Escherichia coli O157:H7 is an enterohemorrhagic pathogen responsible for severe gastrointestinal illness, including hemorrhagic colitis and hemolytic uremic syndrome (HUS), with disease severity primarily driven by Shiga toxin production and other virulence determinants.
Conventional antibiotic therapy is often contraindicated due to toxin induction, intensifying the interest in traditional medicinal plants and their bioactive constituents as alternative therapeutic options.

In this study, we investigated the antibacterial activity of three essential oil-derived phytocompounds widely used in ethnomedicine: geraniol from Cymbopogon martini, cinnamaldehyde from Cinnamomum verum bark oil, and citral from Cymbopogon flexuosus. These compounds are traditionally valued for their antimicrobial and gastrointestinal protective properties. Antibacterial efficacy against E. coli O157:H7 was evaluated using growth inhibition assays and time-kill analyses.

All three phytocompounds demonstrated concentration-dependent inhibition of bacterial growth. Time-kill assays revealed significant reductions in viable bacterial counts at sub-minimal inhibitory concentrations, indicating predominantly bacteriostatic activity. Ongoing real-time PCR studies aim to assess the influence of these compounds on the expression of key virulence-associated genes.

The present findings support the ethnopharmacological relevance of Cymbopogon spp. and C. verum-derived phytochemicals and highlight their potential as natural antibacterial agents against enterohemorrhagic E. coli. These results provide a scientific basis for further exploration of traditionally used essential oil components in the development of alternative strategies for managing enteric infections.

Introduction: Inappropriate urine culture testing can lead to unnecessary antibiotics use and antimicrobial resistance. We evaluated the implementation of a stepwise stewardship intervention, with a focus on the appropriateness of urine culture orders and antibiotic use.Methods: We conducted a quasi-experimental study from August 2021 to Jun 2023 at a teaching hospital in Riyadh, Saudi Arabia. We included adult patients with urine culture orders. A stepwise antimicrobial stewardship intervention was implemented in two phases. In the first phase, a clinical decision support (CDS) tool was introduced in February 2022. In the second phase, a reflux urine culture was implemented in January 2023. Our outcomes were the percentage of inappropriate urine cultures ordered and antibiotic use. Outcomes were assessed at baseline, after the CDS intervention, and after the reflux urine culture intervention. We used multivariable logistic regression to estimate adjusted odds ratio, controlling for potential confounding variables. Results: During the pre-intervention period, the percentage of inappropriate urine culture order was 41.6%. Following the implementation of the first intervention—CDS—the percentage decreased to 36.4%. Subsequently, with the addition of reflux urine culture in the second phase of the stepwise intervention, the percentage further decreased to 28.6% (p value=<0.001). The stepwise intervention was associated with 15 lower odds of inappropriate urine culture ordering (adjOR 0.85; 95%CI 0. 0.69 – 0.90; p = 0.027). A significant reduction in Unnecessary antibiotics was observed across the three phases: 72.9% pre-intervention, 85.7% post-CDS, and 25% post-CDS and reflux urine culture (p <0.0001). The stepwise intervention was associated with 75% reduction in unnecessary antibiotic use (aOR 0.25; 95% CI 0.17 – 0.37, p <0.001)

Conclusions: This stepwise intervention suggest that each intervention contributed incrementally to decrease inappropriate urine culture and unnecessary antibiotic use.

Bone regeneration is frequently compromised by post-surgical infections and the growing prevalence of antimicrobial resistance, underscoring the urgent need for biomaterials with intrinsic, non-leaching antibacterial properties that can mitigate the emergence of resistant strains (Sadowska et al., 2021).

In this study, a multifunctional hybrid biomaterial composed of polycaprolactone (PCL), manganese-doped hydroxyapatite (Mn-HA), and the amphiphilic copolymer inulin-g-branched polyethyleneimine-g-poly(D,L-lactide) (INU-bPEI-PLA) (Mazzacano et al., 2025) was developed and evaluated for its antimicrobial potential. PCL was selected as the structural matrix owing to its established biocompatibility, bioresorbability, mechanical stability, favorable processing characteristics, and controlled degradability (Tommasino et al., 2025). Mn-HA was incorporated as a bioactive inorganic phase capable of enhancing osteogenic responses (Bauer et al., 2024), while released Mn²⁺ ions have also been reported to exert antimicrobial effects (Kolmas et al., 2015). The copolymer INU-bPEI-PLA was introduced to modulate the intrinsic hydrophobicity of PCL, improve blend processability through its amphiphilic nature, and provide cationic PEI domains known to disrupt bacterial membranes (Gibney et al., 2012). We hypothesized that the combined presence of Mn²⁺ ions and PEI moieties could produce a synergistic antibacterial effect while preserving the regenerative functionality of the composite.

Blends with varying compositions were prepared by solvent casting to investigate both the individual and combined effects of Mn-HA and INU-bPEI-PLA on PCL processability and resistance to microbial colonization by selected nosocomial strains. Morphological (SEM), dimensional, and thermal (DSC) analyses confirmed the successful fabrication of homogeneous composite disks suitable for preliminary antibacterial screening.

Overall, this study establishes a rational basis for selecting optimized formulations for extrusion-based 3D printing and for the subsequent development of infection-resilient scaffolds for bone tissue regeneration.

In response to the critical rise in multidrug-resistant (MDR) bacteria, the LAMEXA-LAMA laboratory at the University of Panama has conducted research focused on the search for bacteriophages as a therapeutic and sanitary alternative. This study involved the isolation and biological characterization of lytic phages specific to Klebsiella pneumoniae and Serratia marcescens, utilizing hospital and urban wastewater matrices from the Dr. Arnulfo Arias Madrid Hospital Complex, the Cinta Costera pumping station, and the Panama City Wastewater Treatment Plant (WWTP). The bacterial strains used were previously identified via the Vitek-2 system and endpoint PCR. As a result, 12 phages (7 for K. pneumoniae and 5 for S. marcescens) were isolated and purified using the double-layer agar technique, with subsequent tests conducted using stock concentrations of 10⁷ PFU/mL. Phenotypic evaluation demonstrated that 57% of the K. pneumoniae phages and 20% of the S. marcescens isolates exhibit effective lytic activity against clinical and environmental strains with confirmed MDR profiles. Furthermore, candidates with exceptional physicochemical stability were identified, maintaining viability across a pH range of 3 to 11, thermal resistance up to 60°C, and tolerance to 90% chloroform concentrations. Additionally, phages showed suppression indices of 50% at an MOI of one. These findings lay the groundwork for the genomic sequencing and bioinformatics analysis phase, aimed at validating their application in phage therapy, biological control, and water sanitation protocols. This project seeks to consolidate a robust line of research extending to other pathogens within the ESKAPE group, strengthening Panama's scientific infrastructure against modern medical threats.

Objectives:

The Burkholderia cepacia complex (BCC) comprises significant opportunistic pathogens frequently associated with healthcare-related infections and high levels of multidrug resistance. Due to extensive intrinsic and acquired resistance across multiple antimicrobial classes, these infections pose a major therapeutic challenge, particularly in immunocompromised patients. This study investigated the in vitro activity of imipenem/relebactam (IMI/REL) and evaluated its synergistic and bactericidal effects in combination with meropenem (MEM) and tigecycline (TIG) against clinical BCC isolates.

Methods:

A total of 20 non-epidemiologically related clinical BCC isolates were included. Minimum inhibitory concentrations (MICs) were determined by broth microdilution in accordance with CLSI (2023) guidelines, with Pseudomonas aeruginosa ATCC 27853 as the quality control strain. Synergistic potential and bactericidal activity of IMI/REL-based combinations were assessed using time-kill assays. Bacterial counts (CFU/mL) were measured over 24 hours, and log reductions were calculated relative to the initial inoculum.

Results:

IMI/REL showed 80% susceptibility against the tested BCC isolates. Based on MIC₅₀ and MIC₉₀ values, the activity profiles were as follows: IMI/REL (1/4 and 128/4 mg/L), MEM (4 and 8 mg/L), and TIG (2 and 4 mg/L). Time-kill analyses revealed that the IMI/REL–MEM combination produced the most pronounced synergistic effect, achieving a ≥3-log10 reduction in bacterial counts compared with the initial inoculum within 24 hours. No antagonistic interactions were detected among the tested combinations.

Conclusion:

Our findings indicate that IMI/REL has significant in vitro activity against clinical BCC isolates. The marked synergy and potent bactericidal effect observed with the IMI/REL–MEM combination highlight its potential as a promising therapeutic alternative for treating severe infections in immunocompromised patients caused by this challenging multidrug-resistant pathogen.

Since the clinical introduction of antibiotics, antimicrobial resistance (AMR) has emerged as a global challenge. AMR has been recognized as one of the leading causes of mortality worldwide, impacting human, animal, and environmental health, thereby necessitating an integrated One Health approach. In this context, β-lactamases, enzymes capable of hydrolyzing β-lactam antibiotics, stand as the most significant mechanism of AMR. Consequently, the use and search for β-lactamase inhibitors have become an essential strategy to preserve the efficacy of these antibiotics. Following the analysis of the β-lactamase TEM-1 (PDB ID: 1ERM) active site's chemical features, 34 five-residue peptides were formulated. Peptide construction was performed using the Discovery Studio Visualizer and was subsequently optimized using Foldit Standalone. Docking was carried out with the GOLD software, using the GoldScore function. To date, the three best performing peptides (Peptides 32, 33 and 34) were selected for Molecular Dynamics (MD) studies, which were performed using the Desmond program. Peptide 32 established hydrogen bonds with the conserved residues essential for catalysis (S70, S130, K73, E166, N170). Peptide 34 formed hydrogen bonds with the residues (S130, E166, N170). Furthermore, Peptide 33 exhibited hydrogen bonds with (S130, K73, E166, N170). Considering the MD studies, it was observed that two of the three peptides (Peptides 32 and 34) demonstrated stability in the active site, remaining bound throughout the simulation, which corroborates the prediction of a probable inhibition. Conversely, Peptide 33 did not maintain stable interactions and failed to remain in the active site. Specific analyses of the interactions observed during the simulation time are currently being conducted. Based on these results, these peptides, which are promising as b-lactamase inhibitors, will subsequently be synthesized for minimum inhibitory concentration (MIC) assays to confirm in vitro the results obtained in silico. Moving forward, the peptides will be investigated against other β-lactamases such as KPC and CTX-M.

Introduction: Carbapenem-resistant Acinetobacter baumannii represents a global health problem due to its limited therapeutic options and high associated mortality. Cefiderocol, a novel siderophore cephalosporin derivated has emerged as a potential treatment for infections caused by multidrug resistant Gram-negative bacteria as Acinetobacter baumannii, however, its microbiological activity, clinical performance, and resistance patterns remain heterogeneous across different studies.

Objective: To synthesize and critically evaluate the available scientific evidence regarding the activity of cefiderocol against Acinetobacter baumannii, with particular emphasis on susceptibility profiles and clinical outcomes, including mortality.

Material and methods: A structured literature search was conducted in PubMed, Scopus and Cochrane data bases between the 2018 and 2025 period, where the primary search terms included “Acinetobacter baumannii” and “cefiderocol,” both as MeSH terms. After excluding non-relevant bacterial species, 61 articles were retrieved, of those, 18 studies were excluded for not meeting the predefined inclusion criteria. Consequently, 43 studies were included in the final narrative synthesis and qualitative analysis.

Results: The integrated evidence demonstrates that cefiderocol exhibits relevant in vitro activity against Acinetobacter baumannii. In vivo studies indicate that cefiderocol retains bactericidal activity against susceptible isolates and that combination therapy, particularly with ampicillin/sulbactam, may enhance antimicrobial efficacy. Clinical and observational evidence evaluating mortality was limited. The available observational study reported mortality rates comparable to those previously described for carbapenem-resistant Acinetobacter baumannii infections, with no statistically significant difference between cefiderocol monotherapy and combination therapy.

Conclusions: Cefiderocol demonstrates consistent in vitro and in vivo activity against Acinetobacter baumannii, including carbapenem-resistant and colistin-resistant isolates, however, clinical evidence evaluating mortality outcomes remains limited. Therefore, while cefiderocol represents a promising option for the treatment of Acinetobacter baumannii infections, its impact on mortality cannot be definitively established based on current evidence, highlighting the need for further clinical studies.

The rise of antibiotic‑resistant pathogens in osteoarticular infections underscores the need for alternative antimicrobial strategies acting locally within bone tissue. Antimicrobial peptides (AMPs) such as nisin offer broad‑spectrum activity and low resistance potential, yet their clinical use is limited by rapid degradation and systemic clearance in vivo. To address this limitation, we developed alginate hydrogels capable of encapsulating and protecting nisin while enabling localized antimicrobial action. These hydrogels exhibited clear antibacterial activity against Staphylococcus aureus and S. epidermidis in a 3D agar diffusion assay, generating inhibition halos of 1.84 ± 0.34 mm in width. They also achieved complete eradication of planktonic cultures, corresponding to a ≥5-log reduction in CFU.

To enhance the bone related properties of the system, the hydrogels were mineralized using complementary strategies: (i) encapsulation of preformed calcium phosphate (CaP) powders (hydroxyapatite and β-TCP), and (ii) a novel in situ alginate mineralization method designed to improve the stability and homogeneity of crosslinking and CaP distribution throughout the hydrogel. Notably, hydrogels prepared with our novel method showed enhanced storage stability, remaining active for at least two additional weeks compared to standard preparations. Varying the duration of in situ mineralization enabled the formation of distinct CaP phases, such as hydroxyapatite and brushite, as confirmed by XRD. Importantly, CaP functionalization did not compromise antimicrobial performance, with average halo widths of 1.71 ± 0.30 mm. Preliminary analyses indicate that mineralization increases the mechanical robustness of the hydrogels, with further mechanical, rheological, and stability studies underway. These characterizations will guide the selection of the final application format (injectable, mouldable, or scaffold-like). Ongoing work also focuses on assessing bioactivity through ion release profiling and apatite formation in SBF.

Overall, this work presents a promising antimicrobial and bioactive hydrogel platform that integrates AMP delivery with CaP mineralization, offering potential for localized infection control and bone regeneration in osteoarticular applications.

Antimicrobial resistance (AMR) constitutes a major public health and economic burden in contemporary society. The aim of this work is to identify patterns and trends associated with the resistance behavior of Klebsiella pneumoniae to carbapenems across several European countries in order to better understand its dynamics and public health implications, since it’s a pair considered by the WHO as a critical priority. Variables: The dataset resistance values of K.pneumoniae|Carbapenems for several countries from 2005 to 2021(data available up to 2023) were obtained from the public website of ECDC. Methods: Agglomerative Hierarchical Cluster Analysis (HCA) was based on the generalized Affinity coefficient applied to the estimated ARIMA models. Results:The dendrogram at the cut-off presented four clusters: the first cluster was Slovenia, Luxembourg, Italy, and Estonia; the second cluster was Romania, Malta, Greece, Portugal, and Spain; the third cluster was Denmark, France, and Czechia; and finally, the fourth cluster was Lithuania, Cyprus, Finland, Austria, Belgium, and Slovakia. Although the resistance values show a more visible increasing trend over the years in Clusters II and III, the increase is more pronounced. Data were standardized, and the slopes of the lines obtained between the years 2012 and 2020 were calculated for Clusters II and III. For Clusters I and IV, this was not possible due to the irregularity of the curves. The slopes are higher in the countries belonging to Cluster II. Specifically, the slopes for Cluster II’s countries are m=0.29, m=1.5, m=0.06, m=0.11, and m=0.26 for Portugal, Spain, Greece, Malta, andRomania, respectively, whereas for Cluster III’s countries, the slopes are m=0.02, m=0,08 and m=0.001 for France, Czechia, and Denmark, respectively. It is relevant that within Cluster II, Portugal and Spain show a steeper increase, with Spain showing the most pronounced growth. Conclusions: The application of data analysis, using HCA based on the generalized Affinity coefficient, allows the evaluation of patterns among different regions and gives the possibility to identify alarming groups that need urgent intervention

Background/Objectives: Due to the rising problem of antimicrobial resistance, there is increasing attention in the scientific community towards alternative approaches to combat Antimicrobial-Resistant (AMR) pathogens that do not involve the use of antibiotics. In this regard, the European Medicines Agency (EMA) and the European Food Safety Authority (EFSA) have promoted experimentation with predatory bacteria to fight antibiotic resistance. In this work we isolated a strain of Halobacteriovorax from an estuarine aquatic environment using a CTX-M-producing E. coli strain as prey and characterized it with respect to optimal physico-chemical parameters for growth and predation. Furthermore, we studied its predatory capacity against other E. coli strains and Multi-Drug-Resistant (MDR) Salmonella. Finally, we conducted challenge experiments to evaluate the growth of predator and prey over time. Methods: The Halobacteriovorax strain, designated HE7, was identified by 16S rRNA analysis. To isolate Halobacteriovorax and to evaluate its predatory ability towards different preys, the double-layer agar plating technique was applied. Results: HE7 showed in vitro predatory activity against all MDR strains of E. coli and Salmonella tested. In the 10⁷ predator/10³ prey and 10⁷ predator/10⁷ prey challenges, HE7 after 6 h achieved the total killing and a reduction of about 6 logs in the prey, respectively, maintaining this effect for up to 24 h. Conclusions: The results of this study highlight that HE7, but more generally Halobacteriovorax, could find application both alone and in an integrated context of antimicrobial strategies as an alternative to antibiotics.

This research was supported by the Italian Ministry of Health grant number RC IZS UM 07/23.