Antibiotics

18 pages, 2125 KiB

Open AccessArticle

Beyond One-Size-Fits-All: Addressing Methodological Constraints in Novel Antimicrobials Discovery

by Silvia Puxeddu, Serena Canton, Alessandra Scano, Ilenia Delogu, Andrea Pibiri, Cristiana Cabriolu, Sarah Vascellari, Francesca Pettinau, Tiziana Pivetta, Guido Ennas, Aldo Manzin and Fabrizio Angius

Antibiotics 2025, 14(8), 848; https://doi.org/10.3390/antibiotics14080848 - 21 Aug 2025

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Abstract

Background: Antimicrobial resistance is a growing global health concern that requires multiple strategies to be tackled effectively. While the discovery of new antimicrobial molecules is essential, the repurposing of existing compounds also plays a significant role. Standard methods to evaluate antimicrobial efficacy, [...] Read more.

Background: Antimicrobial resistance is a growing global health concern that requires multiple strategies to be tackled effectively. While the discovery of new antimicrobial molecules is essential, the repurposing of existing compounds also plays a significant role. Standard methods to evaluate antimicrobial efficacy, regulated by the Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Clinical and Laboratory Standards Institute (CLSI), such as the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), are available. However, several potential antimicrobics show interference with these standard methods, resulting in underestimated activity and their premature dismissal from further studies. This work compares reference methods in evaluating different compounds with unique physico-chemical characteristics. We aim to demonstrate that combining different susceptibility tests is mandatory for a successful preclinical screening of antimicrobial compounds. Methods: A selection of substances including natural extracts, both free and in the form of nanocomposites with fumed silica, ionic liquids, ozonated oils, commercial and pure antibiotics, was tested using broth microdilution, disk diffusion, and agar dilution. These methods were chosen following EUCAST and CLSI guidelines, and comparisons were made to evaluate their applicability and limitations for non-conventional substances. Results: The study highlighted significant variability in the outcomes depending on the method used, especially for substances with intrinsic properties such as high viscosity, poor solubility, or specific interactions with the testing medium. In several cases, the use of a single standard method failed to accurately reflect the real antimicrobial activity, leading to potential misinterpretation of effectiveness. Conclusions: A combined methodological approach is recommended to overcome the limitations of individual techniques. The integration of multiple reference methods offers a more accurate screening strategy for identifying and characterizing new and repurposed antimicrobials. Full article

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14 pages, 864 KiB

Open AccessArticle

Blood Cultures Time-to-Positivity as an Antibiotic Stewardship Tool in Immunocompromised Children with Gram-Negative Bacteraemia

by Julià Gotzens, Aina Colom-Balañà, Manuel Monsonís, Laia Alsina, María Antonia Ruiz-Cobo, María Ríos-Barnés, Anna Gamell, Eneritz Velasco-Arnaiz, Irene Martínez-de-Albéniz, Victoria Fumadó, Clàudia Fortuny, Antoni Noguera-Julian and Sílvia Simó-Nebot

Antibiotics 2025, 14(8), 847; https://doi.org/10.3390/antibiotics14080847 - 21 Aug 2025

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Abstract

Background/Objectives: Children and adolescents with haematologic malignancies or other causes of immunosuppression are at high risk of severe infections. Determining the probability of Gram-negative bacilli bloodstream infections (GNB-BSI) within 24 h of blood culture (BC) incubation could support early antibiotic de-escalation, compared [...] Read more.

Background/Objectives: Children and adolescents with haematologic malignancies or other causes of immunosuppression are at high risk of severe infections. Determining the probability of Gram-negative bacilli bloodstream infections (GNB-BSI) within 24 h of blood culture (BC) incubation could support early antibiotic de-escalation, compared to the current guidelines recommending de-escalation after 48–72 h. Methods: Retrospective, observational single-centre study describing BC time-to-positivity (TTP) in GNB-BSI in a paediatric cohort of immunocompromised children. Results: In 128 episodes (100 patients), TTP was less than 24 h in >95% cases. TTP did not differ based on sex, underlying disease, degree of neutropenia, or PICU admission. Antibiotic initiation prior to BC collection and microbiological aetiology (microbiological aetiology different from Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, or Enterobacter cloacae) were the only identified risk factors associated with BC growth beyond 24 h. No patients with late BC growth died or required PICU admission. Conclusions: If BC remains negative after 24 h of incubation, GNB-BSI is unlikely in immunocompromised children and adolescents with fever. These results support early de-escalation strategies, shortening unnecessary exposure to broader-spectrum antibiotics, and potentially decreasing adverse events and costs. Full article

(This article belongs to the Special Issue Inappropriate Use of Antibiotics in Pediatrics)

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25 pages, 889 KiB

Open AccessReview

Advancing Nigerian Indigenous Poultry Health and Production, Use of Probiotics as Viable Alternatives to Antibiotics: A Review

by Shedrach Benjamin Pewan, Dennis Kabantiyok, Paulinus Ekene Emennaa, Joshua Shehu Dawurung, Christiana J. Dawurung, Reuben Kefas Duwil, Olufunke Olufunmilola Olorundare, Hassan Yader Ngukat, Moses Gani Umaru, Garba Mathias Ugwuoke and Chuka Ezema

Antibiotics 2025, 14(8), 846; https://doi.org/10.3390/antibiotics14080846 - 21 Aug 2025

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Abstract

Poultry is a vital component of global meat production, with particular importance in Nigeria and Africa, as it promotes food security, economic growth, and rural livelihoods. Indigenous chickens, although less productive, are well adapted to local environments and provide significant socio-economic and nutritional [...] Read more.

Poultry is a vital component of global meat production, with particular importance in Nigeria and Africa, as it promotes food security, economic growth, and rural livelihoods. Indigenous chickens, although less productive, are well adapted to local environments and provide significant socio-economic and nutritional benefits. The rising demand for animal protein and concerns over antimicrobial resistance (AMR) necessitate the development of sustainable alternatives to antibiotics in poultry production. Probiotics have emerged as effective feed additives that enhance gut health, immunity, nutrient absorption, and overall productivity. While extensively studied in commercial poultry, research on probiotics in Nigerian Indigenous Ecotype Chickens (NIECs) remains limited. Key challenges in indigenous poultry systems include low productivity, disease vulnerability, limited veterinary access, and environmental pressures. Addressing these requires improved management practices, infrastructure, veterinary support, and enabling policies. Multi-strain probiotics, particularly those containing Lactobacillus, Bifidobacterium, and Bacillus species, demonstrate promise in enhancing productivity, improving product quality, promoting environmental sustainability, and ensuring food safety. Focused research on local probiotic strains, field trials, farmer education, and policy support is crucial for harnessing the full benefits of probiotics and transforming indigenous poultry farming into a resilient and sustainable sector. Full article

(This article belongs to the Special Issue Alternative Approaches to Treating Antimicrobial Resistant Infections, 3rd Edition)

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13 pages, 596 KiB

Open AccessArticle

Guideline-Concordant Antibiotic Treatment for Hospitalised Patients with Community-Acquired Pneumonia and Clinical Outcomes at a Tertiary Hospital in Australia

by Yogesh Sharma, Arduino A. Mangoni, Subodha Sumanadasa, Isuru Kariyawasam, Chris Horwood and Campbell Thompson

Antibiotics 2025, 14(8), 845; https://doi.org/10.3390/antibiotics14080845 - 20 Aug 2025

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Abstract

Background/Objectives: Community-acquired pneumonia (CAP) remains a major cause of hospitalisation and death, particularly among older and frail adults. Although treatment guidelines exist, adherence to empiric antibiotic recommendations is variable. This study examined whether receiving guideline-concordant antibiotics for CAP was associated with better short- [...] Read more.

Background/Objectives: Community-acquired pneumonia (CAP) remains a major cause of hospitalisation and death, particularly among older and frail adults. Although treatment guidelines exist, adherence to empiric antibiotic recommendations is variable. This study examined whether receiving guideline-concordant antibiotics for CAP was associated with better short- and long-term clinical outcomes. Methods: We conducted a retrospective cohort study of adults admitted with radiologically confirmed CAP to a tertiary hospital in Australia from 1 January to 31 December 2023. Patients with hospital-acquired pneumonia or COVID-19 were excluded. Antibiotic concordance was assessed against local guidelines. Propensity score matching (PSM) accounted for 16 covariates including age, comorbidities (Charlson Index), frailty (Hospital Frailty Risk Score), and pneumonia severity (SMART-COP). Primary outcomes were in-hospital, 30-day, and one-year mortality. Secondary outcomes included ICU admission, invasive ventilation, vasopressor use, hospital length of stay, and 30-day readmissions. Results: Of 241 patients, 51.4% received guideline-concordant antibiotics. Mean age was 73.5 years; 50.2% were male; 42.2% had severe pneumonia (SMART-COP ≥ 5); 36.5% were frail. In unadjusted analysis, in-hospital mortality was higher in the concordant group (5.6% vs. 0.9%, p = 0.038). After PSM (n = 105 matched pairs), concordant treatment was associated with significantly lower 30-day mortality (coefficient = –0.12; 95% CI: –0.23 to –0.02; p = 0.018) and there was a non-significant trend towards reduced 1-year mortality (p = 0.058). Other outcomes, including in-hospital mortality, were not significantly different. Conclusions: Guideline-concordant antibiotics were associated with reduced 30-day mortality in CAP. These results support adherence to evidence-based treatment guidelines to improve patient outcomes. Full article

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21 pages, 764 KiB

Open AccessArticle

PRACT-India: Practical Recommendations on Acne Care and Medical Treatment in India—A Modified Delphi Consensus

by Nina Madnani, Abir Saraswat, Anand Nott, Deepak Jakhar, Lalit Kumar Gupta, Malavika Kohli, Manas Ranjan Puhan, Prabhakar Sangolli, Rahul Nagar, Sanjay Kumar Rathi, Sanjeev Aurangabadkar, Satish DA, Seetharam KA, Sunil Dogra, Dhiraj Dhoot, Ashwin Balasubramanian, Saiprasad Patil and Hanmant Barkate

Antibiotics 2025, 14(8), 844; https://doi.org/10.3390/antibiotics14080844 - 20 Aug 2025

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Abstract

Background/Objectives: Acne vulgaris is a prevalent dermatological condition, yet clear, region-specific management guidelines, particularly for India’s diverse population, remain limited. Effective acne management extends beyond pharmacologic therapy, emphasizing proper skincare, patient education, and adherence strategies. This consensus aims to provide tailored, evidence-based recommendations [...] Read more.

Background/Objectives: Acne vulgaris is a prevalent dermatological condition, yet clear, region-specific management guidelines, particularly for India’s diverse population, remain limited. Effective acne management extends beyond pharmacologic therapy, emphasizing proper skincare, patient education, and adherence strategies. This consensus aims to provide tailored, evidence-based recommendations for optimizing acne treatment in the Indian context. Methods: A panel of 14 dermatology experts with ≥15 years of experience reviewed literature, real-world clinical practices, and patient-centric factors relevant to acne management in India. Using a modified Delphi process with two virtual voting rounds, 61 statements across seven clinical domains were evaluated. Consensus was defined as ≥75% agreement. Results: Topical retinoids remain the first-line therapy, with combination regimens (benzoyl peroxide or topical antibiotics) preferred to enhance efficacy and minimize antibiotic resistance. Hormonal therapies, including combined oral contraceptives and spironolactone, are recommended for females with resistant acne. Guidance includes individualized treatment plans, baseline investigations, and selection of appropriate topical and systemic agents. Special considerations for pregnancy and lactation prioritize maternal and fetal safety. Conclusions: This expert consensus provides practical, evidence-based recommendations for acne management in India, integrating pharmacological and non-pharmacological approaches. The tailored guidance supports individualized care, antibiotic stewardship, and improved treatment adherence, aiming to enhance patient outcomes nationwide. Full article

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

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22 pages, 3753 KiB

Open AccessArticle

Quinolone Resistance and Zoonotic Potential of Corynebacterium ulcerans from Domestic Animals in Brazil

by Fernanda Diniz Prates, Max Roberto Batista Araújo, Jailan da Silva Sousa, Lincoln de Oliveira Sant’Anna, Tayná do Carmo Sant’Anna Cardoso, Amanda Couto Calazans Silva, Siomar de Castro Soares, Bruno Silva Andrade, Louisy Sanches dos Santos and Vasco Ariston de Carvalho Azevedo

Antibiotics 2025, 14(8), 843; https://doi.org/10.3390/antibiotics14080843 - 20 Aug 2025

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Abstract

Background: Corynebacterium ulcerans is an emerging zoonotic pathogen capable of cau-sing diphtheria-like infections in humans. Objectives: we report, for the first time in Brazil, the detection and phenotypic/genomic characterization of three atoxigenic ST-339 strains isolated from domestic animals, including one with a ciprofloxacin [...] Read more.

Background: Corynebacterium ulcerans is an emerging zoonotic pathogen capable of cau-sing diphtheria-like infections in humans. Objectives: we report, for the first time in Brazil, the detection and phenotypic/genomic characterization of three atoxigenic ST-339 strains isolated from domestic animals, including one with a ciprofloxacin resistance profile linked to double GyrA mutations (S89L, D93G). Methods: species identification was performed by MALDI-TOF MS, followed by in vitro antimicrobial susceptibility testing, whole-genome sequencing, and bioinformatic analyses to predict virulence determinants, antimicrobial resistance genes, CRISPR–Cas systems, mobile genetic elements, and in silico structural analysis as well as phylogenetic reconstruction. Results: whole-genome sequencing confirmed species identity, revealed high genetic similarity, and identified distinct phylogenetic subclades, suggesting potential international dissemination. Genomic analyses showed conserved virulence determinants, such as incomplete pilus clusters, iron acquisition systems, and the pld gene, with the absence of the tox gene. Molecular modeling and dynamics simulations indicated that GyrA mutations disrupt critical ciprofloxacin–magnesium–water interactions, reducing binding stability. Mobile genetic elements, prophages, and CRISPR–Cas systems underscored the genomic plasticity of these isolates. Conclusions: these findings document a little-studied antimicrobial resistance mechanism in zoonotic C. ulcerans, highlighting the need for strengthened surveillance and further research on virulence and resistance, even in ato-xigenic strains. Full article

(This article belongs to the Special Issue Epidemiology and Pathogenomics of the Corynebacterium Genus)

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21 pages, 3142 KiB

Open AccessArticle

Comparative Analysis of Biofilm Formation and Antibiotic Resistance in Five ESKAPE Pathogen Species from a Tertiary Hospital in Bangladesh

by Tasnimul Arabi Anik, Rahat Uzzaman, Khandaker Toyabur Rahman, Abir Hossain, Faruk Islam, Mosammod Nowshin Tasnim, Shahin Ara Begum, Humaira Akhter and Anowara Begum

Antibiotics 2025, 14(8), 842; https://doi.org/10.3390/antibiotics14080842 - 20 Aug 2025

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Abstract

Background: Four of the six ESKAPE pathogens are responsible for a majority of antimicrobial resistance (AMR)-related deaths worldwide. Identifying the pathogens that evade antibiotic treatments more efficiently than others can help diagnose pathogens requiring more attention. The study was thus designed to [...] Read more.

Background: Four of the six ESKAPE pathogens are responsible for a majority of antimicrobial resistance (AMR)-related deaths worldwide. Identifying the pathogens that evade antibiotic treatments more efficiently than others can help diagnose pathogens requiring more attention. The study was thus designed to evaluate the biofilm and resistance properties of five ESKAPE pathogens comparatively. A total of 165 clinical isolates of 5 ESKAPE pathogen species (E. faecium, S. aureus, K. pneumoniae, A. baumannii, and P. aerurginosa) were collected from a tertiary hospital in Bangladesh. Methodology: Following secondary identification, antibiotic susceptibility was determined by the disc diffusion method and minimum inhibitory concentration. The biofilm formation was determined by the microtiter plate biofilm formation assay. The biofilm-forming genes were screened by PCR. Detection of carbapenemase and Metallo-β-lactamase was performed by the modified carbapenem inactivation method (mCIM) and the EDTA-modified carbapenem inactivation method (eCIM) test, respectively. Results: Among Gram-positive isolates, E. faecium exhibited higher multi-drug resistance (MDR) rates (90%) compared to S. aureus (10%). In Gram-negative isolates, A. baumannii and K. pneumoniae showed elevated resistance to carbapenems (74.29% and 45.71%, respectively), cephalosporins, and β-lactam inhibitors, while P. aeruginosa demonstrated relatively lower resistance. Colistin resistance was highest in K. pneumoniae (42.86%). Biofilm formation was prevalent, with 88.5% of isolates forming biofilms, including 15.8% strong biofilm producers. Notably, K. pneumoniae and A. baumannii exhibited higher biofilm-forming capabilities compared to P. aeruginosa. A significant correlation was observed between biofilm formation and resistance to carbapenems, cephalosporins, and piperacillin/tazobactam (p < 0.05), suggesting a potential role of biofilms in disseminating resistance to these antibiotics. Carbapenemase production was detected in 23.8% of Gram-negative isolates, with K. pneumoniae showing the highest prevalence (34.3%). Additionally, 45.8% of carbapenemase producers expressed Metallo-β-lactamases (MBLs). Among S. aureus isolates, 46.7% carried the mecA gene, confirming methicillin resistance (MRSA), while 20% of E. faecium isolates exhibited vancomycin resistance, primarily mediated by the vanB gene. Conclusions: These findings can help pinpoint the pathogens of significant threat. Full article

(This article belongs to the Section Antibiotics Use and Antimicrobial Stewardship)

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26 pages, 4388 KiB

Open AccessArticle

Deciphering Common Genetic Pathways to Antibiotic Resistance in Escherichia coli Using a MEGA-Plate Evolution System

by Nami Morales-Durán, Angel León-Buitimea, Roberto Álvarez Martínez and José Rubén Morones-Ramírez

Antibiotics 2025, 14(8), 841; https://doi.org/10.3390/antibiotics14080841 - 20 Aug 2025

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Abstract

Background. Antimicrobial resistance (AMR) poses a significant global health threat, necessitating a deeper understanding of bacterial adaptation mechanisms. Introduction. This study investigates the genotypic and phenotypic evolutionary trajectories of Escherichia coli under meropenem and gentamicin selection, and it benchmarks these findings against florfenicol-evolved [...] Read more.

Background. Antimicrobial resistance (AMR) poses a significant global health threat, necessitating a deeper understanding of bacterial adaptation mechanisms. Introduction. This study investigates the genotypic and phenotypic evolutionary trajectories of Escherichia coli under meropenem and gentamicin selection, and it benchmarks these findings against florfenicol-evolved strains. Methodology. Utilizing a downsized, three-layer acrylic modified “Microbial Evolution and Growth Arena (MEGA-plate) system”—scaled to 40 × 50 cm for sterile handling and uniform 37 °C incubation—we tracked adaptation over 9–13 days, enabling real-time visualization of movement across antibiotic gradients. Results. Meropenem exposure elicited pronounced genetic heterogeneity and morphological remodeling (filamentous and circular forms), characteristic of SOS-mediated division arrest and DNA-damage response. In contrast, gentamicin exposure produced a uniform resistance gene profile and minimal shape changes, suggesting reliance on conserved defenses without major morphological adaptation. Comprehensive genomic analysis revealed a core resistome of 22 chromosomal loci shared across all three antibiotics, highlighting potential cross-resistance and the central roles of baeR, gadX, and marA in coordinating adaptive responses. Gene ontology enrichment underscored the positive regulation of gene expression and intracellular signaling as key themes in resistance evolution. Discussion. Our findings illustrate the multifaceted strategies E. coli employs—combining metabolic flexibility with sophisticated regulatory networks—to withstand diverse antibiotic pressures. This study underscores the utility of the MEGA-plate system in dissecting spatiotemporal AMR dynamics in a controlled yet ecologically relevant context. Conclusions. The divergent responses to meropenem and gentamicin highlight the complexity of resistance development and reinforce the need for integrated, One Health strategies. Targeting shared regulatory hubs may open new avenues for antimicrobial intervention and help preserve the efficacy of existing drugs. Full article

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

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44 pages, 2296 KiB

Open AccessReview

A Practical Framework for Environmental Antibiotic Resistance Monitoring in Freshwater Ecosystems

by Irene Beltrán de Heredia, Itziar Alkorta, Carlos Garbisu and Estilita Ruiz-Romera

Antibiotics 2025, 14(8), 840; https://doi.org/10.3390/antibiotics14080840 - 19 Aug 2025

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Abstract

Antibiotic resistance (AR) and contamination are critical public and environmental health issues. In the last years, the environmental component of AR has acquired much interest due to its potential links with the human resistome. In particular, freshwater ecosystems are considered strategic sites for [...] Read more.

Antibiotic resistance (AR) and contamination are critical public and environmental health issues. In the last years, the environmental component of AR has acquired much interest due to its potential links with the human resistome. In particular, freshwater ecosystems are considered strategic sites for environmental AR surveillance, since they can act as both reservoirs and transmission routes for antibiotic-resistant bacteria and antibiotic resistance genes. Many studies are needed to deepen our understanding of AR evolution and dynamics in freshwater ecosystems and, specifically, on the existence of links between environmental and human AR. This calls for the design of robust and adaptive AR surveillance strategies and, concomitantly, the implementation of routine monitoring programs that effectively capture the environmental dimension of AR in freshwater ecosystems. Here, a roadmap for AR monitoring in freshwater ecosystems, framed around four essential questions (how? what? where? when?), is presented to guide researchers and decision-makers in designing and implementing effective environmental AR routine monitoring programs. It was concluded that, due to the complexity, heterogeneity, and dynamic nature of freshwater ecosystems, it seems foreseeable that environmental AR monitoring programs need to be carefully adjusted to the particular casuistry of each freshwater ecosystem, as well as to the specific interests of the corresponding program and the resources available. Still, much research is needed to properly assess and monitor the risks derived from the emergence and dissemination of AR determinants in freshwaters for both ecosystem and human health. By synthesizing current knowledge and methodologies, this review consolidates existing approaches and can serve as a guide for planning AR monitoring programs in freshwater ecosystems. Full article

(This article belongs to the Special Issue Antibiotics and the Evolution of Resistance: Insights into Horizontal Gene Transfer)

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19 pages, 400 KiB

Open AccessArticle

Antimicrobial Use and Awareness of Antimicrobial Resistance in the Livestock Sector in the Western Balkans

by Dora Kovacs, Eran Raizman, Anne Deckert, Natalia Ciria Artiga, Marijana Bošković, Ervin Bučan, Jelena Vračar Filipović, Olta Agolli, Dragana Grbić, Mevlida Hrapović, Ivan Ivanović, Nora Jusufi, Saša Lješković, Ljiljana Milovanović, Tamas Nagy, Miloš Palibrk, Milan Rogošić, Anna Sargsyan, Blagojcho Tabakovski and Daniel Beltran-Alcrudo

Antibiotics 2025, 14(8), 839; https://doi.org/10.3390/antibiotics14080839 - 19 Aug 2025

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Abstract

Background/Objectives: Antimicrobial resistance (AMR) is a major threat to human, animal, and environmental health. To tackle AMR in the livestock sector, there is a need to understand the antimicrobial use (AMU) practices of different stakeholders in order to target the common knowledge gaps [...] Read more.

Background/Objectives: Antimicrobial resistance (AMR) is a major threat to human, animal, and environmental health. To tackle AMR in the livestock sector, there is a need to understand the antimicrobial use (AMU) practices of different stakeholders in order to target the common knowledge gaps and inappropriate practices with tailored interventions. In the Western Balkans, published evidence shows the presence of AMR in both humans and animals. Since studies on AMU have mainly been conducted in humans, there is a significant knowledge gap about AMU in the livestock sector. The aim of this study was to assess the knowledge, attitudes, and practices of farmers, veterinarians, veterinary pharmacy personnel, and feed mill personnel related to AMU (focusing on antibiotics) and AMR in Albania, Bosnia and Herzegovina, Kosovo (References to Kosovo shall be understood to be in the context of Security Council resolution 1244 (1999)), Montenegro, North Macedonia, and Serbia. Methods: Field interviews were conducted in 2022 with 2815 participants in selected regions of the countries. Results: The findings showed that farmers engaged in imprudent practices, including purchasing antimicrobials without a prescription, administering antimicrobials for growth promotion, and disposing of expired antimicrobials in the garbage. Farmers’ main knowledge gaps were related to the duration of antimicrobial treatment and the differentiation between AMR and antimicrobial residues. This study also revealed poor record-keeping on animal treatments and a lack of some biosecurity measures. In terms of the attitudes and practices of veterinarians and veterinary pharmacy personnel, the belief that antimicrobial drugs are important for growth promotion, and the common use and sales of highest priority critically important antimicrobials should be targets for future interventions. Conclusions: Despite significant ongoing efforts to tackle AMR, there is still a need for training, awareness-raising, and policy interventions to address the knowledge gaps identified by this study and optimize AMU in the livestock sector in the Western Balkans. Full article

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25 pages, 4667 KiB

Open AccessArticle

In Vitro and In Vivo Characterization of Novel Cathelicidin-Based Peptides with Antimicrobial Activity Against Pseudomonas aeruginosa

by Javier Moreno-Morales, Núria Martín-Vilardell, Salvador Guardiola, Xavier Vila-Farrés, Tania Cebrero, Marko Babić, Clara Ballesté-Delpierre, Daniela Kalafatović, Ernest Giralt, María Eugenia Pachón-Ibañez and Jordi Vila

Antibiotics 2025, 14(8), 838; https://doi.org/10.3390/antibiotics14080838 - 19 Aug 2025

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Abstract

Background/Objectives: Infections caused by multidrug-resistant (MDR) Pseudomonas aeruginosa are steadily increasing, thus the discovery and development of new and effective agents are needed. Antimicrobial peptides (AMPs) are a heterogeneous group of innate defense system peptides with broad antimicrobial activity. In this study, [...] Read more.

Background/Objectives: Infections caused by multidrug-resistant (MDR) Pseudomonas aeruginosa are steadily increasing, thus the discovery and development of new and effective agents are needed. Antimicrobial peptides (AMPs) are a heterogeneous group of innate defense system peptides with broad antimicrobial activity. In this study, 17 AMPs were tested, identifying CAP-18, a cathelicidin-based compound, as the most active. CAP-18 was optimized by synthesizing structural derivatives, which were selected for further studies based on their activity against a collection of MDR and colistin-resistant P. aeruginosa strains. Methods: AMPs collection was initially tested against different P. aeruginosa strains, identifying CAP-18 as the most active. CAP-18 derivatives were synthetized and assessed by the Minimum Inhibitory Concentration (MIC), time-kill kinetics, cytotoxicity against human cell lines, hemolytic activity, and therapeutic index (IC₅₀/MIC₉₀). The mechanism of action was assessed by Transmission Electron Microscopy (TEM), and in vivo efficacy was determined through a murine skin infection model. Results: CAP-18 and D-CAP-18 had a MIC₉₀ of 4 and 2 μg/mL, respectively, whereas CAP-18₃₁ and D-CAP-18₃₁ presented MIC₉₀ values of 16 mg/L. The shorter derivatives of CAP-18 showed a lower activity. Time-kill curves revealed a fast bactericidal effect. These derivatives showed low toxicity against different human cell lines and low hemolysis, resulting in a wide therapeutic index (IC₅₀/MIC₉₀), with D-CAP-18 having the best therapeutic index (137.4). TEM provided insight into the mechanism of action, revealing bacterial membrane damage. In vivo studies of both CAP-18 and D-CAP-18 showed good activity with a 3 log decrease compared to the infected control group. Conclusions: Among the investigated four peptides, D-CAP-18 is the most promising candidate to treat skin infections caused by MDR P. aeruginosa since it shows potent activity both in vitro and in vivo, and a high therapeutic index. Full article

(This article belongs to the Section Antimicrobial Peptides)

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15 pages, 2923 KiB

Open AccessArticle

Ivermectin Identified Using a High-Throughput Screening System Exhibits Anti-Clonorchis sinensis Activity in Rats

by Soon-Ok Lee, Hyeryon Lee, Ki Back Chu, Jianhua Li, Sung-Jong Hong, Sung Soo Kim, Joo Hwan No and Fu-Shi Quan

Antibiotics 2025, 14(8), 837; https://doi.org/10.3390/antibiotics14080837 - 19 Aug 2025

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Abstract

Background: Clonorchiasis, caused by the parasite Clonorchis sinensis, remains a public health concern in East Asian countries. Methods: In this study, high-throughput screening was used to analyze 320 compounds for potential inhibitory activity against Clonorchis sinensis. To ensure the selection of [...] Read more.

Background: Clonorchiasis, caused by the parasite Clonorchis sinensis, remains a public health concern in East Asian countries. Methods: In this study, high-throughput screening was used to analyze 320 compounds for potential inhibitory activity against Clonorchis sinensis. To ensure the selection of high-confidence hits, a stringent inhibition threshold of 80% was applied, leading to the identification of three active compounds: moxifloxacin, hexachlorophene, and ivermectin (IVM). Ivermectin emerged as a hit compound and was assessed for its anti-C. sinensis efficacy. Results: Ivermectin demonstrated dose-dependent trematocidal activity against C. sinensis metacercariae (CsMC) and newly excysted juveniles (CsNEJs), showing superior efficacy against CsMC and CsNEJs compared to praziquantel. To assess in vivo efficacy, rats were infected with CsMC and treated with ivermectin at 1 and 4 weeks post-infection (wpi) to target larval and adult stages, respectively. A significant worm burden reduction was observed compared to untreated control when treatment was administered at 1 wpi, showing an antiparasitic effect against larvae. Parasite-specific IgG levels and ALT/AST responses were comparable to those of the infection control group. Conclusions: These findings suggest that ivermectin may serve as a potential alternative drug targeting C. sinensis larvae. Full article

(This article belongs to the Collection Synthetic and Natural Products-Based Antimicrobial and Antiparasitic Agents)

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16 pages, 1054 KiB

Open AccessArticle

Occurrence and Risk Assessment of Antimicrobials and Resistant Bacteria in Treated Sewage Effluents in South Brazil

by Keite da Silva Nogueira, Ana Paula de Oliveira Tomaz, Gabrielly Cristina Kubis, Raizza Zorman Marques, Nicole Geraldine de Paula Marques Witt, Aliny Lucia Borges Borba, Bárbara Zanicotti Leite and Marcelo Pedrosa Gomes

Antibiotics 2025, 14(8), 836; https://doi.org/10.3390/antibiotics14080836 - 18 Aug 2025

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Abstract

Background/Objectives: The increasing presence of antimicrobial residues and antibiotic-resistant bacteria (ARB) in effluents from wastewater treatment plants (WWTP) has become a critical concern for environmental and public health. This study aimed to investigate the occurrence, concentrations, and ecological risks of commonly used antimicrobials [...] Read more.

Background/Objectives: The increasing presence of antimicrobial residues and antibiotic-resistant bacteria (ARB) in effluents from wastewater treatment plants (WWTP) has become a critical concern for environmental and public health. This study aimed to investigate the occurrence, concentrations, and ecological risks of commonly used antimicrobials as well as the prevalence of clinically relevant ARB in treated effluents. Methods: A five-month monitoring campaign was conducted at a major WWTP in Curitiba, Brazil. Thirteen antibiotics were quantified using LC-MS/MS, resistant bacteria were identified via phenotypic profiling, and ecotoxicological assays were performed with Desmodesmus subspicatus. Risk assessments included hazard quotient (HQ) calculations for ecotoxicity and resistance selection as well as multivariate and correlation analyses. Results: All antibiotics were consistently detected over five months, with total concentrations ranging from 1730 to 2840 ng L⁻¹. Clinically relevant ARB (Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae) resistant to high-priority antibiotics were also isolated. Ecotoxicological tests showed moderate growth inhibition only in undiluted effluent. HQ values for ecotoxicity were <1, but HQ for resistance selection exceeded 1 for all compounds. Multivariate analyses showed strong associations between fluoroquinolone and macrolide concentrations and ARB detection. Conclusions: Although WWTPs reduce pollutant loads, conventional processes may not fully eliminate antimicrobials and ARB, highlighting the need for advanced treatments. Culture-based detection may have underestimated the resistance diversity. These findings support the integration of resistance-based discharge thresholds into regulations, and provide a replicable model for AMR surveillance in tropical urban systems. Full article

(This article belongs to the Special Issue Antimicrobial Resistance in the Era of Climate Change)

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3 pages, 152 KiB

Open AccessEditorial

Integrating Global Surveillance, Local Action, and Innovative Stewardship Against Antimicrobial Resistance

by Jesús Ruiz-Ramos

Antibiotics 2025, 14(8), 835; https://doi.org/10.3390/antibiotics14080835 - 18 Aug 2025

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Abstract

The silent pandemic of antimicrobial resistance (AMR) represents one of the gravest threats to global health of the 21st century [...] Full article

(This article belongs to the Special Issue Optimizing Antimicrobial Use: Antimicrobial Stewardship and Surveillance)

8 pages, 637 KiB

Open AccessArticle

Implementation and Early Outcomes of an Antimicrobial Stewardship Program in South Korea

by Kyeong Min Jo and Tae-Hoon No

Antibiotics 2025, 14(8), 834; https://doi.org/10.3390/antibiotics14080834 - 17 Aug 2025

Viewed by 449

Abstract

Background: Antimicrobial stewardship programs (ASPs) are essential for promoting the rational use of antibiotics and combating resistance. In South Korea, implementation has recently accelerated, but real-world data on short-term program performance remain limited. This study evaluated the early outcomes of a newly [...] Read more.

Background: Antimicrobial stewardship programs (ASPs) are essential for promoting the rational use of antibiotics and combating resistance. In South Korea, implementation has recently accelerated, but real-world data on short-term program performance remain limited. This study evaluated the early outcomes of a newly launched ASP at a tertiary hospital. Methods: This retrospective, single-center study analyzed ASP activity from January to April 2025. Interventions included prospective audit and feedback for restricted antibiotics and recommendations for prolonged antibiotic prescriptions (≥14 days). The primary outcome was the monthly rejection rate of restricted antibiotics. Secondary outcomes included days of therapy (DOT) for restricted antibiotics and the acceptance rate of interventions for prolonged prescriptions. Results: The monthly rejection rate of restricted antibiotics remained stable between 3.65% and 4.68%. Although the DOT values did not show statistical significance, they demonstrated a moderate inverse correlation with the rejection rate (Pearson’s r = –0.868, p = 0.132). Among 826 prolonged prescriptions, 513 (62.1%) received ASP intervention. Acceptance of recommendations increased over time, from 67.0% in January to 82.5% in April. Interventions were primarily based on insufficient evidence of infection or inappropriate antibiotic selection. Conclusions: The newly implemented ASP demonstrated feasibility and early impact in improving antibiotic oversight. Despite the short observation period, the findings suggest a positive influence on prescribing practices. Longer-term studies are needed to evaluate sustained clinical outcomes and broader applicability in diverse healthcare settings. Full article

(This article belongs to the Special Issue Antibiotic Use in Outpatients and Hospitals)

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26 pages, 6488 KiB

Open AccessArticle

Electron Beam Irradiation for Efficient Antibiotic Degradation in Aqueous Solutions

by Anastasia Oprunenko, Ulyana Bliznyuk, Victoria Ipatova, Alexander Nikitchenko, Igor Gloriozov, Arcady Braun, Timofey Bolotnik, Polina Borshchegovskaya, Elena Kozlova, Irina Ananieva and Igor Rodin

Antibiotics 2025, 14(8), 833; https://doi.org/10.3390/antibiotics14080833 - 15 Aug 2025

Viewed by 337

Abstract

Background: Recently, extensive use of antibiotics has increased the amount of antibiotic residues in the natural water environment. Methods: This study presents an experimental investigation into the degradation of penicillins, tetracyclines, streptomycin and chloramphenicol in aqueous solutions when exposed to 1 MeV accelerated [...] Read more.

Background: Recently, extensive use of antibiotics has increased the amount of antibiotic residues in the natural water environment. Methods: This study presents an experimental investigation into the degradation of penicillins, tetracyclines, streptomycin and chloramphenicol in aqueous solutions when exposed to 1 MeV accelerated electrons with doses of 0.1, 1, 3 and 7 kGy using HPLC-HRMS analysis. Results: It was found that electron beam irradiation with a dose of 7 kGy ensures 98–99% removal of antibiotics, with the initial concentrations ranging from 15 mg/L to 30 mg/L depending on the class of antibiotic. The mathematical model proposed in the study, which estimates the dose dependencies of the relative concentrations of antibiotics and their degradation products in aqueous solutions, reveals different decomposition rates of antibiotics of different classes due to the different radiosensitivities of antibiotics. It has been found that tetracycline has a considerably higher radiation–chemical yield compared to the other antibiotics when exposed to accelerated electrons. Conclusions: Using density functional theory in combination with the mathematical model, we have developed a novel approach to establishing a quantitative irradiation marker of antibiotic degradation as a result of irradiation, which involves finding the degradation product whose formation requires a minimum number of ionization events. Using such an approach, it is possible to establish the extent of antibiotic degradation in water after irradiation with different doses and find the optimal irradiation doses for industrial water treatment. Full article

(This article belongs to the Special Issue Antibiotics and Environment − Research and Development toward the One Health Approach)

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14 pages, 3593 KiB

Open AccessArticle

Spontaneous Emergence of Cefiderocol Resistance in Klebsiella pneumoniae KPC-163: Genomic and Transcriptomic Insights

by Irene Luu, Vyanka Mezcord, Jenny Escalante, German M. Traglia, Marisel R. Tuttobene, Cecilia Rodriguez, Chun Fu Cheng, Quentin Valle, Rajnikant Sharma, Marcelo E. Tolmasky, Robert A. Bonomo, Gauri Rao, Fernando Pasteran and Maria Soledad Ramirez

Antibiotics 2025, 14(8), 832; https://doi.org/10.3390/antibiotics14080832 - 15 Aug 2025

Viewed by 390

Abstract

Background/Objectives: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is an urgent public health threat due to its rapid dissemination and resistance to last-line antibiotics. Cefiderocol (FDC), a novel siderophore cephalosporin, targets resistant Gram-negative pathogens by exploiting bacterial iron uptake mechanisms. However, resistance to FDC is emerging [...] Read more.

Background/Objectives: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is an urgent public health threat due to its rapid dissemination and resistance to last-line antibiotics. Cefiderocol (FDC), a novel siderophore cephalosporin, targets resistant Gram-negative pathogens by exploiting bacterial iron uptake mechanisms. However, resistance to FDC is emerging among Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae strains. This study characterizes a spontaneous FDC-resistant subpopulation (IHC216) derived from a KPC-producing strain (KPNMA216) using comprehensive genomic, transcriptional, and phenotypic analyses. Methods: Given the whole-genome sequencing results, where mutations were identified in genes involved in transcriptional regulation and membrane permeability (ompC) among others, in the present work we further explore their potential implications and conduct a more detailed analysis of the IHC216 genome. A qRT-PCR analysis highlighted significant downregulation of classical siderophore-mediated iron acquisition systems (fepA, cirA, iroN) and upregulation of alternative iron uptake pathways (iucA, fiU), reflecting a switch in iron acquisition strategies. Results: A notable downregulation of bla_KPC-163 correlated with restored susceptibility to carbapenems, indicating collateral susceptibility. Altered expressions of pbp2 and pbp3 implicated adaptive changes in cell wall synthesis, potentially affecting FDC resistance mechanisms. Furthermore, enhanced oxidative stress responses via upregulated sodC expression and increased capsule production were observed. Conclusions: These findings underscore the complex interplay of genetic and transcriptional adaptations underlying FDC resistance, highlighting potential therapeutic vulnerabilities. Full article

(This article belongs to the Special Issue Microbial Resistance to Carbapenems: Epidemiology, Detection and Treatment Options)

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22 pages, 5007 KiB

Open AccessArticle

FTIR-Derived Feature Insights for Predicting Time-Dependent Antibiotic Resistance Progression

by Mitchell Bonner, Claudia P. Barrera Patiño, Andrew Ramos Borsatto, Jennifer M. Soares, Kate C. Blanco and Vanderlei S. Bagnato

Antibiotics 2025, 14(8), 831; https://doi.org/10.3390/antibiotics14080831 - 15 Aug 2025

Viewed by 311

Abstract

Background/Objectives: The progression of antibiotic resistance is increasingly recognized as a dynamic and time-dependent phenomenon, challenging conventional diagnostics that define resistance as a binary trait. Methods: Biomolecules have fingerprints in Fourier-transform infrared spectroscopy (FTIR). The targeting of specific molecular groups, combined with principal [...] Read more.

Background/Objectives: The progression of antibiotic resistance is increasingly recognized as a dynamic and time-dependent phenomenon, challenging conventional diagnostics that define resistance as a binary trait. Methods: Biomolecules have fingerprints in Fourier-transform infrared spectroscopy (FTIR). The targeting of specific molecular groups, combined with principal component analysis (PCA) and machine learning algorithms (ML), enables the identification of bacteria resistant to antibiotics. Results: In this work, we investigate how effective classification depends on the use of different numbers of principal components, spectral regions, and defined resistance thresholds. Additionally, we explore how the time-dependent behavior of certain spectral regions (different biomolecules) may demonstrate behaviors that, independently, do not capture a complete picture of resistance development. FTIR spectra were obtained from Staphylococcus aureus exposed to azithromycin, trimethoprim/sulfamethoxazole, and oxacillin at sequential time points during resistance induction. Combining spectral windows substantially improved model performance, with accuracy reaching up to 96%, depending on the antibiotic and number of components. Early resistance patterns were detected as soon as 24 h post-exposure, and the inclusion of all three biochemical windows outperformed single-window models. Each spectral region contributed distinctively, reflecting biochemical remodeling associated with specific resistance mechanisms. Conclusions: These results indicate that antibiotic resistance should be viewed as a temporally adaptive trajectory rather than a static state. FTIR-based biochemical profiling, when integrated with ML, enables projection of phenotypic transitions and supports real-time therapeutic decision-making. This strategy represents a shift toward adaptive antimicrobial management, with the potential to personalize interventions based on dynamic resistance monitoring through spectral biomarkers. Full article

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11 pages, 1184 KiB

Open AccessArticle

Antibiotic Prophylaxis in Instrumented Lumbar Spine Surgery: Cefazolin Outperforms Clindamycin Regardless of Duration

by Zoltán Nagy, Dóra Szabó, Gergely Agócs, Konrád Szilágyi, Zsanett Rojcsik, József Budai, Zoltán Papp, Csaba Padányi, Loránd Erőss, László Sipos and Péter Banczerowski

Antibiotics 2025, 14(8), 830; https://doi.org/10.3390/antibiotics14080830 - 15 Aug 2025

Viewed by 327

Abstract

Background: Surgical site infections (SSIs) are a significant postoperative complication in instrumented lumbar spine surgery, and the selection and duration of appropriate prophylactic antibiotics are key to their prevention. The aim of our study was to evaluate the effectiveness of various prophylactic antibiotics, [...] Read more.

Background: Surgical site infections (SSIs) are a significant postoperative complication in instrumented lumbar spine surgery, and the selection and duration of appropriate prophylactic antibiotics are key to their prevention. The aim of our study was to evaluate the effectiveness of various prophylactic antibiotics, primarily cefazolin and clindamycin, as well as the role of the duration of antibiotic prophylaxis in the development of SSI in instrumented lumbar spine surgeries through retrospective analysis. Methods: We performed a retrospective analysis of data from 915 patients who underwent instrumented lumbar spine surgery between 2016 and 2024 in a university center database. We examined the incidence of SSI according to the type of antibiotic used (cefazolin 1 g or 2 g, or clindamycin 0.6 g) and the duration of prophylaxis (single dose versus 72 h administration). We used the Fisher test and Welch test as a statistical analysis to examine the differences between SSI rates. Results: The incidence of SSI was 11.7%. We measured a significantly lower infection rate with cefazolin compared to clindamycin (OR = 0.45; 95% CI: 0.23–0.94; p = 0.0206), regardless of the duration of antibiotic administration. The 72 h cefazolin prophylaxis showed a slight but statistically insignificant advantage over single dose prophylaxis. The risk of SSI was significantly higher in multi-segment surgeries (p = 0.0005). Conclusions: Cefazolin is a more effective prophylactic antibiotic than clindamycin during instrumented lumbar spine surgery. The duration of antibiotic administration has less influence on the risk of SSI development; therefore, short-term, adequate-dose cefazolin prophylaxis is recommended, which also minimizes the risk of antimicrobial resistance and side effects. Full article

(This article belongs to the Special Issue Diagnostics, Antibiotic Usage and Surgery Related Techniques in Prevention and Treatment of Prosthetic Joint and Implant Related Infections)

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9 pages, 494 KiB

Open AccessReview

Clostridioides difficile in Peripartum Women: Review of Outcomes and Treatment

by Ravina Kullar, Stuart Johnson and Ellie J. C. Goldstein

Antibiotics 2025, 14(8), 829; https://doi.org/10.3390/antibiotics14080829 - 15 Aug 2025

Viewed by 286

Abstract

Background: Clostridioides difficile infection (CDI) is one of the most common healthcare-associated infections in the United States with increasing rates in younger patients and those in the community. CDI incidence may also be on the rise in peripartum women. Methods: We conducted [...] Read more.

Background: Clostridioides difficile infection (CDI) is one of the most common healthcare-associated infections in the United States with increasing rates in younger patients and those in the community. CDI incidence may also be on the rise in peripartum women. Methods: We conducted a literature review to assess the incidence and outcomes of CDI in the peripartum population and review treatment options. Results: Peripartum patients have a high risk of complications and adverse events associated with CDI. Most patients have been treated with vancomycin or metronidazole; however, cases of patients recurring on standard treatment have been described, with patients having successful outcomes with fidaxomicin or fecal microbiota transplantation (FMT). Probiotics have been shown to be safe in peripartum women; however, the role in preventing primary and secondary CDI has not been studied. Conclusions: Peripartum women that develop CDI are at increased risk for complications. Treatment includes vancomycin, metronidazole, or fidaxomicin or FMT for recurrent cases. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Dr. Lynne V. McFarland—Clostridioides difficile Infection and Impact of Antibiotics on the Intestinal Microbiome)

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23 pages, 1362 KiB

Open AccessReview

A Comprehensive Review of Antibiotic Resistance in the Oral Microbiota: Mechanisms, Drivers, and Emerging Therapeutic Strategies

by Ena Kulis, Ivan Cvitkovic, Nikola Pavlovic, Marko Kumric, Doris Rusic and Josko Bozic

Antibiotics 2025, 14(8), 828; https://doi.org/10.3390/antibiotics14080828 - 15 Aug 2025

Viewed by 508

Abstract

Recent advances in microbiome research have highlighted the oral cavity as a complex and dynamic ecosystem, home to over 700 microbial species that play critical roles in both oral and systemic health. The oral microbiota not only maintains local tissue homeostasis but also [...] Read more.

Recent advances in microbiome research have highlighted the oral cavity as a complex and dynamic ecosystem, home to over 700 microbial species that play critical roles in both oral and systemic health. The oral microbiota not only maintains local tissue homeostasis but also serves as a reservoir for antimicrobial resistance (AMR) genes, contributing to the global spread of resistance. Frequent and sometimes inappropriate antibiotic use in dental practice, along with exposure to antiseptics and biocides, drives the emergence and horizontal transfer of resistance determinants within oral biofilms. This review synthesizes current knowledge on the molecular mechanisms and ecological drivers of AMR in the oral microbiome, emphasizing the clinical implications of dysbiosis and drug-resistant infections. The authors advocate for the development of dental clinical guidelines tailored to the unique characteristics of the oral microbiota, focusing on personalized therapy through molecular diagnostics, standardized AMR risk assessment, and the integration of non-antibiotic strategies such as probiotics and photodynamic therapy. Continuous education in antimicrobial stewardship and the implementation of oral-specific AMR surveillance is also highlighted as an essential component of effective resistance management. To support rational prescribing, a dedicated mobile application has been developed, leveraging microbiota data and resistance profiles to guide evidence-based, targeted therapy and reduce unnecessary antibiotic use. Collectively, these strategies aim to preserve antibiotic efficacy, ensure patient safety, and promote sustainable infection management in the dental field. Full article

(This article belongs to the Special Issue Antimicrobial Therapy in Oral Diseases)

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18 pages, 1688 KiB

Open AccessArticle

Nanopore Sequencing-Driven Mapping of Antimicrobial Resistance Genes in Selected Escherichia coli Isolates from Pigs and Poultry Layers in Nigeria

by Akinlabi Oladele Ogunleye, Prakash Ghosh, Adja Bousso Gueye, Foluke Olajumoke Jemilehin, Adelekan Oluseyi Okunlade, Veronica Olatimbo Ogunleye, Rea Maja Kobialka, Finja Rausch, Franziska Tanneberger, Adebowale Titilayo Philip Ajuwape, Ousmane Sow, George Olusegun Ademowo, Ulrike Binsker, Ahmed Abd El Wahed, Uwe Truyen, Yakhya Dieye and Cheikh Fall

Antibiotics 2025, 14(8), 827; https://doi.org/10.3390/antibiotics14080827 - 14 Aug 2025

Viewed by 587

Abstract

Background: Despite the huge burden of deaths associated with or attributable to antimicrobial resistance, studies on sequencing based antimicrobial resistance (AMR) monitoring in Africa are scarce, specifically in the animal sector. Objective and Methods: With a view to deploy rapid AMR monitoring through [...] Read more.

Background: Despite the huge burden of deaths associated with or attributable to antimicrobial resistance, studies on sequencing based antimicrobial resistance (AMR) monitoring in Africa are scarce, specifically in the animal sector. Objective and Methods: With a view to deploy rapid AMR monitoring through leveraging advanced technologies, in the current study, nanopore sequencing was performed with 10 E. coli strains isolated from rectal swabs of pigs and poultry layers in Nigeria. Two sequence analysis methods including command line, where bacterial genomes were assembled, and subsequently antimicrobial resistance genes (ARGs) were detected through online databases, and EPI2ME, an integrated cloud-based data analysis platform with MinION, was used to detect ARGs. Results: A total of 95 ARGs were identified and most of the genes are known to be expressed in the chromosome. Interestingly, few genes including qnrS1, qnrS15, qnrS10, kdpE, cmlA1, MIR-14, sul3 and dfrA12 were identified which were previously reported as transferred through Mobile Genetic Elements (MGEs). The antibiotic susceptibility assay determined that the E. coli isolates were resistant to Penicillin (100%), Ciprofloxacin (70%), tetracycline (50%) and Ampicillin (40%). The accuracies of the command line and EPI2ME methods have been found to be 57.14% and 32.14%, respectively, in predicting AMR. Moreover, the analysis methods showed 62.5% agreement in predicting AMR for the E. coli isolates. Conclusions: Considering the multiple advantages of nanopore sequencing, the application of this rapid and field-feasible sequencing technique holds promise for rapid AMR monitoring in low- and middle-income countries (LMICs), including Nigeria. However, the development of a robust sequence analysis pipeline and the optimization of the existing analysis tools are crucial to streamline the deployment of nanopore sequencing in LMICs for AMR monitoring both in animal and human sectors. Full article

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8 pages, 451 KiB

Open AccessArticle

Diminishing Efficacy of Second-Line Levofloxacin-Based Quadruple Therapy in Helicobacter pylori Eradication: A Prospective Real-World Study in Vietnam Amid Rising Antibiotic Resistance

by Thong Duy Vo, Thao Thu Ngan and Thuy Thi Thanh Trinh

Antibiotics 2025, 14(8), 826; https://doi.org/10.3390/antibiotics14080826 - 14 Aug 2025

Viewed by 362

Abstract

Background/Objectives: Helicobacter pylori (H. pylori) infection remains highly prevalent in Vietnam, associated with chronic gastritis, peptic ulcers, and gastric cancer. This study aimed to evaluate the real-world eradication rate of levofloxacin-based bismuth quadruple therapy (PALB) as second-line treatment, assess adherence, [...] Read more.

Background/Objectives: Helicobacter pylori (H. pylori) infection remains highly prevalent in Vietnam, associated with chronic gastritis, peptic ulcers, and gastric cancer. This study aimed to evaluate the real-world eradication rate of levofloxacin-based bismuth quadruple therapy (PALB) as second-line treatment, assess adherence, and identify associated factors with treatment success. Methods: We conducted a prospective cohort study including 225 patients with confirmed failure of classical bismuth-based quadruple therapy. All received a 14-day PALB regimen. H. pylori eradication was assessed using 13C-urea breath test and/or rapid urease test 4–12 weeks after treatment. Results: Eradication rates were 78.2% (mITT) and 78.6% (PP), with 95% CIs overlapping the 80% benchmark. Adherence was high (91.6%) and significantly associated with success (OR = 2.93; 95% CI: 1.11–7.74; p = 0.039). No other factors were significantly associated. Conclusions: While PALB remains a valid second-line therapy, its efficacy may be declining, though not statistically inferior to 80%. Improving adherence and strengthening stewardship are essential. Full article

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15 pages, 1900 KiB

Open AccessArticle

Lessons from Four Years (2021–2024) of Klebsiella Pneumoniae Resistance Surveillance Epidemiological Trends in a Romanian Intensive Care Unit

by Mihai Sava, Bogdan Ioan Vintila, Alina Simona Bereanu, Anca Maria Fratila and Ioana Roxana Codru

Antibiotics 2025, 14(8), 825; https://doi.org/10.3390/antibiotics14080825 - 12 Aug 2025

Viewed by 535

Abstract

Background: Klebsiella pneumoniae represents a major cause of healthcare-associated infections in intensive care units, with resistance profiles ranging from multidrug-resistant to extensively drug-resistant and pandrug-resistant. Critically ill patients, who often require invasive devices and prolonged antibiotic therapy, are especially vulnerable to colonization [...] Read more.

Background: Klebsiella pneumoniae represents a major cause of healthcare-associated infections in intensive care units, with resistance profiles ranging from multidrug-resistant to extensively drug-resistant and pandrug-resistant. Critically ill patients, who often require invasive devices and prolonged antibiotic therapy, are especially vulnerable to colonization and infection by these strains. Surveillance data on resistance trends and specimen-specific patterns in Romanian intensive care units (ICUs) remain limited. Methods: We conducted a four-year surveillance study (2021–2024) in a tertiary Romanian ICU, analyzing K. pneumoniae isolates collected from diverse clinical specimens. Resistance phenotypes were classified as MDR, XDR, PDR, or susceptible based on standard definitions. Trends over time were assessed using Cramér’s V and correspondence analysis, while stratification by specimen type evaluated associations between anatomical site and resistance profiles. Results: A total of 254 K. pneumoniae isolates were analyzed. MDR strains predominated in 2021 and 2022 but sharply declined by 2024 (from 80% to 8.3%). In parallel, XDR and PDR phenotypes increased substantially, indicating a shift toward more complex resistance profiles. A significant temporal association was found (Cramér’s V = 0.43), with 2024 marked by a sharp decline in MDR isolates and a predominance of XDR and PDR phenotypes, reflecting an advanced resistance profile. Specimen-type analysis showed tracheal aspirates as the main reservoir for resistant strains, followed by urine and blood cultures, with a weaker but meaningful association (Cramér’s V = 0.24). Conclusions: These findings reveal a change in resistance patterns in ICU-acquired K. pneumoniae infections, with MDR strains being displaced by XDR and PDR phenotypes. These findings highlight the urgent need for time- and specimen-informed resistance monitoring and adaptive antimicrobial stewardship. Without targeted interventions, gains made in controlling MDR strains risk being rapidly eclipsed by the spread of highly resistant organisms. Full article

(This article belongs to the Section Antibiotics Use and Antimicrobial Stewardship)

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13 pages, 3990 KiB

Open AccessArticle

Protective Effects of Luteolin on Glaesserella parasuis-Induced Injury: An In Vitro Study with Porcine Vascular Endothelial Cells

by Pu Guo, Xuwen Liu, Xiaoyi Li, Awais Ihsan, Zhongyuan Wu, Shulin Fu, Chun Ye, Yinsheng Qiu, Xu Wang, Qirong Lu and Yu Liu

Antibiotics 2025, 14(8), 824; https://doi.org/10.3390/antibiotics14080824 - 12 Aug 2025

Viewed by 266

Abstract

Background: Glaesserella parasuis (GPS) is a conditional pathogen that colonizes the upper respiratory tract in pigs and causes Glässer’s disease, resulting in high morbidity and mortality in piglets. GPS infection increases the vascular endothelial permeability, but the mechanism has not been fully [...] Read more.

Background: Glaesserella parasuis (GPS) is a conditional pathogen that colonizes the upper respiratory tract in pigs and causes Glässer’s disease, resulting in high morbidity and mortality in piglets. GPS infection increases the vascular endothelial permeability, but the mechanism has not been fully elucidated. Luteolin (Lut) is a naturally occurring flavonoid found in plants such as vegetables, herbs, and fruits, but its potential to treat the increased vascular endothelial permeability caused by GPS infection has not been evaluated. Results: This study revealed that GPS infection induces increased vascular endothelial permeability in porcine iliac artery endothelial cells (PIECs) by increasing the gene expressions of tumor necrosis factor (TNF), interleukin 6 (IL-6), IL-8, and IL-1β, and by regulating F-actin cytoskeleton reorganization. Mechanistically, GPS infection or Cluster of differentiation 44 (CD44) overexpression significantly increased the expressions of vascular-endothelial-permeability-related proteins (CD44; vascular endothelial growth factor (VEGFA); matrixmetalloProteinase-3 (MMP-3); MMP-9; and SRC proto-oncogene, non-receptor tyrosine kinase (c-Src)) and increased the vascular endothelial permeability; these changes were alleviated by a Lut treatment or CD44 silencing in the PIECs. Conclusions: This study comprehensively illustrates the potential targets and molecular mechanism of Lut in alleviating the GPS-induced increase in vascular endothelial permeability. The CD44 pathway and Lut may be an effective target and antibiotic alternative, respectively, to prevent the increased vascular endothelial permeability caused by GPS. Full article

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17 pages, 1453 KiB

Open AccessArticle

Unique Regulation of Sed-1 β-Lactamase in Citrobacter sedlakii: Insights on Resistance to Third-Generation Cephalosporin

by Mako Watanabe, Ryuichi Nakano, Keizo Yamamoto, Akiyo Nakano, Yuki Suzuki, Kai Saito, Satoko Nakashima, Kentaro Endo, Kazuya Narita and Hisakazu Yano

Antibiotics 2025, 14(8), 823; https://doi.org/10.3390/antibiotics14080823 - 12 Aug 2025

Viewed by 268

Abstract

Background: The Citrobacter genus harbors class C (AmpC) and class A β-lactamases. Citrobacter freundii produces an inducible AmpC β-lactamase controlled by the LysR-type transcriptional regulator AmpR and cytosolic amidase AmpD. Citrobacter sedlakii produces the class A β-lactamase Sed-1, whose expression is believed to [...] Read more.

Background: The Citrobacter genus harbors class C (AmpC) and class A β-lactamases. Citrobacter freundii produces an inducible AmpC β-lactamase controlled by the LysR-type transcriptional regulator AmpR and cytosolic amidase AmpD. Citrobacter sedlakii produces the class A β-lactamase Sed-1, whose expression is believed to be regulated by the transcriptional regulator SedR and AmpD. Objectives:C. sedlakii NR2807, isolated in Japan, is resistant to third-generation cephalosporins and displays extended-spectrum β-lactamase characteristics. Here, we sought to understand the mechanism for successful resistance to third-generation cephalosporins by investigating the regulators controlling Sed-1 production. Methods: Plasmids containing bla_Sed-1 and sedR (pCR2807) or truncated sedR (pCR2807ΔSedR) were constructed and introduced into Escherichia coli. Antibiotic-resistant mutants of NR2807 were obtained, and enzyme kinetics were assessed. Results: The AmpD mutant (pCR2807/ML4953) showed an 8-fold increase in cefotaxime MIC and an 8.46-fold increase in Sed-1 activity compared to the wild-type (pCR2807/ML4947). However, induction of pCR2807/ML4947 also led to a 1.32-fold higher Sed-1 activity, indicating semi-inducibility. Deletion of sedR (pCR2807ΔSedR/ML4947) led to a 4-fold decrease in cefotaxime MIC and 1.93-fold lower Sed-1 activity, confirming SedR as an activator. While wild-type C. sedlakii ATCC51115 is susceptible to third-generation cephalosporins, the AmpD mutation in NR2807 led to Sed-1 overproduction and resistance to this class of antibiotics. Finally, mutagenesis revealed that amino acid substitution in Sed-1 conferred resistance to ceftazidime and extended-spectrum β-lactamase characteristics. Conclusions: Sed-1 producers, though usually susceptible to third-generation cephalosporins, may develop extended-spectrum β-lactamase traits due to AmpD or Sed-1 mutations, thereby requiring careful monitoring. Full article

(This article belongs to the Special Issue Genomic Characterization of Antimicrobial Resistance and Evolution Mechanism of Bacteria)

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14 pages, 663 KiB

Open AccessArticle

Diagnostic Accuracy of Presepsin and Its Impact on Early Antibiotic De-Escalation in Burn-Related Sepsis

by Seontai Park, Dohern Kym, Jaechul Yoon, Yong Suk Cho and Jun Hur

Antibiotics 2025, 14(8), 822; https://doi.org/10.3390/antibiotics14080822 - 11 Aug 2025

Viewed by 415

Abstract

Background/Objectives: Despite overlapping inflammatory responses and frequent culture-negative results in severe burn patients, early and accurate sepsis diagnosis remains challenging. We aimed to evaluate the diagnostic performance of seven candidate biomarkers and their clinical utility, particularly in culture-negative cases. Methods: We conducted a [...] Read more.

Background/Objectives: Despite overlapping inflammatory responses and frequent culture-negative results in severe burn patients, early and accurate sepsis diagnosis remains challenging. We aimed to evaluate the diagnostic performance of seven candidate biomarkers and their clinical utility, particularly in culture-negative cases. Methods: We conducted a prospective diagnostic accuracy study (January 2021–December 2022; N = 221) in the burn intensive care unit, applying a two-step feature selection to 41 candidate variables. Seven top biomarkers—presepsin, procalcitonin (PCT), albumin, C-reactive protein (CRP), prothrombin time (PT), hematocrit (Hct), and D-dimer—were measured at the moment of clinical sepsis suspicion, concurrently with blood cultures and prior to empirical antibiotic administration, within ±2 h of Sequential Organ Failure Assessment (SOFA). Diagnostic performance was evaluated using a Receiver Operating Characteristic (ROC) curve analysis to determine the area under the curve (AUC), Youden index-derived cut-offs, decision curve analysis, and Net Reclassification Improvement (NRI). Results: Presepsin achieved the highest overall AUC (0.810; 95% CI, 0.742–0.878) and outperformed other markers in culture-negative cases (AUC, 0.846 vs. 0.604; p = 0.015). In the decision curve analysis, presepsin and PCT maintained the largest net benefits at high thresholds, although PT, D-dimer, and Hct also retained smaller positive benefits. Patients were stratified into high- vs. low-risk groups for survival analysis using Youden index cut-offs; Cox regression confirmed PCT (Hazard Ratio 3.78; p < 0.001) and PT (HR 2.12; p = 0.018) as a significant mortality predictor, with presepsin showing borderline significance (HR 3.14; p = 0.055). Conclusions: The high rate of culture-negative sepsis reflects early antibiotic use suppressing culture yield rather than resistance patterns alone. Presepsin’s rapid rise and preserved accuracy under pre-sampling antibiotics suggest its value for early sepsis detection and antimicrobial stewardship. Future work will incorporate polymicrobial and multidrug-resistant bloodstream infection profiles to refine biomarker utility. Full article

(This article belongs to the Special Issue Antimicrobial Stewardship and Infection Prevention in Intensive Care Unit)

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14 pages, 5087 KiB

Open AccessArticle

Clinical Characteristics and Follow-Up of Children with Primary Haematogenous Osteomyelitis and Septic Arthritis: Eight Years of Experience from Hungary

by Szofia Hajósi-Kalcakosz, Erzsébet Varga, Dorottya Őri, Csaba Ráskai, Borbála Zsigmond, Beáta Visy, Ferenc Fekete, Andrea Horváth, Orsolya Dobay and Bálint Gergely Szabó

Antibiotics 2025, 14(8), 821; https://doi.org/10.3390/antibiotics14080821 - 11 Aug 2025

Viewed by 335

Abstract

Introduction: Paediatric acute haematogenous bone and joint infections (BJIs) are serious conditions. This study aimed to analyse the characteristics of paediatric acute haematogenous osteomyelitis (AHO) and septic arthritis (SA) in Hungary, with a focus on causative pathogens, clinical outcomes, and long-term complications. Methods [...] Read more.

Introduction: Paediatric acute haematogenous bone and joint infections (BJIs) are serious conditions. This study aimed to analyse the characteristics of paediatric acute haematogenous osteomyelitis (AHO) and septic arthritis (SA) in Hungary, with a focus on causative pathogens, clinical outcomes, and long-term complications. Methods: A retrospective cohort study was conducted at a Hungarian tertiary referral centre between 2015 and 2022. Children aged 18 years or younger diagnosed with acute haematogenous osteomyelitis (AHO) or septic arthritis (SA) within two months of symptom onset were included. Exclusion criteria were chronic infection, post-operative infections, or wound-related infections. Complicated AHO was defined by intraosseous abscess or necrosis confirmed radiologically or intraoperatively. The primary outcome was surgical intervention beyond 30 days after diagnosis; secondary outcomes included long-term complications. Results: Forty patients were included (77.5% male, median age 8.7 years). AHO was diagnosed in 8 patients (20.0%), complicated AHO in 22 (55.0%), and SA in 10 (25.0%). MRI had the highest diagnostic sensitivity (97.0%). Pathogens were identified in 72.5% of cases; Staphylococcus aureus (S. aureus) was most common (57.5%), followed by Salmonella and Streptococcus pyogenes (5% each). Surgery was required in 90.0% of SA cases, 77.2% of complicated AHO, and 37.5% of uncomplicated AHO. Long-term complications occurred in 10%, mainly with S. aureus and complicated AHO. Conclusions: Paediatric BJIs, especially due to S. aureus, often require surgery and cause long-term sequelae. 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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14 pages, 4501 KiB

Open AccessArticle

The Small Molecule Inhibitor of the Type III Secretion System Fluorothiazinone Affects Flagellum Surface Presentation and Restricts Motility in Gram-Negative Bacteria

by Alexey Slonov, Mariam Abdulkadieva, Egor Kalinin, Natalya Bondareva, Lydia Kapotina, Svetlana Andreevskaya, Natalia Shevlyagina, Anna Sheremet, Elena Sysolyatina, Vladimir Zhukhovitsky, Mikhail Vasiliev, Oleg Petrov, Svetlana Ermolaeva, Nailya Zigangirova and Alexander Gintsburg

Antibiotics 2025, 14(8), 820; https://doi.org/10.3390/antibiotics14080820 - 11 Aug 2025

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Abstract

Background/Objectives: Fluorothiazinone (FT), a small molecule of the 2,4-disubstituted-4H-[1,3,4]-thiadiazine-5-one class, is known to inhibit the type III secretion system (T3SS) in Gram-negative bacteria and has shown therapeutic potential in animal models and clinical trials. Given the evolutionary relationship between the T3SS and the [...] Read more.

Background/Objectives: Fluorothiazinone (FT), a small molecule of the 2,4-disubstituted-4H-[1,3,4]-thiadiazine-5-one class, is known to inhibit the type III secretion system (T3SS) in Gram-negative bacteria and has shown therapeutic potential in animal models and clinical trials. Given the evolutionary relationship between the T3SS and the bacterial flagellar apparatus, this study aimed to investigate the effects of FT on bacterial motility and flagellum assembly. Methods: Motility was assessed in Pseudomonas aeruginosa, Proteus mirabilis, pathogenic Escherichia coli, and Listeria monocytogenes using a semisolid agar assay and a microfluidic motility system. The mechanism of FT’s action was further examined through time-course analysis, Western blotting of surface flagella proteins, and transmission electron microscopy (TEM). Results: FT inhibited motility of P. aeruginosa, P. mirabilis, and E. coli in a dose-dependent manner, while L. monocytogenes motility remained unaffected. The inhibitory effect was not immediate but delayed 2–3 h post FT addition. Western blotting revealed the absence of surface flagella in EHEC grown with FT, and TEM confirmed structural disruption of flagella in P. mirabilis. Conclusions: FT selectively inhibits flagellum-based motility in Gram-negative bacteria. Obtained data suggested FT interference with flagellum biosynthesis rather than disruption of rotation. Motility inhibition can contribute to FT therapeutic effects on Gram-negative bacterial infections. Full article

(This article belongs to the Section Novel Antimicrobial Agents)

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9 pages, 257 KiB

Open AccessArticle

Clonal Diversity of Extraintestinal Pathogenic Escherichia coli Strains Isolated from Canine Urinary Tract Infections in Brazil

by Luciana Sartori, João Pedro Rueda Furlan, Fábio Parra Sellera, Fernanda Borges Barbosa, Yohanna Carvalho dos Santos Aoun Chikhani, Gabriel Gandolfi and Terezinha Knöbl

Antibiotics 2025, 14(8), 819; https://doi.org/10.3390/antibiotics14080819 - 10 Aug 2025

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Abstract

Background/Objectives: Extraintestinal pathogenic Escherichia coli (ExPEC) strains, particularly those belonging to phylogenetic group B2, are clinically significant due to their frequent involvement in urinary tract infections (UTIs) and display antimicrobial resistance profiles. While the association of phylogroup B2 E. coli with human urinary [...] Read more.

Background/Objectives: Extraintestinal pathogenic Escherichia coli (ExPEC) strains, particularly those belonging to phylogenetic group B2, are clinically significant due to their frequent involvement in urinary tract infections (UTIs) and display antimicrobial resistance profiles. While the association of phylogroup B2 E. coli with human urinary tract infections is well established, the growing number of reports of ExPEC strains in canine UTIs highlights their clinical relevance in small animal medicine and raises concerns about their potential role in zoonotic transmission. This study investigated the microbiological and genomic features of E. coli strains isolated from dogs with UTIs in São Paulo, Brazil. Methods: Between March and May 2023, a total of 60 E. coli strains from canine UTIs were screened for antimicrobial susceptibility and phylotyping. Accordingly, four strains (6.6%) were identified as multidrug-resistant (MDR) or belonging to phylogroup B2 and, therefore, were submitted for characterization by whole-genome sequencing. Results: The four E. coli strains exhibited diverse antimicrobial resistance profiles, including resistance to third- and fourth-generation cephalosporins and fluoroquinolones. Phylogenetic groups B1, B2, and G, and sequence types (ST) 73, ST224, ST1193, and ST12960 were identified. The resistome included clinically important β-lactam resistance genes, such as bla_CTX-M-55 and bla_CMY-2, as well as mutations in the quinolone-resistance-determining region. Virulence factors associated with ExPEC pathogenesis, including adhesion, iron acquisition, immune evasion, and toxin, were detected. Plasmid sequences were identified as carrying antimicrobial resistance and virulence genes, highlighting the potential for horizontal gene transfer. Conclusions: Our findings underscore the importance of genomic surveillance in companion animals to better understand the epidemiology of ExPEC strains and monitor the spread of MDR strains. Full article

(This article belongs to the Special Issue Antimicrobial Resistance and Infections in Animals)

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Antibiotics, Volume 14, Issue 8 (August 2025) – 115 articles

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