Antimicrobial peptides (AMPs) have emerged as promising alternatives to conventional antibiotics, addressing the growing concern of antibiotic resistance. Their efficacy primarily relies on two key properties: amphiphilicity and cationic charge, which promote targeted action on bacterial membranes. The Lynronne family, identified in the bovine rumen through metagenomic screening, already exhibits notable antimicrobial activity and low toxicity, making it a strong candidate for further development [1]. Our goal is to enhance the therapeutic potential of these AMPs using conventional and innovative strategies. Traditional approaches include substitutions with cationic amino acids and D/L enantiomeric modifications.

In parallel, we employed artificial intelligence techniques using the MRL (Molecular Reinforcement Learning) model for AMP design, based on the biophysical properties of the Lynronne family (cationic charge, hydrophobicity). The activity and toxicity of the designed peptides were first evaluated in silico using various prediction tools (MIC predictors and toxicity/hemolysis predictor). Their antimicrobial activity against diverse pathogens and their cytotoxicity on human cells were then measured, allowing comparison between predicted and measured activities. Their mechanism of action was studied via biophysical techniques, membrane permeabilization assays, and molecular dynamics simulations (GROMACS), confirming specific interactions with bacterial membranes and membranolytic effects. This study highlights how combining rational design strategies and AI can optimize Lynronne peptides, reinforcing their potential as alternatives to conventional antibiotics.

The emergence of antibiotic-resistant pathogens has necessitated the exploration of plant-based antimicrobial agents as alternative therapies. This study evaluates the antibacterial activity of Detarium senegalense stem bark extract against clinically significant bacterial species: Staphylococcus aureus, Salmonella species., and Bacillus species. The stem bark was collected from Daura Local Government Area of Katsina state, Nigeria. Clinical isolates were collected from Ahmadu Bello University Medical Centre then taken to Department of Microbiology for reconfirmation using standard microbiological methods. The stem bark was extracted using ethanol, and the antibacterial efficacy was assessed through the agar well diffusion method at concentrations of 100mg/ml, 50mg/ml, 25mg/ml, and 12.5mg/ml. Inhibition zones were recorded to determine the effectiveness of the extract, and the Minimum Inhibitory Concentration (MIC) was established. The extract demonstrated significant antibacterial activity, with notable inhibition zones against S. aureus and Salmonella species at 50mg/ml and 25mg/ml, respectively, indicating its potential as a natural antibacterial agent. Phytochemical analysis revealed the presence of bioactive compounds such as flavonoids, tannins, and alkaloids, which likely contribute to the observed antimicrobial effects. This study supports the potential use of Detarium senegalense stem bark as a source of bioactive compounds against pathogenic bacteria, providing a foundation for future research into its therapeutic applications and possible development as an alternative treatment for bacterial infections.

This review explores the biofilm architecture and drug resistance of Enterococcus faecalis in clinical and environmental settings. The biofilm in E. faecalis is a heterogeneous, three-dimensional, mushroom-like or multilayered structure, characteristically forming diplococci or short chains interspersed with water channels for nutrient exchange and waste removal. Exopolysaccharides, proteins, lipids, and extracellular DNA create a protective matrix. Persister cells within the biofilm contribute to antibiotic resistance and survival. The heterogeneous architecture of the E. faecalis biofilm contains both dense clusters and loosely packed regions that vary in thickness, ranging from 10 to 100 µm, depending on the environmental conditions. The pathogenicity of the E. faecalis biofilm is mediated through complex interactions between genes and virulence factors such as DNA release, cytolysin, pili, secreted antigen A, and microbial surface components that recognize adhesive matrix molecules, often involving a key protein called enterococcal surface protein (Esp). Clinically, it is implicated in a range of nosocomial infections, including urinary tract infections, endocarditis, and surgical wound infections. The biofilm serves as a nidus for bacterial dissemination and as a reservoir for antimicrobial resistance. The effectiveness of first-line antibiotics (ampicillin, vancomycin, and aminoglycosides) is diminished due to reduced penetration, altered metabolism, increased tolerance, and intrinsic and acquired resistance. Alternative strategies for biofilm disruption, such as combination therapy (ampicillin with aminoglycosides), as well as newer approaches, including antimicrobial peptides, quorum-sensing inhibitors, and biofilm-disrupting agents (DNase or dispersin B), are also being explored to improve treatment outcomes. Environmentally, E. faecalis biofilms contribute to contamination in water systems, food production facilities, and healthcare environments. They persist in harsh conditions, facilitating the spread of multidrug-resistant strains and increasing the risk of transmission to humans and animals. Therefore, understanding the biofilm architecture and drug resistance is essential for developing effective strategies to mitigate their clinical and environmental impact.

Antimicrobial-resistance (AMR) is a ‘natural phenomenon’ based on a selection of microorganisms able to survive in an unfavourable environment, owing to genetic mutations or the acquisition of “pre-established” resistance genes. The overuse and misuse of antibiotics can favour the emergence and spread of AMR, with negative impacts on the management of bacterial infections and economic implications for healthcare systems. Research and development of natural antibacterial molecules, which exhibit multiple bio-functionalities and are less likely to induce resistance in bacteria, could represent a priority in the coming years to improve the antibacterial activity of existing molecules and counteract AMR. The present study identified the most effective concentration and contact time of Thymus vulgaris L. essential oil (TEO) to achieve in vitro bactericidal activity against twenty-one bacterial strains isolated from different specimens. In total, 10 μl of a solution containing the TEO and the bacterial strains isolated was sown in Petri-dishes for successive assessments of antibacterial efficacy, in terms of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), after 24 and 48 hours, respectively. The identified strains (Mammaliicoccus lentus, 2Escherichia coli, Salmonella enterica subsp.enterica sierovar derby, 2Staphylococccus, S.xylosus, S.chromogenes, S.epidermidis, S.enterica subsp.diarizonae, S.enterica subsp.salamae, S.enterica subsp.houtenae, E.coli(b), S.aureus(b), Citrobacter freundii, Enterococcus feciorum, Proteus mirabilis, Acinetobacter cioffi, Pseudomonas putrefaciens and Klebsiella pneumoniae), each with different resistance profiles, and two ATCC strains (S.aureus and Streptococcus mutans) were tested after 6, 12, 24, and 48h of contact with TEO at different concentrations, from 5% to 2.5% to 1.25%(v/v), corresponding to 450, 225, and 112.5g/mL, respectively. We observed a complete inhibition of all bacterial strains after 12h of incubation at all TEO concentrations, demonstrating the efficacy of TEO against several Gram-positive and Gram-negative bacteria with different AMR. Further studies are needed to define the exact molecular mechanisms of TEO and its possible uses.

Introduction: Representatives of the genus Trichosporon are basidiomycetous yeast-like microorganisms that are widely distributed in nature. The genus Trichosporon includes species capable of causing both superficial and invasive infections associated with high mortality rates. A notable characteristic of the Trichosporon species is their resistance to many antifungal agents that are commonly used for the treatment of invasive fungal infections.

Materials and Methods: Trichosporon sp. were isolated from samples of the affected skin of a patient with a chronic infection. Identification was performed using MS (mass spectrometry).

The producer Streptomyces sp. strain SVP-71 was isolated from bentonite samples. The antifungal antibiotic was extracted from the culture fluid and biomass using butanol. Primary purification and metabolite separation were carried out using TLC. The obtained antibiotic was applied to sterile paper discs (14 µg per disc). Specific activity control was performed using discs with dried butanol.

The susceptibility of the clinical isolate to the obtained antibiotic was determined using the DDM, according to CLSI M44 guidelines. Caspofungin discs (5 mg, HiMedia), one of the most effective antifungal antibiotics, were used as a reference.

Results: Screening studies revealed the antagonistic activity of Streptomyces sp. strain SVP-71 against a wide range of yeast-like and filamentous fungi that are pathogenic to humans, including the emerging pathogen Candida auris. The disc diffusion method also confirmed the activity of secondary metabolites from Streptomyces sp. strain SVP-71 against the clinical isolate of Trichosporon sp., with growth inhibition zones reaching up to 20 mm. In contrast, echinocandin antibiotics (caspofungin) showed no specific activity against this microorganism.

Conclusions: The strain Streptomyces sp. SVP-71 demonstrates promise as a source of new antifungal agents, particularly for treating infections caused by fungi with natural resistance to standard antibiotics, such as echinocandins. This is of significant importance in the fight against mycoses that present as severe invasive infections.

Introduction: Antimicrobial resistance (AMR) is one of the most significant public health issues of the 21^st century. Numerous professional guidelines highlight the role of nurses and allied healthcare professionals in enabling and promoting appropriate antibiotic use; however, there is limited data on their knowledge and attitudes regarding AMR, despite the fact that they make up 50–70% of the healthcare workforce globally. The aim of the present study is to assess the knowledge and attitudes related to AMR among nurses and allied healthcare professionals in Hungary.

Methods: A quantitative, cross-sectional study was performed, using a 80-item, self-administered questionnaire, which was developed for the purposes of this study. The internal consistency of the instrument was determined during pilot studies (Cronbach’s α: 0.737, Kuder-Richardson KR-20: 0.724). In addition to assessing knowledge and attitudes, the recognition of twelve AMR-related concepts by the participants was also assessed. Data collection was carried out between 01/03/2021 and 01/03/2022. Statistical analyses (descriptive statistics, non-parametric tests, Spearman's rank correlation, χ² test) were performed using IBM SPSS 25.0 software. Ethical approval ID (SZTE-RKEB): 170/2020-SZTE; 4851.

Results: Among the n=255 participants in the study, 90.2% were female, 47.8% were employed in inpatient care, and their median age was 44 years (range: 21–67). The distribution of healthcare-related educational attainment was as follows: 30.6% held a vocational qualification (OKJ), 51.4% held a bachelors (BSc) degree, and 18.0% had a masters (MSc) degree. A majority (69.0%) identified their healthcare education as the primary source of their knowledge related to AMR. A positive self-assessment of academic achievement was associated with significantly higher knowledge scores (19.58±5.37 vs. negative: 16.39±5.42; p<0.001), more favorable attitudes (10.53±3.06 vs. negative: 8.36±2.66; p<0.001), and recognition of a higher number of AMR-related concepts (5.37±1.95 vs. negative: 4.70±1.55; p=0.01). No significant differences were observed in knowledge and attitude scores, or recognized AMR-related concepts based on age or level of educational attainment (p>0.05, respectively). Knowledge scores showed a positive, moderately strong, significant correlation with both attitude scores and the number of recognized concepts (r=0.549 and r=0.470; p<0.001 in both cases).

Conclusions: Nurses and allied healthcare professionals play a key role in integrated, patient-centered healthcare and, within the framework of task-shifting, may acquire additional responsibilities and authorizations within healthcare systems, in the context of AMR. The knowledge and attitudes of healthcare professionals related to AMR may have important implications for their daily clinical practice, and these may be improved through targeted educational interventions.

Currently, antimicrobial resistance is one of the major threats tohealthcare as multidrug-resistant strains of bacteria, yeasts, and molds continue to emerge. To address this issue, innovative solutions are needed, and one promising approach is the development of gemmotherapy extracts (GTEs) from plant parts such as buds and young shoots. In the current study, the antimicrobial activity of eight GTEs—raspberry, blackthorn, sea buckthorn, dog rose, lingonberry, hawthorn, common grapevine, and boxwood—was analyzed using agar diffusion and broth microdilution methods. The latter technique was used to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The antimicrobial efficacy was tested against seven bacterial strains, five mold strains, and two yeast strains, which can cause different health conditions in the human body. Using the agar-diffusion method, we found that Gram-positive bacteria showed good susceptibility, as lingonberry and dog rose GTEs formed inhibition zones even at a concentration of 10-20% in the case of Bacillus cereus and Staphylococcus aureus. On the contrary, none of the GTEs showed activity against Gram-negative bacteria, molds, or yeasts. By the broth microdilution method, we observed that dog rose and lingonberry GTEs were the most effective, inhibiting the growth of Gram-positive bacteria even at relatively low concentrations (10-40%). Gram-negative bacteria were more resistant to most GTEs, as only concentrations above 40-50% showed bacteriostatic effects. Yeast strains were the most resistant, as only concentrations above 60% were effective. Although the bactericidal effects were minimal, the GTEs from the lingonberry and the common grapevine were effective against five strains of bacteria, such as Enterococcus faecalis, Listeria monocytogenes, Enterococcus faecalis, Pseudomonas aeruginosa, and Salmonella enterica, with an MBC of 60-70%. Based on the antimicrobial properties observed, especially for dog rose and lingonberry GTEs, these extracts could be considered as potential agents to enhance the efficacy of antibiotic therapies.

Diabetes and diabetic foot ulcers (DFUs) pose a significant clinical burden. Antibiotic treatments are often ineffective, contributing to the growing antimicrobial resistance crisis.

We investigated interactions between bacterial isolates from diabetic and non-diabetic patients to detect the production of antimicrobial compounds with potential therapeutic applications.

A total of 539 bacterial strains were identified by 16S rRNA gene sequencing. In total, 79 isolates were from DFUs and 55 were from a contralateral non-ulcerated foot (NDFU), while 254 isolates were from diabetic patients without any skin ulcerations (intact diabetic skin - IDS), and 151 were from non-diabetic individuals (CT). The predominant genera identified were Staphylococcus (74.2%), Pseudomonas (5%), and Kocuria (3.3%).

Screening for antimicrobial activity was performed using spot-on-lawn agar diffusion assays against five indicator bacteria isolated from DFU (MDR and non-MDR S. aureus and P. aeruginosa and Staphylococcus CoNS). Overall, 6.7% of isolates exhibited antimicrobial activity against at least one indicator strain. The most active isolates belonged to the genera Staphylococcus (44.4%), Pseudomonas (30.6%), and Aerococcus (13.9%), with single active isolates from Acinetobacter, Bacillus, Enterobacter, and Pseudoxanthomonas.

Antimicrobial activity was mainly detected on isolates from DFU (10.1%), followed by IDS (7.9%), NDFU (7.3%), and, rarely, from CT (2.6%). Contact-dependent killing was ruled out by testing bacterial extracts. Isolates capable of producing diffusible antimicrobial molecules included Pseudomonas (10 isolates), Staphylococcus (5), Aerococcus (1), Bacillus (1), and Enterobacter (1). Additionally, Staphylococcus (2), Aerococcus (1), and Enterobacter (1) required competitive conditions to induce antimicrobial production.

Antimicrobial extracts were fractionated using organic solvents (Methanol, Ethanol, Acetone, Chloroform methanol (2:1), 1-Butanol) and chromatography (C18 cartridge) to isolate bioactive compounds. Whole-genome sequencing and genome-wide mining analysis uncovered promising biosynthetic gene clusters (BGCs), including one predicted to encode a rhizomide-like molecule.

This study highlights the potential of skin bacteria and their interactions as a source of novel antimicrobial compounds.

Funding: 2022.06809.PTDC_AMRFight

The antifungal potential of 12 isolates of Streptomyces derived from the bottom sediments of Trondheim Fjord, the Norwegian Sea, was investigated. It was found that the metabolites produced by the Streptomyces sampsonii INA01478 strain had pronounced antifungal activity against the opportunistic fungi Candida albicans and Fusarium oxysporum. To analyze the biologically active metabolites formed, a method of preparative separation using HPLC and a method for isolating individual compounds from the eluent were selected. The chromatograms of the tested samples obtained using the HPLC method showed two peaks with close retention times. Repeated preparative HPLC resulted in the isolation of two pure compounds that were identified using NMR and an MS data analysis. The major component of the subfraction was determined to be daidzein ([7-hydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one]), an isoflavonoid that has previously been described. The minor component had a similar but simultaneously different structure, the establishment of which is being studied. Daidzein exhibited a direct antifungal effect at 25 – 30 mm on Saccharomyces cerevisiae INA 01042 and the opportunistic filamentous fungi Aspergillus niger ATCC 16404 and Fusarium oxysporum VKPM F-148 and was totally inactive against the bacterial test organisms.

Daidzein is a naturally occurring phytoestrogen belonging to the group of non-steroidal estrogens. It is structurally similar to mammalian estrogen, so it can replace and/or inhibit it and thus has protective effects against diseases associated with estrogen control. _{[Goleij P et al., 2004].} In addition, daidzein inhibits oxidative damage and regulates immune reactions and apoptosis. Daidzein has a wide range of pharmacodynamic properties and represents a promising compound for drug development.

In recent decades, the interest in the Emericellopsis genus as producers of bioactive molecules has increased significantly due to the isolation of new compounds with potential pharmaceutical applications. The species of this genus produce a spectrum of peptide antibiotics with antibacterial and antifungal activity.

Evaluation of the spectrum of antibiotic activity has allowed us to choose a promising producer of new antibacterial compounds, the Emericellopsis sp. E102 strain derived from saline soils. Strain E102, based on molecular and phylogenetic constructions, is allocated into a separate clade within the marine clade of Emericellopsis and is presumably a new species. In this research, three previously undescribed compounds were isolated from the fungal strain E102, grown in both Czapek–Dox and PDB liquid culture media. The ethyl acetate extract of the E102 strain demonstrated significant efficacy against a concentration of 1,000 μg/mL, resulting in inhibition zones measuring 20 - 30 mm against Escherichia coli, ATCC 25922; Klebsiella pneumonia, ATCC 700603; Pseudomonas aeruginosa, ATCC 27853; Bacillus subtilis, АТСС 6633; Staphylococcus aureus, ATCC 29213; and Enterococcus faecalis, ATCC 29212. Based on HPLC separation of the ethanol concentrates, an active compound was obtained and investigated further. The monoisotopic mass of the compound, determined using MS, was 724.5 g/mol. Using the Chemcalc.org service, the most probable gross formulas ffor the required component were determined. Based on the calculations presented, there is a high probability that the substance has a sterane framework.

The work of Vladimir V. Sokolov and Marina L. Georgieva was supported by the Russian Science Foundation (grant #25-24-00291). The work of Ivan V. Mironov was carried out with institutional funding from the Gause Institute of New Antibiotics.