Identification and characterization of a novel lysin-like endopeptidase from the Vibrio cholerae predator phage ICP1.

Shigella flexneri causes bacillary dysentery by invading the colon epithe-lium, leading to inflammation and tissue damage. The emergence of multidrug-resistant (MDR) Shi-gella strains and the lack of effective vaccines have highlighted the need for alternative treatments. Natural plant compounds have been explored as potential antimicrobial agents. This study evaluates the antibacterial activity of ethanolic (70%-96%) and methanolic (70%-99.9%) extracts of Termi-nalia chebula Retz. against MDR S. flexneri and their effect on bacterial invasion of HeLa cells in vitro. We assessed the anti-MDR S. flexneri activity of these extracts by measuring minimum inhib-itory concentration (MIC) and minimum bactericidal concentration (MBC). Four Shigella strains belonging to various serotypes and resistant to multiple drugs were used in this study. The invasiveness of S. flexneri was assayed by plaque formation in HeLa cell culture under in vitro conditions. Ethanolic and methanolic extracts of Terminalia chebula Retz. were made in varying concentrations. The antibacterial effects of these extracts against MDR S. flexneri strains were evaluated by determining minimum inhibitory concentration (MIC) and min-imum bactericidal concentration (MBC). Plaque-forming assay confirmed that all four S. flexneri serotypes were highly invasive in HeLa cells. All the compounds screened herein were found to be antibacterial (MIC = 0.39-12.5 mg/mL) and (MBC = 0.78-25 mg/mL) against the multidrug-resistant invasive S. flexneri strain, while the MBC/MIC ratio showed both bactericidal and bacteriostatic activity. Shigella species are highly infectious and increasingly multidrug-resistant pathogens with significant invasive potential in intestinal cells, as confirmed by our HeLa cell plaque assay results, consistent with prior studies. Our investigation indicates that Terminalia chebula Retz. ex-tracts may exhibit antibacterial activity against multidrug-resistant invasive Shigella isolates. Com-parable research has reported similar antimicrobial effects of T. chebula against various resistant bac-teria, including Shigella sonnei, MRSA, and MDR Escherichia coli. While some studies found other plant extracts, such as Rhus javanica, more potent, bioactive compounds of T. chebula, such as gallic acid derivatives, support its promising role in combating antibiotic-resistant infections. These findings suggest that ethanolic and methanolic extracts of Terminalia chebula may have antimicrobial activity against multidrug-resistant and invasive Shigella flexneri. These pre-liminary results indicate that T. chebula extracts warrant further exploration as potential antimicrobial agents against MDR Shigella infections. However, given the limited sample size in this study, further research with larger and more diverse strains is necessary to confirm the therapeutic potential of these plant extracts.

A photoswitchable silver-(I) complex incorporating two arylazopyrazole ligands was synthesized and characterized. The system undergoes efficient and reversible trans-cis and cis-trans photoisomerization upon irradiation at 365 and 530 nm, respectively, with the metastable cis form exhibiting a thermal half-life of 13 days at 37 °C, indicating potential suitability for photopharmacological applications. The complex showed significant dose-dependent toxicity in both cancer (4T1) and normal (NMuMG) murine mammary gland cells. However, the concentration window around 18 μM was identified in which the cis photoisomer is not toxic in both normal and cancer mammary gland cells, while the trans photoisomer is toxic in cancer cells and nontoxic in normal cells. Favorably, in cancer 4T1 cells, the trans photoisomer was more toxic than cisplatin, which in turn was more toxic than the cis photoisomer. Both photoisomers were nontoxic in human prostate cancer (PC3) and nonsmall cell lung cancer (A549) cells. The complex showed higher fungistatic than bacteriostatic activity, with no differences in toxicity between photoisomers. In human keratinocytes (HaCaT), the cis photoisomer was nontoxic, while the LC50 of the trans one in these cells was 10 times higher than its MIC against Aspergillus fumigatus, revealing the potential of the complex as an antifungal agent.

Multidimensional investigation of Zn(II) and Ni(II) complexes: Crystallography, spectroscopy, TD/DFT calculations, hirshfeld surface analysis, bacteriostatic activity and molecular docking

Antibiotic resistant Gram-negative bacteria, in particular, extended spectrum β-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae are frequently involved in various human infections. Despite traditional applications of honey, a comprehensive evaluation of antimicrobial activity against ESBL-producing bacteria is lacking. This study aims to evaluate the antibacterial activity of honey against ESBL-producing and non-producing bacteria isolated from clinical samples (urine and sputum) by tube dilution method and the time kill viability assay. The minimum inhibitory concentration (MIC) of honey was found to be 25% (v/v) against most of E. coli (13 out of 18 isolates were inhibited by both indigenous and Dabur honey) and 50% (v/v) against most of K. pneumoniae (10 and 11 out of 14 isolates inhibited by indigenous and Dabur honey respectively). The MIC of honey for ESBL-producing and non-producing bacteria was found to be almost similar (p > 0.05). The complete reduction of bacterial population (8 log10 CFU/ml) was observed after 24 hours of exposure to honey at 50% (v/v) concentration. The honey samples showed bacteriostatic and bactericidal activity against tested isolates of ESBL-producing and non-producing E. coli and K. pneumoniae. These findings suggested indigenous honey serve as a promising complementary therapeutic agent in managing resistant bacterial infections.

Pharmacologic principles behind eye drop dosing: From pharmacokinetics to clinical practice.

The impacts of dietary xylooligosaccharide (XOS) were explored on growth, blood biochemistry, immune response, and resilience of olive flounder (Paralichthys olivaceus) against Edwardsiella tarda. Three replicate groups of fish (47.2 ± 0.41 g) were fed four diets incorporating various doses of XOS [0% (control), 1%, 2%, and 3%] to apparent satiety for eight weeks. Dietary inclusion of XOS improved growth performance and increased hepatosomatic and viscerosomatic indices. Serum alanine aminotransferase activity decreased with XOS supplementation, indicating improved liver status. Key innate immune parameters, including serum lysozyme, antiprotease, and alternative complement (ACH50) activities, were enhanced in XOS-fed fish. Skin mucus protein content also increased, whereas serum myeloperoxidase and glutathione peroxidase activities, as well as skin mucus antiprotease and protease activities, remained unchanged. XOS supplementation modulated serum bacteriostatic activity against non-pathogenic Escherichia coli and altered skin mucus lectin-binding patterns. Validation of the enhanced immune competence was confirmed by the enhancement of fish survival rate after exposure to E. tarda. Overall, the results demonstrate that dietary XOS, particularly at 3% inclusion, is effective in enhancing innate immunity and disease tolerance in olive flounder.

Trimethoprim is a clinically important antibiotic used for the routine treatment of urinary tract infections as a cost-effective first-line choice for treatment. A unique feature of the drug is that it can have bacteriostatic or bactericidal effects depending upon the metabolites available in the environment. Bacteriostatic activity requires the absence of nucleoside from the growth media. Conversely, bactericidal activity requires the presence of a nucleoside and the amino acids glycine and methionine. Mechanistically, bacteriostatic action does not appear to be dependent upon protein or RNA synthesis, whereas protein synthesis does not appear to be essential for bactericidal activity. Instead, this is likely due to the inhibition of DNA synthesis and the triggering of programmed cell death, involving the suicide module mazEF. In summary, trimethoprim has a complex mechanism of action that should be considered when researching the antibiotic and informing growth media design to test susceptibility.

The emergence of antimicrobial resistance necessitates the exploration of novel therapeutic agents from natural sources. This study investigated the antimicrobial properties of Clausena anisata fruit ethanol extract (CAFE) and its isolated compounds against 11 bacterial and three fungal strains. The dried fruits were extracted with ethanol using a Soxhlet apparatus. The extract was partitioned and subjected to chromatography to isolate two compounds, which were characterized as stigmasteryl 3-palmitate (C-01) and phellopterin (C-02) using NMR spectroscopy and LC-MS analysis. CAFÉ demonstrated notable inhibition zones in agar well diffusion assays, with the strongest activity against Klebsiella pneumoniae (14.67 ± 2.08 mm) and Staphylococcus saprophyticus (13.67 ± 0.58 mm). Microbroth dilution assays revealed MIC values ranging from 0.0781 to 1.2500 mg/mL for CAFÉ and 0.0781 to 1.2500 mg/mL for stigmasteryl 3-palmitate and phellopterin, respectively. CAFE demonstrated bactericidal activity (MLC/MIC ≤ 4) against Pseudomonas aeruginosa, Proteus mirabilis, Salmonella typhimurium, K. pneumoniae, Streptococcus sanguis, S. saprophyticus, and Candida glabrata, while showing bacteriostatic activity (MLC/MIC > 4) against Candida albicans. Stigmasteryl 3-palmitate exhibited bactericidal activity against P. mirabilis, S. typhimurium, K. pneumoniae, and S. sanguis, with bacteriostatic effects against the other organisms. Phellopterin demonstrated primarily bacteriostatic activity except against S. saprophyticus. Both compounds showed potent fungicidal activity against Candida species. These findings highlight the therapeutic potential of C. anisata fruit and its constituents against typhoid fever, hospital-acquired pneumonia, and invasive candidiasis. This is the first report on the antibacterial and antifungal activities of C. anisata fruit, stigmasteryl 3-palmitate, and phellopterin.

Staphylococcus aureus (S. aureus), a major foodborne pathogen contaminating dairy products, threatens food safety and public health via food poisoning and severe infections like bacteremia. Conventional culture-based methods are time-consuming, while advanced techniques need expensive equipment, limiting on-site use. To address this, we developed a novel Magnetic Mesoporous MnOx Nanozyme Probe (MMMNPs) by integrating Mesoporous MnOx Nanozyme with oxidase-mimetic activity, Fe3O4 magnetic nanoparticles, and S. aureus-specific aptamers. The synthesis involved the preparation of hydrothermal Fe3O4, the synthesis of MnOx, and the construction of a composite with bond positions and electrostatic interactions. For detection, MMMNPs mixed with samples underwent magnetic separation, followed by TMB-triggered color reaction. S. aureus (0 - 106 cfu·mL-1) inhibited probe activity, fading solution from deep blue to colorless. There was a good linear correlation (R2 = 0.980) between the shift of the absorbance peak at 652 nm and the logarithm of S. aureus concentration, with a LOD of 3.33 cfu·mL-1 for UV-Vis detection and 1x102 cfu·mL-1 for naked-eye visual detection.The probe exhibited high specificity, with no response to interfering bacteria, and demonstrated good applicability in spiked milk (recovery: 86.84% - 113.81%, RSD <5%). Unexpectedly, lower detection limits and better linearity were also achieved in the milk samples. Preliminary tests confirmed Mag-MnOx's significant bacteriostatic activity against S. aureus. This low-cost, easy-to-operate strategy enables S. aureus detection and elimination, promising on-site use in food safety and clinical diagnosis.

Coating materials extend fruit shelf life by forming protective barriers against microbial growth and preserving freshness. Herein, three chitooligosaccharide (COS) derivatives were synthesized via grafting protocatechuic acid, caffeic acid, and gallic acid onto COS, with their structures characterized. Fourier transform infrared spectroscopy confirmed successful grafting via amide linkages. 1H NMR analysis revealed new absorption peaks between 6.5 and 7.5 ppm, attributable to the grafted phenolic acids. Compared to ungrafted COS, the derivatives exhibited enhanced antioxidant activity and superior bacteriostatic activity. Spraying 2 mg L-1 derivatives on cherry tomatoes significantly reduced decay (33.7%-44.7%), browning (14.3%-23.6%), and the accumulation of reducing sugars (41.9%-49.6%) and soluble solids (13.3%-22.3%) during storage. These derivatives alleviated oxidative stress by enhancing catalase activity and reducing malondialdehyde levels, while inhibiting polyphenol oxidase to slow phenolic degradation and delay senescence. This grafted COS derivative coating offers enhanced biocompatibility for cherry tomato preservation systems.

Introduction: Upper respiratory tract infections (URTIs) are common and frequently treated with antibiotics, contributing to the emergence of bacterial resistance. Medicinal plant extracts represent a promising natural alternative. Ocimum gratissimum, rich in bioactive secondary metabolites, has noteworthy antiseptic potential. Methods: Leaves of O. gratissimum were extracted by aqueous infusion and phytochemically characterized. Antimicrobial activity was evaluated in vitro against Staphylococcus aureus using broth microdilution with resazurin to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Nine nasal spray formulations were developed, physicochemically evaluated, and subjected to microbiological quality control according to the European Pharmacopoeia. Results: The extraction yield was 33.33%. Phytochemical screening revealed the presence of polyphenols, flavonoids, saponins, alkaloids, sterols, terpenes, and cardiotonic glycosides. Total flavonoid and polyphenol contents were 1413 ± 0.836 mg QE/g dry extract and 202.098 ± 0.691 mg GAE/g dry extract, respectively. The extract exhibited bacteriostatic activity against S. aureus (MIC = 0.048 mg/mL; MBC = 0.195 mg/mL; MBC/MIC ≥ 4). The final formulation showed a pH compatible with the nasal mucosa, consistent spray volume per actuation, and compliance with microbiological standards. Conclusion: The formulated nasal spray containing aqueous extract of O. gratissimum is stable, safe, and demonstrates promising in vitro antimicrobial activity. Further tolerance and clinical efficacy studies are required before therapeutic application.

The use of antibiotics in aquaculture has raised serious concerns regarding the emergence of bacterial resistance and adverse environmental impacts. Red seaweed (Halymenia durvillei) is known to contain bioactive secondary metabolites with potential antibacterial properties. This study aimed to evaluate the antibacterial efficacy of ethanol extract of H. durvillei against four fish pathogenic bacteria, namely Edwardsiella tarda, Aeromonas hydrophila, Aeromonas salmonicida, and Vibrio parahaemolyticus, using agar well diffusion and broth microdilution assays. The experiment was arranged in a completely randomized design consisting of five extract concentrations (100%, 75%, 50%, 25%, and 12.5%) with five replications. The results showed that E. tarda exhibited the largest inhibition zone (16.2 mm) at 100% extract concentration, followed by A. salmonicida (10.8 mm) and A. hydrophila (10.4 mm). In contrast, V. parahaemolyticus did not produce an inhibition zone in the agar diffusion assay. The broth microdilution test revealed minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 25% and 50%, respectively, for all tested bacteria. The red seaweed extract demonstrated both bacteriostatic and bactericidal activity, indicating its potential as a natural antibacterial alternative for disease control in aquaculture.

The use of antibiotics in aquaculture has raised serious concerns regarding the emergence of bacterial resistance and adverse environmental impacts. Red seaweed (Halymenia durvillei) is known to contain bioactive secondary metabolites with potential antibacterial properties. This study aimed to evaluate the antibacterial efficacy of ethanol extract of H. durvillei against four fish pathogenic bacteria, namely Edwardsiella tarda, Aeromonas hydrophila, Aeromonas salmonicida, and Vibrio parahaemolyticus, using agar well diffusion and broth microdilution assays. The experiment was arranged in a completely randomized design consisting of five extract concentrations (100%, 75%, 50%, 25%, and 12.5%) with five replications. The results showed that E. tarda exhibited the largest inhibition zone (16.2 mm) at 100% extract concentration, followed by A. salmonicida (10.8 mm) and A. hydrophila (10.4 mm). In contrast, V. parahaemolyticus did not produce an inhibition zone in the agar diffusion assay. The broth microdilution test revealed minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 25% and 50%, respectively, for all tested bacteria. The red seaweed extract demonstrated both bacteriostatic and bactericidal activity, indicating its potential as a natural antibacterial alternative for disease control in aquaculture.

Introduction: Periodontitis progressively destroys tooth-supporting tissues. Conventional oral therapies often cause systemic side effects and fail to reach therapeutic levels in periodontal pockets. Doxycycline, studied for its local antimicrobial and anti-inflammatory effects, was used here as a 0.1% gargle. Case report: A 58-year-old woman presented with upper left tooth mobility, chewing pain, discomfort, and bleeding on brushing. Treatment included education, scaling/root planing, splinting, and twice-daily 0.1% doxycycline gargle post-brushing. After 2 months, gingival consistency had firmed, color had normalized, tooth mobility had reduced, and pocket depths had decreased. Discussion: Doxycycline inhibits subgingival pathogens and binds to dentin for sustained bacteriostatic action. It also suppresses collagenases (MMPs) from neutrophils and bacteria. Conclusion: In this case, 0.1% doxycycline gargle reduced gingival inflammation and improved clinical parameters as initial therapy before surgery, suggesting potential as a low-cost adjunct.

SPR720 is an aminobenzimidazole that is converted rapidly in vivo to the active moiety SPR719, which inhibits in mycobacteria the ATPase activity of DNA gyrase B. The efficacy, safety, and pharmacokinetics of orally administered SPR720 were evaluated in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD). Twenty-two patients meeting criteria for nodular-bronchiectatic NTM-PD were randomly assigned in a 1:1:1 ratio to placebo, SPR720 500 mg once daily (QD), or SPR720 1000 mg QD for 56 days, and three patients received open-label treatment with SPR720 1000 mg QD or SPR720 500 mg twice daily. For the primary efficacy endpoints, observed weekly sputum log10 CFU/mL and time to positivity, no difference was observed among treatment groups with no dose response between SPR720 500 mg QD and 1000 mg QD. Mycobacterial suppression was maintained through Day 56. Treatment-emergent adverse events were reported in six (75%), seven (100%), and nine (90%) patients with placebo, SPR720 500 mg QD, and SPR720 1000 mg, respectively. Dose-dependent, reversible hepatic enzyme elevations occurred in 11 (65%) patients treated with SPR720, including three (18%) who experienced grade 3 toxicity. Orally administered SPR720 had limited bacteriostatic activity against Mycobacterium avium complex and caused reversible hepatic enzyme elevations in the majority of patients. This study was registered with ClinicalTrials.gov: NCT05496374, 09/08/2022.

Copper and zinc nanoparticles have been suggested as potent anticancer agents, particularly against osteosarcoma, a highly aggressive bone cancer with limited treatment options. In order to avoid systemic toxicity, biomolecular carriers able to chelate metal ions and deliver them in a targeted manner to the vicinity of cancer cells need to be developed. Herein, we have used a histidine-containing, cyclic dipeptide as a carrier able to chelate stabilized copper and zinc nanoparticles. The cyclic peptide cyclo-(histidine-phenylalanine) (cHF) self-assembled into amyloid-type fibrils; morphological and structural characterization following metal addition confirmed the formation of cHF-CuNPs and cHF-ZnNPs. These composite nanoparticles demonstrated bacteriostatic activity against Escherichia coli and Staphylococcus aureus at the in vitro level. We evaluated the optimal concentration of cHF-metalNP complexes with limited cytotoxicity to L929 fibroblasts and high cytotoxic effects against MG-63 osteosarcoma cells. Their cytotoxicity was particularly pronounced at pH 6.4, which emulates the tumor microenvironment. The cHF peptide alone did not demonstrate significant antimicrobial or cytotoxic effects to both cell types, suggesting that it can act as a cytocompatible, pH-responsive carrier of metal ions with targeted dual functionality against both microbial infections and osteosarcoma cancer cells.

The emergence of vancomycin-resistant Enterococcus (VRE) has posed a significant global health threat, especially in healthcare settings where treatment options are increasingly limited due to rising antibiotic resistance. Maslinic acid, a naturally occurring pentacyclic triterpene found in olives, is known for its diverse biological activities, including anti-inflammatory, anticancer, antioxidant, and antimicrobial effects. In this study, we investigated the antibacterial and antibiofilm potential of maslinic acid against VRE. Initial screening identified maslinic acid as a potent hit, with minimum inhibitory concentrations (MICs) ranging from 4 to 8 µg/mL across 13 clinical enterococcal isolates, including multidrug-resistant strains. Time-kill assays demonstrated bacteriostatic activity comparable to linezolid, while cytotoxicity and hemolysis assays confirmed its safety in mammalian cells. Furthermore, maslinic acid disrupted established Enterococcus faecalis biofilms by approximately 50%, whereas linezolid was not effective against biofilms. Notably, maslinic acid significantly reduced bacterial burden in a Caenorhabditis elegans infection model by 80%, outperforming linezolid. These findings highlight maslinic acid as a promising candidate for the development of new therapies targeting VRE, with the added advantage of antibiofilm activity and a favorable safety profile.

Biomimetic gold nanoparticles (Au NPs) were synthesized via a sustainable approach without any additional toxic chemical reagents and fully characterized. It was proven that only whole aqueous extracts of Rosa damascene (RD) and Rosa rugosa (RR) are powerful enough to reduce, graft, and stabilize metallic nanostructures, resulting in the formation of stable, monodisperse nanocolloids (Au@RD NPs and Au@RR NPs) whereas individual constituent molecules were insufficient to yield stable metal NPs. The biological study conducted, both in vitro and in vivo, revealed no acute cytotoxicity (in HaCaT cell lines and zebrafish larval models) but bacteriostatic activity at equivalent doses with potent inhibition of biofilm formation (for a MRSA strain). Noteworthy, the additive antibacterial activity of rose extracts when combined with rifampicin promotes that these attractive inorganic-organic hybrids could be suitable alternatives to combat the acquisition of antimicrobial resistance. This huge application potential was also emphasized by the presence of insignificant changes in the expression of pro-inflammatory cytokine genes (IL-1β, IL-6, and CXCL8) and apoptotic/autophagic associated genes (TP53, MAP1LC3B, and SQSTM1) in treated HaCaT cells at antimicrobial doses. In addition, at the studied doses, the survival of Danio rerio larvae and their proper development (i.e., lack of deformities) endorsed biocompatibility in vivo.

Lactobionic acid (LBA) has demonstrated antibacterial activities against multiple foodborne bacteria; however, few studies have reported on its effect against Cronobacter sakazakii. In this study, the antibacterial activity and mode of LBA against C. sakazakii were explored. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of LBA against C. sakazakii were 12.5 and 25 mg/mL, respectively. LBA exhibited bacteriostatic activity at sub-MIC and bactericidal activity at concentrations ≥ MIC. Alkaline phosphatase (AKP) activity, cell outer membrane (OM) permeability, protein leakage, and gel electrophoresis results suggested that LBA increased the permeability of the cell wall and OM, leading to intracellular protein leakage and a decrease in protein contents and activity, indicating LBA damage to the cell wall and membrane. Among these, the rapid AKP activity surge reached 4.37 U/gprot at 2 MIC, and the OM permeability dramatically increased up to 10 min and stabilized after 30 min. Microscopic observations confirm the disruption to the cell wall and membrane, further showing that LBA disrupted the integrity of the cell wall and membrane. Moreover, LBA disturbs normal cellular functions by binding to deoxyribonucleic acid (DNA), as reflected by the competitive binding assay. Overall, LBA possesses potential multiple applications in the food industry due to its natural and antibacterial properties.