Antibiotics

35 pages, 8009 KB

Open AccessArticle

Retargeting Gram-Positive-Only Adarotene-Derived Antibacterials to Broad-Spectrum Antibiotics

by Salvatore Princiotto, Luigi Cutarella, Alessandra Fortuna, Marta Mellini, Bruno Casciaro, Maria Rosa Loffredo, Alvaro G. Temprano, Floriana Cappiello, Livia Leoni, Maria Luisa Mangoni, Mattia Mori, Loana Musso, Francesca Sacchi, Cecilia Pinna, Giordano Rampioni, Sabrina Dallavalle and Claudio Pisano

Antibiotics 2025, 14(9), 956; https://doi.org/10.3390/antibiotics14090956 - 21 Sep 2025

Abstract

Background: Bacterial resistance to antibiotics continues to rise globally, posing a significant public health challenge and incurring substantial social and economic burdens. In response, the World Health Organization (WHO) has published a list of priority pathogens for which effective treatment options are [...] Read more.

Background: Bacterial resistance to antibiotics continues to rise globally, posing a significant public health challenge and incurring substantial social and economic burdens. In response, the World Health Organization (WHO) has published a list of priority pathogens for which effective treatment options are critically limited. Several antibiotics are categorized as Gram-positive-only (GPO) agents due to their lack of activity against Gram-negative species. Although these compounds often target conserved bacterial processes, their limited spectrum is largely attributed to poor penetration of the Gram-negative outer membrane (OM). Results: In this study, we designed and synthesized a series of adarotene-derived compounds to evaluate the impact of introducing positively charged groups on their interaction with the Gram-negative OM. One of the newly synthesized derivatives, SPL 207, displayed minimum inhibitory concentration (MIC) values ranging from 8 to 64 µM against a panel of Gram-positive and Gram-negative bacteria. The ability of SPL207 to disrupt outer and inner membrane permeability was evaluated using fluorescence assays and confocal microscopy, revealing that the compound compromises membrane integrity across all tested Gram-negative bacteria. Strong synergistic activity was observed in combination with colistin against three P. aeruginosa colistin-resistant strains. Atomistic details of membrane interference were elucidated by molecular dynamics (MD) simulations, with SPL207 clearly acting as a membrane destabilizer by enhancing Ca²⁺ ions diffusion and lipids destabilization. Conclusions: Although the observed MIC values remain above clinically acceptable thresholds, these findings provide a promising proof of concept. The further structural optimization of adarotene derivatives may yield novel broad-spectrum agents with improved antimicrobial potency against MDR pathogens. Full article

(This article belongs to the Special Issue Antibiotic Resistance and Virulence Mechanisms in Gram-Negative Bacteria: An Alliance for Success)

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15 pages, 1192 KB

Open AccessArticle

Resistance Mechanisms of Fluoroquinolone in Escherichia coli Isolated from Taihe Black-Boned Silky Fowl Exhibiting Abnormally Slow Fluoroquinolone Metabolism in Jiangxi, China

by Li Zhang, Mengjun Ye, Yifan Dong, Lijuan Yuan, Jianjun Xiang, Xiren Yu, Qiegen Liao, Qiushuang Ai, Suyan Qiu and Dawen Zhang

Antibiotics 2025, 14(9), 955; https://doi.org/10.3390/antibiotics14090955 - 21 Sep 2025

Abstract

Objectives: The Taihe Black-Boned Silky Fowl (TBSF) is a unique indigenous chicken breed in China, characterized by widespread melanin deposition throughout its body. Fluoroquinolones (FQs) such as enrofloxacin can persist in TBSF for an extended period exceeding 100 days. The aim of this [...] Read more.

Objectives: The Taihe Black-Boned Silky Fowl (TBSF) is a unique indigenous chicken breed in China, characterized by widespread melanin deposition throughout its body. Fluoroquinolones (FQs) such as enrofloxacin can persist in TBSF for an extended period exceeding 100 days. The aim of this study was to examine the current status and development trends of FQ resistance within the TBSF breeding environment. Methods: Whole-genome sequencing was utilized to identify the molecular presence of quinolone resistance-determining region (QRDR) mutations and plasmid-mediated quinolone resistance (PMQR) genes in Escherichia coli isolates obtained from TBSF farms. Network inference based on strong Spearman correlations (ρ > 0.5) and statistically significant associations (p-value < 0.05) was applied to investigate the co-occurrence patterns among FQ residues, resistance phenotypes, and antibiotic resistance genes. Results: The results showed that FQ residues were identified as the primary contributor to FQ resistance in E. coli isolates. Mutations at QRDR sites were the predominant factor driving FQ resistance, rather than PMQR determinants. This study also reported the first identification of GyrA-S83Q mutation being associated with FQ resistance. Conclusions: It was concluded that E. coli strains in TBSF environments, where chickens have a long-term residual metabolic cycle of antimicrobials, may develop and evolve new mechanisms to adapt to this environment. Further research is warranted to investigate the evolution of FQ resistance in E. coli strains within TBSF environments. Full article

(This article belongs to the Special Issue Addressing the Challenge of Antibiotic Resistance with Existing Antibiotics)

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15 pages, 538 KB

Open AccessReview

Postoperative Infections After Appendectomy for Acute Appendicitis: The Surgeon’s Checklist

by Martina Leandri, Carlo Vallicelli, Giorgia Santandrea, Daniele Perrina, Francesca Bravi, Massimo Sartelli, Federico Coccolini, Luca Ansaloni, Vanni Agnoletti and Fausto Catena

Antibiotics 2025, 14(9), 954; https://doi.org/10.3390/antibiotics14090954 - 20 Sep 2025

Abstract

Acute appendicitis remains one of the most common surgical emergencies, with a lifetime incidence of approximately 7–8% in the USA and Europe. Despite the widespread adoption of the laparoscopic approach and advances made in perioperative care, post-operative infections—particularly intra-abdominal abscesses—continue to pose a [...] Read more.

Acute appendicitis remains one of the most common surgical emergencies, with a lifetime incidence of approximately 7–8% in the USA and Europe. Despite the widespread adoption of the laparoscopic approach and advances made in perioperative care, post-operative infections—particularly intra-abdominal abscesses—continue to pose a substantial clinical challenge, with an overall probability that ranges from 5 to 15%. Nowadays, it is essential not only to improve patient outcomes by reducing these complications but also to promote responsible antibiotic use. This review provides an in-depth examination of post-appendectomy infections in adults, synthesizing research from the past decade. It explores the various risks involved, including those related to the patient, the disease itself, and the surgical techniques employed. There is particular emphasis on the impact of surgical approach, closure methods, timing of surgery, and intraoperative decisions such as drain placement, peritoneal lavage, and routine bacterial cultures. Part of the discussion is about emerging data regarding the use of antiseptic solutions and specimen retrieval techniques. Additionally, the review examines current approaches to managing postoperative intra-abdominal abscesses. It assesses when antibiotics are necessary, evaluates image-guided percutaneous drainage, and considers laparoscopic re-intervention as a possible solution. While recent studies offer valuable insights, the heterogeneity of available evidence highlights the pressing need for high-quality, standardized research. Ultimately, a deeper understanding of infection pathways and preventative strategies is vital—not only for reducing morbidity and hospital readmissions, but also for safeguarding the long-term efficacy of antibiotics and delivering safer, more effective surgical care. Full article

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16 pages, 1782 KB

Open AccessArticle

Antibiotic Use in Horses: Analysis of 57 German Veterinary Practices (2018–2023)

by Roswitha Merle, Leonie Feuer, Katharina Frenzer, Jan-Lukas Plenio, Astrid Bethe, Nunzio Sarnino, Antina Lübke-Becker and Wolfgang Bäumer

Antibiotics 2025, 14(9), 953; https://doi.org/10.3390/antibiotics14090953 - 19 Sep 2025

Abstract

Background/Objectives: A mandatory monitoring of the use of antibiotics in horses in the European Union will come into force from 2029 on. The aim of the study was to explore the potential implementation of a monitoring system and to provide an overview [...] Read more.

Background/Objectives: A mandatory monitoring of the use of antibiotics in horses in the European Union will come into force from 2029 on. The aim of the study was to explore the potential implementation of a monitoring system and to provide an overview of antibiotic use in horses in Germany. Methods: Data on all consultations from 57 German practices between 2018 and 2023 were obtained. The dataset included basic data about the horse, free-text diagnoses (allocated to one of 20 categories), and treatments. Information on the administered or dispensed pharmaceutical product was recorded for antibiotic treatment consultations. Results: This study analyzed 225,622 consultations with more than 50,000 horses. Antibiotics were administered in around 7% of consultations, but practice-specific rates varied considerably. Treatment was most frequent in ophthalmology cases. The most commonly used drug classes were sulfonamides combined with trimethoprim and aminopenicillins. Horses receiving antibiotics required follow-up visits more often than untreated animals, and changes in antibiotic substance occurred occasionally. Conclusions: Routine practice data provide valuable insights into antibiotic use in equine medicine. While incomplete entries and imprecise details (e.g., missing concentrations or diagnoses) remain a limitation, the approach offers clear advantages: it is cost-effective, allows large-scale data collection, and supports continuous monitoring over time. Such systems can be used to evaluate the effects of upcoming EU regulations and to identify priorities for antibiotic stewardship in equine practice. Full article

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

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12 pages, 483 KB

Open AccessArticle

Local Vancomycin Application Reduces Periprosthetic Joint Infections in Oncologic Megaprosthetic Reconstruction: A Retrospective Cohort Study

by Andreas G. Tsantes, Dimitrios V. Papadopoulos, Stavros Goumenos, Petros Ioannou, Nikolaos Stavropoulos, Eleni Petrou, Ioannis G. Trikoupis, Christos Koutserimpas, Alexandra Mpakosi, Vasileios A. Kontogeorgakos, Stefanos Bonovas, Panayiotis J. Papagelopoulos, Athanasios Tsakris and Argirios E. Tsantes

Antibiotics 2025, 14(9), 952; https://doi.org/10.3390/antibiotics14090952 - 19 Sep 2025

Abstract

Background/Objectives: Periprosthetic joint infections (PJIs) represent a serious complication following musculoskeletal tumor resection and megaprosthetic reconstruction. Local antibiotic administration may reduce infection risk by achieving high local drug concentrations. The aim of this study was to evaluate whether local vancomycin powder reduces postoperative [...] Read more.

Background/Objectives: Periprosthetic joint infections (PJIs) represent a serious complication following musculoskeletal tumor resection and megaprosthetic reconstruction. Local antibiotic administration may reduce infection risk by achieving high local drug concentrations. The aim of this study was to evaluate whether local vancomycin powder reduces postoperative periprosthetic infections in bone tumor surgeries involving megaprostheses. Methods: This retrospective cohort study included 276 patients who underwent bone tumor resection and megaprosthetic reconstruction. Study subjects were divided into two groups: the control group (n = 142) that received standard perioperative intravenous antibiotics, and the vancomycin group (n = 134) that received an additional 1 g of vancomycin powder locally at wound closure. Periprosthetic joint infections were defined using the 2018 International Consensus Meeting (ICM) criteria and monitored for 2 years. A multivariable competing risks regression model was used to assess the independent effect of local vancomycin on infection risk. Results: Periprosthetic joint infections occurred in 28 patients in the control group (19.7%) vs. eight patients in the vancomycin group (5.9%, p = 0.001). The most frequently isolated pathogens were coagulase-negative staphylococci (52.7%), followed by Staphylococcus aureus (22.2%). Among infected patients in the vancomycin group, only two had Gram-positive infections, suggesting efficacy against staphylococcal PJIs. The multivariable regression confirmed a significantly lower risk of infection in the vancomycin group (hazard ratio [HR]: 0.40, 95% confidence interval [CI]: 0.16–0.95, p = 0.040), while pelvic tumors were associated with a higher infection risk (HR: 5.82, p < 0.001). Conclusions: Our results indicate that local vancomycin may reduce periprosthetic infection rates in oncologic megaprosthetic reconstruction without added complications. Randomized studies are warranted to confirm these findings and refine dosing strategies. Full article

(This article belongs to the Special Issue Diagnostics and Antibiotic Therapy in Bone and Joint Infections)

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14 pages, 1775 KB

Open AccessSystematic Review

Nationwide Burden of Metallo-β-Lactamase Genes in Brazilian Clinical Klebsiella pneumoniae Isolates: A Systematic Review and Meta-Analysis

by Carolynne Silva dos Santos, Marcos Jessé Abrahão Silva, Pabllo Antonny Silva dos Santos, Emilly Victória Correia de Miranda, Ana Beatriz Tavares Duarte, Caio Augusto Martins Aires, Luana Nepomuceno Gondim Costa Lima, Danielle Murici Brasiliense, Cintya de Oliveira Souza, Karla Valéria Batista Lima and Yan Corrêa Rodrigues

Antibiotics 2025, 14(9), 951; https://doi.org/10.3390/antibiotics14090951 - 19 Sep 2025

Abstract

Background: Class B carbapenemases confer high-level resistance to carbapenems in Klebsiella pneumoniae. In Brazil, data on the national burden and geographic distribution of these genes among clinical K. pneumoniae isolates are sporadic. We performed a systematic review and meta-analysis to estimate [...] Read more.

Background: Class B carbapenemases confer high-level resistance to carbapenems in Klebsiella pneumoniae. In Brazil, data on the national burden and geographic distribution of these genes among clinical K. pneumoniae isolates are sporadic. We performed a systematic review and meta-analysis to estimate the prevalence of MβL genes in Brazilian clinical K. pneumoniae. Methods: We searched SciELO, PubMed, ScienceDirect and LILACS for original studies published between 2006 and 2024 reporting molecular detection of MβL in clinical K. pneumoniae isolates from Brazil. Articles were independently screened, along with the extracted data and appraised study quality using Joanna Briggs Institute checklists. A random-effects meta-analysis estimated the pooled prevalence of MβL producers and assessed heterogeneity and publication bias. Results: Fifteen studies including 3.533 clinical K. pneumoniae isolates met inclusion criteria. Overall, 402 isolates (11.4%) harbored MβL genes, yielding a pooled prevalence of 44.6%. Subgroup analysis demonstrated highest prevalence in the Southeast. bla_NDM was the dominant variant (present in 14/15 studies), with bla_VIM and bla_IMP rarely detected. Meta-regression revealed an inverse association between sample size and reported prevalence, and no significant publication bias was observed. Conclusions: MβLs, particularly NDM, are widespread in Brazilian clinical K. pneumoniae but show marked regional heterogeneity driven by differences in study design, laboratory capacity, and outbreak dynamics. Urgent expansion of standardized and multicenter molecular surveillance, including allele-specific detection, and strengthened laboratory infrastructure are needed and may inform targeted infection-control and antimicrobial-stewardship interventions. Full article

(This article belongs to the Special Issue Antimicrobial Resistance Genes: Spread and Evolution)

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12 pages, 1601 KB

Open AccessArticle

Antimicrobial Resistance of Clostridioides (Clostridium) difficile in Cambodia

by Lengsea Eng, Papanin Putsathit, Su-Chen Lim, Jessica M. Chisholm, Deirdre A. Collins, Archie C. A. Clements, Kefyalew Addis Alene and Thomas V. Riley

Antibiotics 2025, 14(9), 950; https://doi.org/10.3390/antibiotics14090950 - 19 Sep 2025

Abstract

Background/Objectives: Antimicrobial resistance (AMR) remains a major topic of interest in infectious disease management. We studied AMR in Clostridioides difficile isolated in Cambodia. Methods: Agar dilution susceptibility testing was performed according to the CLSI guidelines to determine minimal inhibitory concentrations (MICs) of 10 [...] Read more.

Background/Objectives: Antimicrobial resistance (AMR) remains a major topic of interest in infectious disease management. We studied AMR in Clostridioides difficile isolated in Cambodia. Methods: Agar dilution susceptibility testing was performed according to the CLSI guidelines to determine minimal inhibitory concentrations (MICs) of 10 antimicrobials for 192 isolates of C. difficile from four populations in Cambodia: hospitalised adults, hospitalised children, children from an outpatient department (OPD), and healthy adolescents in the community. Results: Using the CLSI MIC breakpoints for anaerobes and EUCAST breakpoints for C. difficile, all isolates were susceptible to vancomycin, metronidazole, fidaxomicin, and amoxicillin/clavulanic acid, and none were resistant to meropenem. The resistance proportions were for clindamycin, 88% (169/192); tetracycline, 50% (96/192); moxifloxacin, 20% (38/192); and rifaximin, 8% (15/192). Among the 169 clindamycin-resistant isolates, 56.8% (96/169) had an erythromycin MIC of >512 mg/L. Multidrug resistance (MDR) occurred in 20% (39/192) of the isolates, of which 82% (32/39) were non-toxigenic strains. The proportion of MDR varied between collections of isolates from different populations: 28.6% (22/77) in hospitalised adults, 29.8% (14/47) in hospitalised children, 5% (3/59) in OPD children, and none (00/07) in healthy adolescents in the community. Conclusions: C. difficile isolates from Cambodia remained susceptible to antimicrobials used to treat C. difficile infection: vancomycin, metronidazole, and fidaxomicin; however, high proportions of resistance to clindamycin and tetracycline were observed. The high number of MDR strains of C. difficile is a threat to AMR management in Cambodia and a factor contributing to the persistent spread of C. difficile in both hospital and community settings. 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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6 pages, 169 KB

Open AccessCommentary

Smart Phages: Leveraging Artificial Intelligence to Tackle Prosthetic Joint Infections

by Nicita Mehta, Andrew T. Nguyen, Edward K. Rodriguez and Jason Young

Antibiotics 2025, 14(9), 949; https://doi.org/10.3390/antibiotics14090949 - 19 Sep 2025

Abstract

Traditional antibiotic therapy has encountered significant challenges for clinical treatment of infections for multiple reasons, including antimicrobial resistance (AMR) and poor efficacy against biofilms, demanding research into alternative therapeutic agents. Because of their unique antimicrobial mechanisms as well as their target specificity, diversity, [...] Read more.

Traditional antibiotic therapy has encountered significant challenges for clinical treatment of infections for multiple reasons, including antimicrobial resistance (AMR) and poor efficacy against biofilms, demanding research into alternative therapeutic agents. Because of their unique antimicrobial mechanisms as well as their target specificity, diversity, exponential self-amplification, and anti-biofilm activity, combined with recent advances in genomics and synthetic biology, bacteriophages have attracted increased interest as potential alternatives or therapeutic adjuncts to antibiotics. However, obstacles such as phage-host specificity, bacterial resistance, and the selection of optimal phages, amongst other factors, impede clinical adoption of phage therapy. Here, machine learning (ML) and artificial intelligence (AI) tools have the opportunity to revolutionize phage therapy by enhancing scalability, efficiency and precision of these therapies. This article highlights potential key applications of ML/AI in the study, development and deployment of phage therapy. Full article

(This article belongs to the Special Issue Bacteriophage Therapy a Renaissance Weapon Recent Developments and Application, 2nd Edition)

16 pages, 2196 KB

Open AccessArticle

Liposomal Fluopsin C: Physicochemical Properties, Cytotoxicity, and Antibacterial Activity In Vitro and over In Vivo MDR Klebsiella pneumoniae Bacteremia Model

by Mickely Liuti Dealis Gomes, Leandro Afonso, Kawany Roque Basso, Leonardo Cruz Alves, Enri Josué Navia Macías, Sueli Fumie Yamada-Ogatta, Ana Carolina Guidi, João Carlos Palazzo de Mello, Fábio Goulart Andrade, Luís Fernando Cabeça, Martha Viviana Torres Cely and Galdino Andrade

Antibiotics 2025, 14(9), 948; https://doi.org/10.3390/antibiotics14090948 - 19 Sep 2025

Abstract

Introduction: Antimicrobial resistance has become a global concern, and few new antimicrobials are currently being developed. Fluopsin C has proven broad-spectrum activity, being a promising candidate for new antimicrobial development. To optimize antimicrobial activity, this research aimed at fluopsin C (Flp) encapsulation in [...] Read more.

Introduction: Antimicrobial resistance has become a global concern, and few new antimicrobials are currently being developed. Fluopsin C has proven broad-spectrum activity, being a promising candidate for new antimicrobial development. To optimize antimicrobial activity, this research aimed at fluopsin C (Flp) encapsulation in liposomes to achieve controlled release and reduce cytotoxicity. Methods: Liposomal formulations were prepared by extruding formulations based on soy phosphatidylcholine (SPC) or poly (ethylene glycol)-distearoylphosphatidylethanolamine (DSPE-PEG) plus cholesterol, and were characterized by their size, polydispersity index, zeta potential, encapsulation efficiency, shelf-life stability, in vitro release profile, cytotoxicity, and antimicrobial activity against Klebsiella pneumoniae in vitro and in vivo. Results: The results indicated that the DSPE-PEG DMSO+Flp formulation presented superior physicochemical stability and unaltered antimicrobial activity. In vitro, CC₅₀ decreased by 54%. No lethal dose was obtained in mice within the concentration range tested. The most effective doses in vivo were 2 × 2 mg/kg for free fluopsin C and 1 × 2 mg/kg for DSPE-PEG DMSO+Flp, resulting in a 40% reduction in mortality from bacteremia. Only discrete inflammatory infiltration was detected in the liver, while kidney necrosis ranged from discrete to moderate. Encapsulation of fluopsin C in liposomes showed promising features supporting to use against infections by MDR K. pneumoniae. Full article

(This article belongs to the Section Novel Antimicrobial Agents)

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21 pages, 3518 KB

Open AccessArticle

New Insights in bla_KPC Gene Mobilization in Pseudomonas aeruginosa: Acquisition of bla_KPC-3 and Identification of a New Tn2-like NTE Mobilizing bla_KPC-2

by Deisy Abril, Juan Bravo-Ojeda, Julio-Cesar Garcia, Aura Lucia Leal-Castro, Carlos Humberto Saavedra-Trujillo, Johana Madroñero, Rosa-Helena Bustos, Ricaurte Alejandro Marquez-Ortiz, Zayda Lorena Corredor Rozo, Natasha Vanegas Gómez and Javier Escobar-Pérez

Antibiotics 2025, 14(9), 947; https://doi.org/10.3390/antibiotics14090947 - 19 Sep 2025

Abstract

Carbapenem-resistant Pseudomonas aeruginosa is a major cause of healthcare associated infections in hospitalized patients and what is more warring with reduced therapeutic options. The KPC is a powerful enzyme capable of hydrolyzing the carbapenems, described first in Klebsiella pneumoniae and it already has [...] Read more.

Carbapenem-resistant Pseudomonas aeruginosa is a major cause of healthcare associated infections in hospitalized patients and what is more warring with reduced therapeutic options. The KPC is a powerful enzyme capable of hydrolyzing the carbapenems, described first in Klebsiella pneumoniae and it already has found in P. aeruginosa.Objective: To perform a comparative genomic analysis of two new genetic platforms mobilizing the bla_KPC-2 and bla_KPC-3 in two ST111 and ST235 pandemic clones of P. aeruginosa in Colombia, South America. Methods: Sixty-six bla_KPC-harboring P. aeruginosa isolates were identified and characterized during a prospective study conducted in six high complex hospitals in Colombia. Genetic platforms mobilizing the bla_KPC were analyzed. Results: The bla_KPC-2 and bla_KPC-3 were identified in 24 and 42 isolates, respectively. The bla_KPC-2-harboring isolates belonged to ST235 and bla_KPC-3 to ST111. The whole genome sequencing indicated that the bla_KPC-3 gene was mobilized by the Tn4401b within a 55-kb-size environmental origin plasmid, which, in other isolates, was inserted into the chromosome through a transposition event of ISPa38. Regarding the bla_KPC-2 gene, this was mobilized by a new Non-Tn4401 Element (NTE) derived from transposon Tn2 (proposed as variant IIg), which has been transposed into a 43-Kb-size little-studied plasmid related to Klebsiella spp. Conclusions: Our results reveal a new acquisition event of bla_KPC in P. aeruginosa, in this case bla_KPC-3. Likewise, the pandemic high-risk clones ST111 and ST235 of P. aeruginosa continues to spread bla_KPC gene through different mobile genetic elements, jumping of conventional Tn4401b and acquiring new Tn2-derived NTE, which were inserted in diverse plasmids. Full article

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

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33 pages, 7123 KB

Open AccessReview

Climate Change and AMR: Interconnected Threats and One Health Solutions

by Bilal Aslam and Sulaiman F. Aljasir

Antibiotics 2025, 14(9), 946; https://doi.org/10.3390/antibiotics14090946 - 18 Sep 2025

Abstract

Climate change is a significant driver of antimicrobial resistance (AMR) and infectious disease dynamics, presenting urgent and interconnected global health challenges. Rising temperatures, ecosystem alterations, and extreme weather events amplify the global spread of resistant pathogens, zoonotic infections, and vector-borne diseases. These impacts [...] Read more.

Climate change is a significant driver of antimicrobial resistance (AMR) and infectious disease dynamics, presenting urgent and interconnected global health challenges. Rising temperatures, ecosystem alterations, and extreme weather events amplify the global spread of resistant pathogens, zoonotic infections, and vector-borne diseases. These impacts disproportionately affect low- and middle-income countries (LMICs), escalating healthcare costs and straining limited infrastructure. A critical characteristic of bacterial resistance is that it often does not incur a fitness cost, underscoring the necessity of preventive strategies to mitigate climate-driven AMR emergence, rather than relying on reactive treatments after resistance is established. Climate change accelerates AMR primarily by increasing the prevalence of infectious diseases, which in turn drive higher antibiotic use and select resistance. The socioeconomic consequences are particularly severe in LMICs, where high climate vulnerability converges with weaker health systems. Pandemic-related disruptions provided key insights into environmental dynamics, with notable temporary reductions in nitrogen dioxide (NO₂) emissions, i.e., 20–30% in China, Italy, France, and Spain, and approximately 30% in the USA, which highlights the responsiveness of ecosystems to human activity. Unlike prior reviews that treated AMR and climate change as separate issues, this article integrates mechanistic evidence, epidemiological insights, and global strategies to provide a comprehensive One Health framework addressing these synergistic threats. We conclude that AMR and climate change are interlinked crises requiring urgent, integrated interventions. The quadripartite (FAO, UNEP, WHO, WOAH) provides a crucial framework for the coordinated cross-sectoral strategies, strengthened surveillance, and robust antibiotic stewardship required to mitigate this dual threat and safeguard global health security. Full article

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

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3 pages, 147 KB

Open AccessEditorial

Genomic Characterization of Antimicrobial Resistance and Evolution Mechanism of Bacteria

by Daniel Gyamfi Amoako and Linda Antionette Bester

Antibiotics 2025, 14(9), 945; https://doi.org/10.3390/antibiotics14090945 - 18 Sep 2025

Abstract

Antimicrobial resistance (AMR) continues to rank among the most pressing global health threats, frequently referred to as a “silent pandemic” that undermines decades of progress in infectious disease control while jeopardizing both human and animal health [...] Full article

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

16 pages, 12268 KB

Open AccessArticle

Whole-Genome Sequencing and Antibiotic Resistance Profiling of Helicobacter pylori Isolates from a Tertiary Hospital in Southern Thailand

by Chonticha Romyasamit, Apichat Kaewdech, Pimsiri Sripongpun, Naichaya Chamroonkul, Komwit Surachat, Sirikan Suwannasin, Yosita Leepromma, Morteza Saki, Maseetoh Samaeng and Phoomjai Sornsenee

Antibiotics 2025, 14(9), 944; https://doi.org/10.3390/antibiotics14090944 - 18 Sep 2025

Abstract

Background: Helicobacter pylori is associated with a wide range of gastroduodenal diseases, including chronic gastritis, peptic ulcer disease, and gastric cancer. Eradication efforts are challenged by increasing antimicrobial resistance rates, particularly in Southeast Asia. We sequenced the whole genomes of clinical H. [...] Read more.

Background: Helicobacter pylori is associated with a wide range of gastroduodenal diseases, including chronic gastritis, peptic ulcer disease, and gastric cancer. Eradication efforts are challenged by increasing antimicrobial resistance rates, particularly in Southeast Asia. We sequenced the whole genomes of clinical H. pylori isolates from Southern Thailand to elucidate their resistance profiles, virulence determinants, and evolutionary relationships. Methods: Three clinical H. pylori isolates (004, 117, and 189) were subjected to whole-genome sequencing, phenotypic antimicrobial susceptibility testing, and comparative genomic analyses. Results: All strains exhibited high-level resistance to metronidazole. Additionally, H. pylori 117 was resistant to both amoxicillin and levofloxacin, classifying it as multidrug-resistant. Genomic analysis revealed mutations in rdxA, frxA, and rpoB, as well as in penicillin-binding protein genes (pbp2 and pbp3), supporting the phenotypic findings. While all isolates harboured clarithromycin resistance mutations (A2142G and A2143G in the 23S rRNA gene), they were phenotypically susceptible, highlighting a potential discordance that requires further investigation. Virulence gene profiling identified 115–118 conserved genes per strain, including cagA, vacA, oipA, babA, and flagellar, urease, and lipopolysaccharide biosynthesis genes. Phylogenetic analysis using core-genome single-nucleotide polymorphisms demonstrated that these strains formed a distinct Southern Thai monophyletic clade, suggesting localised clonal expansion driven by regional selective pressures. Conclusions: Region-specific surveillance strategies and treatment guidelines are urgently needed in Thailand. The combination of high-risk virulence genes and rising antimicrobial resistance in H. pylori strains necessitates tailored therapeutic approaches, the integration of genomic surveillance into clinical diagnostics, and expanded studies linking genotype to clinical outcomes in diverse populations. Full article

(This article belongs to the Special Issue Genomic Insights into Dissemination of Multi-Drug Resistance Pathogens)

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33 pages, 2301 KB

Open AccessArticle

Antimicrobial and Antibiofilm Activities of Some Antioxidant 3,4-Dihydroxyphenyl-Thiazole-Coumarin Hybrid Compounds: In Silico and In Vitro Evaluation

by Daniel Ungureanu, Gabriel Marc, Mihaela Niculina Duma, Radu Tamaian, Dan Cristian Vodnar, Brîndușa Tiperciuc, Cristina Moldovan, Ioana Ionuț, Anca Stana and Ovidiu Oniga

Antibiotics 2025, 14(9), 943; https://doi.org/10.3390/antibiotics14090943 - 18 Sep 2025

Abstract

Background/Objectives: In this study, we aimed to investigate the antimicrobial and antibiofilm activity of seven hydroxyphenyl-thiazolyl-coumarin hybrid compounds with antioxidant properties (1a–g), previously reported by our group. Methods: The compounds were evaluated in vitro through MIC, MBC, [...] Read more.

Background/Objectives: In this study, we aimed to investigate the antimicrobial and antibiofilm activity of seven hydroxyphenyl-thiazolyl-coumarin hybrid compounds with antioxidant properties (1a–g), previously reported by our group. Methods: The compounds were evaluated in vitro through MIC, MBC, and MFC determinations, and percentage of biofilm (BF) inhibition and in silico, respectively, through molecular docking, molecular dynamics simulations, and ADMETox prediction. Results: All compounds showed antibacterial and antifungal activities. In terms of antibacterial activity, all the compounds were active on Pseudomonas aeruginosa (MICs = 15.62–31.25 μg/mL), Enterococcus faecalis (MICs = 15.62–31.25 μg/mL), and Staphylococcus aureus (MICs = 62.5–125 μg/mL). Regarding the antifungal activity, the effect against Candida albicans was similar to fluconazole (MIC = 15.62 μg/mL), compounds 1b and 1g being the most active against Aspergillus brasiliensis (MIC = 15.62 μg/mL). Furthermore, all compounds were both bactericidal and fungicidal. Regarding the antibiofilm activity, compounds 1d–g showed superior P. aeruginosa BF inhibition compared to gentamicin. The in vitro results for the antibacterial activity were well correlated with the observations drawn in the molecular docking studies, where the best binding affinities (BAs) were observed against P. aeruginosa PAO1 GyrB subunit, and the molecular dynamics simulations confirmed the antibacterial mechanism of compounds 1a, 1b, 1d, 1f, and 1g through GyrB subunit inhibition. Regarding the antifungal activity, all compounds showed better BAs than fluconazole against CYP51 in all instances. ADMETox predictions concluded that all the compounds could have low gastrointestinal absorption and reduced risk of pharmacokinetic interactions. Conclusions: The investigated compounds bring novelty into the actual research due to their dual antibacterial and antibiofilm activity against biofilm-associated P. aeruginosa infections. Full article

(This article belongs to the Special Issue Discovery and Design of New Antimicrobial Agents)

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20 pages, 4943 KB

Open AccessArticle

Phage Resistance Modulates Escherichia coli B Response to Metal-Based Antimicrobials

by Franklin C. Ezeanowai, Akamu J. Ewunkem, Ugonna C. Morikwe, Larisa C. Kiki, Lindsey W. McGee, Joseph L. Graves, Jr. and Liesl K. Jeffers-Francis

Antibiotics 2025, 14(9), 942; https://doi.org/10.3390/antibiotics14090942 - 18 Sep 2025

Abstract

Background/Objective: The rise of multidrug-resistant bacteria underscores the urgent need for alternative antimicrobial strategies. Metal-based compounds and bacteriophage (phage) therapy have emerged as promising candidates, but the evolutionary trade-offs associated with these selective pressures and their combination remain poorly understood. This study [...] Read more.

Background/Objective: The rise of multidrug-resistant bacteria underscores the urgent need for alternative antimicrobial strategies. Metal-based compounds and bacteriophage (phage) therapy have emerged as promising candidates, but the evolutionary trade-offs associated with these selective pressures and their combination remain poorly understood. This study aimed to investigate how prior exposure to T4 phage influences Escherichia coli B’s subsequent adaptation to iron (III) stress and to assess the resulting phenotypic and genomic signatures of dual resistance. Method: In this study, we performed experimental evolution using Escherichia coli B to investigate adaptive responses under four conditions: control (LB broth), T4 phage-only, iron (III) sulfate-only, and sequential phage followed by iron (III) exposure. Each treatment consisted of ten independently evolved populations (biological replicates), all derived from a common ancestral strain and passaged daily for 35 days. Phage resistance evolved rapidly, with complete resistance observed within 24 h of exposure. Results: In contrast, iron-selected populations evolved tolerance to high iron concentrations (1000–1750 mg/L) over time at a cost to resistance in other metals (gallium and iron (II) and antibiotics (tetracycline). Notably, prior phage exposure altered these outcomes: phage/iron-selected populations retained phage resistance and iron tolerance but showed diminished resistance to iron (II) and distinct antibiotic sensitivity profiles. Whole-genome sequencing revealed stressor-specific adaptations: large deletions in phage receptor-related genes (waaA and waaG) under phage pressure, and selective sweeps in iron-adapted populations affecting regulatory and membrane-associated genes (qseB, basR, aroK, fieF, rseB, and cpxP). Conclusions: These results demonstrate that the sequence of environmental stressors significantly shapes phenotypic and genetic resistance outcomes. Our findings highlight the importance of fitness epistasis and historical contingency in microbial adaptation, with implications for the design of evolution-informed combination therapies. Full article

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16 pages, 843 KB

Open AccessArticle

α-Amylase-Mediated Antibiotic Degradation and Sequestration in Pseudomonas aeruginosa Biofilm Therapy

by Robert K. Murray, Allison E. Martin, Sarah Zipkowitz, Nusrat Jahan, Tony D. Davis and Whitni K. Redman

Antibiotics 2025, 14(9), 941; https://doi.org/10.3390/antibiotics14090941 - 18 Sep 2025

Abstract

Background: As of 2022, 80% of all documented microbial infections are biofilm-associated: communities of microorganisms adhered to a surface and enclosed in a complex extracellular polymeric substance (EPS). The EPS acts as a physical barrier protecting the bacteria from antimicrobial agents and host [...] Read more.

Background: As of 2022, 80% of all documented microbial infections are biofilm-associated: communities of microorganisms adhered to a surface and enclosed in a complex extracellular polymeric substance (EPS). The EPS acts as a physical barrier protecting the bacteria from antimicrobial agents and host immune responses. To combat this hurdle, the application of glycoside hydrolases (GH) has been investigated due to their ability to cleave particular structural polysaccharides within the EPS, thus breaking down the protective barrier and improving antibiotic clearance. While various studies demonstrate the capacity of GHs to improve antibiotic efficacy against biofilms in combination, there is clear differential success between these treatments depending on the GH and antibiotic chosen. Due to the overlap of GH targets and antibiotic structures, it is imperative to ensure that the antibiotics in combinatorial treatments are not degraded by the GH. Methods: This study aimed to screen the GH α-amylase produced from Aspergillus oryzae (AO) and Bacillus subtilis (BS), combined with various antibiotics from different classes, charges, and mode of actions by determining MICs. against the bacterium Pseudomonas aeruginosa (PA) of 6 antibiotics with or without α-amylase and treat 2-day PA biofilms with antibiotics with or without GHs. Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) stability assays and Differential Scanning Fluorimetry (DSF) were conducted to determine antibiotic and GH degradation as well as antibiotic sequestration. Results: Increased MICs in the presence of GHs as well as decreased antibiotic clearance against 2-day biofilms were suggestive of antibiotic degradation. LC-MS/MS stability assays of tetracycline and ciprofloxacin in the presence and absence of α-amylase further demonstrated the α-amylase-mediated antibiotic sequestration. Differential scanning fluorimetry (DSF) assays confirmed α-amylase-antibiotic interactions. Conclusions: This study suggests that α-amylase is capable of degrading and sequestering a variety of antibiotics, and the degree to which these phenomena occur varies depending upon the source of the GH. As a potential treatment for biofilm-associated infections, it is imperative that the GH + antibiotic combinations are determined compatible prior to clinical use. Full article

(This article belongs to the Special Issue Antimicrobial Resistance in Biofilm-Associated Infections)

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19 pages, 1268 KB

Open AccessSystematic Review

Health Literacy and Interventions on Antibiotics Use and AMR in Younger Generations in High-Income Countries—A Systematic Review

by Katja Molan, Anamarija Zore and Nevenka Kregar Velikonja

Antibiotics 2025, 14(9), 940; https://doi.org/10.3390/antibiotics14090940 - 17 Sep 2025

Abstract

Antimicrobial resistance (AMR) is a growing threat to global health, accelerated by the widespread inappropriate use of antibiotics. Although educational initiatives have been launched worldwide, there is little evidence on how younger generations in high-income countries (HICs) understand and address AMR. Addressing the [...] Read more.

Antimicrobial resistance (AMR) is a growing threat to global health, accelerated by the widespread inappropriate use of antibiotics. Although educational initiatives have been launched worldwide, there is little evidence on how younger generations in high-income countries (HICs) understand and address AMR. Addressing the AMR crisis requires proactive education of younger generations, including children, adolescents, and young adults, who will shape future healthcare practices. This review analyzes existing research on AMR literacy among these age groups in HICs, as knowledge gaps and risky behaviors persist even in HICs, despite their strong education and health infrastructures. The purpose of this review is to examine the knowledge, attitudes, and behaviors related to antibiotic use and antibiotic resistance in younger generations while identifying effective educational interventions. Methods: We performed a comprehensive literature search in PubMed until June 2025, followed by AI-assisted screening (Claude 4.0 Sonnet) and a manual review. The search strategy combined terms from the areas of health literacy, antibiotics, antibiotic resistance/AMR, and young populations. Studies in HICs that examined the younger generation’s knowledge about antibiotics and AMR, analyzed their attitudes or behavior toward them, or evaluated relevant educational interventions were included. Data were synthesized thematically across all included studies. Results: Nineteen studies from 11 HICs were included, including thirteen cross-sectional surveys and six educational intervention studies. The results showed that misconceptions about how antibiotics work are still very common. Several of those asked (22–80%) incorrectly stated that resistance develops in the human body and not in bacteria. Many (26–77%) mistakenly agreed with the statement that antibiotics treat viral infections. Concerning behaviors included high rates of self-medication, non-adherence to treatment, and unsafe storage practices. Several authors propose an amendment of curricula. Educational interventions, particularly gamification and peer education approaches, showed improvements in knowledge and sustained learning outcomes. Conclusions: Knowledge of AMR among young people in HICs is still inadequate, despite educational advantages. Most existing studies focus on college students, while children and adolescents, crucial groups for early prevention, are underrepresented. Targeted, age-appropriate education employing interactive methods represents an evidence-based strategy to improve antibiotic use behavior and support global AMR control efforts. Full article

(This article belongs to the Special Issue Knowledge, Attitudes and Practices of Antimicrobial Resistance and Stewardship in Primary Care Setting: From Understanding to Informing Interventions)

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14 pages, 414 KB

Open AccessArticle

Optimising Meropenem and Piperacillin Dosing in Patients Undergoing Extracorporeal Membrane Oxygenation Without Renal Dysfunction (MEPIMEX)

by Mar Ronda, M Paz Fuset, Erika Esteve-Pitarch, Josep Llop, Victor Daniel Gumucio-Sanguino, Evelyn Shaw, Daniel Marco Mula, Kristel Maisterra-Santos, Joan Sabater, Xose L. Pérez, Sara Cobo-Sacristan, Raül Rigo, Fe Tubau, Jordi Carratalà, Helena Colom-Codina and Ariadna Padullés

Antibiotics 2025, 14(9), 939; https://doi.org/10.3390/antibiotics14090939 - 17 Sep 2025

Abstract

Background/Objectives: Antibiotic pharmacokinetics (PK) and pharmacodynamics (PD) are altered during extracorporeal membrane oxygenation (ECMO). Meropenem and piperacillin are among the most commonly prescribed antibiotics for infections in this population. However, guidance on dosage adjustments in the ECMO setting remains limited. We aim [...] Read more.

Background/Objectives: Antibiotic pharmacokinetics (PK) and pharmacodynamics (PD) are altered during extracorporeal membrane oxygenation (ECMO). Meropenem and piperacillin are among the most commonly prescribed antibiotics for infections in this population. However, guidance on dosage adjustments in the ECMO setting remains limited. We aim to assess differences in meropenem and piperacillin concentrations achieved and identify the clinical, physiological, and mechanical factors influencing antibiotic exposure. Methods: This is a retrospective, single-centre, observational study comparing an ECMO cohort with a population control group from a prior study, without renal dysfunction. Demographic, clinical, PK/PD parameters, and ECMO-related data were analysed using univariate and generalised estimating equations. For both antimicrobials, the PK/PD target was set at 100%fT_>4xMIC. Results: A total of 130 critically ill patients were included: 18 in the ECMO group and 112 in the control group. The mean age was 65 years (23), 67% were male and 26.9% were classified as obese. For meropenem, renal function and ECMO support significantly influenced drug exposure, with PK/PD targets being achieved in 67% of measurements; in contrast, piperacillin exposure exhibited greater variability, primarily driven by renal function and mechanical ventilation. Notably, PK/PD targets for piperacillin were met in only 20% of measurements. Conclusions: Our findings highlight the considerable variability in β-lactam exposures and PK/PD target attainment in critically ill patients. This study underscores the importance of therapeutic drug monitoring and individualised dosing in attempts to improve antimicrobial efficacy and patient outcomes in this challenging setting. Full article

(This article belongs to the Special Issue Antibiotic Stewardship Implementation Strategies)

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9 pages, 412 KB

Open AccessArticle

Prediction Score for Identification of ESBL Producers in Urinary Infections Overestimates Risk in High-ESBL-Prevalence Setting

by Jorge Alberto Cortés, Julián Antonio Niño-Godoy and Heidi Johanna Muñoz-Latorre

Antibiotics 2025, 14(9), 938; https://doi.org/10.3390/antibiotics14090938 - 17 Sep 2025

Abstract

Background/Objectives: Urinary tract infections (UTIs) caused by extended-spectrum beta-lactamase (ESBL) Enterobacterales have become more frequent. Therefore, strategies for assessing the risks posed by ESBL-producing infections have been developed, creating the need for local validation. The aim of this study was to validate the [...] Read more.

Background/Objectives: Urinary tract infections (UTIs) caused by extended-spectrum beta-lactamase (ESBL) Enterobacterales have become more frequent. Therefore, strategies for assessing the risks posed by ESBL-producing infections have been developed, creating the need for local validation. The aim of this study was to validate the scoring system designed by Tumbarello et al. to identify ESBL producers in patients with a UTI that require hospital care in a region with a high prevalence of ESBL Escherichia coli. Methods: A retrospective cohort study was conducted in a third-level hospital in Bogotá (Colombia) between 2013 and 2020.The study included 817 patients, who were hospitalized due to pyelonephritis and treated with cefuroxime (the first-line antibiotic according to local guidelines), with an ESBL frequency of 9.68%. Diagnostic performances were estimated for a modified version of Tumbarello’s score (omitting admission from another healthcare facility) evaluating the area under the curve (AUC) for ESBL presence with respect to resistance to second- and third-generation cephalosporins. Results: With an index cut-off of ≥6, the score showed a sensitivity of 18% and a specificity of 83%. The AUC for this cut-off was 0.47. This threshold index could not efficiently predict either third- (AUC = 0.49) or second-generation cephalosporin resistance (AUC = 0.51). Conclusions: In Colombia, a region with a high prevalence of ESBL E. coli producers, as the use of the Tumbarello index would result in excessive utilization of wide-spectrum antibiotics, it is not recommended in this specific scenario for UTIs. Further studies are required in order to develop accurate tools to assess the risk of ESBL producers in high-prevalence settings. Full article

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

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