sugar and food syrups from vegetable raw materials was determined

Application of antibiotics in agriculture and alternatives of their use

The use of antibiotics in medicine, plant growing and animal husbandry has led to the spread of bacterial resistance to antimicrobial drugs. Tetracyclines are a chemical group of great importance due to the widespread use of these preparations in agriculture. Due to the fact that significant quantities of tetracycline antimicrobial drugs are used all over the world, their monitoring plays an important role. Therefore, progress needs to be made in antibiotic analysis to assess the correct use and dosage of tetracyclines in food and feed, as well as possible residues in relevant environmental samples. The review presents an analysis of the data of modern studies aimed at studying the problem of antibiotic resistance caused by antimicrobial preparations of the tetracyclines group in world agricultural practice. Data on existing and potential alternatives to antibiotics in animal husbandry are presented.

Antimicrobial resistance. Characteristic of resistance to antimicrobial preparations of Gram-negative bacteria

The scope is the literature review on the resistance of Gramnegative bacteria to antimicrobial preparations is presented. 131 different materials were analyzed, including WHO documents and scientifi c publications. Bacterial resistance remains a significant threat and a leading cause of death worldwide. Resistant bacteria proliferate by natural selection when drug-sensitive ones are removed by antibiotics. These organisms can be spread to all health care facilities as well in community, which requires increased attention to infection control measures and the administration of β-lactamcontaining medicines in an effort to control the selection of other even more harmful pathogens. Several strategies for combating and controlling Gram-negative resistant bacteria have been reported, such as the development of antimicrobial auxiliaries, structural modifi cation of existing antibiotics, research and study of chemical structures with new mechanisms of action. In addition to new therapy, an effective infection control system, along with the prudent use of antimicrobials, is extremely important.

In vitro antibacterial activity of Loxostylis alata extracts and isolated compounds against Salmonella species

BackgroundOwing to antibiotic resistance, alternative antimicrobials from medicinal plants are receiving attention as leads for anti-infective agents. This study aimed to investigate selected tree species and their constituents for activity against bacterial foodborne pathogens, particularly Salmonella serovars.MethodsAntibacterial activity of ten plant species was determined by serial microdilution against bacteria implicated in causing gastrointestinal ailments. Active compounds were isolated from Loxostylis alata using bioassay-guided fractionation. Antioxidant activity was determined using free-radical scavenging assays. Cytotoxicity and genotoxicity of the extracts was ascertained on Vero cells, and using the Ames assay respectively.ResultsExtracts had low to moderate MIC values from 0.04 to 2.5 mg/mL. Protorhus longifolia and Loxostylis alata were most active and L. alata had the highest selectivity index value (2.51) against Salmonella Typhimurium, as well as high antioxidant activity. Cytotoxicity values ranged from 0.02 to 0.47 mg/mL, while tested extracts were not genotoxic. Bioactive compounds isolated from L. alata included delicaflavone and a polymethoxyflavone.ConclusionsThe Loxostylis alata leaf extract had strong activity against Salmonella serovars but isolated compounds were less active, indicating likely synergistic effects. Extracts of L. alata are promising candidates for development of antimicrobial preparations or food additives against microbial contamination.

The problem of resistance of microorganisms ‒ challenge to humanity

One of the XXI century public health urgent problems is the antibiotic therapy effectiveness decrease as a result of microorganisms resistant strains emergence and spread.
 The aim of review is the antibiotic resistance causes and medicines effects on the formation of microorganisms resistance to antibiotics modern data analysis.
 Сontent analysis, bibliosemantic, scientometric and systemic methods was used in the work.
 Our analysis showed that at present the question of the non-antimicrobial medicines role in the antibiotic resistance formation remains open. Medicines of different pharmacotherapeutic groups are able to demonstrate antimicrobial activity, realizing both by microorganisms inhibition and their growth stimulation. The problem of such medicines influence on the antibiotics specific activity needs additional investigation in order to possible antagonistic effects identification. Special attention deserves the question of non-antimicrobial medicines subinhibitory concentrations accumulation in the environment in view of their ability to stimulate biofilms formation.
 Antibiotic resistance is a global problem; in order to its spread repression and antimicrobial therapy effectiveness preservation, it is necessary to establish all its possible causes and contributing factors. Non-antimicrobial medicines role in the resistance formation detection is one of the ways to control these processes. Such complex measures allow preserving the existing antimicrobial preparations effectiveness for the future generations.

Studying the preservation of Brussels sprout depending on its treatment with antimicrobial preparations before storage

The effect of antimicrobial preparations on the intensity of losses in the quality of Brussels sprout heads during storage has been scientifically substantiated. Brussels sprout heads were treated with antimicrobial solutions before storage. The following solutions were used: 0.05 % sorbic acid, 0.2 % benzoic, 0.5 % citric acid, Baikal EM-1, 0.5 % solution of ascorutin. The heads were stored in boxes lined with a 40 µm thick polyethylene film.Treatment with antimicrobial preparations increases the shelf life of Brussels sprout to 50 days without significant weight loss. A solution of sorbic acid significantly reduces the natural mass loss by Brussels sprout after 10 days of storage. The effect of other preparations is observed only on day 30 of storage. Standard product output is 85.2–86.9 % depending on the features of the hybrid.Antimicrobial preparations contribute to the preservation of chemical components in Brussels sprout heads. At the end of storage, the content of dry matter, dry soluble substances, total sugar, and ascorbic acid is 5‒8 % higher than that in the control variant. A greater content of some components of the chemical composition is observed in produce treated with solutions of sorbic and benzoic acids before storage.Solutions of sorbic and benzoic acids effectively hinder the development of harmful microorganisms on the heads of Brussels sprout.The result of this study has established that a 0.05 % solution of sorbic acid and a 0.2 % solution of benzoic acid are more effective at contributing to the preservation of quality by Brussels sprout heads. Sorbic and benzoic acids do not affect the organoleptic properties of products and are safe for humans. This makes it possible to recommend to use their solutions as an effective and safe measure to preserve the quality of vegetable produce over its long-term storage

1597. Ceftolozane-Tazobactam and Meropenem Synergy Testing Against Multi-Drug and Extensively-Drug Resistant Pseudomonas aeruginosa

BackgroundMultidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa (PA) have limited therapeutic options for treatment. Ceftolozane/tazobactam is a newer anti-pseudomonal drug effective against resistant PA infections, however resistance against this drug has now also developed and is increasing. In this study, we explored the combination of ceftolozane/tazobactam (CT) and meropenem (MP) as a possible effective regimen against MDR and XDR PA.MethodsWe obtained 33 non-duplicate isolates of MDR and XDR PA grown from blood, urine and respiratory samples collected from patients admitted between 2015 and 2019 at our two affiliate teaching hospitals. MDR PA was defined as resistance to 3 or more classes of anti-pseudomonal antibiotics, and XDR PA as resistance to all but two or less classes of anti-pseudomonal antibiotics. Antimicrobial preparations of both MP and CT were made according to manufacturer instructions. Susceptibility testing was performed using the checkerboard method in accordance to CLSI guidelines (CLSI M100, 2017). The ATCC 27853 strain of PA used as control. Synergy, additive effect, indifference and antagonism were defined as FIC (fractional inhibitory concentration) indices of ≤0.5, >0.5 to <1, >1 to <4, and >4, respectively.ResultsThirteen (39%) of 33 PA isolates were classified as XDR, while 20 (61%) PA isolates were MDR. All isolates were resistant to MP (MIC50 >32 ug/mL), while only 2 (6%) isolates were susceptible to CT (MIC50 64 ug/mL). A synergistic effect was seen in 9 (27.3%) of PA isolates (FIC index range 0.28 to 0.5)— 2 of which were XDR PA, and 7 were MDR PA. An additive effect was seen in 12 (36.4%), with indifference seen in 12 (36.4%) of isolates. In this study, no antagonism was seen when CT and MP were combined.ConclusionWhen used in combination, CT and MP can exert a synergistic effect against MDR and XDR PA. Additive effect and indifference can also be seen when both antibiotics were used. Moreover, there was no antagonism seen when both antibiotics were combined. This study shows that the use of CT and MP in combination may be an option against XDR and MDR PA infections.Disclosures All Authors: No reported disclosures

Antimicrobial consumption: Comparison of three different data collection methods

The increasing incidence of antimicrobial resistance represents a global threat. As a result, surveillance programmes monitoring antimicrobial consumption and resistance in animals have been implemented in several countries throughout the world. However, such programmes depend on the accurate and detailed collection of data on antimicrobial consumption. For this reason, the aim of this longitudinal study was to compare the consistency of data on antimicrobial consumption between three different data collection methods.Antimicrobial consumption data associated to udder health were collected from 20 veterinary practices and 92 dairy farms for 18 months. The compared data sources were: 1) data extracted from veterinary practice software 2) farm treatment journals and 3) on-farm discarded drug packages (garbage). Two different procedures were chosen to analyse the data issued from treatment journals: 1) only complete entries were analysed 2) entries with missing dosage were supplemented with the information provided by the Swiss Compendium of Veterinary Medicinal Products. The antimicrobial data were divided into intramammary preparations used during lactation (IMM), intramammary preparations used for dry off (DRY) and systemic treatments (SYS). We compared the quantities of injectors (IMM and DRY), the quantities of active substances (SYS) and the treatment incidences (TI) for the defined daily dose (DDD) per 1000 cow-days (IMM and SYS) and the defined course dose (DCD) per 1000 cow-days (DRY). Additionally, the variety of antimicrobial products among the different data sources was compared.The highest quantity of antimicrobials for IMM, DRY and SYS could be collected with the software data. The lowest quantity was collected by using the data of the treatment journal with only complete entries. For IMM and DRY, software and garbage performed similar, with agreement on the number of injectors used in 56.1% of the analysed cases. The widest variety of intramammary antimicrobial preparations was found in the garbage whilst most systemic preparations were collected using software data. The results of the study show a lack of data consistency between the three different data sources. None of the methods was able to collect the integral antimicrobial consumption in the participating farms. Finally, the results emphasise the need to implement a standardised system to quantify and assess the antimicrobial consumption at veterinary practice and farm level.

Overcoming Antibiotic Resistance in Microorganisms: Molecular Mechanisms.

This issue of the Biochemistry (Moscow) journal presents reviews and experimental articles on the new strategies for solving the problem of antibiotic resistance and on the search for novel antimicrobial preparations using the methods of molecular biology, genetics, and nanotechnology. A wide variety of scientific approaches and successful (as a rule) research results give hope for overcoming microbial antibiotic resistance in the fight against infectious diseases.

Synthesis and antimicrobial properties of CaCO3-nAg and nAg-CaCO3 nanocomposites

The nanocomposites of nAg-CaCO3 and CaCO3-nAg with different mass content of silver nanoparticles were obtained in a two-stage continuous microwave process. The nanocomposites were characterized by XRD, TEM, UV–vis, and FTIR spectroscopy. The effects of microwave radiation, silver nanoparticles content in the composite and the molar ratio of tannic acid to silver on the size of salt crystallites were studied. The effectiveness of combining silver nanoparticles with CaCO3 was confirmed to exceed 99%. Depending on the input parameters applied, the size of salt crystals in nAg/CaCO3 nanocomposites ranged from 25 to 45 nm, while the size of salt crystals in CaCO3/nAg nanocomposites ranged from 26 to 41 nm. In addition, some of the compositions were tested for their antimicrobial activity on selected yeast and bacterial microorganisms. The prepared materials present a biocidal effect, which makes them suitable for use in antimicrobial preparations.

Prospects for the application of lignin containing sorbents in veterinary medicine

Vaccines against colibacillosis are mainly used, containing only one specific variant of pathogenic E. coli with a preventive purpose among the livestock of stationary dysfunctional farms in conditions of Krasnoyarsk region. For therapeutic purposes, veterinarians usually use wide range of antimicrobial preparations to combat outbreaks of gastrointestinal infections. Many researchers point to the high variability of E. coli bacteria. Use of such preparations, in addition to the formation of high resistance in opportunistic microorganisms to the latter, provoke the accumulation of antibacterial drugs in animal products. Authors conducted studies of the possibility of the practical use of lignin-containing sorbents for therapeutic and prophylactic purposes in field of veterinary medicine in the period from 2001 to 2020. Authors proposed to use the residues after extraction, formed during the complex processing of larch bark, as an enterosorbent. Authors studied the therapeutic and prophylactic effect of enterosorbent from larch bark in case of gastrointestinal infections in experiments in vivo. It was found that the use of the sorbent for therapeutic purposes for 2 days ensured the safety of laboratory animals in the acute form of colibacillosis infection. Preservation was ensured by preventing the penetration of microbial toxins into the tissues of the gastrointestinal tract. The prophylactic and therapeutic efficacy of the investigated type of enterosorbent is associated with angioprotective, antitoxic effects due to the high sorption capacity of the drugs.

Efficiency of combined action of antimicrobial preparations against poly-resistant strains of conditionally-pathogenic bacteria isolated from wounds of surgery patients

The strategy of use of combination therapy of antibacterial preparations is being broadly introduced to clinical practice to fight bacterial infections caused by poly-resistant strains of microorganisms. From the wounds of surgery patients, we isolated 67 clinical strains of conditionally-pathogenic bacteria identified as Staphylococcus aureus, S. epidermidis, Escherichia coli, Klebsiella pneumoniaе, Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa. Using disk diffusion method, the isolated bacterial strains were found to be most resistant to penicillin preparations: ampicillin, oxacillin, amoxicillin/clavulanat; tetracycline and cephalosporin of the II generation – cefoxitin. The percentage of strains insusceptible to these antibacterial preparations accounted for 65.0%. The division of antibiotic-resistant cultures regarding phenotype groups according to the level of their antibiotic resistance allowed determination of 4 PDR-, 8 XDR- and 14 MDR-strains. During the studies on experimental determining of MIC of antibiotic and antiseptics in the condition of applying them as monopreparations against isolated bacterial cultures, we saw significant exceess in the threshold values of MIC, and, first of all, regarding pandrug-resistant and extensive drug-resistant clinical microbial isolates. Use of combinations of antibacterial preparations was found to show the synergic effect of antibiotics (ceftriaxone, ofloxacin, gentamicin) and antiseptics (chlorhexidine, decasan), which is expressed in simultaneous decrease in MIC of each of the tested preparations by 2–8 times compared with their isolative application. Such combinatory approach regarding simultaneous application of antibacterial preparations may be considered as one of the most promising ways to combat poly-resistant clinical isolates of conditionally-pathogenic microorganisms and to offer a new strategic approach to prevention of spread of antibiotic resistance as a phenomenon in medical practice.

Application of artificial neural networks to prediction of new substances with antimicrobial activity against Escherichia coli.

This article presents models of artificial neural networks (ANN) employed to predict the biological activity of chemical compounds based of their structure. Regression and classification models were designed to determine antimicrobial properties of quaternary ammonium salts against Escherichia coli strain. The minimum inhibitory concentration microbial growth E. coli was experimentally determined by the serial dilution method for a series of 140 imidazole derivatives. Then, three-dimensional models for imidazole chlorides were constructed with computational chemistry methods which allowed to calculate molecular descriptors. The transformation of chemical information into a useful number is a main result of this operation. The designed regression and classification ANN models were characterized by a high predictive ability (classification accuracy was 95%, regression model: learning set R=0.87, testing set R=0.91, validation set R=0.89). Artificial neural networks can be successfully used to find potential antimicrobial preparations. The neural networks are a very elaborate modelling technique, which allows not only to optimize and minimize labour costs but also to increase food safety.

Species composition and methicillin resistance of staphylococci taken on dairy farms

Methicillin-resistant staphylococci can often asymptomatically colonize animals and humans and are capable of causing disease in them. Therefore, their identification and species identification are important for establishing the source of zoonotic infection and the reservoirs of antimicrobial resistance genes. The purpose of the search was to study the spread of methicillin-resistant staphylococci on dairy farms in the Western region of Ukraine. BD Baird-Parker Agar (HiMedia, India) was used to isolate staphylococci. Specific identification of pure cultures was performed using “RapID Staph Plus” kits (Oxord, UK). Staphylococcus sensitivity to methicillin was determined by inoculum application on Muller-Hinton agar with oxacillin (HiMedia, India). The sensitivity of the isolates to antibacterial preparations was determined by disco-diffusion method. The results of our searches show that Staphylococcus aureus is virtually identical in the amount both from cows (50.1 %) and from humans (62.4 %). In this case the frequency of its isolation among other species was 20.3 %. Along with Staphylococcus aureus there are such species as: S. haemolyticus (20.3 %), S. saprophyticus (13.6 %), S. xylosus (14.0 %), S. chromogenes (11.1 %), S. sciuri (8.8 %), S. epidermidis (4.8 %), S. hominis (3.4 %), S. cohnii (2.6 %) and S. warner (0.7 %). In this case, approximately the same irradiation of cows, humans and the environment by species S. haemolyticus (44.5:70.8:58.8 %), S. epidermidis (12.7:16.6:9.1 %), S. xylosus (26.0:37.4:52.9 %) is observed. The share of S. aureus strains on methicillin-resistant dairy farms in the Western Ukraine is 26.8 %. The proportion of S. aureus strains on methicillin-resistant dairy farms in the Western Ukraine is 26.8 %. Methicillin resistance is also shown S. haemolyticus, S. saprophyticus, S. xylosus та S. chromogenes. In this case their number is 1.1, 1.3, 1.6 and 5.5 times lower, respectively, and S. hominis 1.2 times higher than S. aureus. In addition, the selected cultures simultaneously show resistance to two or more antibiotics. Thus, staphylococci circulating on dairy farms are a large reservoir of resistance genes of antimicrobial preparations. Therefore, it is necessary to establish a constant control of the secretion of staphylococci resistant to β-lactam antibiotics.

Simultaneous and sequential influence of metabolite complexes of Lactobacillus rhamnosus and Saccharomyces boulardii and antibiotics against poly-resistant Gram-negative bacteria

For the first time the poly-resistant strains of Gram-negative microorganisms were studied for the sensitivity to combined simultaneous and sequential influence of metabolic complexes of Lactobacillus rhamnosus GG and Saccharomyces boulardii, obtained by the author’s method without using the growth media, with antibiotics. The synergic activity of antibacterial preparations and metabolic complexes of L. rhamnosus GG and S. boulardii were studied using modified disk-diffusive method of Kirby-Bauer. During the sequential method of testing (at first the microorganisms were incubated with structural components and metabolites, then their sensitivity to the antibacterial preparations was determined), we observed increase in the diameters of the zones of growth inhibition of Pseudomonas aeruginosa PR to the typical antibiotics (gentamicin, amіcyl, ciprofloxacin, сefotaxime) and non-typical (lincomycin, levomycetin) depending on the tested combinations. Acinetobacter baumannii PR exhibited lower susceptibility: growth inhibition was seen for the combination with ciprofloxacin, сefotaxime, levomycetin. Susceptibility of Lelliottia amnigena (Enterobacter amnigenus) PR increased to levofloxacin, lincomycin. The zones of growth inhibition of Klebsiella pneumoniae PR increased to gentamicin, amіcyl, tetracycline, сeftriaxone. Maximum efficiency was determined during sequential combination of antibiotics with separate metabolic complexes of L. rhamnosus and S. boulardii, and also their combination (to 15.2, 20.2 and 15.4 mm respectively) compared with their simultaneous use (to 12.2, 15.2 and 13.0 mm respectively) for all the tested poly-resistant pathogens, regardless of the mechanism of action of antibacterial preparation. Metabolic complexes of L. rhamnosus GG and S. boulardii, due to increase in the susceptibility of microorganisms, can decrease the therapeutic concentration of antibiotic, slow the probability of the development of resistance of microorganisms, and are therefore promising candidates for developing “accompanying medications” to antibiotics and antimicrobial preparations of new generation.

Thymol and carvacrol in nanoliposomes: Characterization and a comparison with free counterparts against planktonic and glass-adhered Salmonella

Nanoliposome-encapsulated and free thymol, carvacrol, and thymol/carvacrol (1:1) were assessed as antimicrobials against a Salmonella pool. Liposome-encapsulated thymol (TL), carvacrol (CL) and thymol/carvacrol (TCL) presented 230–270 nm diameter, satisfactory polydispersity (0.24–0.31), zeta potential of approximately −30 mV and high encapsulation efficiencies (~99%), remaining stable during 28 days at 4 °C. Minimum inhibitory concentrations (MIC) of free antimicrobials were 331 μg/mL. Encapsulation increased MIC to 663 (TL, CL) and 1325 μg/mL (TCL). Time-kill curves with antimicrobial preparations (265.0 μg/mL) demonstrated superior activities for free antimicrobials; among nanoliposomes, TCL exhibited higher activity. At MIC, antimicrobials impeded bacterial adhesion to glass. Without antimicrobials, Salmonella (~8 log Colony Forming Units (CFU)/mL) adhered to glass reaching 5.89 log CFU/cm2 after 15 min. Inactivation of glass-attached Salmonella was complete following 1-min treatments with free (MIC, 2 × MIC) or encapsulated (2 × MIC) antimicrobials. At MIC, antimicrobial-loaded nanoliposomes decreased adhered populations by ~3.9 log CFU/cm2; at 0.5 × MIC, reductions of 1.93 (CL) and 1.58 log CFU/cm2 (TCL) were observed. Free antimicrobials were more effective against planktonic and sessile Salmonella at contact times employed in food processing environments. Nanoliposome-encapsulated natural antimicrobials warrant investigations on surface disinfection schemes and incorporation into foods.