Bacteriostatic Effect Research Articles

Exploring Propolis as a Sustainable Bio-Preservative Agent to Control Foodborne Pathogens in Vacuum-Packed Cooked Ham.

The search for natural food additives makes propolis an exciting alternative due to its known antimicrobial activity. This work aims to investigate propolis' behavior as a nitrite substitute ingredient in cooked ham (a ready-to-eat product) when confronted with pathogenic microorganisms of food interest. The microbial evolution of Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Clostridium sporogenes inoculated at known doses was examined in different batches of cooked ham. The design of a challenge test according to their shelf life (45 days), pH values, and water activity allowed the determination of the mesophilic aerobic flora, psychotropic, and acid lactic bacteria viability. The test was completed with an organoleptic analysis of the samples, considering possible alterations in color and texture. The cooked ham formulation containing propolis instead of nitrites limited the potential growth (δ < 0.5 log10) of all the inoculated microorganisms until day 45, except for L. monocytogenes, which in turn exhibited a bacteriostatic effect between day 7 and 30 of the storage time. The sensory analysis revealed the consumer's acceptance of cooked ham batches including propolis as a natural additive. These findings suggest the functionality of propolis as a promising alternative to artificial preservatives for ensuring food safety and reducing the proliferation risk of foodborne pathogens in ready-to-eat products.

Preparation of protein-stabilized Litsea cubeba essential oil nano-emulsion by ultrasonication: Bioactivity, stability, in vitro digestion, and safety evaluation

Litsea cubeba essential oil (LCEO) has garnered widespread attention due to its robust biological activity. However, challenges such as high volatility, limited water solubility, and low bioavailability impede its application. Nano-emulsion encapsulation technology offers an effective solution to these issues. In this study, we prepared litsea cubeba essential oil nano-emulsion (LCEO-NE) for the first time using whey protein (WP) as the emulsifier through an ultrasonic-assisted method, achieving high efficiency with minimal energy consumption. Transmission electron microscopy and dynamic light scattering analyses revealed that the nanoparticles were uniformly spherical, with a particle size of 183.5 ± 1.19 nm and a zeta potential of −35.5 ± 0.95 mV. Stability studies revealed that LCEO-NE exhibited excellent thermal and salt stability, maintaining its integrity for up to four weeks when stored at 4 °C and 25 °C. In vitro digestion assays confirmed the digestibility of LCEO-NE. Furthermore, evaluation of the DPPH, ABTS, and antimicrobial activities revealed that LCEO-NE displayed superior bacteriostatic and antioxidant properties compared to LCEO. Scanning electron microscopy elucidated that its bacteriostatic effect involved the disruption of bacterial microstructure. Hemocompatibility and cytotoxicity assays demonstrated the safety of LCEO-NE within the effective concentration range. This research supports the utilization of nanoparticles for encapsulating LCEO, thereby enhancing its stability and bioactivity, and consequently expanding its applications in the food and pharmaceutical industries.

Antibacterial and anti-biofilm activities of antibiotic-free phosphatidylglycerol/docosahexaenoic acid lamellar and non-lamellar liquid crystalline nanoparticles

Infectious diseases, particularly those associated with biofilms, are challenging to treat due to an increased tolerance to commonly used antibiotics. This underscores the urgent need for innovative antimicrobial strategies. Here, we present an alternative simple-by-design approach focusing on the development of biocompatible and antibiotic-free nanocarriers from docosahexaenoic acid (DHA) that has the potential to combat microbial infections and phosphatidylglycerol (DOPG), which is attractive for use as a biocompatible prominent amphiphilic component of Gram-positive bacterial cell membranes. We assessed the anti-bacterial and anti-biofilm activities of these nanoformulations (hexosomes and vesicles) against S. aureus and S. epidermidis, which are the most common causes of infections on catheters and medical devices by different methods (including resazurin assay, time-kill assay, and confocal laser scanning microscopy on an in vitro catheter biofilm model). In a DHA-concentration-dependent manner, these nano-self-assemblies demonstrated strong anti-bacterial and anti-biofilm activities, particularly against S. aureus. A five-fold reduction of the planktonic and a four-fold reduction of biofilm populations of S. aureus were observed after treatment with hexosomes. The nanoparticles had a bacteriostatic effect against S. epidermidis planktonic cells but no anti-biofilm activity was detected. We discuss the findings in terms of nanoparticle-bacterial cell interactions, plausible alterations in the phospholipid membrane composition, and potential penetration of DHA into these membranes, leading to changes in their structural and biophysical properties. The implications for the future development of biocompatible nanocarriers for the delivery of DHA alone or in combination with other anti-bacterial agents are discussed, as novel treatment strategies of Gram-positive infections, including biofilm-associated infections.

Gut bacterium Burkholderia cepacia (BsNLG8) and immune gene Defensin A contribute to the resistance against Nicotine-induced stress in Nilaparvata lugens (Stål)

Nicotine, a naturally occurring alkaloid found in tobacco, is a potent neurotoxin extensively used to control Nilaparvata lugens (Stål), a destructive insect pest of rice crops. The insect gut harbors a wide array of resident microorganisms that profoundly influence several biological processes, including host immunity. Maintaining an optimal gut microbiota and immune homeostasis requires a complex network of reciprocal regulatory interactions. However, the underlying molecular mechanisms driving these symbiotic exchanges, particularly between specific gut microbe and immunity, remain largely unknown in insects. Our previous investigations identified and isolated a nicotine-degrading Burkholderia cepacia strain (BsNLG8) with antifungal properties. Building on those findings, we found that nicotine intake significantly increased the abundance of a symbiotic bacteria BsNLG8, induced a stronger bacteriostatic effect in hemolymph, and enhanced the nicotine tolerance of N. lugens. Additionally, nicotine-induced antimicrobial peptides (AMPs) exhibited significant antibacterial effects against Staphylococcus aureus. We adopted RNA-seq to explore the underlying immunological mechanisms in nicotine-stressed N. lugens. Bioinformatic analyses identified numerous differentially expressed immune genes, including recognition/immune activation (GRPs and Toll) and AMPs (i.e., Defensin, Lugensin, lysozyme). Temporal expression profiling (12, 24, and 48 hours) of immune genes revealed pattern recognition proteins and immune effectors as primary responders to nicotine-induced stress. Defensin A, a broad-spectrum immunomodulatory cationic peptide, exhibited significantly high expression. RNA interference-mediated silencing of Defensin A reduced the survival, enhanced nicotine sensitivity of N. lugens to nicotine, and decreased the abundance of BsNLG8. The reintroduction of BsNLG8 improved the expression of immune genes, aiding nicotine resistance of N. lugens. Our findings indicate a potential reciprocal immunomodulatory interaction between Defensin A and BsNLG8 under nicotine stress. Moreover, this study offers novel and valuable insights for future research into enhancing nicotine-based pest management programs and developing alternative biocontrol methods involving the implication of insect symbionts.

Rutin Attenuates Gentamycin-induced Hair Cell Injury in the Zebrafish Lateral Line via Suppressing STAT1.

Aminoglycoside antibiotics, including gentamicin (GM), induce delayed ototoxic effects such as hearing loss after prolonged use, which results from the death of hair cells. However, the mechanisms underlying the ototoxicity of aminoglycosides warrant further investigation, and there are currently no effective drugs in the clinical setting. Herein, the therapeutic effect of the flavonoid compound rutin against the ototoxic effects of GM in zebrafish hair cells was investigated. Animals incubated with rutin (100-400 µmol/L) were protected against the pernicious effects of GM (200 µmol/L). We found that rutin improves hearing behavior in zebrafish, and rutin was effective in reducing the number of Tunel-positive cells in the neuromasts of the zebrafish lateral line and promoting cell proliferation after exposure to GM. Subsequently, rutin exerted a protective effect against GM-induced cell death in HEI-OC1 cells and could limit the production of cytosolic reactive oxygen species (ROS) and diminish the percentage of apoptotic cells. Additionally, the results of the proteomic analysis revealed that rutin could effectively inhibit the expression of necroptosis and apoptosis related genes. Meanwhile, molecular docking analysis revealed a high linking activity between the molecular docking of rutin and STAT1 proteins. The protection of zebrafish hair cells or HEI-OC1 cells from GM-induced ototoxicity by rutin was attenuated by the introduction of STAT1 activator. Finally, we demonstrated that rutin significantly improves the bacteriostatic effect of GM by in vitro experiments, emphasising its clinical application value. In summary, these results collectively unravel a novel therapeutic role for rutin as an otoprotective drug against the adverse effects of GM.

Antimicrobial efficacy of Punica granatum Lythraceae peel extract against pathogens belonging to the ESKAPE group.

The improper use and abuse of antibiotics have led to an increase in multidrug-resistant (MDR) bacteria resulting in a failure of standard antibiotic therapies. To date, this phenomenon represents a leading public health threat of the 21st century which requires alternative strategies to fight infections such as the identification of new molecules active against MDR strains. In the last 20 years, natural extracts with biological activities attracted scientific interest. Following the One Health Approach, natural by-products represent a sustainable and promising alternative solution. Consistently, the aim of the present study was to evaluate the antimicrobial activity of hydro-alcoholic pomegranate peel extract (PPE) against MDR microorganisms belonging to Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. "ESKAPE" group pathogens. Through semiquantitative and quantitative methods, the PPE showed effective antimicrobial activity against Gram-positive and Gram-negative MDR bacteria. The kinetics of bactericidal action of PPE highlighted that microbial death was achieved in a time- and dose-dependent manner. High concentrations of PPE exhibited antioxidant activity, providing a protective effect on cellular systems and red blood cell membranes. Finally, we report, for the first time, a significant intracellular antibacterial property of PPE as highlighted by its bactericidal action against the staphylococcal reference strain and its bacteriostatic effect against clinical resistant strain in the HeLa cell line. In conclusion, due to its characterized content of polyphenolic compounds and antioxidant activity strength, the PPE could be considered as a therapeutic agent alone or in conjunction with standard antibiotics against challenging infections caused by ESKAPE pathogens.

Preparation of Hydrophilic Hyper-Cross-Linked Polystyrene Nanospheres with Antibacterial for Improved Water Lubrication Performance.

The present study utilizes styrene as a raw material to prepare hyper-cross-linked polystyrene nanospheres (HPSs) through the Friedel-Crafts reaction, establishing stable covalent bond structures within the polymer chains. The hydrophilic polystyrene nanospheres─TMA@SHPSs were successfully synthesized via sulfonation and ion exchange reactions, demonstrating exceptional properties in reducing friction and wear. Compared with pure water, the addition of 4.0 wt % TMA@SHPSs results in a 62.2% reduction in the friction coefficient, accompanied by a significant decrease to 1.17 × 105 μm3 in wear volume. The results demonstrate that TMA@SHPSs, as water-based lubrication additives, generate composite protective films (tribo-chemical protective films and physical protective films) during the friction process, which effectively prevents direct contact between the friction pairs and achieves remarkable antifriction and antiwear effects. The results of the antimicrobial activity test indicate that TMA@SHPSs demonstrate exceptional antibacterial efficacy due to the bacteriostatic effect induced by hydration and the bactericidal properties of quaternary ammonium cations.

Semi‐Interpenetrated Polymer Networks Based on PHEMA and Modified Chitosan as a Potential Bactericide Hydrogel for Wound‐Healing

AbstractA series of crosslinked hydrogel are developed to evaluate their applicability as efficient carriers for sustained release of ciprofloxacin (CFX) with bactericidal activity. The hydrogels are prepared from 2‐hydroxyethyl methacrylate (HEMA) and carboxymethyl‐chitosan (CMCS) using ethylene glycol dimethacrylate (EGDMA) as crosslinker to yield a semi‐interpenetrating polymer networks (semi‐IPNs) by a photoinitiated chemical method. Molecular weight and concentration of CMCS in the network are varied to optimize its properties as a wound dressing. PHEMA‐CMCS semi‐IPNs (HC‐IPNs) are characterized by their swelling ratio (Q), glass transition temperature (Tg), Young's moduli by mechanical compression submerged in water at different pHs at 37 °C, CFX delivery mimicking skin conditions, cell viability, biodegradability study and by their antibacterial activity. Results show that addition of CMCS results in pH sensitive behavior. HC‐IPNs show thermal reinforcement, and they are softer materials as compared to plain PHEMA hydrogels when submerged in water. The in vitro release of CFX suggests that the HC‐IPNs release the drug continuously up to 50 h. Unloaded HC‐IPNs show inhibition effects against Escherichia coli strain and show bacteriostatic effects against Staphylococcus aureus strain. Results suggest that HC‐IPNs probably be a potential candidate that can be applied as wound dressing for topical CFX controlled delivery.

COMPLEX RESEARCH HERB OF THE FRAGRANT VIOLET GROWING IN THE NORTH CAUCASUS AND WAYS OF ITS USE

Introduction. Fragrant violet (Viola odorata L., family Violaceae) is a perennial herbaceous plant, widespread in the North Caucasus and the European part of Russia. The aerial part of the plant contains various active biologically active substances, such as phenolic and triterpene glycosides, polysaccharides, phenolic compounds, coumarins and flavonoids, ascorbic acid, macro and microelements, which are responsible for its medicinal properties. In modern herbal medicine, fragrant violet is used as an anti-inflammatory, analgesic, antioxidant, diuretic, antihypertensive and antibacterial agent. However, further research is needed to confirm these medicinal properties. Objectives. Preparation of a dry extract from the herb violet fragrant and evaluation of its antibacterial activity against the clinical strain of Staphylococcus aureus III. Material and methods. The object of the study was a dry extract from the herb of fragrant violet, collected on the territory of three municipalities of the Stavropol Territory in the flowering phase of 2020-2022, obtained by exhaustive extraction with 70% ethyl alcohol. For microbiological studies, the serial dilution method was used. Meat-peptone broth (MPB) was used as a control, without adding a suspension of microorganisms to control the sterility of the environment and with the addition of microorganisms to control the growth of the microorganism, as well as a number of serial dilutions of the reference drug: “Ceftriaxone”. Results. It was established that the studied extract from fragrant violet has antibacterial properties, which is confirmed by the identified bacteriostatic effect (reduction in the number of colonies formed compared to the control) and a change in the cultural properties of the colonies relative to the control. Conclusions. The obtained screening results actualize further study of the extract from the herb violet fragrant in relation to representatives of opportunistic flora and the prospects of its use as an antimicrobial and anti-inflammatory agent of plant origin.

Klebsiella pneumoniae peptide hijacks a Streptococcus pneumoniae permease to subvert pneumococcal growth and colonization.

Treatment of pneumococcal infections is limited by antibiotic resistance and exacerbation of disease by bacterial lysis releasing pneumolysin toxin and other inflammatory factors. We identified a previously uncharacterized peptide in the Klebsiella pneumoniae secretome, which enters Streptococcus pneumoniae via its AmiA-AliA/AliB permease. Subsequent downregulation of genes for amino acid biosynthesis and peptide uptake was associated with reduction of pneumococcal growth in defined medium and human cerebrospinal fluid, irregular cell shape, decreased chain length and decreased genetic transformation. The bacteriostatic effect was specific to S. pneumoniae and Streptococcus pseudopneumoniae with no effect on Streptococcus mitis, Haemophilus influenzae, Staphylococcus aureus or K. pneumoniae. Peptide sequence and length were crucial to growth suppression. The peptide reduced pneumococcal adherence to primary human airway epithelial cell cultures and colonization of rat nasopharynx, without toxicity. We identified a peptide with potential as a therapeutic for pneumococcal diseases suppressing growth of multiple clinical isolates, including antibiotic resistant strains, while avoiding bacterial lysis and dysbiosis.

Targeting Intracellular Bacteria with Dual Drug-loaded Lactoferrin Nanoparticles.

Treatment of microbial infections is becoming daunting because of widespread antimicrobial resistance. The treatment challenge is further exacerbated by the fact that certain infectious bacteria invade and localize within host cells, protecting the bacteria from antimicrobial treatments and the host's immune response. To survive in the intracellular niche, such bacteria deploy surface receptors similar to host cell receptors to sequester iron, an essential nutrient for their virulence, from host iron-binding proteins, in particular lactoferrin and transferrin. In this context, we aimed to target lactoferrin receptors expressed by macrophages and bacteria; as such, we prepared and characterized lactoferrin nanoparticles (Lf-NPs) loaded with a dual drug combination of antimicrobial natural alkaloids, berberine or sanguinarine, with vancomycin or imipenem. We observed increased uptake of drug-loaded Lf-NPs by differentiated THP-1 cells with up to 90% proportion of fluorescent cells, which decreased to about 60% in the presence of free lactoferrin, demonstrating the targeting ability of Lf-NPs. The encapsulated antibiotic drug cocktail efficiently cleared intracellular Staphylococcus aureus (Newman strain) compared to the free drug combinations. However, the encapsulated drugs and the free drugs alike exhibited a bacteriostatic effect against the hard-to-treat Mycobacterium abscessus (smooth variant). In conclusion, the results of this study demonstrate the potential of lactoferrin nanoparticles for the targeted delivery of antibiotic drug cocktails for the treatment of intracellular bacteria.

Estimation of MBC: MIC Ratio of Herbal Extracts against Common Endodontic Pathogens

ABSTRACT Herbal extracts have evoked interest owing to the small number of terpenoids and phenolic compounds, which impart antimicrobial, antioxidant, and anti-inflammatory properties. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) of four herbal extracts (lemon grass oil, basil oil, peppermint oil, and Obicure tea extract) against endodontic pathogens along with the MIC: MBC/MFC ratio were evaluated. The antimicrobial activity by detecting the MIC of three essential oils and tea extract was evaluated against eight common endodontic pathogens by the broth dilution method, while MBC was detected by subculturing onto blood agar from the first –three to five tubes from the MIC dilution tubes (showing no turbidity), which were plated on blood agar. All herbal extracts proved to be effective antimicrobials against tested endodontic pathogens. Basil oil had a bacteriostatic effect on all the organisms (P &lt; 0.05). Mint oil showed bacteriostatic activity on Enterococcus (E.) faecalis and Peptostreptococcus (P &gt; 0.05). Tea extract had a bacteriostatic effect (P &gt; 0.05) against all tested microbes except Actinomyces, Lactobacilli, Staphylococcus (S.) aureus, and Fusobacterium (F.) nucleatum. Lemon grass oil had a bactericidal effect against all the organisms and a bacteriostatic effect against Peptostreptococcus (P &gt; 0.05). It can be concluded that basil oil showed a strong bactericidal effect on the test organisms. The MIC for the organisms ranged from 0.2 to 50 μg/ml.

Tailoring ZnO nanoparticles for biomedical applications: Surface functionalization of ZnO nanoparticles with 2-oxo-2H-chromene-3-carboxylic acid coupled beta-cyclodextrin for enhanced antimicrobial and anticancer effect

Nanomedicine has newly emerged as a superior alternative for the treatment of numerous life-threatening illnesses. Zinc oxide nanomaterials have attracted a lot of attention in this decade because of their enormous potential in a wide range of biomedical applications. This work describes the surface functionalization of zinc oxide nanoparticles (ZnO NPs) with 2-oxo-2H-chromene-3-carboxylic acid (3-CCA) coupled beta-cyclodextrin (β-CD) to create a biocompatible system (ZnO-β-CD-3-CCA) and the evaluation of its antimicrobial and anticancer properties. Different characterization techniques, such as X-ray powder diffraction, UV–Vis spectroscopy, FTIR, transmission, and scanning electron microscopy, were used to characterize the biocompatible system. The antimicrobial properties of the synthesized ZnO NPs and the surface functionalized ZnO-β-CD-3-CCA system were evaluated using the disc diffusion method. Modification with functionalized β-CD systems increased the bacteriostatic effect of ZnO nanoparticles against various microbes. In vitro cytotoxicity of ZnO NPs and surface functionalized ZnO-β-CD-3-CCA system was evaluated against two distinct cancer cell lines: MCF-7, Hep G2, and normal rat spleen cells employing MTT assay, and the results highlight that the selective cytotoxicity of the surface functionalized ZnO-β-CD-3-CCA system against the human breast cancer (MCF-7) and human liver cancer (Hep G2) cell lines were superior to that of ZnO NPs. Also, the developed systems were less toxic to normal rat spleen cells. This work is significant because it could result in next-generation nanoparticle-based cancer treatments that are more successful.

Chitosan-Oxidized Pullulan Hydrogels Loaded with Essential Clove Oil: Synthesis, Characterization, Antioxidant and Antimicrobial Properties.

Emulsion hydrogels are promising materials for encapsulating and stabilizing high amounts of hydrophobic essential oils in hydrophilic matrices. In this work, clove oil-loaded hydrogels (CS/OP-C) are synthesized by combining covalent and physical cross-linking approaches. First, clove oil (CO) was emulsified and stabilized in a chitosan (CS) solution, which was further hardened by Schiff base covalent cross-linking with oxidized pullulan (OP). Second, the hydrogels were subjected to freeze-thaw cycles and, as a result, the clove oil was stabilized in physically cross-linked polymeric walls. Moreover, due to cryogelation, the obtained hydrogels exhibited sponge-like porous interconnected morphology (160-250 µm). By varying the clove oil content in the starting emulsion and the degree of cross-linking, the hydrogels displayed a high water retention capacity (swelling ratios between 1300 and 2000%), excellent elastic properties with fast shape recovery (20 s) after 70% compression, and controlled in vitro clove oil release in simulated skin conditions for 360 h. Furthermore, the prepared clove oil-loaded hydrogels had a strong scavenging activity of 83% and antibacterial and antifungal properties, showing a bacteriostatic effect after 48 and 72 h against S. aureus and E. coli. Our results recommend the new clove oil-embedded emulsion hydrogels as promising future materials for application as wound dressings.

The effect of Bacillus in the composition of the probiotic Natupro® against bacterial pathogenic strains in vitro

Relevance. The use of probiotics for health benefits is becoming popular because of the quest for safer products with protective and therapeutic effects against diseases and infectious agents. The emergence and spread of antimicrobial resistance among pathogens had prompted restrictions over the nontherapeutic use of antibiotics for prophylaxis and growth promotion, especially in animal husbandry. While single-strain probiotics are beneficial to health, multi-strain probiotics might be more helpful because of synergy and additive effects among the individual isolates.Methods. In this study, the effectiveness of the multi-strain probiotic Natupro on pathogenic bacterial strains (Escherichia coli 320, Salmonella typhimurium 415, Staphylococcus aureus 12600, Streptococcus uberis 700407, Klebsiella pneumoniae 13883, Listeria monocitogenes 766/20) in vitro was studied.Results. According to the results of the work carried out, it was found that the bacterial strains in Natupro® exhibit lytic activity against pathogenic strains of Salmonella typhimurium 415 and Klebsiella pneumoniae 13883 and have a bacteriostatic effect on Escherichia coli strain 320 and Salmonella typhimurium 415.

Antibiotic's target site affects the potentiation of Lactiplantibacillus plantarum inhibition and inactivation by electroporation.

Antibiotic resistance represents a growing global threat, and thus the motivation to develop novel and combined methods of bacterial inactivation is increasing. Electroporation is a technique in which electric pulses of sufficient strength are applied to permeabilize cells, including bacteria. Combining antibacterials with electroporation is a promising strategy to potentiate their bactericidal and bacteriostatic effectiveness. This approach has already proved useful for increasing bacterial inactivation, yet most studies so far have mainly focused on the maximal achievable effects, and less on the underlying mechanisms. We recently demonstrated that in the Gram-negative (G-) bacterium Escherichia coli, electroporation potentiates antibacterials targeting the peptidoglycan wall more than those with intracellular targets. However, in Gram-positive (G+) bacteria, the wall is directly accessible from the outside, and thus the dependence of potentiation on the antibacterial's target may be rather different. Here, we compare the inactivation and growth inhibition of the G+ bacterium Lactiplantibacillus plantarum for two antibiotics with different modes of action: ampicillin (inhibits cell-wall synthesis) and tetracycline (inhibits intracellular protein synthesis). We used antibiotic concentrations ranging from 0 to 30 × MIC (minimum inhibitory concentration that we predetermined for each antibiotic), a single 1-ms electric pulse with an amplitude from 0 to 20 kV/cm, and post-pulse pre-dilution incubation of 24 h or 1 h. Electroporation increased the inhibition and inactivation efficiency of both antibiotics, but this was more pronounced for tetracycline, with statistical significance mostly limited to 24-h incubation. In general, both inhibition and inactivation grew stronger with increasing antibiotic concentration and electric field amplitude. Our results indicate that electroporation potentiates inactivation of G+ bacteria to a larger extent for antibiotics that inhibit intracellular processes and require transport into the cytoplasm, and to a smaller extent for antibiotics that inhibit cell-wall synthesis. This is the inverse of the relation observed in G- bacteria, and can be explained by the difference in the envelope structure: in G- bacteria the outer membrane must be breached for wall-inhibiting antibiotics to access their target, whereas in G+ bacteria the wall is inherently accessible from the outside and permeabilization does not affect this access.

Study of disinfectant activity against bee pathogenic enterobacteria in vitro

Dysbiosis is a pathological condition caused by violating the normal coexistence of bacterial organisms in one or more body systems. This disease arises due to the action of many ethological factors, the mechanisms of which arise from each other. Klebsiellosis of bee colonies is a relatively new disease of Apis mellifera, caused by pathogenic enterobacteria, which leads to the mass death of bees with signs of acute dyspepsia, particularly in the spring and autumn periods. To prevent klebsiellosis in bees, it is necessary to carry out veterinary and sanitary measures in apiaries every year, including disinfection. Modern beekeeping encourages the search for new antibacterial drugs to ensure the production technology of safe and high-quality beekeeping products suitable for sale. Preliminary laboratory assessment (in vitro) of the effectiveness of disinfectants against specific pathogens of specific diseases of bees will ensure an increase in the effectiveness of such agents in apiaries, which is economically effective for practical beekeeping. The purpose of the research was to determine the activity of different concentrations of the disinfectant (0.25 %, 0.5 %, 1.25 %, 2.5 %) with an active substance of an organic nature with covalent weakly polar bonds against pure cultures of pathogenic enterobacteria of bees of the species Klebsiella pneumoniae and Klebsiella (Enterobacter) aerogenes in vitro. The modified Kirby-Baur method on Mueller-Hinton agar was used for research. A bactericidal effect against a pure culture of Klebsiella pneumoniae species was registered after 24 hours with lysis zone diameters at 8.6 ± 0.27 mm (0.25 % concentration) – 15.0 ± 0.35 mm (2.5 % concentration). On the 3rd day of research, a bacteriostatic effect was registered with the largest diameter of the zone of growth retardation (24.4 ± 0.27 mm) at 2.5 % disinfectant concentration. Bactericidal and bacteriostatic effects were recorded on the culture of enterobacteria of bees of the species Klebsiella (Enterobacter) aerogenes for 24 hours of cultivation with zones of lysis – 6.8 ± 0.42 mm (0.25 %) – 11.8 ± 0.22 mm (2.5 %) and inhibition of bacterial growth at the level of – 21.8 ± 0.42 mm (0.25 %) – 25.8 ± 0.42 mm (2.5 %). At the same time, there was no significant difference between the zones of Klebsiella (Enterobacter) aerogenes growth retardation in concentrations of 0.5 % – 2.5 % on the 3rd day of research. The studied disinfectant has bactericidal and bacteriostatic effects on pure cultures of bee enterobacteria of the species Klebsiella pneumoniae and Klebsiella (Enterobacter) aerogenes in laboratory conditions, which is promising for further study of the drug.

Hyaluronic acid-based gels for oral application: Comparison of in vitro effects on gingival cells and bacteria

PurposeThis study aimed to evaluate the cytotoxic effects of different topical hyaluronic acid-based gels on human gingival fibroblasts and oral bacteria. MethodsFour different hyaluronate gels - Bexident® Aftas (BA), GUM® AftaClear (AfC), Gengigel®(G), Aloclair® Plus (AlC) and a chlorhexidine gel - Bexident®Gums(BG) were selected. Human gingival fibroblasts (HGF) were seeded in 48-well plates with different gel/culture medium concentrations (v/v%) and cell viability was evaluated at 1 and 3 days of culture. Cell morphology was assessed, and alterations graded according to ISO 10993–5:2009(E). Streptococcus oralis CECT 907T colony was, seed on 48-well plate or spread onto the blood agar plates and exposed to the different gel's concentration. The optical density (OD) was assessed, and the diameter of the inhibition zone was measured (mm). ResultsBA and G elicited reduced HGF cytotoxicity, followed by AfC. AlC and BG were cytotoxic at concentrations up to 3% for all exposure times. PCM images of HGF showed moderate-to-severe alterations for AlC and BG and slight to mild changes, for BA, AfC and G. The highest antibacterial activity against S.oralis was observed on AlC and AfC, and no antibacterial activity was observed for BA and G. Inhibitory effect in sessile colonies was only observed in AlC and BG. ConclusionsAlC demonstrated superior antibacterial activities against S.oralis but a higher cytotoxic potential in HGF. BA and G presented the lowest cytotoxicity with little to no antibacterial effect. AfC demonstrated bacteriostatic effects and low cytotoxicity on HGF.

The Role of Probiotics in the Eradication of Helicobacter pylori and Overall Impact on Management of Peptic Ulcer: A Study Involving Patients Undergoing Triple Therapy in Bangladesh.

Background Helicobacter pylori infection has been identified to cause constantly recurring inflammation, leading to gastrointestinal tract disorders, including carcinoma. The standard triple therapy (STT), used to eradicate H. pylori, includes two antimicrobials and a proton pump inhibitor for two weeks. Other drug regimens have also been developed since H. pylori exhibits antimicrobial resistance. These regimens, including probiotics, have been shown to lower adverse drug reactions (ADR), improve drug adherence, exert bacteriostatic effect, and reduce inflammation. Objective This study intended to explore probiotic intervention for improving eradication rates and mitigating adverse effects while administrating STT. Methods This prospective study was conducted from May to December, 2021, in the Department of Gastroenterology of Ship International Hospital, Dhaka, Bangladesh, to observe the effects of probiotics inclusion along with STT on H. pylori eradication. A total of 100 patients aged ≥18 years who tested positive for H. pylori were included. The experimental group (n=50) was given STT and probiotics, and the control group (n=50) was given only STT without probiotics for 14 days. Necessary follow-up was done six weeks after treatment. An independent sample t-test, chi-square test, and multiple regression analysis were used for statistical analysis. Result The odds of getting rapid urease test (RUT) negative results from positive were 2.06 times higher (95%CI= 0.95, 3.22, p=0.054) in the experimental group. ADRs were crucially towering in the control group (p=0.045) compared to the probiotics group. The probiotics group had a lower risk of having adverse effects by 0.54 times (95%CI=0.19, 0.84, p=0.032) than the control group. Conclusion Using probiotics and STT together to eradicate H. pylori may lower ADR and improve treatment adherence. It may also help terminate H. pylori infection more effectively. More research is required as H. pylori is very contagious and can ultimately cause life-threatening gastric cancer.

Bacteriostasis of nisin against planktonic and biofilm bacteria: Its mechanism and application.

Food safety incidents caused by bacterial contamination have always been one of the public safety issues of social concern. Planktonic cells, viable but non-culturable (VBNC) cells, and biofilm cells of bacteria can coexist in food or food processing, posing more serious challenges to public health and safety by increasing bacterial survival and difficulty in detection. As a non-toxic, no side effect, and highly effective bacteriostatic substance, nisin has received wide attention from researchers. In this review, we summarized the species and biosynthesis of nisin, the effects of nisin alone or in combination with other treatments on planktonic and biofilm cells, and its applications in the fields of food, feed, and medicine by consulting numerous studies. Meanwhile, the mechanism of nisin on planktonic and biofilm cells was proposed based on existing researches. Nisin not only has antibacterial activity against most G+ bacteria but also exhibits a bacteriostatic effect on G- bacteria when combined with other antibacterial treatments. In addition to planktonic cells, nisin also has significant effects on bacterial cells in biofilms by changing the thickness, density, and composition of biofilms. Based on the three action processes of nisin on biofilms, we summarized the changes of bacteria in biofilms, including the causes of bacterial death and the formation of the VBNC state. We consider that research on the relationship between nisin and VBNC state should be strengthened.