Antibiotics

39 pages, 6201 KB

Open AccessReview

Unlocking Antimicrobial Peptides from Marine Invertebrates: A Comprehensive Review of Antimicrobial Discovery

by Md. Abu Kawsar, Chengqing Zhao, Fan Mao, Ziniu Yu and Yang Zhang

Antibiotics 2025, 14(9), 924; https://doi.org/10.3390/antibiotics14090924 (registering DOI) - 12 Sep 2025

Unlike other animals, marine invertebrates lack an adaptive immune system and instead rely on innate immunity as their first line of defense. A key component of this innate response is the production of biologically active molecules, particularly antimicrobial peptides (AMPs), which offer promising [...] Read more.

Unlike other animals, marine invertebrates lack an adaptive immune system and instead rely on innate immunity as their first line of defense. A key component of this innate response is the production of biologically active molecules, particularly antimicrobial peptides (AMPs), which offer promising solutions to the escalating global crisis of antimicrobial resistance (AMR). This review comprehensively examines the sources, structural diversity, mechanisms of action, biological functions, and therapeutic potential of AMPs derived from a wide range of marine invertebrate phyla. These evolutionarily conserved peptides exhibit broad-spectrum antibacterial, antifungal, antiviral, antiparasitic, and even anticancer activities. The review also summarizes strategies for AMP isolation and production, ranging from natural extraction to recombinant expression and chemical synthesis, and outlines their potential biotechnological applications. Furthermore, we highlight the transformative role of artificial intelligence (AI) in accelerating AMP discovery, design, and production, including predictive modeling, de novo peptide generation, and optimization workflows. Despite significant progress, challenges remain in large-scale production, pharmacokinetic characterization, and functional validation. Addressing these gaps through integrative omics, structural biology, and AI-driven innovation will be crucial for unlocking the full therapeutic potential of marine invertebrate AMPs in combating infectious diseases and antimicrobial resistance. Full article

(This article belongs to the Special Issue Antimicrobial Bioactives from Invertebrates)

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12 pages, 689 KB

Open AccessArticle

Synergistic Antimicrobial Activity of Vancomycin, Ceftriaxone, and Gentamicin Against Cutibacterium acnes Strains: An In Vitro Checkerboard Analysis and In Vivo Interaction with Bioactive Glass Using Galleria mellonella

by Mariana Neri Lucas Kurihara, Isabelle Frois Brasil, Mayara Muniz de Andrade Silva and Mauro Jose Salles

Antibiotics 2025, 14(9), 923; https://doi.org/10.3390/antibiotics14090923 - 12 Sep 2025

Abstract

Background/Objectives: Cutibacterium acnes is increasingly recognized as a relevant pathogen in orthopaedic implant-associated infections, yet treatment strategies remain largely empirical. With rising antimicrobial resistance and scarce data on drug interactions, optimizing targeted therapies is essential. This preclinical study investigated the efficacy and synergism [...] Read more.

Background/Objectives: Cutibacterium acnes is increasingly recognized as a relevant pathogen in orthopaedic implant-associated infections, yet treatment strategies remain largely empirical. With rising antimicrobial resistance and scarce data on drug interactions, optimizing targeted therapies is essential. This preclinical study investigated the efficacy and synergism of vancomycin (VA), gentamicin (GEN), and ceftriaxone (CTX) against two clinical phylotype IB strains from orthopaedic infections and the reference strain C. acnes ATCC 6919, using both in vitro and in vivo models. Methods: Minimum inhibitory concentrations (MICs) were determined using broth microdilution following BrCAST guidelines. Synergistic activity was assessed using the checkerboard assay and interpreted via fractional inhibitory concentration indices (FICIs). The in vivo efficacy of antibiotic combinations with bioactive glass S53P4 (BAG) was evaluated in the Galleria mellonella infection model. Results: All C. acnes strains exhibited uniformly low MICs. Synergistic activity was observed for CTX combined with GEN in strain 2 (FICI range 0.25–0.37), while partial synergy was detected for CTX with GEN in strain 1 (FICI ≈ 0.56–0.63), and for CTX combined with VA in the ATCC strain (FICI = 0.66). All other combinations demonstrated indifferent interactions. In the G. mellonella model, a high bacterial inoculum (OD₆₀₀ of 3.0) was needed to establish an infection. For all strains tested, the use of antibiotics in combination with BAG improved larval survival. For the clinical strains, the combination of CTX + GEN + BAG and BAG alone demonstrated greater efficacy in promoting larval survival. Conclusions: Acombination of a cephalosporin with an aminoglycoside, particularly when incorporated into a biomaterial matrix, enhances antimicrobial activity against both clinical and reference strains of C. acnes. Full article

(This article belongs to the Special Issue Bone and Joint Infections: The Challenges of Prevention, Diagnosis and Treatment and Opportunities for Future Research)

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24 pages, 4295 KB

Open AccessArticle

Genomic Profiling Reveals Clinically Relevant Antimicrobial Resistance and Virulence Genes in Klebsiella pneumoniae from Hong Kong Wet Markets

by Wing Yui Ngan, Subramanya Rao, Aster Hei Yiu Fung and Olivier Habimana

Antibiotics 2025, 14(9), 922; https://doi.org/10.3390/antibiotics14090922 - 12 Sep 2025

Abstract

Background:Klebsiella pneumoniae is a highly dangerous microorganism that presents significant challenges to effectively eliminate in food production facilities, making it a serious and urgent public health concern. The wet markets of Hong Kong represent a considerable yet insufficiently explored source for the [...] Read more.

Background:Klebsiella pneumoniae is a highly dangerous microorganism that presents significant challenges to effectively eliminate in food production facilities, making it a serious and urgent public health concern. The wet markets of Hong Kong represent a considerable yet insufficiently explored source for the spread of microorganisms. Methods: This investigation employed whole-genome sequencing and comparative genomics to assess the genomic variation and adaptive traits of K. pneumoniae extracted from wooden cutting boards in these marketplaces. We examined four wet market isolates in conjunction with 39 publicly accessible genomes from diverse origins. Results: Pan-genome analysis revealed a diverse and open genetic structure significantly shaped by horizontal gene transfer. Phylogenetic reconstruction did not categorize the wet market isolates into a singular clade, indicating varied contamination sources; nonetheless, certain market isolates exhibited close phylogenetic affiliations with high-risk clinical clones, implying possible spillover events. These isolates exhibited a concerning variety of antimicrobial resistance genes (ARGs), chiefly encoding efflux pumps (acrAB, oqxAB), which confer resistance to numerous drug categories. Moreover, the evaluation for pathogenicity attributes uncovered genes associated with robust biofilm development (fim and mrk operons) and efficient iron procurement strategies. Conclusions: The existence of these genetically adaptable isolates, possessing multidrug resistance and virulence factors, renders wet markets potential amplifiers and reservoirs for the spread of resistant pathogens. These findings present the initial genomic evidence of such risks in Hong Kong’s wet markets and emphasize the immediate necessity for improved hygiene protocols and comprehensive One Health surveillance to reduce transmission at the human–animal–environment interface. Full article

(This article belongs to the Special Issue Challenges and Strategies for the Antibiotic Resistance Crisis)

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1 pages, 130 KB

Open AccessRetraction

RETRACTED: Quazi et al. The Discovery of Novel Antimicrobial Agents Through the Application of Isocyanide-Based Multicomponent Reactions. Antibiotics 2023, 12, 849

by Sameer Quazi, Maliha Tabassum Rashid, Javid Ahmad Malik and Shreelaxmi Gavas

Antibiotics 2025, 14(9), 921; https://doi.org/10.3390/antibiotics14090921 - 12 Sep 2025

Abstract

The Antibiotics Editorial Office retracts the paper “The Discovery of Novel Antimicrobial Agents through the Application of Isocyanide-Based Multicomponent Reactions” [...] Full article

20 pages, 5032 KB

Open AccessCommunication

One Earth–One Health to Combat Antimicrobial Resistance Having a Dual Mutation Pattern, Based on the Robust Self-Regulation and Perpetual Reconstruction of Ecosystems

by Ganjun Yuan, Jianing Hu, Meifang Zhang, Xingguyue Chen and Yumei Luo

Antibiotics 2025, 14(9), 920; https://doi.org/10.3390/antibiotics14090920 - 11 Sep 2025

Abstract

Background/Objectives: Antimicrobial resistance (AMR) has emerged as a grave threat to human health, and a One Earth–One Health (OE-OH) concept was proposed for addressing this challenge in 2024. Here, this concept was systematically defined, clarified, and refined, for better understanding, interpreting related results, [...] Read more.

Background/Objectives: Antimicrobial resistance (AMR) has emerged as a grave threat to human health, and a One Earth–One Health (OE-OH) concept was proposed for addressing this challenge in 2024. Here, this concept was systematically defined, clarified, and refined, for better understanding, interpreting related results, and taking some measures to combat the crisis. Methods: Using logical reasoning and deductive methods, a dual mutation pattern was put forward for microbial resistance, adhering to the principle of parsimony and integrating Lamarckian, Darwinian, and Niche construction theories, and the evolutionary origins of current AMR were schematically presented. Subsequently, its theoretical foundation, together with a fundamental mathematical model, was defined and clarified based on the robust self-regulation and perpetual reconstruction of ecosystems, and then the generation, dissemination, and elimination of AMR and antibiotic resistance genes (ARGs) were sorted out and elucidated from abiotic and biotic factors. Finally, learning from the approach of problem management, some crucial measures are suggested for the research and development, application, and management of antibiotics, emphasizing the key role of simulating and utilizing the self-regulation of ecosystems. Results: A dual mutation pattern of microbial resistance and the evolutionary origins of current AMR was put forward. The theoretical foundation of the OE-OH concept, together with a fundamental mathematical model, was presented. Some unique perspectives, such as the emergence of AMR and ARGs 3.5 billion years ago and their ubiquity across the globe prior to antibiotic use, were clarified. Moreover, some crucial measures are proposed for addressing AMR. Conclusions: It is essential to implement the OH Joint Plan of Action from the OE-OH perspective, strongly emphasizing the key role of simulating and utilizing the self-regulation of ecosystems on addressing AMR. Full article

(This article belongs to the Special Issue The Spread of Antibiotic Resistance in Natural Environments)

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12 pages, 684 KB

Open AccessArticle

Incidence of Acute Kidney Injury in Autologous Hematopoietic Stem Cell Transplant Recipients According to the Administration of Empirical Amikacin: A Two-Centre Retrospective Cohort Study

by Sophie Schürch, Sarah Dräger, Michèle Hoffmann, Severin Bausch, Nicolas Gürtler, Cédric Hirzel, Jakob Passweg, Stefano Bassetti, Thomas Pabst, Parham Sendi and Michael Osthoff

Antibiotics 2025, 14(9), 919; https://doi.org/10.3390/antibiotics14090919 - 11 Sep 2025

Abstract

Background: The benefit of adjunctive aminoglycosides in the treatment of patients with febrile neutropenia (FN) is controversial. We investigated the incidence of acute kidney injury (AKI) in patients with FN or suspected infection according to empirical amikacin treatment. Methods: This two-centre, [...] Read more.

Background: The benefit of adjunctive aminoglycosides in the treatment of patients with febrile neutropenia (FN) is controversial. We investigated the incidence of acute kidney injury (AKI) in patients with FN or suspected infection according to empirical amikacin treatment. Methods: This two-centre, retrospective cohort study was conducted at the University Hospitals of Basel (amikacin group) and Bern (non-amikacin group), Switzerland, between 2016 and 2022. Adult patients requiring antibiotic treatment after autologous hematopoietic stem cell transplantation (HSCT) were included. All patients received empiric beta-lactam treatment combined with amikacin in the amikacin group (only University Hospital Basel). The primary endpoint was the incidence of AKI within seven days after the initiation of antibiotic treatment. Results: Overall, 250 patients were included. The majority was male (n = 163, 65.2%) and had a median age of 61 years (interquartile range (IQR) 55 to 67). The median baseline eGFR was similar in both groups (>90 mL/min/1.7 m²). There was no statistically significant difference in the incidence of AKI (4/125 vs. 5/125, p = 1.0). The maximum decline in eGFR from baseline within 7 days was significantly higher in the amikacin group (−4 mL/min/1.7 m² (IQR 8 to −12) vs. −2 mL/min/1.7 m² (IQR −7 to −1), p = 0.001). Two patients suffered from an infection with an extended spectrum beta-lactamase producing (ESBL) pathogen. Conclusions: Amikacin treatment did not significantly impact the incidence of AKI in patients undergoing autologous HSCT. The short-term administration of amikacin in patients with normal to high baseline eGFR is safe regarding renal function. However, in a low-resistance setting, the omission of empirical amikacin treatment should be considered. Full article

(This article belongs to the Section Antibiotic Therapy in Infectious Diseases)

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21 pages, 888 KB

Open AccessArticle

Assessment of Factors Contributing to Multidrug Resistance in Urinary Tract Infections: Focus on Carbapenem Resistance

by Carina Alexandra Bandac, Constantin Ristescu, Pavel Onofrei, Ionela-Larisa Miftode, Rodica Radu, Vasile Lucian Boiculese, Ana-Maria Raluca Pauna, Theodor Florin Pantilimonescu, Andreea Luduşanu and Viorel Dragoș Radu

Antibiotics 2025, 14(9), 918; https://doi.org/10.3390/antibiotics14090918 - 11 Sep 2025

Abstract

Introduction: Urinary tract infections (UTIs) caused by carbapenem-resistant pathogens are increasingly common and pose serious treatment challenges due to limited antibiotic options and high complication rates. Identifying patients at risk is essential for guiding empirical therapy and improving outcomes. The primary objective of [...] Read more.

Introduction: Urinary tract infections (UTIs) caused by carbapenem-resistant pathogens are increasingly common and pose serious treatment challenges due to limited antibiotic options and high complication rates. Identifying patients at risk is essential for guiding empirical therapy and improving outcomes. The primary objective of this study was to identify risk factors associated with carbapenem-resistant (CR) UTIs by comparing them with carbapenem-susceptible (CS) UTIs. Secondary objectives included analyzing the types of microorganisms involved in both groups, their antibiotic susceptibility profiles, and the presence of carbapenemase enzymes among CR UTI cases. Method: We conducted a retrospective case-control study involving 127 hospitalized patients with UTIs caused by CR microorganisms and 91 patients with UTIs caused by multidrug-resistant (MDR) strains that retain susceptibility to carbapenems, admitted between 1 October 2023, and 31 March 2025. Results: In univariate analysis, CR UTI patients had significantly higher rates of neoplasia, neurological disorders, urosepsis at admission, septic shock, the presence of urinary catheters at diagnosis, permanent nephrostomy catheters, hospitalizations within the past 180 days, previous antibiotic exposure including carbapenems, and recent urological procedures. Multivariate analysis revealed four independent risk factors for CR UTIs: neoplasia (OR = 2.152; 95% CI: 1.044–4.436; p = 0.038), neurological disorders (OR = 7.427; 95% CI: 2.804–19.674; p < 0.0001), antibiotic use in the previous 180 days (OR = 2.792; 95% CI: 1.487–5.396; p = 0.001), and prior carbapenem treatment OR = 10.313; 95% CI: 1.277–83.248; p = 0.029). Most of the isolated organisms belonged to the Enterobacterales genus, with Klebsiella spp. and Pseudomonas aeruginosa being the most common pathogens in CR UTIs, accounting for over 90% of cases. Among patients tested for carbapenemase production, all but one tested positive for at least one carbapenemase. Conclusions: Neoplasia, neurological disorders, recent antibiotic therapy, and prior carbapenem use were significantly associated with increased risk of developing CR UTIs. Klebsiella spp. and Pseudomonas aeruginosa were the predominant causative organisms, with New Delhi metallo-β-lactamase (NDM) and Klebsiella pneumoniae carbapenemase (KPC) being the most frequently identified resistance mechanisms. Full article

(This article belongs to the Special Issue Antibiotic Resistance in Hospital-Acquired Infections)

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26 pages, 57341 KB

Open AccessArticle

AI-Powered Embedded System for Rapid Detection of Veterinary Antibiotic Residues in Food-Producing Animals

by Ximing Li, Lanqi Chen, Qianchao Wang, Mengting Zhou, Jingheng Long, Xi Chen, Jiangsan Zhao, Junjun Yu and Yubin Guo

Antibiotics 2025, 14(9), 917; https://doi.org/10.3390/antibiotics14090917 - 11 Sep 2025

Abstract

Background: Veterinary antibiotics are widely used in food-producing animals, raising public health concerns due to drug residues and the risk of antimicrobial resistance. Rapid and reliable detection systems are critical to ensure food safety and regulatory compliance. Colloidal gold immunoassay (CGIA)-based antigen–antibody test [...] Read more.

Background: Veterinary antibiotics are widely used in food-producing animals, raising public health concerns due to drug residues and the risk of antimicrobial resistance. Rapid and reliable detection systems are critical to ensure food safety and regulatory compliance. Colloidal gold immunoassay (CGIA)-based antigen–antibody test cards are widely used in food safety for the rapid screening of veterinary antibiotic residues. However, manual interpretation of test cards remains inefficient and inconsistent. Methods: To address this, we propose a complete AI-based detection system for veterinary antibiotic residues. The system is built on the Rockchip RK3568 platform and integrates a five-megapixel OV5640 autofocus USB camera (60° field of view) with a COB LED strip (6000 K, rated 5 W/m). It enables high-throughput, automated interpretation of colloidal gold test cards and can generate structured detection reports for regulatory documentation and quality control. The core challenge lies in achieving accurate and fast inference on resource-constrained embedded devices, where traditional detection networks often struggle to balance model size and performance. To this end, we propose VetStar, a lightweight detection algorithm specifically optimized for this task. VetStar integrates StarBlock, a shallow feature extractor, and Depthwise Separable-Reparameterization Detection Head (DR-head), a compact, partially decoupled detection head that accelerates inference while preserving accuracy. Results: Despite its compact size, with only 0.04 M parameters and 0.3 GFLOPs, VetStar maintains strong performance after distillation with the Bridging Cross-task Protocol Inconsistency Knowledge Distillation (BCKD) method. For our custom Veterinary Drug Residue Rapid Test Card (VDR-RTC) dataset, it achieves an mAP50 of 97.4 and anmAP50-95of 89.5. When deployed on the RK3568 device, it delivers results in just 5.4 s—substantially faster than comparable models. Conclusions: These results highlight the system’s strong potential for high-throughput, cost-effective, and rapid veterinary antibiotic residue screening, supporting food safety surveillance efforts. Full article

(This article belongs to the Special Issue Veterinary Antibiotics in Food-Producing Animals: Residue Detection, Risk Assessment and Regulatory Advances)

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19 pages, 338 KB

Open AccessReview

The Impact of COVID-19 on the Epidemiology of Carbapenem Resistance

by Aikaterini Sakagianni, Christina Koufopoulou, Petros Koufopoulos, Georgios Feretzakis and Vasiliki Koumaki

Antibiotics 2025, 14(9), 916; https://doi.org/10.3390/antibiotics14090916 - 11 Sep 2025

Abstract

Background: The global COVID-19 pandemic has significantly disrupted healthcare systems, inadvertently influencing the epidemiology of antimicrobial resistance (AMR). Among the most critical AMR threats are carbapenem-resistant organisms (CROs), which include carbapenem-resistant Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa. This review [...] Read more.

Background: The global COVID-19 pandemic has significantly disrupted healthcare systems, inadvertently influencing the epidemiology of antimicrobial resistance (AMR). Among the most critical AMR threats are carbapenem-resistant organisms (CROs), which include carbapenem-resistant Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa. This review explores the pandemic’s impact on carbapenem resistance patterns worldwide. Objectives: This study aimed to assess the effects of the COVID-19 pandemic on carbapenem resistance trends, identify key drivers, and discuss implications for clinical practice and public health policy. Methods: A comprehensive review of peer-reviewed literature, national surveillance reports, and WHO/ECDC data from 2019 to 2025 was conducted, with emphasis on hospital-acquired infections, antimicrobial use, and infection control practices during the pandemic. Results: The pandemic has led to increased use of broad-spectrum antibiotics, including carbapenems, often in the absence of confirmed bacterial co-infections. Overwhelmed healthcare systems and disruptions in infection prevention and control (IPC) measures have facilitated the spread of carbapenem-resistant organisms, particularly in intensive care settings. Surveillance data from multiple countries show a measurable increase in CRO prevalence during the pandemic period, with regional variations depending on healthcare capacity and stewardship infrastructure. Conclusions: COVID-19 has accelerated the emergence and dissemination of carbapenem resistance, underscoring the need for resilient antimicrobial stewardship and IPC programs even during public health emergencies. Integrating pandemic preparedness with AMR mitigation strategies is critical for preventing further escalation of resistance. Full article

(This article belongs to the Section Mechanism and Evolution of Antibiotic Resistance)

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16 pages, 3955 KB

Open AccessArticle

Postβ-Lactamase-Inhibiting Effect of Sulbactam in Combination with Ceftriaxone on Extended-Spectrum-β-Lactamase-Producing Escherichia coli

by Ru Wang, Kun Mi, Aihua Lu, Chengyang Zhang, Lei Sun, Yuxiang Chen, Yuanhu Pan, Yanfei Tao and Lingli Huang

Antibiotics 2025, 14(9), 915; https://doi.org/10.3390/antibiotics14090915 - 11 Sep 2025

Abstract

Background/Objectives: Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli poses a significant global health challenge, as it leads to antimicrobial treatment failure and is associated with elevated mortality rates. The use of β-lactam/β-lactamase inhibitor combinations offers an alternative approach for combating ESBL-producing bacteria. Ceftriaxone (CRO) [...] Read more.

Background/Objectives: Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli poses a significant global health challenge, as it leads to antimicrobial treatment failure and is associated with elevated mortality rates. The use of β-lactam/β-lactamase inhibitor combinations offers an alternative approach for combating ESBL-producing bacteria. Ceftriaxone (CRO) and sulbactam have been coadministered in the clinical settings; however, discrepancies in their pharmacokinetics raise concerns regarding the rationality of this combination. Methods: This study was designed to investigate the postβ-lactamase inhibitor effect (PLIE) under both static and dynamic conditions, with the aim of supporting the clinical application of this combination. Results: The minimum inhibitory concentration (MIC) of CRO/SBT (2:1 ratio) against E. coli NCTC 13353 was determined to be 32/16 μg/mL. The PLIEs were determined to be −1.26, −0.57, and 0.37 h at CRO/SBT concentrations ranging from 1/2 MIC to 2 MIC, respectively. The results of CRO concentration, β-lactamase activity, bla_CTX-M-15 expression, and cell morphology collectively support that SBT exerts PLIEs and protects against the antibacterial activity of CRO. In the dynamic hollow-fiber infection model, CRO monotherapy showed no inhibitory effect on E. coli, whereas CRO/SBT combination therapy rapidly eliminated SBT, achieved comparable bactericidal effects, prolonged CRO exposure, and maintained low β-lactamase activity levels. Conclusions: In conclusion, CRO/SBT exerts an inhibitory effect on enzyme-producing strains by being able to produce PLIE to maintain the inhibition of β-lactamase. Full article

(This article belongs to the Special Issue Clinical Guidelines and Real Practice of Antimicrobial Pharmacotherapy)

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22 pages, 790 KB

Open AccessArticle

Determinants of Implementation of Antimicrobial Stewardship Interventions for Managing Community Adult Acute Respiratory Infections: Qualitative Analysis from the OPTIMAS-GP Study Co-Design Phase

by Margaret Jordan, Mary Burns, Colin Cortie, Janette Radford, Christine Metusela, Judy Mullan, Simon Eckermann, Fiona Williams, Caitlin Keighley, Danielle Mazza, Indra Gajanayake, Stephen Barnett and Andrew Bonney

Antibiotics 2025, 14(9), 914; https://doi.org/10.3390/antibiotics14090914 - 11 Sep 2025

Abstract

Background/Objectives: Antimicrobial stewardship (AMS) interventions are critical to reducing inappropriate antibiotic prescribing for acute respiratory infections (ARIs) in primary care and mitigating antimicrobial resistance (AMR). While interventions are routinely employed in hospitals, implementation in general practice is nascent. This qualitative study, part of [...] Read more.

Background/Objectives: Antimicrobial stewardship (AMS) interventions are critical to reducing inappropriate antibiotic prescribing for acute respiratory infections (ARIs) in primary care and mitigating antimicrobial resistance (AMR). While interventions are routinely employed in hospitals, implementation in general practice is nascent. This qualitative study, part of the OPTIMAS-GP project, explored determinants influencing the implementation of evidence-based AMS strategies in Australian general practice. Methods: Using Experience-Based Co-Design, three rounds of online focus groups were conducted with ten healthcare professionals (GPs, pharmacists, microbiologist, practice staff) and ten adult patients who had experienced ARI management in primary care. Participants discussed the feasibility and acceptability of AMS interventions: shared decision-making (SDM) tools, delayed prescribing (DP) and point-of-care testing (PoCT) for C-reactive protein (CRP). Results: Thematic analysis of focus group transcriptions identified four interrelated themes: ‘Patient acceptance and engagement’, ‘Practising within a system’, ‘Prescribing stewardship’, and ‘Diagnostic stewardship’. Patient engagement was dependent upon expectations, trust, and personalised care, while systemic factors such as continuity of care, practice culture, and resource availability influenced implementation. DP was viewed as a pragmatic but potentially confusing strategy, requiring clear patient guidance and interprofessional collaboration. SDM tools were conceptually supported but challenged by time constraints and poor health literacy. PoCT-CRP was cautiously welcomed for selective use, with concerns expressed about workflow integration and overreliance on testing. Findings were mapped to the Capability, Opportunity, Motivation-Behaviour (COM-B) and Theoretical Domains Framework (TDF) to identify behavioural determinants and inform future implementation strategies. Recommendations include co-designing patient-centred AMS tools with clear instructions and red flags, enhancing GP-pharmacist collaboration, and addressing barriers to PoCT integration. Conclusions: These insights highlight the complexity of implementing AMS interventions in general practice and underscore the need for tailored, system-supported approaches to optimise antibiotic use and reduce AMR. Full article

(This article belongs to the Special Issue A One Health Approach to Antimicrobial Resistance, 2nd Edition)

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26 pages, 3530 KB

Open AccessArticle

Temporizin-1 Meets the Membranes: Probing Membrane Inser-Tion and Disruption Mechanisms

by Rosa Bellavita, Sara Palladino, Karyne Rangel, Guilherme Curty Lechuga, Lorenzo Emiliano Imbò, Lucia Falcigno, Gabriella D’Auria, Leonardo da Silva Lara, Mirian Cláudia de Souza Pereira, Salvatore Giovanni De-Simone, Stefania Galdiero and Annarita Falanga

Antibiotics 2025, 14(9), 913; https://doi.org/10.3390/antibiotics14090913 - 10 Sep 2025

Abstract

Background/Objectives: Temporizin-1, a hybrid antimicrobial peptide derived from the combination of Temporin A, Gramicidin peptide, and a poly-leu sequence, has strong trypanocide activity against Trypanosoma cruzi and moderate cytotoxicity towards mammalian cells. In this study, we investigated the mode of action of the [...] Read more.

Background/Objectives: Temporizin-1, a hybrid antimicrobial peptide derived from the combination of Temporin A, Gramicidin peptide, and a poly-leu sequence, has strong trypanocide activity against Trypanosoma cruzi and moderate cytotoxicity towards mammalian cells. In this study, we investigated the mode of action of the peptide upon interaction with protozoan and eukaryotic membranes. Methods: To this end, we conducted a series of biophysical assays using liposomes as biomimetic models, along with fluorescence-based experiments such as lipid mixing, membrane leakage, and assays involving Thioflavin and Laurdan. Results: Temporizin-1 displayed potent membranolytic activity on protozoan and eukaryotic membranes, causing significant membrane fusion and leakage with consequent pore formation. In addition, we also performed structural studies on liposome interaction, where we observed a helical structure that is conserved during membrane interaction. The NMR study confirms all the data obtained, providing both the structure of free Temporizin-1 in solution and the way it interacts with micelles. Moreover, Temporizin-1 demonstrated high selectivity against intracellular forms of T. cruzi and exhibited an additive effect when combined with benznidazole, highlighting its promising therapeutic activity. Conclusions: In conclusion, elucidating the mechanism of action of Temporizin-1 is essential for optimizing its structure and improving target selectivity, and driving the rational design of next-generation antimicrobial peptides by applying chemical strategies and delivery system’s conjugation. Full article

(This article belongs to the Special Issue Development of Antimicrobial Peptides from Amphibian, 2nd Edition)

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22 pages, 2905 KB

Open AccessArticle

In Vitro and In Silico Analysis of Differential Antibacterial Activity of Pomegranate Polyphenols Against Gram-Positive and Gram-Negative Bacteria

by Relja Suručić, Maja Travar, Tatjana Kundaković Vasović, Jelena Radović Selgrad, Ljiljana Suručić, Milan Momčilović, Miloš P. Stojiljković and Ranko Škrbić

Antibiotics 2025, 14(9), 912; https://doi.org/10.3390/antibiotics14090912 - 10 Sep 2025

Abstract

Background/Objectives: This study investigates the antimicrobial properties of pomegranate peel extract (PoPEx) and its major polyphenolic constituents against Gram-positive and Gram-negative bacteria, employing six clinical isolates of Staphylococcus aureus and five isolates of Escherichia coli. The study further aims to elucidate mechanisms [...] Read more.

Background/Objectives: This study investigates the antimicrobial properties of pomegranate peel extract (PoPEx) and its major polyphenolic constituents against Gram-positive and Gram-negative bacteria, employing six clinical isolates of Staphylococcus aureus and five isolates of Escherichia coli. The study further aims to elucidate mechanisms of action through molecular docking and transport studies. Methods: Chemical composition was analyzed using liquid chromatography–mass spectrometry (LC–MS). Antimicrobial activity was determined by the broth microdilution method. Molecular docking was performed with the AutoDock Vina algorithm, and transport studies through porin channels were carried out using Caver software. Results: PoPEx showed stronger activity against Gram-positive (MICs 15.62–500.00 μg/mL) than Gram-negative bacteria (MICs 125.00–500.00 μg/mL). Punicalagin was most active against S. aureus, while gallic acid was most effective against E. coli. Docking revealed high affinities of punicalagin and punicalin, whereas transport studies highlighted the advantage of smaller phenolics like gallic acid in crossing porins. Conclusions: Larger tannins exhibited strong target binding but limited porin permeability, reducing efficacy in Gram-negative bacteria. These findings provide insights into structure–activity relationships of pomegranate polyphenols and support their potential as natural antimicrobial agents. Full article

(This article belongs to the Special Issue Bioactive Natural Products in Antimicrobial Resistance Management)

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13 pages, 215 KB

Open AccessArticle

Antibiotic Prescription Patterns in the Post-COVID-19 Era in Six European Countries: A Cross-Sectional Study

by Karel Kostev, Swati Upadhyaya, Oliver Utsch, Katarzyna Sosnowska, Marcel Konrad and Christian Tanislav

Antibiotics 2025, 14(9), 911; https://doi.org/10.3390/antibiotics14090911 - 10 Sep 2025

Abstract

Background/Objective: After the relaxation of acute containment measures during the COVID-19 pandemic, Europe experienced a substantial rebound of non-COVID infections surpassing pre-pandemic levels and causing significant clinical burden. The aim of our study is to analyze outpatient prescription data in Germany, France, Italy, [...] Read more.

Background/Objective: After the relaxation of acute containment measures during the COVID-19 pandemic, Europe experienced a substantial rebound of non-COVID infections surpassing pre-pandemic levels and causing significant clinical burden. The aim of our study is to analyze outpatient prescription data in Germany, France, Italy, Belgium, the UK, and Poland in order to assess trends and disparities in the post-COVID landscape. Methods: The present cross-sectional study utilized data from six independently collected datasets containing details from longitudinal prescription (LRx) databases. We aimed to evaluate changes in the number of antibiotic prescriptions issued in 2022 (the first post-pandemic year) compared to 2021 (a pandemic year), as well as subsequent developments in 2023 and 2024. Analyses were stratified by age group and by sex. In addition, the most frequently prescribed antibiotics in each year and country were reported. Results: All countries experienced a marked increase in antibiotic use in 2022 compared to 2021. The year-on-year growth in 2022 ranged from +12.0% in France to a substantial +39.3% in Belgium. Germany, Poland, and the UK also showed strong increases of over 25%, while Italy rose by 21.5%. Growth slowed in 2023 and stabilized or declined in 2024, particularly in Poland, Italy, and Belgium. Pediatric antibiotic use surged in 2022, especially among children under 10 (+75% in the UK), then leveled off and even declined in some cases in 2024, while the number of antibiotic prescriptions in older adults either decreased or increased only slightly. Germany and the UK showed continued pediatric antibiotic use increases through 2023. Amoxicillin dominated prescriptions in most countries, but drug choice patterns varied widely by country. Conclusions: This study shows a clear increase in outpatient antibiotic prescriptions issued across Europe after the COVID-19 pandemic, particularly among children and teenagers. Although the overall trends are now starting to level out, some countries still show rising numbers. These findings underscore the importance of a renewed focus on antibiotic stewardship programs, particularly in outpatient and primary care settings. Full article

(This article belongs to the Special Issue Therapy of Infectious Diseases Among Children and Adults: The Role of Antibiotics in Daily Practice)

12 pages, 1411 KB

Open AccessArticle

Antimicrobial Resistance of Staphylococcus borealis Isolated from Pig Farms: High Prevalence of SCCmec Type V and Emergence of cfr-Positive Isolates

by Ji Hyun Lim, Ji Heon Park, Gi Yong Lee and Soo-Jin Yang

Antibiotics 2025, 14(9), 910; https://doi.org/10.3390/antibiotics14090910 - 9 Sep 2025

Abstract

Background: The emergence of livestock-associated antimicrobial-resistant staphylococci, particularly non-aureus staphylococci, has become a major public health problem requiring immediate global attention. Methods: In this study, 92 Staphylococcus borealis isolates from 20 different pig farms in Korea were examined to determine the following: [...] Read more.

Background: The emergence of livestock-associated antimicrobial-resistant staphylococci, particularly non-aureus staphylococci, has become a major public health problem requiring immediate global attention. Methods: In this study, 92 Staphylococcus borealis isolates from 20 different pig farms in Korea were examined to determine the following: (1) antimicrobial-resistance (AMR) profiles of the isolates, (2) prevalence of methicillin resistance and staphylococcal cassette chromosome methicillin resistance gene (SCCmec) types, (3) occurrence of chloramphenicol–florfenicol resistance gene (cfr)-mediated oxazolidinone resistance, and (4) genomic characteristics of cfr-positive methicillin-resistant S. borealis (MRSB) via whole-genome sequence (WGS) analysis. Results: The overall rate of S. borealis isolation was 9.1% (92 isolates/1009 swabs), and 34.8% (32/92) of the isolates were MRSB. Surprisingly, all 32 MRSB isolates carried SCCmec V for methicillin resistance, and 31/32 MRSB isolates displayed multidrug-resistance phenotypes. Although 22 cfr-positive S. borealis isolates (20 MRSB and two methicillin-susceptible S. borealis) were identified, most of the isolates were susceptible to linezolid because they carried the 35-bp insertion sequence in the cfr promoter. Moreover, WGS analyses suggested horizontal transmission of SCCmec V and cfr-containing plasmids among different staphylococci species, including Staphylococcus aureus, S. epidermidis, and S. borealis. Conclusions: To the best of our knowledge, this study is the first to describe the AMR characteristics of livestock-associated S. borealis isolates, particularly the high prevalence of SCCmec V and cfr. Collectively, these results suggest that S. borealis is a crucial reservoir of AMR genes on pig farms in Korea. Full article

(This article belongs to the Special Issue Antimicrobial Resistance of Staphylococcus spp. in Animals: A One Health Perspective)

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11 pages, 863 KB

Open AccessArticle

Testing Analytical Methods for Antibiotic Detection in Tenebrio molitor Larvae: A Controlled Feeding Trial

by Tomke Asendorf, Christine Wind and Andreas Vilcinskas

Antibiotics 2025, 14(9), 909; https://doi.org/10.3390/antibiotics14090909 - 9 Sep 2025

Abstract

Background: As edible insects gain importance as sustainable protein sources, their integration into the food system requires that they meet the same safety standards as conventional animal products. This includes systematic testing for residues of pharmacologically active substances, such as antibiotics. To enable [...] Read more.

Background: As edible insects gain importance as sustainable protein sources, their integration into the food system requires that they meet the same safety standards as conventional animal products. This includes systematic testing for residues of pharmacologically active substances, such as antibiotics. To enable such monitoring, validated analytical methods for insect matrices are essential—but currently lacking. This study evaluates whether LC-MS/MS methods already validated for conventional animal products are suitable for detecting antibiotics in edible insects. Methods:Tenebrio molitor larvae were fed wheat flour containing 10 mg of tiamulin or chloramphenicol and 31.3 mg erythromycin per 100 g flour. The antibiotics were mixed into the feed, and their homogeneity and stability were confirmed. After seven days of feeding and a 24-h fasting period, larval samples were analyzed by LC-MS/MS. Results: All three antibiotics were detected in the insects. After seven days, mealworms contained 6.8 ± 0.3 mg/kg tiamulin, 1.4 ± 0.2 mg/kg chloramphenicol, and 224.5 ± 111 mg/kg erythromycin. Following the 24-hour fasting period, concentrations declined markedly to 0.6 ± 0.03 mg/kg, 0.2 ± 0.002 mg/kg, and 130.5 ± 0.7 mg/kg, respectively. Conclusions: The detection of all three antibiotics demonstrates that existing LC-MS/MS methods can be applied to insect matrices. Owing to the small number of replicates and the exploratory nature of the trial, these residue levels should be interpreted qualitatively as a proof of concept. The study provides a reproducible model for further feeding trials and underscores the need for more comprehensive validation. Potential drivers of antibiotic misuse in insect farming are discussed as a basis for developing and expanding testing methods to ensure the food safety of edible insects. Full article

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16 pages, 3035 KB

Open AccessArticle

Co-Culturing Bacillus Strains for Enhanced Antimicrobial Activity

by Charlie Tran, Russell S. Addison, Ian E. Cock, Xiaojing Chen and Yunjiang Feng

Antibiotics 2025, 14(9), 908; https://doi.org/10.3390/antibiotics14090908 - 8 Sep 2025

Abstract

Background/Objectives: Bacillus probiotic mixtures have been used as a novel source of antimicrobial production. However, there is a need to emphasize the potential of co-cultured Bacillus strains and to understand the underlying mechanisms involved in their combination formulation. Methods: Bacillus strains [...] Read more.

Background/Objectives: Bacillus probiotic mixtures have been used as a novel source of antimicrobial production. However, there is a need to emphasize the potential of co-cultured Bacillus strains and to understand the underlying mechanisms involved in their combination formulation. Methods: Bacillus strains BPR-11, BPR-16, and BPR-17, were cultured either as mono or multi-cultures. The bacterial growth and density were evaluated by measuring their optical density. The chemical profiles of their bioactive extracts were analysed by LC-MS, and their antimicrobial activity were tested against selected pathogens. Results: Our results reveal that co-cultured strains significantly increased bacterial growth, with an optical density level of, 2.67 which was significantly higher than the monocultures of BPR-11 (2.24), BPR-16 (2.32), and BPR-17 (2.22). Furthermore, the ethyl acetate extracts from these bacterial cultures showed that the combined co-culture (F1) exhibited the highest antimicrobial activity, with MICs of 25 µg/mL against C. perfringens, E. coli, and S. aureus, and 50 µg/mL against P. aeruginosa and S. enterica. In contrast, the monocultures BPR-16 and BPR-17 showed moderate activity with MICs of 50 µg/mL against C. perfringens, E. coli, and S. aureus, and 100 µg/mL against P. aeruginosa and S. enterica. BPR-11 had the lowest antimicrobial activity, with MICs of 100 µg/mL against C. perfringens, E. coli, and S. aureus, and no activity against P. aeruginosa and S. enterica. Metabolite profiling showed that the extract from the co-culture had a marked increase in the production of antimicrobial metabolites, including C₁₃-C₁₆ surfactin C. Lastly, the metabolism study of surfactin C analogues suggested that they were highly stable (99%) when incubated with cytochromes P450 over 120 min. Conclusions: Together, these findings highlight the potential for multi-strain co-culturing to develop new antimicrobials and provide valuable insights into the synergistic effects for antimicrobial production. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Rob Capon—Outstanding Contributions in the Field of Anti-Infectives)

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12 pages, 606 KB

Open AccessArticle

High Prevalence of Antimicrobial Resistance Genes in Rabbit Farms from Sumy Region, Ukraine

by Sara Gomes-Gonçalves, Jaqueline T. Bento, Ana Machado, Yevheniia Dudnyk, Oksana Shkromada, Halyna Rebenko, Adriano A. Bordalo and João R. Mesquita

Antibiotics 2025, 14(9), 907; https://doi.org/10.3390/antibiotics14090907 - 8 Sep 2025

Abstract

Background/Objectives: Antimicrobial resistance (AMR) poses a significant threat to public health, food security, and sustainable livestock production. Despite increasing concern, AMR remains poorly studied in cuniculture, particularly in regions where rabbit farming is predominantly small-scale and household-based. This study aimed to assess [...] Read more.

Background/Objectives: Antimicrobial resistance (AMR) poses a significant threat to public health, food security, and sustainable livestock production. Despite increasing concern, AMR remains poorly studied in cuniculture, particularly in regions where rabbit farming is predominantly small-scale and household-based. This study aimed to assess the prevalence and diversity of antimicrobial resistance genes (ARGs) in rabbit farms in northeastern Ukraine. Methods: A total of 100 fecal samples were collected from clinically healthy rabbits housed in two farms and one vivarium. DNA was extracted and analyzed using real-time PCR targeting 21 ARGs associated with resistance to major antibiotic classes, including tetracyclines, sulfonamides, β-lactams, macrolides, quinolones, carbapenems, and multidrug efflux systems. Results: A diverse and widespread resistome was identified. The most prevalent genes included sul1 (96%), blaTEM (95%), tetM (94%), and ermB (93%). AcrB (78%) and qnrS/oqxB (approximately 67%) were also frequently detected. Carbapenemase genes (blaKPC, blaNDM, blaVIM) were identified in 6% of samples, despite limited veterinary use of carbapenems. Notably, 96% of samples harbored ARGs from three or more antibiotic classes, indicating a high potential for multidrug resistance. Conclusions: The findings demonstrate a high prevalence and diversity of ARGs in rabbit farming systems in northeastern Ukraine. The presence of clinically significant resistance genes, including those conferring carbapenem resistance, underscores the urgent need for targeted AMR surveillance and improved antibiotic stewardship in cuniculture, particularly in regions with minimal regulatory oversight of antimicrobial use. Full article

(This article belongs to the Special Issue Antibiotic Resistance in a One Health Context: Bridging Environmental, Agricultural, Nutritional, Veterinary, and Clinical Perspectives)

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17 pages, 2591 KB

Open AccessArticle

Comparative Analysis of Phenotypic and Genotypic Antibiotic Susceptibility of Pasteurella multocida Isolated from Various Host Species in France and Hungary

by Krisztina Pintér, Marianna Domán, Enikő Wehmann, Hubert Gantelet and Tibor Magyar

Antibiotics 2025, 14(9), 906; https://doi.org/10.3390/antibiotics14090906 - 8 Sep 2025

Abstract

Background/Objectives: Pasteurella multocida is responsible for a wide variety of animal diseases worldwide, causing major economic losses. These infections are usually treated with antibiotics; however, the emergence of multidrug-resistant (MDR) strains is increasingly hindering. Understanding antibiotic resistance in P. multocida is important [...] Read more.

Background/Objectives: Pasteurella multocida is responsible for a wide variety of animal diseases worldwide, causing major economic losses. These infections are usually treated with antibiotics; however, the emergence of multidrug-resistant (MDR) strains is increasingly hindering. Understanding antibiotic resistance in P. multocida is important for effective treatment strategies and public health, as it impacts both animal and human welfare. Methods: In this study, the antibiotic susceptibility of 80 P. multocida isolates was evaluated by phenotypic (disk diffusion and broth microdilution) and genotypic analysis via whole-genome sequencing, with particular attention to the occurrence of MDR strains. The strains were tested against antibiotics from nine antimicrobial classes (penicillins, cephalosporins, aminoglycosides, tetracyclines, macrolides, fluoroquinolones, lincosamides, phenicols, and sulfonamides). Antimicrobial resistance gene (ARG) sequences and single-nucleotide polymorphisms (SNPs) were evaluated in paired reads using the Bacterial and Viral Bioinformatics Resource Center (BV-BRC) and the Comprehensive Antibiotic Resistance Database (CARD) via Resistance Gene Identifier (RGI), respectively. Results: Phenotypic results indicated that cephalosporins and phenicols were the most effective drugs against P. multocida; however, the majority of strains were also susceptible to fluoroquinolones and tetracyclines. In contrast, high resistance rates were observed to sulfamethoxazole and clindamycin. The most prevalent resistance genes were strA, sul2, and tetH, while none of the strains harbored the bla-_TEM or erm (42) genes. Conclusions: Of the two phenotypic methods, MIC values showed a stronger positive correlation with genotypic results, making it a more suitable method for determining antibiotic susceptibility. The phenotypic results for phenicols, tetracyclines, and fluoroquinolones showed a strong correlation with the detected resistance genes. In contrast, resistance to sulfamethoxazole, β-lactams, and macrolides remained genetically unexplained, suggesting the existence of additional resistance mechanisms to be explored. Full article

(This article belongs to the Section Antibiotics in Animal Health)

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