Background: Carbapenem-resistant Enterobacteriaceae (CRE) prevalence has shown increasing prevelance in Saudi Arabia, which poses a significant health concern. The antimicrobial stewardship program (ASP) plays an important role in reducing resistance by ensuring appropriate use of antibiotics.

Method: This is a retrospective data collection study performed over 3 years from 2020 to 2022, at a tertiary hospital which included adult patients who were hospitalized in the ICU and received Meropenem. The primary objective was to evaluate the appropriateness of meropenem prescription in the ICU pre-ASP and post-ASP implementation. The secondary objectives were assessing the reason for inappropriateness and the implemented action in response to inappropriate meropenem prescription.

Result: In total, 113 patients were included. The pre-ASP group included 34 patients; 41 patients were in the first year post-ASP intervention and 38 patients were in the second year post-ASP implementation. There was a significant increase in the number of patients who received appropriate prescriptions in the post-ASP intervention group 2021 and 2022 compared to pre-ASP implementation (26.8%, 53.7% vs 23.5%, p-value 0.002). The most observed reason for inappropriateness in the post-ASP group compared to the pre-ASP group varied (84.8% vs 76.9%, p value 0.53). Discontinuation of treatment in the post-ASP group was higher compared to the pre-ASP group (60% vs. 30.8%, p-value 0.036) meropenem use.

Conclusion: Approximately more than 70% of meropenem prescriptions were inappropriate, and the implementation of ASP shows a significant impact in promoting appropriate meropenem prescription patterns and shorter treatment durations in the ICU.

Introduction: Antimicrobial resistance (AMR) is among the top three health threats worldwide. It requires an effective response by implementing proper antimicrobial stewardship (AMS) measures. In Hungary, AMR is also a considerable problem, with overuse and misuse of antimicrobials. Despite still being one of the highest in Europe, Hungarian veterinary antibiotic consumption has significantly improved over the past decade. In contrast, however, the quantity of antibiotics used in human health care is relatively low, measured as DDD per 1000 inhabitants per day, but utilization and resistance patterns show worsening tendencies. In this study, we wanted to explore the quality of the current Hungarian AMS systems in human and animal health care and the barriers and facilitators of their operations.

Methods: We conducted a qualitative study using in-depth interviews with twelve Hungarian stakeholders representing the human, animal, and environmental sectors at ministerial, regulatory authority, and hospital/university levels. Semi-structured interviews were transcribed and analyzed using NVivo 15.

Results and discussion: Key informants revealed that the Hungarian veterinary antibiotic policy is greatly driven by the legal obligations of the EU Common Agricultural Policy, with its strong financial protection system focusing on food-producing animals. All sectorial interviewees emphasized that their national veterinary heath sector is aware of the problem of AMR and actively take all measures to achieve their goals. The identified facilitators were good intrasectorial communication and cooperation, ambitious leadership, efficient law-making, high-level education of vets, and the existence of antibiotic reduction strategies. In human health care, almost only pull-back factors were reported by the participants about the weak sectorial antibiotic policy, such as institutional (no dedicated leadership at any levels, no institutional framework, and lack of proper data collection and monitoring), juridical (no implemented national action plan, no legal background,and lack of funding), and personal factors (clinicians’ resistance to change and the general population’s low health literacy).

Introduction: Perspectives and competencies developed during undergraduate health education critically influence antimicrobial resistance (AMR)-associated attitudes and future clinical decision-making in healthcare staff, particularly with regard to fostering patient safety and rational antimicrobial utilization. The aim of our study was to assess nursing and allied health science students’ knowledge, attitudes, and practices related to AMR.

Methods: A quantitative, single-centre cross-sectional study was performed with purposive sampling between 01/09/2021 and 20/09/2025. Data collection was carried out using an 83-item, self-administered online questionnaire consisting of the following domains: i) socio-demographic characteristics, ii) AMR-related knowledge, iii) attitudes towards AMR, iv) recognition of AMR-related terms, and v) practices related to antimicrobial consumption. Statistical analyses (descriptive statistics, Welch’s t-tests, binary logistic regression, and a 95% confidence interval [95%CI]) were performed using IBM SPSS 28.0. The study followed the Checklist for Reporting Results of Internet E-Surveys (CHERRIES) guidelines.

Results: Among participants (N=312), 85.6% and 46.2% identified their formal health science training and the Internet as their main sources of AMR-related information, respectively. Participants enrolled in study programmes (e.g., nursing, dental hygiene) with stronger clinical and pharmacological components were more likely to possess adequate knowledge (OR=2.36; 95%CI: 1.49–3.71; p<0.001), hold positive attitudes (OR=2.19; 95%CI: 1.38–3.46; p<0.001), and recognize more AMR-related concepts (OR=2.95; 95%CI: 1.49–5.83; p=0.002). Overall, 51.3% demonstrated adequate knowledge, 59.3% had appropriate attitudes, while 15.4% correctly recognized a sufficient number of AMR-related concepts. In the past 12 months, 24.4% had used antibiotics (sources: medical prescription: 81.4%; leftover antibiotics: 6.7%; antibiotics from friends or family members: 7.4%), most commonly taking them to treat a throat ache (34.3%), fever (22.1%), or cough (18.9%).

Conclusions: Strengthening knowledge and attitudes toward AMR during undergraduate training is key to fostering evidence-based clinical decision-making in future practice. Continuous evaluation and enhancement of AMR-specific curricula should be considered ascore components of comprehensive AMR mitigation strategies.

Denture-associated biofilms remain a significant cause of oral infections such as denture stomatitis. This study evaluated the antibiofilm efficacy of a newly developed silver-based antimicrobial denture material fabricated via stereolithography and compared its performance with that of three-dimensional printed (3DP) methacrylate dentures without an antimicrobial additive (Control). Rectangular test specimens (7.5 cm × 2.5 cm) were printed using stereolithography. The experimental denture material incorporated sodium silver zirconia hydrogen phosphate (SSZHP) as an antimicrobial additive (GL3D), while the control group comprised non-antimicrobial dentures. Both materials were tested in a mouth-simulated drip-flow biofilm reactor inoculated with pooled human saliva and enriched with clinically relevant oral microorganisms, including Candida albicans, Staphylococcus aureus, Streptococcus spp., methicillin-resistant S. aureus (MRSA), and vancomycin-resistant enterococci (VRE). The biofilm's growth and testing were carried out in accordance with a modified version of ASTM E2647-24 protocol. Microbial attachment was quantified on agar media by colony-forming unit (CFU) enumeration. Biofilm architectures were analyzed by confocal laser scanning microscopy (CLSM). Two-way ANOVA was performed using Minitab 2. The log CFU counts in GL3D were consistently lower than those in control (p < 0.05) across all microbial groups tested. CLSM analysis showed a 75.37% decrease in biofilm volume, a 49.02% reduction in mean biovolume, a 93.78% decrease in biomass, a 79.03% drop in substratum coverage, and a 92.37% decline in average thickness compared to controls. The incorporation of SSZHP into a 3D-printed denture material markedly reduced microbial viability and disrupted biofilm formation and structure. These findings demonstrate the potential of silver-based 3D-printed denture materials to improve oral health by minimizing biofilm-associated infections and enhancing the hygiene and longevity of prosthetic devices.

Urban wastewater treatment plants (WWTPs) are increasingly recognized as critical control points in the environmental dissemination of antibiotics and antibiotic resistance genes (ARGs), playing a central role within the One Health framework. If insufficient removal of antibiotics or ARGs occurs during wastewater treatment, it may facilitate the spread of antimicrobial resistance (AMR), underscoring the need to assess treatment performance.

This study investigated the occurrence, concentration, and removal of selected ARGs and antibiotics in two urban WWTPs in southeastern Spain. The plants differed in their treatment schemes, with one conducting conventional secondary treatment and the other incorporating tertiary treatment; both included lagooning systems as additional stages. A total of nine ARGs associated with resistance to clinically relevant antibiotics were analysed, intI1, sul1, mcr-1, blaKPC-3, blaTEM, blaCTX-M, blaCTX-M-32, blaOXA-48, and blaOXA-58, together with the bacterial marker gene 16S rRNA. ARG concentrations were quantified by quantitative polymerase chain reaction (qPCR) and expressed as log₁₀ absolute gene copies. In parallel, selected antibiotics were quantified using high-performance liquid chromatography.

The results showed substantial reduction of both antibiotics and most ARGs in the final effluents, indicating that the applied treatment configurations, including lagooning, effectively reduce the environmental load of AMR. This reduction is particularly relevant from a One Health perspective, as it limits the dissemination of resistant bacteria and determinants from urban wastewater into receiving aquatic environments and water reuse systems. However, certain genes of high clinical and epidemiological relevance, such as intI1, mcr-1, and blaOXA-48, showed limited removal or, in some cases, higher concentrations in effluents than in influents. Correlation analyses revealed relationships between antibiotic concentrations and ARG abundances, providing insight into interactions driving resistance dissemination. This behaviour may reflect complex microbial and physicochemical processes during treatment and highlights the need to better understand ARG dynamics, reinforcing the role of WWTPs as key monitoring interfaces.

The bacterial cytoplasmic membrane is a compelling target for novel antibiotics due to its essential nature and relative genetic stability. Agents disrupting membrane integrity are less prone to developing conventional resistance, remain effective against metabolically dormant persister cells and biofilms, and employ rapid, diverse bactericidal mechanisms. Natural products have consistently proven to be a fertile ground for drug discovery, yielding unique molecular scaffolds with therapeutic potential (Butler et al., J. Nat. Prod., 2025). A prominent class among them is natural antimicrobial peptides (AMPs), which often operate via membrane-associated mechanisms. Within this promising landscape, our research focuses on the gausemycins—a unique family of Ca²⁺-dependent (glyco)lipopeptide antibiotics that exhibit activity against Gram-positive pathogens (Tyurin et al., Angew. Chem. 2021; Kravchenko et al., J. Nat. Prod. 2024). However, the precise details of their membrane interaction and subsequent bactericidal mechanism remain to be fully elucidated. This study aims to define these molecular details and evaluate their specific interplay with key membrane components.

Our approach combines kinetic analysis of bactericidal activity with studies using model lipid membranes to define the membrane-disrupting properties of gausemycins. To validate the membrane as the primary target and probe resistance pathways, we characterized spontaneous resistant mutants and assessed activity against bacterial strains with engineered membrane alterations, including Bacillus subtilis overexpressing the ugtP gene and clinically relevant daptomycin-resistant strains with lysyl-phosphatidylglycerol-enriched membranes. Finally, fluorescence microscopy was utilized to directly visualize the cellular localization of gausemycin, providing direct evidence for its membrane-targeting mechanism.

This work unravels the mechanism of gausemycin action, positioning it as a distinct class of membrane-targeting antibiotics. The established combination of membrane association and bactericidal efficacy highlights their potential as a promising new class of antibiotics.

This work was supported by the Russian Science Foundation (project № 25-14-00281).

Introduction

Acinetobacter baumannii is a critical global health threat due to its opportunistic nature and ability to evolve multidrug resistance. To combat the lack of effective treatments, adjuvants such as the cyclic peptide MV6 are being explored. While MV6 lacks intrinsic antimicrobial activity, it enhances the activity of aminoglycosides such as netilmicin. This project aims to elucidate the mechanism by which MV6 potentiates the activity of netilmicin.

Methods

Spontaneous mutants were generated under selective pressure from netilmicin alone or in combination with MV6. Whole-genome sequencing (WGS) and a custom variant-calling pipeline identified the mutational distribution. A representative subset of mutants, with the wild-type reference, underwent transcriptomic analysis. To validate the role of efflux systems, Minimum Inhibitory Concentrations (MICs) were determined in the presence and absence of the efflux pump inhibitor PaβN.

Results

WGS and variant-calling analysis revealed a convergent mutational profile across both spontaneous mutant groups; no differences were detected between mutants generated with or without MV6. Key mutations were identified in a tetR-family transcriptional regulator located in cis to a multidrug efflux pump, alongside a recurrent deletion in the intergenic region downstream of an adeABC operon. Additionally, diverse mutations were detected in the coding sequence or promoter region of an ATP-binding protein. Remarkably, transcriptomic analysis confirmed that these mutations resulted in the overexpression of the adeABC operon and the multidrug efflux pump. Preliminary phenotypic assays with PaβN corroborated that, as efflux inhibition partially restored netilmicin susceptibility, efflux systems are the primary driver of resistance.

Conclusion

Our results demonstrate that netilmicin resistance is primarily driven by overexpression of efflux systems. Interestingly, MV6 did not alter the mutational or transcriptomic profile of the mutants. This suggests that MV6 enhances netilmicin without exerting additional selective pressure, supporting its potential role as a “silent” adjuvant that may interfere with efflux function.

Delafloxacin is a new fluoroquinolone agent that has been introduced into clinical application. In this study, efficacy of delafloxcin on clinical isolates of Escherichia coli and Klebsiella pneumoniae was evaluated. Altogether, 80 E. coli and 43 K. pneumoniae were included in this study in Budapest, Hungary. Antimicrobial susceptibility testing was performed by broth microdilution for ciprofloxacin, delafloxacin, levofloxacin, moxifloxacin, ceftazidime, cefotaxime, and imipenem. Selected multidrug-resistant and delafloxacin resistant strains were further analyzed by whole-genome sequencing (WGS) on Illumina MiSeq platform to detect resistance determinants and sequence types (ST). Based on susceptibility results of E. coli, delafloxacin and ciprofloxacin resistance rates were 38.75% (31/80) and 41.25% (33/80), respectively. In the case of K. pneumoniae, delafloxacin and ciprofloxacin resistance rates were 46.5% (20/43) and 51% (22/43), respectively. WGS analysis detected mutations of quinolone resistance determining regions (QRDR) in selected delafloxacin resistant E. coli strains; namely, mutations in gyrA Ser83Leu, Asp87Asn and parC Ser80Ile were detected in ST162, ST57 and ST15840 strains. In the case of ST131 strains, five combined mutations were detected: gyrA Ser83Leu, Asp87Asn, parC Ser80Ile, Glu84Val, and parE Ile549Leu. In ST43 strains, gyrA S83L, D87N, parC S80I, and E84V mutations were detected. In delafloxacin-resistant K. pneumoniae, gyrA Ser83Ile and parC Ser80Ile mutations were detected in ST307 and ST147 strains. In the ST377 strain, gyrA Ser83Tyr, Asp87Ala, and parC Ser80Ile mutations were detected. Each delafloxacin-resistant K. pneumoniae strain carried OqxAB and AcrAB efflux pumps. Delafloxacin demonstrates efficacy against certain populations of E. coli and K. pneumoniae. However, multiple QRDR mutations can confer delafloxacin resistance in E. coli and K. pneumoniae clinical isolates.

Traveler’s diarrhea (TD) remains one of the most prevalent health concerns affecting individuals visiting low- and middle-income countries. TD is mainly caused by infectious agents, particularly enteroaggregative E. coli (EAEC) and enterotoxigenic E. coli (ETEC). The aim of this study is to characterize antibiotic resistance patterns and underlying resistance mechanisms in EAEC and ETEC isolates causing TD (2018-2023).

A total of 46 ETEC and 44 EAEC strains isolated from TD patients attending Hospital Clínic (Barcelona) were analyzed. Antibiotic resistance profiles were determined using phenotypic methods based on minimum inhibitory concentration (MIC) and genotypic analysis by whole-genome sequencing using Illumina technology.

Phenotypic resistance patterns were similar between pathotypes, except for levofloxacin (LEV), ciprofloxacin (CIP) and ceftriaxone (CRO), for which ETEC showed higher resistance rates. Among EAEC isolates, resistance rates were: cefepime (FEP) 9.1%, cefazolin (FAZ) 50%, ceftazidime (TAZ) 13.6%, CRO 11.4%, ampicillin (AMP) 52.3%, aztreonam (AZT) 18.2%, LEV 2.3%, CIP 2.3%, and trimethoprim/sulfamethoxazole (SXT) 61.4%. In ETEC isolates, resistance rates were: FEP 17.4%, FAZ 65.2%, TAZ 17.4%, CRO 21.7%, AMP 52.2%, AZT 19.6%, LEV 13.3%, CIP 13%, and SXT 43.5%. All phenotypically resistant isolates showed corresponding genotypic resistance mechanisms. For β-lactams, the most frequent mechanisms were TEM-1 (n=32) and CTX-M-15 (n=13). The dfrA gene was identified in SXT-resistant isolates, while mutations in gyrA and parC were responsible for LEV and CIP resistance. Isolates acquired in Asia showed the highest overall resistance rates, whereas SXT resistance was more frequent in isolates from Africa.

The dissemination of multidrug-resistant EAEC and ETEC through international travel represents a significant risk for the spread of antimicrobial resistance, both through the introduction of multidrug-resistant strains and via the dissemination of resistance genes carried on mobile genetic elements. This risk appears to be elevated in Asia and Africa, highlighting the need for continuous surveillance and antimicrobial stewardship in TD management.

Background: Catheter-associated bloodstream infections (CABSIs) represent a major challenge in neonatal intensive care units (NICUs), particularly among preterm infants requiring invasive procedures. Umbilical and peripheral venous catheters are indispensable in neonatal care but pose significant infection risks. Methods: A microbiological study was conducted between 2020 and 2023 at the Research Centre for Maternal and Child Health Care in Yerevan, Armenia. Catheters removed from 109 neonates admitted to a category 3 NICU were examined to determine microbial growth and antimicrobial resistance. Demographic, clinical, and microbiological data were analyzed using descriptive statistics and chi-squared tests. Results: The mean gestational age of neonates was 31 weeks; 60% were born preterm, with 23% extremely low birth weight (<1000 g). Catheters were in place for an average of 32 hours. Microbial growth was identified in 26 catheters (24%), including 23 with bacterial isolates (21%) and 3 with fungal isolates (3%). The predominant bacterial genera were Klebsiella spp. (n=7 (27%)), Enterobacter spp. (n = 6 (23%)), Escherichia spp. and Staphylococcus spp. (both with n=4 (15%)). The susceptibility of the 23 bacterial cultures isolated from the catheters was tested against a common set of antibiotics. The discovered bacterial species were most often resistant to Vancomycin and Gentamicin in a pooled analysis (100% and 96%, respectively). Conversely, Meropenem and Ciprofloxacin showed the least resistance rate (30% and 17%, respectively). Conclusion: This study underscores the importance of microbiological surveillance in NICUs to better understand the etiology and resistance profiles of pathogens associated with CABSIs. By refining our approach to catheter management and infection control, we can enhance the safety and outcomes for neonates requiring invasive procedures. Future research should focus on improving catheter care protocols and investigating interventions that may reduce the incidence of infections in this high-risk group.