Minimum Bactericidal Concentration Research Articles

Enhanced Detection of Escherichia coli Lipids and Proteins Using Graphene-Polyglycerol Amine via Mass Spectrometry.

The accurate and rapid identification of bacterial pathogens poses a significant challenge in clinical diagnostics, environmental monitoring, and microbial research. Lipidomics and proteomics serve as powerful methodologies for bacterial characterization; however, the complexity of biological matrices and the low abundance of bacterial lipids often limit effective detection. This study introduces graphene-polyglycerol amine (G-PGA) as a novel nanomaterial that enhances the selective trapping and detection of Escherichia coli (E. coli) using desorption electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The antimicrobial properties of G-PGA reveal a minimum inhibitory concentration (MIC) of 250 μg/μL and a minimum bactericidal concentration (MBC) of 500 μg/μL. Optimal sonication conditions (10 min) maximize G-PGA's surface activity, facilitating effective bacterial trapping while maintaining cellular integrity, as confirmed by scanning electron microscopy and atomic force microscopy. Molecular docking simulations show a strong affinity between G-PGA and the β-barrel assembly machinery (BAM) proteins of E. coli, suggesting potential disruption of critical bacterial processes. Preconcentration with G-PGA significantly improves detection sensitivity and signal-to-noise ratio in mass spectrometry analyses, highlighting its potential as a transformative tool for rapid, sensitive, and highly specific bacterial identification in lipidomics and proteomics.

Emilia sonchifolia (L.) DC. inhibits the growth of Methicillin-Resistant Staphylococcus epidermidis by modulating its physiology through multiple mechanisms

Bloodstream infections (BSIs) are a public health concern, causing substantial morbidity and mortality. Staphylococcus epidermidis (S. epidermidis) is a leading cause BSIs. Antibiotics targeting S. epidermidis have been the mainstay of treatment for BSIs, however their efficacy is diminishing in combating with drug-resistant bacteria. Therefore, alternative treatments for antibiotic-resistant infections are urgently required. Studies have demonstrated that certain traditional Chinese medicine (TCM) exhibit notable antimicrobial activity and can help mitigate bacterial resistance. Among these, The ethanol extract of Emilia sonchifolia (L.) DC (E. sonchifolia) (10 g crude drug/1 g extract ) exhibits a noteworthy anti-methicillin-resistant S. epidermidis (MRSE) effect. This study explores antibacterial activity and underlying mechanisms of E. sonchifolia against MRSE. The antibacterial activity of E. sonchifolia against MRSE was assessed in vitro by measuring the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The MRSE-induced mouse BSIs model was used to evaluate the antibacterial activity of E. sonchifolia in vivo. Proteomic and transcriptomic analyses were performed to elucidate the underlying antibacterial mechanisms. The MIC and MBC values of E. sonchifolia against MRSE were 5 mg/mL and 20 mg/mL, respectively. In vivo, E. sonchifolia effectively treated MRSE-induced BSIs. Additionally, proteomic and transcriptomic analyses revealed considerable down-regulation of purine metabolism, that were associated with oxidative stress and cell wall synthesis. The enzyme linked immunosorbent assay(ELISA) results showed decreased levels of inosine monophosphate (IMP), Adenosine monophosphate(AMP) and guanine monophosphate (GMP), indicating inhibited purine metabolism. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis confirmed bacterial cell wall damage. E. sonchifolia exerts antibacterial effects by inhibiting purine metabolism, promoting bacterial oxidative stress, and impairing cell wall synthesis. These findings provide novel insights into the mechanistic understanding of E. sonchifolia's efficacy against MRSE, offering potential strategies for managing MRSE infections.

Anti-Virulence Properties of Curcumin/CuO-NPs and Their Role in Accelerating Wound Healing In Vivo

Background and Objectives: This study introduces an innovative approach to accelerating wound healing by leveraging the bactericidal properties of mycosynthesized copper oxide nanoparticles (CuO-NPs) and their combination with curcumin against Pseudomonas aeruginosa. The study aims to evaluate their antimicrobial efficacy, impact on quorum sensing-associated virulence factors, and potential therapeutic applications in wound healing. Materials and Methods: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CuO-NPs were determined to be 25 μg/mL and 50 μg/mL, respectively. At sub-inhibitory concentrations (0.5 MIC, 0.25 MIC, and 0.125 MIC), their effects on P. aeruginosa growth and quorum sensing-associated virulence factors were assessed. Antioxidant activity and cytotoxicity were also evaluated. Additionally, the combination of CuO-NPs and curcumin (CUR) was tested for its enhanced wound-healing efficacy. Results: While CuO-NPs did not inhibit P. aeruginosa growth at sub-inhibitory concentrations, they significantly reduced quorum sensing-associated virulence factors in a dose-dependent manner: LasB elastase (81.8%, 60.6%, and 53.03%), LasA protease (70%, 68.5%, and 57.1%), and pyocyanin (85.7%, 71.4%, and 55.9%). CuO-NPs exhibited strong antioxidant activity by scavenging free radicals. The combination of CuO-NPs and CUR demonstrated the highest wound-healing efficacy, outperforming the negative control and Mebo ointment by 193.9% and 61.6%, respectively. Additionally, CuO-NPs exhibited selective cytotoxicity against HepG2 cancer cells while displaying minimal toxicity toward normal human skin cells. Conclusions: CuO-NPs, particularly in combination with CUR, show promising potential as a therapeutic agent for wound healing by inhibiting quorum sensing-associated virulence factors, exhibiting strong antioxidant activity, and demonstrating selective cytotoxicity. These findings highlight their potential biomedical applications.

Harnessing in vitro cytotoxicity and antibacterial potential of a novel silver-DABCO framework against multi-drug-resistant pathogens.

This study aimed to synthesize and characterize silver-based metal-organic frameworks (Ag-MOFs) using 1,4-diazabicyclo[2.2.2]octane (DABCO) as the organic ligand and to assess their antibacterial and cytotoxic properties. The formation of Ag-MOF-D was confirmed by the appearance of a brown solution and a surface plasmon resonance peak at 394 nm in UV-vis spectroscopy. Fourier-transform infrared spectra showed characteristic peaks at 673, 705, 883, 1060, 1382, 1654, and 3250 cm-1. Powder X-ray diffraction patterns indicated a crystalline structure with peaks at 33°, 38°, 55°, and 66°, with an average particle size of 15.68 nm. Ag-MOF-D displayed thermal stability up to 650 °C with a residual mass of 91.50%. Scanning electron microscopy revealed spherical morphology with minimal aggregation, while energy-dispersive X-ray spectroscopy showed 88.64 wt% Ag+. Transmission electron microscopy indicated mono-dispersed spherical particles with an average diameter of 10.47 ± 1.80 nm and a lattice fringe spacing of 0.19 nm. The type II isotherm and Brunauer-Emmett-Teller analysis suggested a mesoporous structure of Ag-MOF-D with a surface area of 5.3005 m2 g-1 and an average pore diameter of 9.46 nm. Minimum inhibitory and minimum bactericidal concentration values against multi-drug-resistant bacterial strains ranged from 3.90 to 7.80 μM and 7.8 to 62.5 μM, respectively. In vitro cytotoxicity testing on Vero cell lines indicated a dose-dependent decrease in cell viability, with an IC50 value of 1.701 × 10-2 mg mL-1. These findings suggest that Ag-MOF-D holds potential for antibacterial applications and biocompatibility, with future opportunities for environmental and food safety applications.

Identification of Antibacterial Agents with a Synergistic Effect in Pteris vittata L. by Exploration of Metabolome Data and Multivariate Analysis.

In metalliferous ecosystems, bacteria could develop membrane efflux pumps to extrude heavy metals. Native plants, frequently exposed to such bacteria, may serve as rich chemical reservoirs for discovering potential antibacterial and/or resistance-modifying agents. This study aims to investigate the antibacterial properties of Pteris vittata L., a metal hyperaccumulator abundant in metal-rich environments, against Stenotrophomonas maltophilia K279a, an opportunistic nosocomial pathogen linked to severe respiratory tract infections. A novel approach was used, employing the metabolome of P. vittata in a partial least squares regression model to predict the correlation between the whole chemical profile and activity. Marked compounds were then subjected to invitro test for bactericidal and synergistic properties using broth dilution and time-kill assays. The multivariate analysis demonstrated a strong synergistic effect among a range of flavonoids compared to the individual responses. Notably, nine flavonoids were confirmed to reduce the minimum inhibitory concentration and minimal bactericidal concentration values of active compounds, cyanidin-3,5-O-diglucoside and perlagonin, from 64.0 and 108 μg/mL to 0.25 and 3.38 μg/mL, respectively. These results provide insights into the possibility of combating clinical infections caused by S. maltophilia and highlight the potential of exploring new synergetic interactions among natural products as an alternative to the conventional bio-guided isolation strategy.

Multifunctional Z‐scheme NaGdF4:Yb,Tm@ZnO/Ag3PO4 nanoheterojunction photocatalysts for water purification and antibacterial wound healing

AbstractPhotocatalysts with dual functionalities of decomposing organic pollutants in water and combating bacterial infections are increasingly important. Herein, NaGdF4:Yb,Tm@ZnO/Ag3PO4 (UZA) nanoheterojunction photocatalysts were synthesized via hydrothermal, sol–gel, and in situ deposition methods. The UZA photocatalyst demonstrated exceptional efficiency in generating reactive oxygen species (ROS), crucial for organic pollutant degradation. The incorporation of Ag facilitated efficient charge transfer in the all‐solid‐state Z‐scheme nanoheterojunction system. Furthermore, UZA exhibited potent antibacterial properties against both Gram‐positive Staphylococcus aureus (S. aureus) and Gram‐negative Escherichia coli (E. coli). The minimum bactericidal concentrations (MBC) of UZA were 50 µg/mL for S. aureus and 25 µg/mL for E. coli under natural irradiation, and 100 µg/mL for S. aureus and 25 µg/mL for E. coli under 980 nm irradiation, respectively. In vivo studies using a mouse model of acute bacterial‐infected wounds demonstrated that UZA incorporated into chitosan hydrogel dressings accelerated wound healing through photodynamic therapy within 9 days. The treated wounds exhibited rapid reduction to 9.95% of the initial area, diminished inflammatory responses, and enhanced re‐epithelialization attributed to sustained antibacterial effects and pathogen inhibition. Moreover, UZA composites showed excellent biocompatibility with a minimal hemolysis rate of 0.5% on erythrocytes. These findings underscore the promising application of UZA in water treatment for organic pollutants and in the treatment of skin wound infections caused by pathogenic bacteria.

Efficiency of apple cider vinegar individually and in combination with selected antibiotics, and the potential impact of circadian rhythm on bacterial response to treatment in methicillin- resistant Staphylococcus aureus

This study evaluated the antibacterial properties of apple cider vinegar (ACV) in two commercial forms, liquid and powder, against Methicillin-resistant Staphylococcus aureus (MRSA). The analysis employed the disk diffusion method, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Undiluted liquid ACV produced a 7 mm inhibition zone, while the powdered form exhibited inhibition zones of 7 mm, 10 mm, and 12 mm at dilutions of 1:5, 1:125, and 1:40, respectively. The MIC and MBC results were consistent for both forms, with the liquid form achieving MIC and MBC values of 6.25%, and the powdered form showing values of 15.63 mg/mL. Despite variations in geographic origin, the ACV samples demonstrated reproducible antibacterial efficacy. Combining ACV with cefoxitin (Fox30) and vancomycin (VA30) antibiotics, significantly enhanced antibacterial activity, particularly with Fox30, where the inhibition zone increased from 15.6 mm to 19.3 mm. However, combining gentamicin (CN10) with ACV at 500 mg/mL reduced the inhibition zone from 23 mm to 16 mm, indicating an antagonistic effect. Testing the effectiveness of Fox30, VA30, CN10, and neat liquid ACV at three different times of the day (spaced 8 hours apart) revealed no significant time-dependent changes. Slight variations in the powdered form’s efficacy warrant further investigation.

Mixture Containing 5% Polysaccharide Extract of Cerioporus squamosus (Huds.) Quélet, 5% Dexpanthenol, and 0.2% Hyaluronic Acid Shows In Vitro and In Vivo Wound Healing Properties

Background: This study explores wound healing and the antimicrobial potential of a natural formulation containing a polysaccharide extract from Cerioporus squamosus, hyaluronic acid, and dexpanthenol. Methods: Wound healing effects were assessed using HaCaT keratinocytes, while antimicrobial activity was evaluated against human skin pathogens using a microdilution assay. In vitro cytotoxicity tests ensured formulation safety, whereas in vivo wound healing was further investigated using an animal model. Gene expression analysis was performed to assess the molecular mechanisms involved. Results: The unique glucan composition of C. squamosus (15.38% α-glucans and 7.91% β-glucans) deviated from typical mushroom polysaccharide profiles, warranting further exploration of its bioactivity. In vitro mushroom polysaccharides promoted 25.35% wound closure after 24 hours, while the three-component formulation achieved 35.81% closure. Antibacterial activity showed a minimum inhibitory concentration (MIC) of 0.44–1.75 mg/mL and minimum bactericidal concentration (MBCs) of 0.88–3.50 mg/mL, while antifungal activity ranged from 0.22 to 0.44 mg/mL (MICs) and 0.44 to 0.88 mg/mL (minimum fungicidal concentration—MFC). In vivo data showed that 60% of treated wounds fully closed by day 11, despite no statistically significant difference from the control. However, gene expression analysis highlighted VEGF and collagen upregulation, indicating an enhancement of wound healing on a molecular level. Conclusions: The novel three-component formulation demonstrated consistent wound healing and antimicrobial properties, supporting its potential as a safe and effective treatment for chronic and acute wounds.

ANTIBACTERIAL AND ANTIOXIDANT PROPERTIES OF OCIMUM SANCTUM EXTRACTS AGAINST STREPTOCOCCUS MUTANS AND ESCHERICHIA COLI

The rise of antibiotic-resistant bacteria has increased the demand for alternative antimicrobial and antioxidant agents. Ocimum sanctum (holy basil) is widely recognized for its medicinal properties, particularly its antibacterial and antioxidant potential. This study evaluates the antibacterial activity of O. sanctum extracts against Streptococcus mutans and Escherichia coli, comparing ethanol, methanol, and aqueous extractions. The study also investigates the dose-response relationship, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antioxidant potential of the extracts. O. sanctum extracts were prepared using ethanol, methanol, and aqueous solvents. The antibacterial activity was assessed using the disc diffusion method at different extract concentrations (10, 25, 50, 75, and 100 mg/mL). The MIC and MBC values were determined using the broth dilution method, while a time-kill assay monitored bacterial reduction over 24 hours. The antioxidant activity of the extracts was analyzed using the DPPH radical scavenging assay to evaluate their free radical neutralization ability. The ethanol extract exhibited the highest antibacterial activity, with inhibition zones of 28.6 ± 1.3 mm for S. mutans and 33.2 ± 1.4 mm for E. coli at 100 mg/mL. The MIC values for ethanol extract were 6 mg/mL for S. mutans and 4 mg/mL for E. coli, while MBC values were 12 mg/mL and 8 mg/mL, respectively. The time-kill assay demonstrated that 18 mg/mL ethanol extract reduced bacterial counts by 99.9% within 24 hours, whereas methanol and aqueous extracts required higher concentrations (30 mg/mL and 60 mg/mL). The antioxidant assay showed that ethanol extract had the highest free radical scavenging activity (82.5 ± 2.1%) compared to methanol (76.3 ± 1.8%) and aqueous extracts (64.7 ± 1.5%). The findings suggest that O. sanctum extract, particularly in ethanol form, possesses significant antibacterial and antioxidant properties. Its strong antimicrobial activity and free radical scavenging potential highlight its role as a natural therapeutic agent. Further in vivo and clinical studies are needed to validate its effectiveness in pharmaceutical and nutraceutical applications.

First metabolic profiling of Indian wild edible mushroom Amanita hemibapha reveals antimicrobial compounds that infers selective activity against gram-positive human pathogens

Amanita hemibapha, a wild edible mushroom from Western Ghats area of India, has been underexplored for its therapeutic properties. The present study uncovered selective inhibition of gram-positive human pathogens by the mushroom extracts and antibiofilm activity as the first report among the Amanita genus. The chloroform extract displayed the most effective inhibition against Streptococcus pyogenes, with both Minimum inhibitory concentration and Minimum bactericidal concentration registering at 6 mg/mL, and effective biofilm inhibition was recording at 4 mg/mL. Metabolic profiling of the chloroform fraction revealed an array of fatty acids, especially oleic acid and its derivatives like Oleoyl lysophosphatidylcholine and Azelaic acid, known to be selective for gram-positive pathogens. Sphingolipids like D-Sphingosine, Safingol, and threo-sphingosine profiled in the extract are effective gram-positive inhibitors. Metabolic profiling revealed the presence of medicinal and health-beneficial fatty acids/lipids in A. hemibapha.

Antibacterial and Antibiofilm Activities of Hydralazine, an Antihypertensive Drug: In Vitro and In Silico Approaches

Background: The rise of multidrug-resistant (MDR) bacteria poses a significant challenge to global public health, contributing to increased morbidity and mortality rates. In this context, the repurposing of existing drugs has emerged as a promising strategy. In this study, hydralazine (HDZ), a vasodilator used as an antihypertensive since 1952, demonstrated antibacterial and antibiofilm activity against both Gram-positive and Gram-negative bacteria. Methods: In this study, the antibacterial activity of the antihypertensive hydralazine (HDZ) was evaluated against Gram-positive and Gram-negative strains through minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), growth curve with MIC and sub-MIC doses, combinatorial effect with gentamicin, scanning electron microscopy (SEM), molecular docking, and antibiofilm activity. Results: The MIC and MBC values ranged from 39.5 to 1.250 μg/mL, respectively. A change in the growth kinetics of the strains was observed when exposed to MIC and 1/2 MIC values, with a delay in the phases of up to 12 h. The combinatorial effect with gentamicin demonstrated an additive and indifferent potential when combined with HDZ. Conclusions: Furthermore, hydralazine showed antibiofilm activity against the tested strains, including MRSA. Electron microscopy analysis revealed significant changes in bacterial morphology when exposed to the MIC dose of HDZ for 4 h. The overall results of the study indicate hydralazine as a potential agent in the fight against bacterial infections.

Saponins from sea cucumber disrupt Aeromonas hydrophila quorum sensing to mitigate pathogenicity

Aeromonas hydrophila, a Gram-negative bacterium, poses significant threats to aquaculture, leading to substantial economic losses. Its pathogenicity is primarily driven by a sophisticated quorum sensing (QS) system that regulates virulence factors. This study investigates saponins extracted from the sea cucumber Holothuria leucospilota as potential natural inhibitors of QS in A. hydrophila, offering a novel disease management strategy for aquaculture. Specimens of H. leucospilota were collected, and saponins were extracted from their Cuvierian tubules through a process of homogenization, solvent extraction, and purification. The saponin extract's minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) against A. hydrophila were found to be 80 μg/mL and 30 μg/mL, respectively. Hemolysin, lipase, and protease are examples of QS-regulated virulence factors whose activities were found to be significantly reduced by sub-MIC levels of saponins. Additionally, swarming motility and biofilm formation were notably inhibited. A significant downregulation of the QS genes ahyI and ahyR was observed, indicating an effective disruption of the QS system.These findings suggest that saponins from H. leucospilota can inhibit the QS system in A. hydrophila, thereby reducing its pathogenicity. This disruption offers a promising method for controlling bacterial infections without directly killing the bacteria, potentially mitigating antibiotic resistance. The study highlights the potential of marine-derived compounds as natural QS inhibitors, contributing to environmentally friendly aquaculture practices. Overall, it provides evidence that sea cucumber saponins could serve as a novel class of anti-QS agents, presenting a new perspective on disease management in aquaculture and other bacterial infection contexts.

Investigation of Nigella sativa seed ethanolic extract using gas chromatography-mass spectrometry and study of its antibacterial activity against different bacterial species

Medicinal plants are one of the valuable natural resources that developed countries today consider to be safe alternative medicines for humans. The current study focused on Gas chromatography-mass spectrometry (GC-MS) investigations and the antibacterial properties of Nigella sativa (N. sativa) seed extract. The maceration process, the soxhlet method and suitable extraction solvents have all been used to create various extracts from N. sativa seeds. The GC-MS analyses identified around 25 chemical compounds with known bioactivities and/or uses that are crucial for the treatment of illnesses that pose a serious hazard to life. Using the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and Well diffusion methods, the seed extract demonstrated antibacterial activity against Gram-positive (Staphylococcus aureus, Bacillus cereus) and Gram-negative (Escherichia coli, Salmonella typhimurium) bacteria with varying degrees of efficacy. The antibacterial activity of the extract was dose-dependent and more potent against Gram-positive bacteria than Gram-negative bacteria. Considering the findings of this study, N. sativa seed extracts contain a variety of chemical elements associated with their antibacterial capabilities.

The ability of Salmonella enterica subsp. enterica strains to form biofilms on abiotic surfaces and their susceptibility to selected essential oil components.

The ability of Salmonella enterica subsp. enterica to persist and form biofilms on different surfaces can constitute a source of food contamination, being an issue of global concern. The objective of this study was to understand the biofilm formation profile of fourteen S. enterica strains among different serovars and sources and to evaluate the ability of essential oil (EO) components (carveol, citronellol, and citronellal) to disinfect the biofilms formed on stainless steel and polypropylene surfaces. All the strains were able to form biofilms with counts between 5.34 to 6.78 log CFU cm-2. Then, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of EO components were evaluated on two selected strains. All compounds inhibited the growth of S. Typhimurium (strain 1; MIC = 800-1000 µg ml-1) and S. Enteritidis (strain 5; MIC = 400-1000 µg ml-1) and only carveol showed bactericidal activity against strains 1 and 5 (MBC=1200 µg ml-1). Biofilms were exposed to the EO components at 10 × MIC for 30 min and polypropylene surfaces were more difficult to disinfect showing reductions between 0.9 and < 1.2 log CFU cm-2. In general, the S. enterica biofilms demonstrated a significant tolerance to disinfection, demonstrating their high degree of recalcitrance on food processing surfaces.

Antibacterial Activity of Ziziphus Spina-Christi Leaf Extract and Its Effect on Gene Expression of Some Virulence Factors of Some Pathogenic Bacteria

Given the increasing frequency of antibiotic-resistant bacteria, other antimicrobial therapies have to be looked at. The antibacterial activity of Ziziphus spina-christi leaf extract against Staphylococcus aureus and Klebsiella pneumoniae is evaluated in this work using disk diffusion, least inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The results indicated a concentration-dependent inhibitory effect as S. aureus had larger inhibition zones (18 mm at 100 mg/mL) than K. pneumoniae (14 mm at 100 mg/mL). MIC and MBC values helped to further confirm S. aureus's (MIC = 16 mg/mL, MBC = 32 mg/mL) better sensitivity in relation to K. pneumoniae (MIC = 32 mg/mL, MBC = 64 mg/mL). Gene expression findings indicate that the agrA gene, a vital regulator of quorum sensing and pathogenicity, was greatly downregulated in S. aureus with a 65% drop at 100 mg/mL (p &lt; 0.001). Likewise, the highest dosage produced a 50% reduction in fimH expression in K. pneumoniae, a component of adhesion and biofilm development. These findings suggest that since the extract reduces pathogenicity in addition to suppressing bacterial growth, it is a suitable choice for antimicrobial therapy. Structural changes in their cell walls most likely explain the different sensitivity of the two bacterial species; K. pneumoniae exhibits stronger resistance due to its outer membrane barrier. Further investigation on the effects of the extract on additional illnesses, its synergistic effects with other antibiotics, and its in vivo efficacy will help to assess its possible clinical usage.

Antimicrobial Efficacy of Electrolyzed Waters and Chlorine-Based Disinfectants: The Role of pH, Free Chlorine, and Oxidation-Reduction Potential Over Time.

This study evaluated the antimicrobial efficacy of electrolyzed water (EW) and chlorine-based disinfectant (CLD) over time, focusing on the impact of pH, free chlorine (FCL), and oxidation-reduction potential (ORP). EW and CLD are commonly used for wound care and surgical instrument disinfection, but their chemical instability limits their use. The study was conducted in the Microbiology Laboratory of the University of Guanajuato, using Escherichia coli ATCC 25922 as the test organism. Disinfectants were maintained at 40°C, with systematic monitoring of pH, FCL, and ORP. Minimum bactericidal concentration was used to assess antimicrobial activity before and after thermal exposure. Statistical analyses included Kruskal-Wallis one-way ANOVA, and the Friedman test. Results showed that the antimicrobial activity of EW depended on FCL concentration, with a significant correlation between the absence of FCL and increased minimum bactericidal concentration (p < 0.01). Disinfectants with alkaline pH demonstrated greater stability over time (p < 0.01). The findings highlight the importance of FCL, pH, and ORP in the effectiveness of these disinfectants and underscore their limitations due to chemical instability in clinical settings.

ANTIBACTERIAL ACTIVITY OF ALLIUM SATIVUM EXTRACT AGAINST STAPHYLOCOCCUS AUREUS AND ESCHERICHIA COLI: A PHYTOCHEMICAL APPROACH

The increasing resistance of bacterial pathogens to conventional antibiotics has led to a growing interest in natural antimicrobial agents. Allium sativum (garlic) is widely recognized for its medicinal properties, particularly its antibacterial effects. This study aimed to evaluate the antibacterial activity of garlic extract against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) using the agar well diffusion and broth dilution methods. The results revealed that garlic extract exhibited a stronger antibacterial effect against S. aureus, with inhibition zones of 9.5 ± 0.3 mm, 12.3 ± 0.4 mm, 15.0 ± 0.5 mm, and 18.2 ± 0.4 mm at concentrations of 10 mg/mL, 25 mg/mL, 50 mg/mL, and 100 mg/mL, respectively. In contrast, E. coli showed lower susceptibility, with inhibition zones of 7.8 ± 0.5 mm, 10.5 ± 0.3 mm, 13.2 ± 0.4 mm, and 15.6 ± 0.6 mm at the same concentrations. The Minimum Inhibitory Concentration (MIC) values were 8 mg/mL for S. aureus and 16 mg/mL for E. coli, while the Minimum Bactericidal Concentration (MBC) values were 16 mg/mL and 32 mg/mL, respectively, indicating that E. coli required a higher concentration for bacterial killing. Phytochemical analysis confirmed the presence of flavonoids (2.5 ± 0.2 mg/g), tannins (1.8 ± 0.1 mg/g), saponins (3.2 ± 0.3 mg/g), alkaloids (2.1 ± 0.2 mg/g), and glycosides (1.5 ± 0.2 mg/g), which contribute to the antimicrobial effects of garlic. The presence of these bioactive compounds suggests that garlic extract exerts its antibacterial effects by disrupting bacterial cell membranes and inhibiting essential bacterial enzymes. The MIC to MBC ratio for S. aureus (2.0) and E. coli (2.0) indicated a bactericidal effect of garlic extract on both bacterial strains. Compared to the standard antibiotic ciprofloxacin (5 µg/mL), which exhibited inhibition zones of 26.5 ± 0.5 mm for S. aureus and 24.3 ± 0.4 mm for E. coli, garlic extract showed lower but significant antibacterial activity. These findings suggest that Allium sativum extract possesses strong antibacterial properties, particularly against Gram-positive bacteria, and may serve as a natural alternative or complementary treatment for bacterial infections. Future research should focus on isolating specific active compounds, optimizing extraction methods, and exploring their synergistic effects with antibiotics to enhance antibacterial efficacy, particularly against antibiotic-resistant pathogens.

Comparison of Chemical Profile and Antibacterial Activity of Cinnamomum cassia Bark Essential Oil from Three different Vietnamese Provinces

Background: This study aimed to investigate the variations in constituents, physicochemical properties and antibacterial activity of Cinnamomum cassia bark essential oils from three selected regions of Vietnam (Yen Bai, Quang Ngai and Kon Tum). Methods: Gas chromatography- Mass spectroscopy was employed for the analysis of essential oils extracted by hydro-distillation. Physicochemical properties were analyzed per standard test methods (AOAC). The antibacterial activity of Cinnamomum cassia bark essential oils against ten different microbial strains was assayed by the determination of minimum inhibitory concentration and minimum bactericidal concentration values employing the broth macro-dilution and inoculation methods. Result: The Cinnamomum cassia bark essential oil from Quang Ngai was recorded to be the highest yield (2.600 ± 0.037%), followed by Kon Tum essential oil (1.505 ± 0.045%) and Yen Bai essential oil (1.315 ± 0.136%). GC-MS analysis revealed the extremely high content of trans-cinnamaldehyde present in Cinnamomum cassia bark essential oils from Kon Tum (96.07%), followed by Yen Bai essential oil (94.72%) and Quang Ngai essential oil (94.06%). There were generally no significant differences in physicochemical parameters among the three essential oils tested; however, variations in antibacterial activity against ten studied microbial strains have been documented in terms of MIC and MBC values. These findings confirmed the high quality of Cinnamomum cassia bark essential oils from three selected provinces but varying in MIC and MBC values against ten studied microbial strains.

In Vitro Activity of the Triazinyl Diazepine Compound FTSD2 Against Drug-Resistant Mycobacterium tuberculosis Strains

Background/Objectives: Compounds derived from pyrimido-diazepine have shown selective inhibition of the susceptible Mycobacterium tuberculosis strain H37Rv. However, there is a need for studies that evaluate the activity of these compounds against multidrug-resistant strains and clinical isolates. This study aims to evaluate the antitubercular potential of FTSD2 against drug-resistant strains of M. tuberculosis. Methods: The compound 4-(2,4-diamino-8-(4-methoxyphenyl)-8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepin-6-yl)-N-(2-(4-(dimethylamino)-6-(4-fluorophenyl)amino-1,3,5-triazin-2-yl)amino)ethyl)benzenesulfonamide (FTSD2) was tested against drug-resistant M. tuberculosis strains at minimal inhibitory and bactericidal concentrations (MIC and MBC). Kill curve assays were performed to assess bactericidal activity, and cytotoxicity was evaluated in human monocyte-derived macrophages and the RAW 264.7 murine macrophage cell line. Intracellular death assays, specifically macrophage infection assays, were also conducted to evaluate the effect of FTSD2 on intracellular M. tuberculosis growth. Results: FTSD2 inhibited the growth of drug-resistant M. tuberculosis at MIC and MBC values between 0.5 and 1 mg/L. Kill curve assays demonstrated concentration-dependent bactericidal activity. No cytotoxicity was observed in macrophages at concentrations below 64 mg/L. Additionally, FTSD2 significantly suppressed intracellular M. tuberculosis growth after 192 h. FTSD2 did not inhibit the growth of nontuberculous mycobacteria, including M. avium, M. abscessus, M. fortuitum, M. chelonae, and M. smegmatis at 50 mg/L. Conclusions: FTSD2 exhibits strong potential as a leading compound for the development of new antitubercular drugs, with selective activity against M. tuberculosis and minimal cytotoxic effects on macrophages. Further studies are needed to explore its mechanisms of action and therapeutic potential.

Anti-biofilm potential of some fish probiotics, alone and in combination with antibiotics against isolated aquaculture pathogens; a preliminary data.

Anti-biofilm potential of some fish probiotics, alone and in combination with antibiotics against isolated aquaculture pathogens; a preliminary data.