Antibiotics

11 pages, 1036 KB

Open AccessArticle

Antimicrobial Activity of Aztreonam-Avibactam and Other β-Lactamase Inhibitor Combinations Tested Against Enterobacterales Isolates from Pediatric Patients from United States Medical Centers (2019–2023)

by Helio S. Sader, Marisa L. Winkler, Krisztina M. Papp-Wallace, Rodrigo E. Mendes and Mariana Castanheira

Antibiotics 2025, 14(11), 1107; https://doi.org/10.3390/antibiotics14111107 - 3 Nov 2025

Abstract

Objective: To evaluate the antimicrobial susceptibility of Enterobacterales isolated from pediatric patients. Methods: A total of 5723 isolates were consecutively collected (1/patient) from pediatric patients (<18 years old [yo]) from 82 United States medical centers in 2019–2023 and susceptibility-tested by broth microdilution method. [...] Read more.

Objective: To evaluate the antimicrobial susceptibility of Enterobacterales isolated from pediatric patients. Methods: A total of 5723 isolates were consecutively collected (1/patient) from pediatric patients (<18 years old [yo]) from 82 United States medical centers in 2019–2023 and susceptibility-tested by broth microdilution method. Susceptibility was stratified by infection type and patient age: ≤1 yo (n = 2275), 2–5 yo (n = 1130), 6–12 yo (n = 1213), and 13–17 yo (n = 1105) and compared to adults (18–64 yo; n = 17,712). Results: Pediatric isolates were mainly from pneumonia (21.8%), bloodstream (BSI; 15.3%), and urinary tract infection (UTI; 51.8%). Aztreonam–avibactam, ceftazidime–avibactam, and meropenem–vaborbactam were active against ≥99.4% of ceftriaxone-nonsusceptible (99.4–100.0% susceptible), multidrug-resistant (MDR; 99.7–100.0% susceptible), and ESBL producer (99.7–100.0% susceptible) isolates from pediatric patients. Susceptibility to imipenem–relebactam varied from 97.1% (ceftriaxone-nonsusceptible) to 100.0% (ESBL producers). Ceftolozane–tazobactam showed good activity against ESBL producers (91.8% susceptible), but limited activity against ceftriaxone-nonsusceptible (75.8% susceptible) and MDR isolates (80.9% susceptible). The MDR phenotype varied from 14.3% (13–17 yo) to 19.7% (6–12 yo) among pediatric isolates (15.8% overall) and was 20.7% among adult Enterobacterales. Carbapenem resistance rates were markedly lower in pediatric (0.1%) isolates compared to adult isolates (1.3%). The ESBL profiles were similar among pediatric and adult isolates; 90.1% of ESBL producers from pediatric patients and 88.5% from adults carried a CTX-M +/− an OXA-1/30 gene. Conclusions: Antimicrobial resistance was generally lower among Enterobacterales from pediatric patients compared to adults. ESBL-producing Enterobacterales, mainly CTX-M, remain an important cause of infection in children. Aztreonam–avibactam, ceftazidime–avibactam, and meropenem–vaborbactam were highly active against isolates from both pediatric and adult population. Full article

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

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51 pages, 1350 KB

Open AccessReview

Enrichment of Antibiotic Resistance Genes on Plastic Waste in Aquatic Ecosystems, Aquatic Animals, and Fishery Products

by Franca Rossi, Serena Santonicola and Giampaolo Colavita

Antibiotics 2025, 14(11), 1106; https://doi.org/10.3390/antibiotics14111106 - 2 Nov 2025

Abstract

This comprehensive review compiles current knowledge about the connection between plastic waste and the selection and transmission of antibiotic resistance genes (ARGs) in aquatic ecosystems, which can result in ARG contamination of fishery products—a significant source of microplastic (MP) introduction into the food [...] Read more.

This comprehensive review compiles current knowledge about the connection between plastic waste and the selection and transmission of antibiotic resistance genes (ARGs) in aquatic ecosystems, which can result in ARG contamination of fishery products—a significant source of microplastic (MP) introduction into the food chain. Plastic debris in aquatic environments is covered by a biofilm (the plastisphere) in which antibiotic-resistant bacteria (ARB) are selected and horizontal gene transfer (HGT) of ARGs is facilitated. The types of plastic waste considered in this study for their role in ARG enrichment are mainly microplastics (MPs), and also nanoplastics (NPs) and macroplastics. Studies regarding freshwaters, seawaters, aquaculture farms, and ARG accumulation favored by MPs in aquatic animals were considered. Most studies focused on the identification of the microbiota and its correlation with ARGs in plastic biofilms, while a few evaluated the effect of MPs on ARG selection in aquatic animals. A higher abundance of ARGs in the plastisphere than in the surrounding water or natural solid substrates such as sand, rocks, and wood was repeatedly reported. Studies regarding aquatic animals showed that MPs alone, or in association with antibiotics, favored the increase in ARGs in exposed organisms, with the risk of their introduction into the food chain. Therefore, reducing plastic pollution in water bodies and aquaculture waters could mitigate the ARG threat. Further investigations focused on ARG selection in aquatic animals should be conducted to better assess health risks and increase awareness of this ARG transmission route, enabling the adoption of appropriate countermeasures. Full article

(This article belongs to the Special Issue Origins and Evolution of Antibiotic Resistance in the Environment)

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12 pages, 911 KB

Open AccessArticle

Environmental Footprint of Antibiotics: A Multi-Source Investigation of Wastewater Systems in UAE

by Shahana Seher Malik, Balamurugan Sadaiappan, Ashraf Aly Hassan, Iltaf Shah, Sampathkumar Elangovan and Sunil Mundra

Antibiotics 2025, 14(11), 1105; https://doi.org/10.3390/antibiotics14111105 - 2 Nov 2025

Abstract

Background/Objectives: Antibiotic resistance is a growing global health threat, requiring comprehensive investigations into the occurrence, distribution, and diversity of antibiotics across environmental systems. This study aimed to examine the distribution and prevalence of commonly used antibiotics in various wastewater sources across the [...] Read more.

Background/Objectives: Antibiotic resistance is a growing global health threat, requiring comprehensive investigations into the occurrence, distribution, and diversity of antibiotics across environmental systems. This study aimed to examine the distribution and prevalence of commonly used antibiotics in various wastewater sources across the United Arab Emirates (UAE), providing insights into potential environmental reservoirs contributing to antimicrobial resistance dissemination. Methods: Wastewater samples were collected from the outlets of three hospitals, three residential communities, and the influent and return activated sludge of two wastewater treatment plants. Samples were prepared using solid-phase extraction (SPE) and analyzed via liquid chromatography–mass spectrometry (LC–MS/MS) to quantify antibiotic concentrations and compare their distribution among sources. Results: Significant variations were observed in antibiotic concentrations across the different wastewater sources. Ciprofloxacin concentrations were highest in hospital wastewater, reaching up to 247.9 ng/mL, while cefuroxime and vancomycin ranged between 0.2 and 10.9 ng/mL across samples. Clindamycin was notably prevalent in wastewater treatment plant samples (up to 10.9 ng/mL), whereas vancomycin and cefuroxime were dominant in residential community samples, reflecting diverse antibiotic usage patterns and persistence in treatment systems. Conclusions: The findings reveal substantial antibiotic contamination in United Arab Emirates wastewater systems, underscoring the need for ongoing surveillance and regulatory measures. Continuous monitoring, coupled with effective wastewater treatment and antibiotic stewardship strategies, is critical to mitigating the environmental spread of antimicrobial resistance and safeguarding public and environmental health. Full article

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12 pages, 260 KB

Open AccessArticle

Fosfomycin in Complicated Intra-Abdominal Infections in an Intensive Care Setting: Does It Improve the Outcome? A Retrospective Observational Study

by Giovanni Genga, Federico Ragni, Maria Carolina Benvenuto, Elisabetta Svizzeretto, Andrea Tommasi, Giuseppe Vittorio Luigi De Socio, Daniela Francisci and Carlo Pallotto

Antibiotics 2025, 14(11), 1104; https://doi.org/10.3390/antibiotics14111104 - 2 Nov 2025

Abstract

Background: Intra-abdominal infection (IAI) is a challenging condition that needs both medical and surgical treatment and it is still associated with high morbidity and mortality rates. Fosfomycin is approved for use in combination therapy for IAIs. The aim of this study was to [...] Read more.

Background: Intra-abdominal infection (IAI) is a challenging condition that needs both medical and surgical treatment and it is still associated with high morbidity and mortality rates. Fosfomycin is approved for use in combination therapy for IAIs. The aim of this study was to evaluate the impact of intravenous fosfomycin addition in a combination regimen for IAI treatment in an intensive care setting. Methods: We performed a retrospective, observational, monocentric study. We enrolled patients admitted to the ICU with IAIs from April 2022 to June 2024. Patients were divided into two groups: Group A, standard treatment; and Group B, combination therapy including fosfomycin. Primary endpoints were clinical response at 7 days and in-hospital mortality; moreover, a risk factor analysis for mortality was also performed. Results: In total, 104 patients were enrolled, 85 in Group A, and 19 in Group B. Groups were homogenous in regard to demographics, but clinical condition was slightly worst in Group B. Source control < 24 h was performed in 69.6% and 33.3% cases in Group A and Group B, respectively (p = 0.017). Clinical response on day 7 (81.2% vs. 73.7%, p = 0.675) and in-hospital mortality (27.1% vs. 47.2%, p = 0.145) were comparable. Univariate and multivariate analysis highlighted Charlson Comorbidity Index (CCI) (p = 0.04) and septic shock (p = 0.029) as risk factors, and effective empirical therapy (p = 0.04) as the protective factor; fosfomycin was not directly associated with outcome improvement. Conclusions: The outcome was comparable between groups; clinicians preferred to administer a combination regimen including fosfomycin in patients with statistically significant greater severity of illness and without early source control. Full article

(This article belongs to the Special Issue Antibiotic Treatment on Surgical Infections)

13 pages, 462 KB

Open AccessArticle

The Impact of a Structured Outpatient Parenteral Antimicrobial Therapy (OPAT) Programme on Quality of Care, Optimisation of Antimicrobial Use, and Healthcare Costs: A Retrospective Cohort Study

by Irene G. Manders, Darya Comello, Dennis Souverein, Sjoerd Euser, Bjorn L. Herpers, Judith Vetten, Jayant S. Kalpoe, Marco Goeijenbier and Steven F. L. van Lelyveld

Antibiotics 2025, 14(11), 1103; https://doi.org/10.3390/antibiotics14111103 - 2 Nov 2025

Abstract

Background/Objectives: In 2022, Spaarne Gasthuis hospital implemented an outpatient parenteral antimicrobial therapy (OPAT) programme, including mandatory infectious disease (ID) specialist assessment and integrated structured workflow, aiming to improve quality of care, optimize antimicrobial use, and reduce healthcare costs. Our objective was to evaluate [...] Read more.

Background/Objectives: In 2022, Spaarne Gasthuis hospital implemented an outpatient parenteral antimicrobial therapy (OPAT) programme, including mandatory infectious disease (ID) specialist assessment and integrated structured workflow, aiming to improve quality of care, optimize antimicrobial use, and reduce healthcare costs. Our objective was to evaluate the impact of the OPAT programme on patient outcomes (IV duration, clinical response, adverse clinical outcomes, timely peripherally inserted central catheter (PICC) removal), antimicrobial stewardship parameters, and healthcare costs. Methods: This retrospective before–after cohort study used electronic health record data to compare patients treated with outpatient parenteral antimicrobial therapy before (2019) and after (August 2022–December 2024) OPAT programme implementation. Using linear and logistic regression analyses, the association between the independent variable (pre-OPAT vs. OPAT) and outcomes were assessed and adjusted for potential confounders (sex, age, department, primary and additional indications). Cost analysis was performed, and ID specialist-recommended therapy adjustments were evaluated. Results: In total, 529 patients were included: 118 in the pre-OPAT group, and 411 in the OPAT group. In 36.3% of OPAT cases, therapy was adjusted, thereby optimizing antimicrobial stewardship. The OPAT programme was associated with significantly shorter IV therapy duration of 13.97 (mean) days (95%CI −9.15–−18.79; p < 0.001), significantly less meropenem use (p < 0.001), and significantly less adverse clinical outcomes (OR 0.58, 95%CI 0.37–0.92; p = 0.021), whereas no significant difference was found in clinical response (OR 1.22; 95%CI 0.67–2.32; p = 0.527). The programme led to cost savings of 3.343 EUR per patient. Conclusions: The OPAT programme optimized antimicrobial use and reduced IV therapy duration, adverse clinical outcomes, and healthcare costs. Full article

(This article belongs to the Special Issue Antibiotic Use in the Communities—2nd Edition)

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21 pages, 1746 KB

Open AccessArticle

Antimicrobial Resistance Profiles of Bacteria Isolated from the Animal Health Sector in Zambia (2020–2024): Opportunities to Strengthen Antimicrobial Resistance Surveillance and Stewardship Programs

by Taona Sinyawa, Fusya Goma, Chikwanda Chileshe, Ntombi B. Mudenda, Steward Mudenda, Amon Siame, Fred Mulako Simwinji, Mwendalubi Albert Hadunka, Bertha Chibwe, Kaunda Kaunda, Geoffrey Mainda, Bruno S. J. Phiri, Maisa Kasanga, Webrod Mufwambi, Samson Mukale, Andrew Bambala, Jimmy Hangoma, Nawa Mabuku, Benson Bowa, Obrian Kabunda, Mulumbi Nkamba, Ricky Chazya, Ruth Nakazwe, Mutila Malambo, Zoran Muhimba, Steven Mubamba, Morreah Champo, Mercy Mukuma, George Dautu, Chileshe Lukwesa, O-Tipo Shikanga, Freddie Masaninga, Mpela Chibi, Sandra Diana Mwadetsa, Theodora Savory, Joseph Yamweka Chizimu, John Bwalya Muma, Charles Maseka and Roma Chilengi Show full author list Hide full author list

Antibiotics 2025, 14(11), 1102; https://doi.org/10.3390/antibiotics14111102 - 2 Nov 2025

Abstract

Background/Objectives: Antimicrobial resistance (AMR) is a major global health threat that undermines treatment in humans and animals. In Zambia, where livestock production underpins food security and livelihoods, AMR challenges are aggravated by limited surveillance, weak diagnostics, and poor regulatory enforcement, facilitating the spread [...] Read more.

Background/Objectives: Antimicrobial resistance (AMR) is a major global health threat that undermines treatment in humans and animals. In Zambia, where livestock production underpins food security and livelihoods, AMR challenges are aggravated by limited surveillance, weak diagnostics, and poor regulatory enforcement, facilitating the spread of resistant pathogens across the human–animal–environment interface. This study aims to analyse AMR patterns of bacterial isolates collected from Zambia’s animal health sector between 2020 and 2024, to generate evidence that informs national AMR surveillance, supports antimicrobial stewardship (AMS) interventions, and strengthens One Health strategies to mitigate the spread of resistant pathogens. Methods: We conducted a retrospective descriptive analysis of previously collected routine laboratory data from five well-established animal health AMR surveillance sentinel sites between January 2020 and December 2024. Data were analysed by year, sample type, and antimicrobial susceptibility testing (AST) profiles using WHONET. Results: A total of 1688 samples were processed, with faecal samples accounting for 87.6%. Animal environmental samples (feed, manure, litter, abattoir/meat processing floor, wall, and equipment surface swabs) (collected from abattoirs, water, and farms) increased significantly over time (p = 0.027). Overall, Escherichia coli (E. coli) (50.4%) and Enterococcus spp. (30%) were the most frequently isolated bacteria. E. coli exhibited high resistance to tetracycline (74%) and ampicillin (72%) but remained susceptible to aztreonam (98%), nitrofurantoin (95%), and imipenem (93%). Enterococcus spp. were susceptible to penicillin (84%) and ampicillin (89%) but showed borderline resistance to vancomycin (53%) and linezolid (50%). Klebsiella spp. demonstrated resistance to ciprofloxacin (52%) and gentamicin (40%), whereas Salmonella spp. remained highly susceptible. Notably, resistance to amoxicillin/clavulanic acid rose sharply from 22.2% to 81.8% (p = 0.027). Across 1416 isolates, high levels of multidrug resistance (MDR) were observed, particularly in E. coli (48.4%) and K. pneumoniae (18.6%), with notable proportions progressing toward possible Extensively Drug-Resistant (XDR) and Pan-Drug-Resistant (PDR) states. Conclusions: The findings of this study reveal rising resistance to commonly used antibiotics in the animal health sector. Despite the lack of molecular analysis, our findings underscore the urgent need for AMS programs and integrated AMR surveillance under Zambia’s One Health strategy. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Jae-hyuk Yu—Antimicrobial Resistance in the Foodborne Pathogens)

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19 pages, 823 KB

Open AccessArticle

Antimicrobial Resistance Phenotypes and Genotypes of Escherichia coli Isolates from Artisanal Minas Frescal Cheeses from the Federal District, Brazil

by Letícia Fernandes Silva Rodrigues, Rodrigo Araújo de Melo, Nathalia Mateus Borges, Anna Cléa Silva Aragão, Marta Oliveira de Araújo, Rebeca Dias dos Santos, Carla Azevedo Bilac, Karolina Oliveira Gomes, Bruno Alcântara do Prado, Lívia Cristina Lira de Sá Barreto, Izabel Cristina Rodrigues da Silva and Daniela Castilho Orsi

Antibiotics 2025, 14(11), 1101; https://doi.org/10.3390/antibiotics14111101 - 2 Nov 2025

Abstract

Background/Objectives: This study characterized the phenotypic and genotypic profiles of antimicrobial resistance in 104 Escherichia coli isolates obtained from 22 samples of artisanal Minas Frescal cheese from the Federal District, Brazil. Methods: The antimicrobial susceptibility of E. coli isolates was assessed using [...] Read more.

Background/Objectives: This study characterized the phenotypic and genotypic profiles of antimicrobial resistance in 104 Escherichia coli isolates obtained from 22 samples of artisanal Minas Frescal cheese from the Federal District, Brazil. Methods: The antimicrobial susceptibility of E. coli isolates was assessed using the disk diffusion method and antimicrobial resistance genes were detected using polymerase chain reaction methods with specific primers. Results: The highest rates of phenotypic antimicrobial resistance were observed for sulfonamides (85.58%, 89/104) and tetracyclines (38.46%, 40/104). In the genotypic profiles, most E. coli isolates carried the sulfonamide resistance genes sul1/sul2 (62.50%, 65/104), tetracycline resistance genes tetA/tetB (65.38%, 68/104), and β-lactam resistance genes blaCTX-M/blaTEM/blaSHV (55.77%, 58/104). Most E. coli strains that presented sulfonamide resistance genes carried the sul1 gene (49.04%, 51/104) and were phenotypically sulfonamide-resistant strains (59.61%, 62/104). Regarding the E. coli strains that carried tetracycline resistance genes, the majority harbored both tetA and tetB genes (34.61%, 36/104), with 35.56% (37/104) being phenotypically resistant and 29.80% (31/104) being phenotypically susceptible. For E. coli strains that presented β-lactam resistance genes, the most frequently detected gene was blaCTX-M (21.15%, 22/104) and, notably, most E. coli strains (43.26%, 45/104) were phenotypically susceptible. The cat1 and clmA genes (associated with phenicol resistance) were detected in 22.12% of the E. coli isolates (23/104), with only two strains (1.92%) being phenotypically resistant to chloramphenicol. Conclusion: The high prevalence of E. coli carrying antimicrobial resistance genes in artisanal cheese raises public health concerns regarding the dissemination of potentially pathogenic antimicrobial-resistant microorganisms through the food chain. Full article

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17 pages, 1730 KB

Open AccessArticle

Targeting Oral Pathogens with Salvia officinalis and Nigella sativa Supercritical CO₂ Extracts: A Pharmacodynamic Approach and Three-Dimensional Checkerboard Synergy for Novel Dental Antimicrobials

by Luka Tucakov, Ana Tomić, Olja Šovljanski, Milica Aćimović and Ana Miljković

Antibiotics 2025, 14(11), 1100; https://doi.org/10.3390/antibiotics14111100 - 2 Nov 2025

Abstract

Background: Oral infections such as dental caries and candidiasis are mediated by resilient biofilms, which are increasingly tolerant to conventional antimicrobials. This study investigated the antimicrobial and antibiofilm effects of Salvia officinalis and Nigella sativa CO₂ extracts against Streptococcus mutans and [...] Read more.

Background: Oral infections such as dental caries and candidiasis are mediated by resilient biofilms, which are increasingly tolerant to conventional antimicrobials. This study investigated the antimicrobial and antibiofilm effects of Salvia officinalis and Nigella sativa CO₂ extracts against Streptococcus mutans and Candida albicans, with emphasis on synergistic interactions. Methods: Extracts were analyzed using gas chromatography–mass spectrometry analysis (GC–MS) and evaluated through planktonic MIC/MBC assays, time–kill kinetics, and biofilm models (MBIC/MBEC, biomass, metabolic activity). A novel three-dimensional checkerboard (3D-CB) and fractional inhibitory concentration index (FICI) approach was applied to optimize extract ratios, concentrations, and exposure times. Results: S. officinalis extract showed greater activity against S. mutans (MIC 256 mg/L; MBC 512 mg/L), while N. sativa was more effective against C. albicans (MIC 256 mg/L; MFC 512 mg/L). Both extracts reduced biofilm biomass and metabolic activity by over 70% at higher doses. Synergy was confirmed at ratios of 70:30 (S. officinalis: N. sativa) for S. mutans (FICI 0.38) and 40:60 for C. albicans (FICI 0.42). The achieved synergistic effect further decreased MBEC values fourfold and prolonged post-antibiotic effects. Conclusions: Synergistic S. officinalis–N. sativa formulations enhanced antimicrobial activity against oral pathogens in both planktonic and biofilm states, supporting their potential as next-generation dental antimicrobials. Full article

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19 pages, 6323 KB

Open AccessArticle

Green Synthesized Copper-Oxide Nanoparticles Exhibit Antifungal Activity Against Botrytis cinerea, the Causal Agent of the Gray Mold Disease

by Erisneida Campos-Jiménez, Karla Juarez-Moreno, Domingo Martínez-Soto, Alejandro Cabello-Pasini and Ernestina Castro-Longoria

Antibiotics 2025, 14(11), 1099; https://doi.org/10.3390/antibiotics14111099 - 2 Nov 2025

Abstract

Background/Objectives: Botrytis cinerea is a necrotrophic fungal plant pathogen responsible for the gray mold disease, affecting several crops of economic importance worldwide. The primary line of control for the disease in the field and post-harvest fruits includes the application of fungicides. However, [...] Read more.

Background/Objectives: Botrytis cinerea is a necrotrophic fungal plant pathogen responsible for the gray mold disease, affecting several crops of economic importance worldwide. The primary line of control for the disease in the field and post-harvest fruits includes the application of fungicides. However, the emergence of fungal populations resistant to one or more fungicides has increased their application and diminished their effectiveness. Looking at new control strategies, metallic nanoparticles have appeared as a promising alternative for disease treatment. Green-synthesized copper oxide nanoparticles (CuONPs) are considered a feasible alternative, aiming to reduce the generation of environmentally toxic waste through chemical methods. Methods: In this work, CuONPs biosynthesized using the supernatant of Trichoderma asperellum and Trichoderma ghanense were evaluated to determine their antifungal activity against B. cinerea. Results: Four different formulations of CuONPs were obtained: Ta1, Ta2, Tg1, and Tg2. All formulations displayed antifungal properties, with Tg2 being the most effective and having a high potential in controlling the phytopathogen. CuONPs in the Tg2 formulation were quasi-spherical, ranging in size from 1 to 2.7 nm. Conclusions: Furthermore, Tg2 demonstrated greater efficacy than the copper-based commercial fungicide NORDOX^® 75W, which showed no inhibitory effect on B. cinerea mycelial growth. In summary, the CuONPs reported in this work offer a sustainable and effective alternative for managing the gray mold disease. Full article

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25 pages, 352 KB

Open AccessArticle

Respiratory Bacteria and Antimicrobial Resistance Genes Detected by Long-Read Metagenomic Sequencing Following Feedlot Arrival, Subsequent Treatment Risk and Phenotypic Resistance in Feedlot Calves

by Jennifer N. Abi Younes, Lianne McLeod, Stacey R. Lacoste, Zhijian Chai, Emily K. Herman, E. Luke McCarthy, John R. Campbell, Sheryl P. Gow, Paul Stothard, Matthew G. Links, Simon J. G. Otto and Cheryl L. Waldner

Antibiotics 2025, 14(11), 1098; https://doi.org/10.3390/antibiotics14111098 - 1 Nov 2025

Abstract

Background/Objectives: Long-read metagenomic sequencing can assign antimicrobial resistance genes (ARGs) to speciated bacterial reads. This study evaluated whether metagenomic data from respiratory bacteria derived from feedlot calves sampled in the early feeding period were associated with subsequent bovine respiratory disease (BRD) treatment [...] Read more.

Background/Objectives: Long-read metagenomic sequencing can assign antimicrobial resistance genes (ARGs) to speciated bacterial reads. This study evaluated whether metagenomic data from respiratory bacteria derived from feedlot calves sampled in the early feeding period were associated with subsequent bovine respiratory disease (BRD) treatment and phenotypic antimicrobial resistance (AMR) at treatment. Methods: Deep nasopharyngeal swabs (DNPSs) obtained at arrival processing (1 day on feed; DOF), 13 DOF, and the time of BRD treatment were cultured and subjected to antimicrobial susceptibility testing (AST) and long-read metagenomic sequencing. Analyses focused on macrolide (mphE-msrE, EstT) and tetracycline (tet(H)) ARGs within reads assigned to Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, or Bibersteinia trehalosi. Generalized estimating equations assessed associations between metagenomic results from 1 and 13 DOF and subsequent BRD treatment risk and AST outcomes at treatment, at both the individual animal (calf) and pen levels. Results: Calf-level detection of H. somni at 13 DOF was associated with a greater BRD treatment risk between 14 and 45 DOF. An increased pen prevalence of either M. haemolytica or P. multocida at 13 DOF was associated with a greater BRD treatment risk from 14 to 45 DOF. At 13 DOF, detections of mphE-msrE, EstT, or tet(H) in target bacteria were associated with corresponding phenotypic AMR at BRD treatment. Similarly, a higher pen-level prevalence of mphE-msrE or EstT at 13 DOF was also associated with increased macrolide resistance at BRD treatment. Conclusions: The results from long-read metagenomic sequencing of DNPSs collected at 13 DOF were associated with both BRD risk and AMR at treatment. These findings align with prior culture-based results and support the potential utility of pen-level metagenomic testing for AMR surveillance and informing antimicrobial selection in feedlots. Full article

(This article belongs to the Special Issue Antibiotic Resistance and Antimicrobial Stewardship in Veterinary Medicine)

19 pages, 564 KB

Open AccessReview

β-Lactam/β-Lactamase Inhibitor Combinations in Sepsis-Associated Acute Kidney Injury and Renal Replacement Therapy

by Antonio Lacquaniti, Valentina Pistolesi, Antonella Smeriglio, Domenico Santoro, Cristina Iannetti, Giuseppe Lentini, Roberto Chimenz, Valeria Chirico, Domenico Trombetta, Santo Morabito and Paolo Monardo

Antibiotics 2025, 14(11), 1097; https://doi.org/10.3390/antibiotics14111097 - 1 Nov 2025

Abstract

Sepsis-associated acute kidney injury (SA-AKI) often requires renal replacement therapy (RRT), which markedly alters antimicrobial pharmacokinetics (PK) and pharmacodynamics (PD). Novel β-lactam/β-lactamase inhibitor (BL/BLI) combinations broaden options against multidrug-resistant Gram-negative bacteria, but dosing during RRT remains uncertain. This review summarizes PK/PD features, extracorporeal [...] Read more.

Sepsis-associated acute kidney injury (SA-AKI) often requires renal replacement therapy (RRT), which markedly alters antimicrobial pharmacokinetics (PK) and pharmacodynamics (PD). Novel β-lactam/β-lactamase inhibitor (BL/BLI) combinations broaden options against multidrug-resistant Gram-negative bacteria, but dosing during RRT remains uncertain. This review summarizes PK/PD features, extracorporeal clearance, and practical dosing considerations about ceftolozane–tazobactam, ceftazidime–avibactam, aztreonam–avibactam, cefiderocol, meropenem–vaborbactam, imipenem–relebactam, and newer agents including sulbactam–durlobactam, cefepime–enmetazobactam, and cefepime–taniborbactam. Pharmacokinetic data, RRT impact, PK/PD targets, pediatric aspects, and clinical outcomes were extracted from experimental models, case reports, and clinical studies. Drug exposure varies with RRT modality, effluent flow, membrane properties, and patient-specific factors such as augmented renal clearance, hypoalbuminemia, and fluid overload. Standard renal-adjusted dosing often yields subtherapeutic concentrations in critically ill patients. Pediatric data remain scarce and largely limited to case reports. Optimal BL/BLI use in septic patients with SA-AKI on RRT requires individualized dosing that accounts for PK/PD variability and dialysis settings. Full-dose initiation during the first 24–48 h, followed by careful adjustment, appears prudent. Therapeutic drug monitoring should be used when available, and institution-specific protocols should be integrated into stewardship programs to improve efficacy and minimize resistance. Full article

(This article belongs to the Special Issue Antimicrobial Stewardship and Optimizing Antibiotic Dose in Critically Ill Patients)

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13 pages, 405 KB

Open AccessArticle

Functional Potential of Red Dragon Fruit (Hylocereus polyrhizus) Juice By-Products as a Natural Feed Additive for Juvenile Red Seabream (Pagrus major): Implications for Antibiotic-Free Aquaculture

by Hwa Yong Oh, Ki-Tae Kim, Tae Hoon Lee, Da Ye Kang, Do-Hyun Kwon, Young Wook Kim and Hee Sung Kim

Antibiotics 2025, 14(11), 1096; https://doi.org/10.3390/antibiotics14111096 - 1 Nov 2025

Abstract

Background: The extensive use of antibiotics in aquaculture has raised serious concerns, emphasizing the need for sustainable and natural alternatives. This study evaluated the potential of red dragon fruit (Hylocereus polyrhizus) juice by-products (RJB) as a functional feed additive for juvenile [...] Read more.

Background: The extensive use of antibiotics in aquaculture has raised serious concerns, emphasizing the need for sustainable and natural alternatives. This study evaluated the potential of red dragon fruit (Hylocereus polyrhizus) juice by-products (RJB) as a functional feed additive for juvenile red seabream (Pagrus major). Materials and Methods: The bioactive composition and antioxidant capacity of RJB were analyzed, and five experimental diets containing 0, 0.2, 0.4, 0.8, and 1% RJB were fed to fish for 56 days. Results: Growth performance, feed utilization, body composition, antioxidant enzyme activities, and lysozyme activity were evaluated. RJB contained substantial levels of phenolic and flavonoid compounds and exhibited strong radical-scavenging activity. Dietary inclusion of up to 1% RJB did not significantly affect growth, feed efficiency, or plasma biochemistry. However, fish fed the 1% RJB diet showed increased catalase and glutathione levels, significantly enhanced lysozyme activity, and improved survival following Edwardsiella tarda infection. Conclusion: These results demonstrate that RJB can be safely incorporated into marine fish diets to enhance antioxidant capacity and innate immune defense. The valorization of fruit-processing by-products such as RJB offers a promising strategy for developing antibiotic-free and sustainable aquaculture practices. Full article

(This article belongs to the Special Issue Antibiotics and Antimicrobial Resistance in Aquaculture: Alternative and Complementary Treatment Methods)

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19 pages, 473 KB

Open AccessReview

by Julie Lourtet-Hascoët, Eric Bonnet, Anna Maria Spera, Tiziana Ascione, Monica Chan, Silvano Esposito, Pasquale Pagliano, Antonia Scobie, Serhat Ünal, Gérard Giordano and Kordo Saeed

Antibiotics 2025, 14(11), 1095; https://doi.org/10.3390/antibiotics14111095 - 1 Nov 2025

Abstract

Fracture-related infections (FRIs) represent a significant complication in orthopedic trauma care, often leading to delayed bone healing, prolonged hospital stays, and increased patient morbidity. Pathogenesis involves microbial contamination during injury or surgery, compounded by patient-related risk factors such as diabetes, smoking, or immunosuppression. [...] Read more.

Fracture-related infections (FRIs) represent a significant complication in orthopedic trauma care, often leading to delayed bone healing, prolonged hospital stays, and increased patient morbidity. Pathogenesis involves microbial contamination during injury or surgery, compounded by patient-related risk factors such as diabetes, smoking, or immunosuppression. Diagnosis of FRI relies on a combination of clinical, radiological, and microbiological criteria. Common signs include persistent pain, swelling, erythema, purulent discharge, and non-union of the fracture. FRIs are classified based on the timing of infection onset into acute, delayed, and chronic forms, each requiring tailored management strategies. Treatment generally involves aggressive surgical debridement, possible hardware removal or retention, and targeted antibiotic therapy. In cases of severe tissue loss, reconstructive procedures may be necessary to restore bone and soft tissue integrity. Treatment strategies include early administration of prophylactic antibiotics, meticulous surgical technique, and timely soft tissue coverage in open fractures. A multidisciplinary approach involving orthopedic surgeons, infectious disease specialists, and microbiologists is essential for successful management. Early recognition and appropriate intervention are crucial to improving outcomes and minimizing long-term disability in patients with fracture-related infections. Full article

(This article belongs to the Special Issue Advances in the Field of Biofilm-Associated Musculoskeletal Infections)

17 pages, 296 KB

Open AccessArticle

Antimicrobial Stewardship Program Implementation, Perceptions, and Barriers in Zambia: A Cross-Sectional Study Among Healthcare Professionals

by Steward Mudenda, Joseph Yamweka Chizimu, Victor Daka, Jimmy Hangoma, Kelvin Mwangilwa, Priscilla Gardner, Chikwanda Chileshe, Taona Sinyawa, Zoran Muhimba, Charles Chileshe, Sandra Diana Mwadetsa, Shikanga O-Tipo, Duncan Chanda, Maisa Kasanga, Geoffrey Mainda, Webrod Mufwambi, Samson Mukale, Andrew Bambala, Fusya Goma, Aubrey Chichonyi Kalungia, Yasuhiko Suzuki, Brian Godman, John Bwalya Muma and Roma Chilengi Show full author list Hide full author list

Antibiotics 2025, 14(11), 1094; https://doi.org/10.3390/antibiotics14111094 - 1 Nov 2025

Abstract

Background/Objectives: Antimicrobial stewardship programs (ASPs) play a vital role in combating antimicrobial resistance (AMR). However, their implementation in Zambia remains variable despite some notable progress. This study assessed healthcare professionals’ awareness of the Multisectoral National Action Plan (NAP) on AMR, alongside their [...] Read more.

Background/Objectives: Antimicrobial stewardship programs (ASPs) play a vital role in combating antimicrobial resistance (AMR). However, their implementation in Zambia remains variable despite some notable progress. This study assessed healthcare professionals’ awareness of the Multisectoral National Action Plan (NAP) on AMR, alongside their perceptions, barriers, and implementation practices related to ASPs. Methods: A cross-sectional survey conducted between August and December 2024 included 364 healthcare professionals (HCPs) in 58 randomly selected public healthcare facilities in Zambia. Data were analysed using IBM SPSS 25.0. Results: Findings revealed that while 75.3% of respondents were aware of the Zambian NAP on AMS, only 68.1% of the respondents reported that their hospitals had established AMS committees. Conversely only 41.2% of the respondents stated that their hospitals possessed hospital-specific treatment guidelines. Encouragingly, 97.5% believed ASPs could enhance clinical outcomes and reduce AMR. Key barriers included limited funding (75.9%), inadequate IT infrastructure (64.1%), limited access to essential data (64%), and healthcare workforce shortages (53.8%). Conclusions: Whilst HCPs in Zambia demonstrated high awareness of the NAP and supported ASP implementation, systemic challenges hindered their consistent execution across health facilities. Gaps in treatment guideline development, AMR data usage, and the integration of antimicrobial susceptibility recording systems into clinical activities must be addressed to strengthen ASP efforts nationwide. Full article

(This article belongs to the Special Issue Current Challenges in Antimicrobial Stewardship)

12 pages, 229 KB

Open AccessCommunication

Development of the Zambian Standard Treatment Guidelines in the Animal Health Sector: A Key Step in Advancing Antimicrobial Stewardship

by Chikwanda Chileshe, Fusya Goma, Ntombi B. Mudenda, Steward Mudenda, Taona Sinyawa, Mwendalubi Hadunka, Geoffrey Mainda, Namukolo Muyamwa, Chrisborn Mubamba, Niwael Jesse Mtui Malamsha, Suze Percy Filippini, Maisa Kasanga, Victor Daka, Webrod Mufwambi, Amon Siame, Aubrey C. Kalungia, Zoran Muhimba, Mercy Mukuma, Sandra Diana Mwadesta, Shikanga O-Tipo, Jimmy Hangoma, John Bwalya Muma, Joseph Yamweka Chizimu, Charles Maseka and Roma Chilengi Show full author list Hide full author list

Antibiotics 2025, 14(11), 1093; https://doi.org/10.3390/antibiotics14111093 - 1 Nov 2025

Abstract

Background: Zambia, like many low- and middle-income countries, faces a growing burden of antimicrobial resistance (AMR), driven by the misuse of antimicrobials in both human and animal health, a limited diagnostic capacity, and weak regulatory enforcement. To address this challenge, Standard Treatment [...] Read more.

Background: Zambia, like many low- and middle-income countries, faces a growing burden of antimicrobial resistance (AMR), driven by the misuse of antimicrobials in both human and animal health, a limited diagnostic capacity, and weak regulatory enforcement. To address this challenge, Standard Treatment Guidelines (STGs) were developed for the veterinary sector, which represents a major milestone in the country’s AMR containment strategy. STGs are evidence-based protocols that guide veterinary professionals in consistently and appropriately diagnosing and treating animal diseases. They promote the rational use of veterinary medicines, and can mitigate AMR and improve animal health outcomes. By translating the best evidence into best practices, STGs also provide a practical foundation for antimicrobial stewardship (AMS) programs. Until 2023, Zambia lacked nationally adopted STGs for the veterinary sector. The introduction and standardization of these guidelines are expected to promote prudent antimicrobial use and raise the standard of care delivered to animal patients across the country. Objective: The aim of this paper is to provide a practical reference for future revisions of STGs and outline the successful methodology used to create STGs in the Zambian animal sector. Methods: A situational analysis was conducted to identify priority animal health conditions and existing treatment gaps within the veterinary sector. A multidisciplinary expert committee was then formed, comprising veterinarians, veterinary paraprofessionals, academics, regulatory authorities, and private sector stakeholders, to lead the development of the STGs. The process was guided by the WHO methodology for developing treatment guidelines, including a comprehensive review of the clinical evidence, local disease patterns, antimicrobial resistance data, and existing treatment practices. Draft STGs were developed with clearly defined, species-specific treatment protocols tailored to the Zambian context. For the validation process, the AGREE II instrument was used to assess the quality, clarity, and applicability of the guidelines. Structured stakeholder consultations with practitioners, policy-makers, and technical experts were held to ensure that the guidelines were practical, evidence-based, and aligned with national priorities. The validated drafts were then disseminated and piloted in selected districts. Conclusions: The development of the species-specific STGs represents an essential turning point in the country’s efforts to promote responsible veterinary care and contain AMR. STGs have become a prominent key support in the delivery of quality animal care. Further, the guidelines will assist in the optimization of antimicrobial use in animal health in Zambia. Full article

(This article belongs to the Special Issue Antibiotics Stewardship in Low and Middle-Income Countries)

2 pages, 545 KB

Open AccessCorrection

Correction: Mikhailova, E.O. Green Silver Nanoparticles: An Antibacterial Mechanism. Antibiotics 2025, 14, 5

by Ekaterina O. Mikhailova

Antibiotics 2025, 14(11), 1092; https://doi.org/10.3390/antibiotics14111092 - 30 Oct 2025

Abstract

Error in Figure [...] Full article

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17 pages, 1847 KB

Open AccessArticle

Epidemiological Characteristics, Antibiotic Resistance Patterns and Genomic Analysis of Shigella Isolated in Pudong, Shanghai During 2013–2024

by Yue Zhang, Xiao Wang, Yanru Liang, Wenqing Wang, Hong Huang, Bowen Yang, Anran Zhang, Yuan Zhuang, Min Chen, Jun Feng and Bing Zhao

Antibiotics 2025, 14(11), 1091; https://doi.org/10.3390/antibiotics14111091 - 30 Oct 2025

Abstract

Background: Shigella spp. are critical pathogens causing diarrheal diseases. This study analyzed the epidemiological characteristics, antimicrobial resistance profiles, virulence factor profiles, and molecular patterns of Shigella isolates in Pudong New Area, Shanghai, from 2013 to 2024. Materials and Methods: Antimicrobial susceptibility of [...] Read more.

Background: Shigella spp. are critical pathogens causing diarrheal diseases. This study analyzed the epidemiological characteristics, antimicrobial resistance profiles, virulence factor profiles, and molecular patterns of Shigella isolates in Pudong New Area, Shanghai, from 2013 to 2024. Materials and Methods: Antimicrobial susceptibility of Shigella isolates was determined using the broth microdilution method. All molecular characterization analyses were based on whole-genome next-generation sequencing of Shigella strains. Results: A total of 55 Shigella spp. isolates were obtained from 17,670 enrolled diarrheal cases between 2013 and 2024, including 47 S. sonnei and 8 S. flexneri isolates. Resistance rates to sulfamethoxazole-trimethoprim (SXT), streptomycin (STR), nalidixic acid (NAL), ampicillin (AMP), and tetracycline (TET) all exceeded 90.00%. The resistance rate to azithromycin (AZI) increased from 12.50% to 60.00% with a fluctuating upward trend from 2013 to 2019; 97.87% of S. sonnei and 100.00% of S. flexneri isolates were multidrug-resistant. These isolates harbored multiple resistance genes and virulence factors. S. sonnei was dominated by ST152, while S. flexneri was predominantly ST245. These isolates were phylogenetically close to domestic (Beijing) and international (USA) strains of the same sequence typing collected at different time points, suggesting a common origin and stable transmission characteristics. Conclusion: From 2013 to 2024, the prevalent Shigella species in Pudong were S. sonnei and S. flexneri. Shigella isolates exhibited high resistance rates, and the situation of multidrug resistance was severe. Therefore, strengthening antimicrobial resistance monitoring and controlling regional transmission are of great significance. Meanwhile, genomic surveillance of Shigella ST152/ST245 is recommended for Pudong’s enteric pathogen control programs. Full article

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11 pages, 260 KB

Open AccessArticle

Profile of Multidrug-Resistant Bacteria in Intensive Care Units of a Maternal and Child Hospital in Rio de Janeiro, Brazil

by Lucas Meneses de Oliveira Villar, Natalie Del-Vecchio Lages Costa, Danielle Bonotto Cabral Reis, Adriana Teixeira Reis, Leticia Linhares Braga, Fabíola Cristina de Oliveira Kegele, Maria da Conceição Borges Lopes, Maria Francisca da Silva Neta Soares, Maria Elisabeth Lopes Moreira, Natália Chantal Magalhães da Silva, Leonardo Henrique Ferreira Gomes and Letícia da Cunha Guida

Antibiotics 2025, 14(11), 1090; https://doi.org/10.3390/antibiotics14111090 - 30 Oct 2025

Abstract

Background/Objectives: Epidemiological surveillance of healthcare-associated infections (HAIs) and multidrug-resistant (MDR) bacteria is a key responsibility of hospital infection control committees (HICC). Active surveillance swabs facilitate the early detection of colonized patients; helping to prevent MDR pathogen transmission in intensive care units. This study [...] Read more.

Background/Objectives: Epidemiological surveillance of healthcare-associated infections (HAIs) and multidrug-resistant (MDR) bacteria is a key responsibility of hospital infection control committees (HICC). Active surveillance swabs facilitate the early detection of colonized patients; helping to prevent MDR pathogen transmission in intensive care units. This study aimed to describe antimicrobial resistance profiles of bacterial isolates from clinical samples in neonatal and pediatric intensive care units. Methods: A retrospective cross-sectional study was conducted at a maternal and child hospital in Rio de Janeiro, Brazil including patients aged 0–18 years admitted to neonatal (NICU), surgical (SICU), and pediatric (PICU) intensive care units between January and December 2023. A total of 286 positive cultures were analyzed from different sample types including blood, urine, tracheal aspirates, cerebrospinal fluid (CSF), and catheter tips as well as screening swabs (nasal and rectal) for colonization surveillance. Bacterial isolates were identified and tested for antimicrobial susceptibility following BrCAST (Brazilian Committee on Antimicrobial Susceptibility Testing) guidelines. Results: Of the 286 cultures, 146 (51%) originated from the NICU, 70 (24%) from the SICU, and 70 (24%) from the PICU. Coagulase-negative staphylococci (CoNS) predominated in blood cultures, especially among neonates, while MRSA was found in all nasal swabs. Among the Gram-negative bacteria; Klebsiella pneumoniae and Pseudomonas aeruginosa were the most frequent isolates, with 30–50% resistant to third-generation cephalosporins or carbapenems. ESBL-producing organisms were found in 40% of rectal swabs. Conclusions: The predominance of CoNS in neonatal ICUs and high resistance rates among Gram-negative bacteria highlight the urgent need for continuous microbiological surveillance and antimicrobial stewardship in vulnerable pediatric populations. Full article

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

8 pages, 979 KB

Open AccessCase Report

First Report of Multidrug-Resistant Staphylococcus sciuri Isolated from the Urinary Bladder of a Domestic Rabbit in Romania: A Case Study

by Bogdan Florea, Doru Morar, Cristina Văduva, Florin Simiz, Simina Velescu, Corina Kracunovic, Vlad Iorgoni, Paula Nistor, Janos Degi, Ionica Iancu, Viorel Herman, Alexandra Pocinoc and Eugenia Dumitrescu

Antibiotics 2025, 14(11), 1089; https://doi.org/10.3390/antibiotics14111089 - 29 Oct 2025

Abstract

Background/Objectives: Staphylococcus sciuri, traditionally regarded as a commensal organism in animals and the environment, is increasingly recognized as a potential opportunistic pathogen with zoonotic significance. Its genomic reservoir of methicillin resistance homologues further raises concern regarding its role in antimicrobial resistance [...] Read more.

Background/Objectives: Staphylococcus sciuri, traditionally regarded as a commensal organism in animals and the environment, is increasingly recognized as a potential opportunistic pathogen with zoonotic significance. Its genomic reservoir of methicillin resistance homologues further raises concern regarding its role in antimicrobial resistance dissemination. This study describes the first documented case of S. sciuri isolated from the urinary bladder of a domestic rabbit (Oryctolagus cuniculus) in Romania, emphasizing its clinical relevance and antimicrobial profile. Methods: A seven-year-old intact female rabbit presenting with apathy, dysuria, and hematuria underwent clinical evaluation, ultrasonography, and cystocentesis. The aspirated intravesical content was subjected to bacterial culture, MALDI-TOF MS identification, and antimicrobial susceptibility testing via the VITEK 2 system. Results: Pure colonies of Gram-positive cocci were identified as S. sciuri with high confidence. Antimicrobial susceptibility testing revealed susceptibility to β-lactams, aminoglycosides, glycopeptides, linezolid, rifampicin, fusidic acid, tigecycline, and trimethoprim-sulfamethoxazole, while resistance was observed against fluoroquinolones, macrolides, lincosamides, and tetracycline, indicating a multidrug-resistant phenotype. Treatment with trimethoprim-sulfamethoxazole combined with ultrasound-guided bladder lavage and supportive therapy resulted in complete clinical recovery within 10 days. Conclusions: This case highlights the pathogenic potential of S. sciuri in domestic rabbits and its capacity to exhibit multidrug resistance. The findings underscore the necessity of including rabbits in antimicrobial resistance surveillance programs and reinforce the importance of culture and sensitivity testing in guiding the therapeutic management of exotic companion animals. Full article

(This article belongs to the Special Issue Veterinary Microbiology and Antimicrobial Resistance—the One Health Approach)

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