Lowest Minimum Inhibitory Concentration Research Articles

Phytochemical Screening and Antifungal Evaluation of Leaf Extracts of Nephrolepis undulata Afzel. Ex Sw. (Nephrolepidaceae) against selected Fungi

Nephrolepis undulata (sword fern) is a medicinal plant used traditionally for treatment of various ailments including stomach ache, infections and cough. Therefore, the objective of this study is to undertake a phytochemical screening and antifungal activity evaluation of leaf extracts of Nephrolepis undulata Afzel. Ex Sw. (Nephrolepidaceae) against selected fungi (Aspergilus fumigatus, Rhodotorula mucilagenosa, Trichophyton rubrum, Mucor indicus, Candida parapsilosis and Cryptococcus neoformans) using appropriate methods. Phytochemical screening was done using standard methods of analyses while antifungal evaluation of the extracts was done using the agar diffusion method. Phytochemical screening of the extracts revealed the presence of alkaloids, anthracene derivative, carbohydrate, flavonoid and saponin in the methanol, chloroform and petroleum ether extracts. Tannins was present in the methanol extract but absent in chloroform and petroleum ether extracts. The antifungal sensitivity test revealed that the extracts had concentration dependent inhibitory activities against the clinical isolates used in the study; with the methanol extract having the best and broadest spectrum of activity. It had the lowest Minimum Inhibitory Concentration (MIC) of 0.3 mg/mL against A. fumigatus. However, its activity was only next to Ketoconazole, the reference drug. The extracts contained active phytochemicals which may be responsible for the varied antifungal actions of the extracts. These positive finding validates the ethnomedicinal application of the plant in the management of various ailments and further demonstrates the applicability of the plant as a possible raw material, in the pharmaceutical industry.

Exploring the antibacterial mechanisms of chemically characterized essential oils from leaves and buds of Syzygium aromaticum (L.) Merr. et Perry against Staphylococcus aureus and Pseudomonas aeruginosa

Syzygium aromaticum (L.) Merr. et Perry is a medicinal plant extensively used in international pharmacopeia to treat different ailments, including infectious diseases. In this study, we designed to determine the chemical constituents of S. aromaticum essential oils extracted from leaves (CEOL) and floral buds (CEOB) and their antibacterial mechanism of action against S. aureus and P. aeruginosa. The volatile components from CEOL and CEOB were detected using gas chromatography coupled to a mass spectrometer (GC/MS). The results indicated that eugenol was the major component for both CEOL (65.75%) and CEOB (74.03%). The antibacterial findings demonstrated the potent antibacterial activity of CEOL and CEOB. These oils exhibited significant zones of inhibition against all tested bacteria, including S. aureus ATCC 29213, K. aerogenes ATCC 13048, P. aeruginosa ATCC 27853, and E. coli ATCC 25922, surpassing the effects of antibiotics. Additionally, they displayed low minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs), indicating their bactericidal nature (MBC/MIC < 4.0). Time-kill kinetics revealed that CEOB was more effective than CEOL at sub-MIC doses, eradicating S. aureus within 12 h and P. aeruginosa within 12–24 h. The cell membrane permeability test demonstrated that CEOL and CEOB treatment affected the relative conductivity of S. aureus and P. aeruginosa at both MIC and sub-MIC concentrations, indicating disruption of the bacterial membrane and influencing their growth and viability. Furthermore, the cell membrane integrity test showed that the addition of CEOL and CEOB to S. aureus and P. aeruginosa cultures led to significant protein release from the bacterial cells. The results of the anti-biofilm activity test confirmed the efficacy of S. aromaticum EOs, particularly CEOB, as potent anti-biofilm agents, suggesting its potential effect on inhibiting quorum sensing. Scanning electron microscope (SEM) microscopy further revealed significant alterations in bacterial cells treated with CEOB essential oil, including damage to the cell wall and distorted cell morphology, highlighting its impact on bacterial cell structure. Presented information suggests the use of clove EOs as natural alternatives for sustainable application in food and pharmaceutical industries.

돼지감자차 추출물의 여드름균에 대한 항균효과

This study analyzed the antibacterial activity of drying methods, including sun drying, hot air drying, and freeze drying of Helianthus tuberosus tea, against acne-causing microorganisms, Candida albicans, Propionibacterium acnes, Staphylococcus aureus, and Staphylococcus epidermidis. The antibacterial activity of the microorganisms related to acne was searched for extracts of H. tuberosus tea using the paper disk method to measure the antibacterial activity. Among the H. tuberosus tea extracts, the hot air-dried product B and freeze-dried products A and B exhibited antibacterial activity against acne-causing bacteria. Under the condition of culturing acne-causing bacteria together with H. tuberosus tea extract in a liquid medium for 24 hours, strong inhibitory effects were observed in hot air-dried product B and freeze-dried products A and B. The minimum inhibitory concentration (MIC) of H. tuberosus tea against acne-causing bacteria ranged from 0.5 to 1.0 mg eq. for the hot air-dried extract and 0.1 to 0.5 mg eq. for the freeze-dried extract. This finding showed that the freeze-dried product had a lower MIC, indicating higher antibacterial activity. The total polyphenol and flavonoid contents in the six types of H. tuberosus tea were high in the order of sun drying, hot air drying, and freeze drying, indicating apparent differences in the active ingredients depending on the manufacturing method. Considering these results, H. tuberosus tea is believed to have an inhibitory effect against acne-causing bacteria and potential antibacterial effects against acne-causing bacteria.

Expanding the Role of Boron in New Drug Chemotypes: Properties, Chemistry, Pharmaceutical Potential of Hemiboronic Naphthoids.

New chemotypes and bioisosteres can open a new chemical space in drug discovery and help meet an urgent demand for novel agents to fight infections and other diseases. With the aim of identifying new boron-containing drug chemotypes, this article details a comprehensive evaluation of the pseudoaromatic hemiboronic naphthoids, benzoxaza- and benzodiazaborines. Relevant physical properties in aqueous media (acidity, solubility, log P, and stability) of prototypic members of four subclasses were determined. Both scaffolds are amenable to common reactions used in drug discovery, such as chemoselective Suzuki-Miyaura, Chan-Lam, and amidation reactions. Small model libraries were prepared to assess the scope of these transformations, and the entire collection was screened for antifungal (Candida albicans) and antibacterial activity (MRSA, Escherichia coli), unveiling promising benzoxazaborines with low micromolar minimum inhibitory concentration values. Select DMPK assays of representative compounds suggest promising drug-like behavior for all four subclasses. Moreover, several drug isosteres were evaluated for anti-inflammatory and anticancer activity as appropriate.

Unleashing the Potential of Benincasa hispida Peel Extract: Synthesizing Selenium Nanoparticles with Remarkable Antibacterial and Anticancer Properties.

In this study, we successfully synthesized selenium nanoparticles (P-SeNPs) using an environment-friendly approach. This method involves utilizing the aqueous peel extract of Benincasa hispida (ash gourd) in combination with selenium salt. Through our innovative procedure, we harnessed the impressive bio-reduction capabilities, therapeutic potential, and stabilizing attributes inherent in B. hispida. This results in the formation of P-SeNPs with distinct and noteworthy qualities. Our findings were thoroughly substantiated through comprehensive characterizations employing various techniques, including ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential analysis, and Fourier transform infrared spectroscopy (FTIR). The nanoparticles exhibited a spherical shape, considerable size (22.32 ± 2nm), uniform distribution, and remarkable stability (-24mV), all of which signify the effective integration of the phytoconstituents of B. hispida. Furthermore, P-SeNPs displayed robust antibacterial efficacy against pathogenic bacterial strains, as indicated by their low minimum inhibitory concentration values. Our research also revealed the remarkable ability of P-SeNPs to fight cancer, as demonstrated by their impressive IC50 value of 0.19µg/mL against HeLa cells, while showing no harm to primary human osteoblasts, while simultaneously demonstrating no toxicity toward primary human osteoblasts. These pivotal findings underscore the transformative nature of P-SeNPs, which holds promise for targeted antibacterial treatment and advancements in cancer therapeutics. The implications of these nanoparticles extend to their potential applications in therapies, diagnostics, and various biomedical contexts. Notably, the environmentally sustainable synthesis process and exceptional properties established this study as a significant milestone in the field of nanomedicine, paving the way for a more promising and health-enhancing future.

QUERCUS CERRIS L.: ANTIBACTERIAL AND ANTIBIOFILM POTENTIAL

Invasion of pathogenic infections, antibiotic resistance, and formation of biofilms represent serious contemporary issues that threaten human health. Quercus cerris L. is a deciduous Mediterranean tree that has been used in folk medicine since the ancient times but without knowing its phytochemical profile. The aim of this study was to evaluate the antibacterial potential of aqueous and ethanolic leaf extracts against two Gram-positive bacteria (Streptococcus intermedius and Enterococcus faecium) and two Gram-negative bacteria (Escherichia coli and Stenotrophomonas maltophilia) using agar well diffusion and broth microdilution methods. The antibiofilm properties of Quercus cerris L. extracts were also tested against the listed bacteria. The results of this study showed that both extracts displayed antibacterial capacity. However, the test cultures were found to be more susceptible to the ethanolic extract than the aqueous one. The lowest minimum inhibitory concentration (MIC) (12 mg/ml) and minimum bactericidal concentration (MBC) (25 mg/ml) values of the ethanolic extract were registered against Escherichia coli, while the highest values were noted against Streptococcus intermedius. As for the aqueous extract, it showed only a bacteriostatic activity against all the tested bacteria with a MIC of 100 mg/ml. The results of the antibiofilm assays also showed that the ethanolic extract exhibited significant antibiofilm effects against the investigated microorganisms. In the light of the findings of this research study, the aqueous and ethanolic extracts of Quercus cerris L. may be very useful in the development of new plant-based antimicrobial agents.

Comparative chemomicrobiomic analysis of bacteriocins

Objective: comprehensive analysis of the spectrum of antibacterial action of bactеriocins.Material and methods. Chemomicrobiome analysis of bacteriocins A/B, C, S, 28b, RS-2020 was performed to assess the minimum inhibitory concentration (MIC) values for 152 strains of pathogenic bacteria and the area under the growth curve (AUC) values for a representative sample of normobiota (38 human commensal bacteria).Results. Compared to other molecules, bacteriocin C was characterized by lower MIC constants for a wide range of pathogenic bacterial strains. Thus, it more effectively inhibited strains of pathogens of bacterial pneumonia (H. influenzae, S. mutans, S. pneumoniae, S. pyogenes), nosocomial infections (K. pneumoniae, P. aeruginosa, S. aureus, S. epidermidis, S. pneumoniae), skin diseases (M. audouinii, T. mentagrophytes, etc.), urinary tract infections (E. cloacae, P. mirabilis and P. vulgaris), Fusobacterium necrophorum and Candida fungi. At the same time, bacteriocin C to a lesser extent than the reference molecules inhibited the growth of the normophysiological microbiota of the Bacteroides, Enterococcus genera, non-pathogenic Escherichia, yeast S. cerevisiae and others. By stimulating butyrate (butyric anion) producing microorganisms, bacteriocin C can exhibit prebiotic properties.Conclusion. The main structural features of the bacteriocin C molecule associated with the antibacterial effect on pathogenic microbiota were identified and described.

Comparing minimum inhibitory concentrations of amikacin for pulmonary Mycobacterium avium complex disease: An analysis of culture media differences

Mycobacterium avium complex (MAC) is considered a paramount microbe, especially in East Asia, including Japan. The commonly used commercial Minimum Inhibitory Concentrations (MIC) assay using Middlebrook 7H9 (7H9) medium deviates from the latest Clinical and Laboratory Standards Institute (CLSI) guidelines. Alternatively, measurement with cation-adjusted Mueller-Hinton broth (CAMHB) that conforms to CLSI standards is not yet widely available. Following the approval and commercialization of amikacin liposome inhalation suspension (ALIS) in 2021, a more precise evaluation of amikacin (AMK) susceptibility in MAC is necessary for treatment decisions. In the present study, 33 sputum samples were extracted from 27 patients, and MICs of AMK were compared between the frequently used 7H9 and the recommended CAMHB of the isolated MAC strains. The history of exposure to aminoglycosides for each sample was also added as clinical information. The findings indicated that there was only an 18% concordance rate in MIC between the two media, with 19 samples (58%) indicating lower MICs in 7H9 relative to CAMHB. The 17 samples had a history of exposure to aminoglycosides for periods ranging from 1.5 to 28 months. Specifically, 10 samples were exposed to amikacin by inhalation and intravenous injection, and the remaining seven samples had a history of ALIS inhalation. Samples with a prior utilization of aminoglycosides were significantly predisposed to developing resistance to ALIS compared to those without such a history (P = 0.046). Physicians are encouraged to scrutinize the findings of susceptibility testing utilizing CLSI-endorsed MIC assay using CAMHB medium to ascertain the optimal therapeutic approach.

Fabrication of Marsdenia tenacissima with decorated nickel oxide nanoparticles: Investigation of anticancer activity in lung cancer cells and its apoptosis

The possibility of fabricating metal nanoparticles using plant extracts has already been explored in phytomedicines. Nanobiotechnology has a wide range of potential applications, including the cosmetics industry, packaging, coatings, biomedicine, and the enhancement of biological activity. Nickel oxide (NiO) was fabricated in a waste-free, low-cost method and then used to adorn Marsdenia tenacissima extract (MTE), a crucial plant leaf. After forming the nanoparticles, MTE@NiO-NPs were also tested for their optical and biological qualities. The morphological characteristics of NiO-NPs are rhombohedra and slightly agglomerated, and the particle size of the biosynthesized NiO-NPs is observed in the range of ∼ 15 nm. The in vitro cytotoxicity of Marsdenia tenacissima extract (MTE) and nanoparticles on lung cancer cells (A549 and H1299) by MTT assay. The in vitro cytotoxicity assay results revealed that the newly fabricated nanoparticles effectively kill cancer cells with low minimal inhibitory concentration. The various biochemical staining assays assessed the cell death and morphological investigation. Furthermore, the mode of cell death was evaluated by mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS). Therefore, the study concludes that the plant leaves extract of Marsdenia tenacissima is a powerful reducing/capping agent in fabricating MTE@NiO-NPs, demonstrating useful biological features.

Genetic alterations in methicillin-susceptible Staphylococcus aureus associated with high vancomycin minimum inhibitory concentration

There are many reports on gene mutations observed in methicillin-resistant Staphylococcus aureus (MRSA) showing reduced susceptibility to vancomycin. However, there are limited studies on the genetic alterations that contribute to high vancomycin minimum inhibitory concentrations (MICs) in methicillin-susceptible S. aureus (MSSA). This study aimed to compare MSSA strains with high vancomycin MICs with those with low MICs, and to identify specific genetic alterations associated with increased vancomycin MICs. In total, 124 MSSA strains were analysed, with 62 having vancomycin MICs of 1-2 mg/L (MS-HV) and the remaining 62 having MICs <1 mg/L (MS-LV) as control. Polymerase chain reaction amplification and sequencing were conducted to identify point mutations and amino acid changes in the vraSR, graRS and walRK operons and rpoB gene. The number of single nucleotide polymorphisms (SNPs) and specific mutations in the indicated gene were compared between the two groups. The MS-HV strains had a significantly higher median number of SNPs in studied genes than the MS-LV strains (5 vs 3; P < 0.0001), with higher frequency of SNPs in the graR and walK genes. The MS-HV strains also displayed a significantly higher prevalence of specific mutations in the graR gene (V135I, I136V and V136I) compared with the MS-LV strains. The odds of having a high vancomycin MIC was 5.54 times higher in strains with a mutation in the graR gene, and 5.32 times higher in strains with a mutation in the walK gene, compared with those without these mutations. Mutations in the graR and walK genes may contribute to reduced vancomycin susceptibility in MSSA. This study gives key insights into the mechanisms underlying this phenomenon.

Evaluation of the Antimicrobial Activity of Chitosan Nanoparticles against Listeria monocytogenes.

Chitosan is obtained from the deacetylation of chitin, and it is known to possess antimicrobial activity. It has attracted attention as it may be used for treating infections caused by different types of microorganisms due to its broad spectrum. Its application in the form of micro- or nanoparticles (CM/CN) has expanded its usage, as in this form, it retains its activity, and remain stable in aqueous solutions. However, inconsistencies in the results reported by different authors have been identified. In this communication, the antimicrobial activity of CN produced from different starting materials was tested against Listeria monocytogenes. It was observed that, even though all the starting materials were reported to have a molecular weight (MW) below 200 kDa and degree of deacetylation (DD) > 75%, the size of the CNs were significantly different (263 nm vs. 607 nm). Furthermore, these differences in sizes exerted a direct effect on the antimicrobial properties of the particles, as when testing the ones with the smallest size, i.e., 263 nm, a lower Minimum Inhibitory Concentration (MIC) was achieved, i.e., 0.04 mg/mL. Even though the largest particles, i.e., 607 nm, in individual experiments were able to achieve an MIC of 0.03 mg/mL, the results with CN presented great variation among replicates and up to 0.2 mg/mL were needed in other replicates. The starting material has a critical impact on the properties of the CN, and it must be carefully characterized and selected for the intended application, and MW and DD solely do not fully account for these properties.

Selected antimicrobial essential oils to eradicate multi-drug resistant bacterial biofilms involved in human nosocomial infections

Biofilms are the primary source of contamination linked to nosocomial infections by promoting bacterial resistance to antimicrobial agents, including disinfectants. Using essential oils, this study aims to inhibit and eradicate the biofilm of enterobacteria and staphylococci responsible for nosocomial infections at Guelma Hospital, northeastern Algeria. Thymbra capitata, Thymus pallescens and Artemesia herba-alba essential oils were evaluated against clinical strains of Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus. The antimicrobial activity of the essential oils under consideration was assessed using an agar disc diffusion assay and the determination of minimum inhibitory concentrations (MICs). In addition, the crystal violet method and scanning electron microscopy (SEM) evaluated biofilm inhibition and eradication by those antimicrobial agents. The results indicate that T. pallescens essential oil was the most effective antimicrobial agent against pathogenic bacteria, with large zones of inhibition (up to 50 mm against S. aureus), low MICs (0.16 to 0.63 mg/mL), and powerful biofilm eradication up to 0.16 mg/mL in both 24 h and 60-min exposure times. Thus, Algerian thyme and oregano could be used in various ways to combat the biofilm that causes nosocomial infection in local hospitals.

Red light enhances the antibacterial properties, biofabrication, and stability of Fagonia indica callus-based silver nanoparticles.

Plant-based nanoparticles can be tuned through the frequency of light for efficient synthesis, structural properties, and antibacterial applications. This research assessed the effect of material type (callus and whole-plant extract) and the interaction with a specific range of light wavelength on AgNP synthesis. All types of AgNPs were characterized by their size, shape, associated functional groups, and surface charge. Interestingly, the size of red light and callus-based AgNPs (RC-AgNPs) was smaller (6.32 nm) compared to 14.59 nm for Ultraviolet light and callus-based AgNPs (UV-C-AgNPs). Zeta potential analysis showed that RC-AgNPs had higher stability (-29.2 mV) compared to UV-C-AgNPs (-16.7 mV). Similarly, red light-based AgNPs had higher Oxidation reduction potential in both whole-plant-based and callus-based AgNPs, indicating a more oxidizing nature compared to those synthesized under UV light. This was confirmed by the lower total phenolic and flavonoid content associated with them and their lower antioxidant activity. The higher antibacterial activities and lower minimum inhibitory concentrations of red light-based AgNPs against highly resistant pathogenic bacteria demonstrated the role of red light in enhancing antibacterial activity. These results indicate that AgNPs synthesized in red light and callus extract are more active compared to those synthesized under other wavelengths and/or in whole-plant extracts.

Klebsiella pneumoniae co-harbouring bla NDM-1 , armA and mcr-10 isolated from blood samples in Myanmar.

Background. The spread of Enterobacteriaceae coproducing carbapenemases, 16S rRNA methylase and mobile colistin resistance proteins (MCRs) has become a serious public health problem worldwide. This study describes two clinical isolates of Klebsiella pneumoniae coharbouring bla IMP-1, armA and mcr-10.Methods. Two clinical isolates of K. pneumoniae resistant to carbapenems and aminoglycosides were obtained from two patients at a hospital in Myanmar. Their minimum inhibitory concentrations (MICs) were determined by broth microdilution methods. The whole-genome sequences were determined by MiSeq and MinION methods. Drug-resistant factors and their genomic environments were determined.Results. The two K. pneumoniae isolates showed MICs of ≥4 and ≥1024 µg ml-1 for carbapenems and aminoglycosides, respectively. Two K. pneumonaie harbouring mcr-10 were susceptible to colistin, with MICs of ≤0.015 µg ml-1 using cation-adjusted Mueller-Hinton broth, but those for colistin were significantly higher (0.5 and 4 µg ml-1) using brain heart infusion medium. Whole-genome analysis revealed that these isolates coharboured bla NDM-1, armA and mcr-10. These two isolates showed low MICs of 0.25 µg ml-1 for colistin. Genome analysis revealed that both bla NDM-1 and armA were located on IncFIIs plasmids of similar size (81 kb). The mcr-10 was located on IncM2 plasmids of sizes 220 or 313 kb in each isolate. These two isolates did not possess a qseBC gene encoding a two-component system, which is thought to regulate the expression of mcr genes.Conclusion. This is the first report of isolates of K. pneumoniae coharbouring bla NDM-1, armA and mcr-10 obtained in Myanmar.

Control the carcinogenic bacteria with new polysaccharides from agricultural wastes

Agriculture activities industries produce a huge amount of waste every year. Agricultural wastes are a great source of natural polysaccharides characterized by accessibility, biocompatibility, and ease of modification. Finding new safe antibacterial agents has become one of the top priorities of health organizations worldwide. This priority emerged from the antibiotic resistance pathogenic bacteria hazard. Carcinogenic bacteria are one of the most dangerous antibiotic-resistant pathogenic bacteria. This study tries to investigate the antibacterial activity of polysaccharides from some agricultural wastes against carcinogenic bacteria related to gastrointestinal cancers. We determined the antibacterial activity (in terms of minimum inhibitory concentration (MIC)) and the biofilm reduction capacity. We studied the mechanism of the antibacterial activity by determining the effect of the MIC of the extracted polysaccharides on the plasma membrane permeability and the bacterial DNA content. All extracted polysaccharides showed effective antibacterial activity with low MICs ranging from 2 to 20 μg/mL. The barely straw polysaccharides showed the highest MIC (19.844 μg/mL) against Bacteroides fragilis, while the grape bagasse showed the lowest MIC (2.489 μg/mL) against Helicobacter pylori. The extracted polysaccharide showed high antibiofilm activity. Their capacity to reduce the formation of the pathogenic biofilm ranged from 75 to 95%. Regarding the antibacterial mechanism, the extracted polysaccharides showed destructive action on the DNA and the plasma membrane permeability. The bacterial DNA change percent after the treatment with the different polysaccharides ranged from 29% to −58%. The plasma membrane permeability increased by a high percentage, ranging from 92% to 123%. Agricultural waste polysaccharides are a promising antibacterial agent against antibiotic-resistant carcinogenic bacteria.

From Environmental Toxicants to Antibacterial Agents: BPA Analogues Selectively Inhibit the Growth of Gram-Positive Bacteria by Disturbing Biosynthesis of the Cell Wall.

Remarkable antibacterial activity of BPA analogues especially for tetrabromobisphenol A against Staphylococcus aureus 25923 (Sa25923) and methicillin-resistant Staphylococcus aureus (MRSA) has been reported in our previous studies. However, the toxic effects of the compounds as environmental contaminants on the endocrine system limited their applications in the field of medicine and health. Given the abuse of antibiotics has led to the emergence of multiple super-resistant bacteria, we considered that structural modifications based on the BPA structure will be available for molecular designing of potential antimicrobial agents without drug resistance. In this study, to further improve the antibacterial activity and reduce the biological toxicity, we performed the computational models to evaluate the binding affinities of BPA analogues to the potential target DltA protein in the biosynthesis of cell wall. A series of synthesized achiral analogues of α,α,α'-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene (α,α,α'-TEIB) exhibited low minimum inhibitory concentration against Sa25923 and MRSA (2 or 1 μg mL-1). Especially, the analogue A4 did not induce the drug-resistant mutants for all tested Gram-positive bacterial strains and exhibited relatively lower cytotoxicity in HepG2 cells. The developed classification model based on the light gradient boosting algorithm showed the superior performances on the internal robustness and generalization ability for the ligand-based virtual screening of bisphenol and polyphenol antimicrobial substances. Collectively, our findings suggest that the molecular structure of α,α,α'-TEIB is promising as a scaffold, which is expected to achieve a breakthrough in the development of antibiotics which can prevent the invasion of MRSA and other super bacteria.

Antibacterial and Anti-Biofilm Activities of Cinnamon Oil against Multidrug-Resistant Klebsiella pneumoniae Isolated from Pneumonic Sheep and Goats.

The primary objectives were to isolate and identify Klebsiella pneumoniae (K. pneumoniae), and determine the antimicrobial resistance patterns and biofilm formation abilities of the isolates. Additionally, the study aimed to investigate the antimicrobial and anti-biofilm effects of cinnamon oil against K. pneumoniae isolates. A cross-sectional study was conducted from March 2022 to April 2023 to collect 200 samples (including 156 nasal swabs and 44 lung specimens) from pneumonic sheep and goats admitted to the Veterinary Teaching Hospital of Zagazig University, Egypt. K. pneumoniae was isolated from a total of 72 (36%) samples, with 53 (73.6%) isolates recovered from nasal swabs and 19 (26.4%) from lung samples. Among the samples, 52 (36.9%) were from sheep and 20 (33.9%) were from goats. Antimicrobial susceptibility testing of the 72 K. pneumoniae isolates to 18 antimicrobials revealed that all isolates were resistant to ampicillin, amoxicillin/clavulanic acid, cefotaxime, ceftriaxone, tetracycline, colistin, fosfomycin, and trimethoprim/sulphamethoxazole. None of the isolates were resistant to amikacin, imipenem, and norfloxacin. Multidrug resistance (MDR) was observed in all K. pneumoniae isolates recovered from sheep and goats. The average MAR index was 0.71, ranging from 0.50 to 0.83. Regarding biofilm formation, among the K. pneumoniae isolates with a high MAR index (n = 30), 10% exhibited strong formation, 40% showed moderate formation, 43.3% displayed weak formation, and 6.7% did not form biofilms. Additionally, the biofilm-forming genes treC and fimA were present in all 28 biofilm-forming K. pneumoniae isolates, while the mrkA gene was detected in 15 (53.6%) of the 28 isolates. MDR K. pneumoniae isolates with strong biofilm formation abilities were treated with cinnamon oil at varying concentrations (100%, 75%, 50%, and 25%). This treatment resulted in inhibition zone diameters ranging from 35 to 45 mm. Cinnamon oil exhibited lower minimum inhibitory concentration and minimum bactericidal concentration values compared to norfloxacin for all isolates. Additionally, cinnamon oil significantly reduced the expression of biofilm-associated genes (treC, fimA, and mrkA) when compared to isolates treated with norfloxacin or untreated. In conclusion, this study identified a high level of MDR K. pneumoniae with strong and moderate biofilm formation abilities in pneumonic sheep and goats in Sharika Governorate, Egypt. Although cinnamon oil demonstrated potential antibacterial and anti-biofilm properties against K. pneumoniae, further research is required to investigate its effectiveness in treating K. pneumoniae infections in pneumonic sheep and goats.

Chemical composition and antimicrobial activity of essential oils from the leaves and rhizomes of Hedychium yunnanense Gagnep. (Zingiberaceae) collected in Vietnam

Hedychium yunnanense Gagnep., belonging to the Zingiberaceae family, has aroused much interest due to its non-volatile chemical constituents. Nevertheless, no data about essential oils (EOs) of this species is available. In this study, the chemical composition and antimicrobial activity of EOs from leaves and rhizomes of H. yunnanense collected in Vietnam were analyzed. The EOs of the rhizomes and leaves were obtained as yellow oils with extraction yields of 0.21 and 0.09%, respectively. Fifty-seven chemical components, accounting for 94.35-98.92%, were identified in the two EOs. The rhizomes EO mainly contains β-pinene (21.07%), 1,8-cineole (20.63%), α-pinene (8.80%) and camphene (6.35%), while the leaves EO was rich in β-pinene (45.92%), α-pinene (19.48%), and β-caryophyllene (18.26%). Both EOs exhibited more potent antimicrobial activities than the standard drug, streptomycin, as they demonstrated significantly lower minimum inhibitory concentrations against the tested bacteria and fungus. Additionally, the leaves EO may possess stronger antimicrobial activities than the rhizomes EO. The findings of the study will provide a better understanding of the chemical composition and bioactivities of H. yunnanense.

Antibacterial Activities and Chemical Compounds of Plantago lanceolata (Ribwort Plantain) and Plantago major (Broadleaf Plantain) Leaf Extracts

Background: Plantago lanceolata L. (ribwort plantain) and Plantago major L. (broadleaf plantain) are widely used in ethnobotanical studies and for treating various diseases. This study aims to investigate the antimicrobial activity and chemical compounds of these plants. Methods: The leaf extracts of P. lanceolata and P. major were fractioned using different solvents. The phytochemical screening was carried out by the gas chromatography-mass spectrometry (GC-MS) method. The antibacterial activity of extracts was assessed using the disc diffusion method, and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) were measured by microtiter-broth dilution method. Results: The dichloromethane leaf extract of P. lanceolata and P. major showed the highest antibacterial activity against Salmonella paratyphi (diameter of the inhibition zone: 18.83 and 20.00 mm, respectively) at 100 mg/mL concentration. The lowest MIC was related to dichloromethane extracts of both plants against S. paratyphi (500 µg/mL). The lowest MBC (1000 µg/mL) was related to the dichloromethane extract of P. major against S. paratyphi. The main compounds of P. lanceolata leaf extracts were bis(2-ethylhexyl) phthalate (41.96%), 1-methoxy-3-(2-hydroxyethyl)nonane (32.69%), bicyclo[3.1.1]heptane, 2,6,6-trimethyl- (1.alpha.,2.beta.,5.alpha.)- (10.45%), and cycloheptasiloxane tetradecamethyl- (27.96% and 31.33%). The main compounds of P. major leaf extracts were eicosane (23.62%), cyclohexasiloxane dodecamethyl- (18.21%), 1-methyl-3-n-propyl-2-pyrazolin-5-one (18.08%), cycloheptasiloxane tetradecamethyl- (33.85%), and 1,2-benzisothiazole-3-acetic acid, methyl ester (34.26%). Conclusion: Fractionation of the methanolic leaf extract of P. lanceolata and P. major can help better isolate active components from these plants. The antibacterial properties of the extracts of two plants may be due to the presence of antibacterial compounds detected in GC-MS.

In vitro sensitivity of Malassezia furfur isolates from HIV-positive and negative patients to antifungal agents

Malassezia is a lipophilic and lipid-dependent yeast genus belonging to the skin microbiota of humans and other animals. However, due to dysbiosis processes or other factors in the host, this yeast can cause different pathologies, ranging from skin diseases, such as seborrheic dermatitis, to fungemia. Isolation of Malassezia furfur has been reported in HIV-positive patients with or without skin lesions. Due to its opportunistic nature and its variable resistance to antifungal compounds, it is relevant to know the Malassezia sensitivity profiles. To determine the sensitivity to different antifungal agents, of clinical isolates of M. furfur obtained from HIV-positive or negative patients, with or without seborrheic dermatitis. Assessment of isolates sensitivity to itraconazole, voriconazole, fluconazole, and amphotericin B was performed by two techniques: (1) Broth microdilution using Clinical and Laboratory Standards Institute (CLSI) protocol M27-A3 with modifications; and (2) agar tests using Etest®. Isolates obtained from HIV patients showed an increase in the minimum inhibitory concentration of fluconazole, voriconazole, and amphotericin B, compared with those of non-HIV patients. Itraconazole was the antifungal with the lowest minimum inhibitory concentration (MIC) in most isolates. We observed differences in the sensitivity profiles of M. furfur isolates according to the context of the patient. High MIC of antifungals like fluconazole, commonly used for treating pathologies caused by Malassezia, were identified.