Antibiotics

17 pages, 967 KB

Open AccessReview

From Bench to Bedside: Personalized Genomics in the Diagnosis and Treatment of Osteomyelitis

by Amir Human Hoveidaei, Arian Rahimzadeh, Sara Mohammadi, Pranav Thota, Kimia Vakili, Parsa Yazdanpanahi, Ali Homaei, Seyed Arad Mosalamiaghili, Jakob Adolf and Janet D. Conway

Antibiotics 2026, 15(2), 210; https://doi.org/10.3390/antibiotics15020210 (registering DOI) - 14 Feb 2026

Abstract

Osteomyelitis (OM), an inflammatory condition of the bone tissue, is a complex orthopedic condition marked by chronic inflammation, diagnostic uncertainty, and recurrent infections. Despite standard treatments—including surgical debridement, antimicrobial therapy, and bone reconstruction—many patients continue to experience recurrence and treatment failure. Growing molecular [...] Read more.

Osteomyelitis (OM), an inflammatory condition of the bone tissue, is a complex orthopedic condition marked by chronic inflammation, diagnostic uncertainty, and recurrent infections. Despite standard treatments—including surgical debridement, antimicrobial therapy, and bone reconstruction—many patients continue to experience recurrence and treatment failure. Growing molecular evidence indicates that host genetic factors play a crucial role in shaping immune responses and influencing disease progression in OM. This narrative review synthesizes current knowledge from candidate gene single-nucleotide polymorphism (SNP) association studies to illustrate how specific genetic variations contribute to OM pathogenesis, diagnostic refinement, and treatment outcomes. We examined key immunogenetic variants within genes involved in inflammatory signaling, pathogen recognition, and neutrophil regulation. Our synthesis identifies a landscape of pro-inflammatory SNPs, such as IL-1β rs16944 and NLRP3 rs10754558, that are associated with increased susceptibility to chronic or post-traumatic OM, as well as SNPs that are associated with protective effects that may favor infection resolution, such as within the NOS2 and VDR genes. These SNP-driven differences in inflammasome activity, cytokine pathways, and oxidative stress responses highlight emerging opportunities for individualized therapeutic strategies. This review consolidates these variants, providing a genetic framework to analyze host susceptibility and differentiating high risk from protective genetic profiles. Integrating genomic insights into OM management represents a promising shift toward personalized medicine, enhancing diagnostic precision, informing targeted interventions, and improving prognostic assessment. Continued large-scale validation of candidate SNPs and translational genomic models will be essential to support their future clinical application. Full article

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

32 pages, 7039 KB

Open AccessSystematic Review

Prevalence of Carbapenem-Resistant Gram-Negative Bacilli from Intensive Care Units from Latin America and the Caribbean: A Systematic Review and Meta-Analysis

by Jesús D. Rojas, Mercy Carolina Merejildo Vera, Juan Carlos Benites Azabache, Valeria De La Cruz Surco, Juan Raúl Lucas López and Rafael Pichardo-Rodriguez

Antibiotics 2026, 15(2), 209; https://doi.org/10.3390/antibiotics15020209 (registering DOI) - 14 Feb 2026

Abstract

Background: Carbapenem-resistant Gram-negative bacilli (CR-GNB) represent a critical threat to patients in intensive care units (ICUs), where limited therapeutic options contribute to elevated mortality. In Latin America and the Caribbean (LAC), the epidemiological burden of CR-GNB remains insufficiently characterized due to fragmented surveillance [...] Read more.

Background: Carbapenem-resistant Gram-negative bacilli (CR-GNB) represent a critical threat to patients in intensive care units (ICUs), where limited therapeutic options contribute to elevated mortality. In Latin America and the Caribbean (LAC), the epidemiological burden of CR-GNB remains insufficiently characterized due to fragmented surveillance systems. This systematic review aimed to synthesize pooled prevalence estimates of CR-GNB among Gram-negative isolates recovered from ICUs across LAC countries. Methods: This systematic review was prospectively registered with PROSPERO (CRD420251177826), followed PRISMA 2020 guidelines and the JBI Manual for prevalence reviews. We searched PubMed, Scopus, LILACS, and SciELO from January 2015 to October 2025 without language restrictions. Observational studies reporting phenotypic carbapenem resistance data from ICUs in LAC countries were eligible. Two reviewers independently screened studies and extracted data. A two-level multilevel generalized linear mixed model (GLMM) with logit transformation was employed using a random-effects approach. Risk of bias was assessed using the JBI critical appraisal checklist. Results: Of 25 eligible studies spanning eight countries, 12 contributed 49 observations to quantitative synthesis. Overall pooled prevalence of CR-GNB was 28.88% (95% CI: 17.32–44.05%), with considerable heterogeneity (I² = 95.24%). Species-specific prevalence was highest for Acinetobacter baumannii (72.58%), followed by Klebsiella pneumoniae (37.48%) and Pseudomonas aeruginosa (29.93%). Regional stratification revealed higher prevalence in South America (31.81%) compared to North America (22.65%) and the Caribbean (11.63%). Conclusions: Nearly one-third of Gram-negative isolates from LAC ICUs exhibit carbapenem resistance, with A. baumannii predominating. Substantial inter-study heterogeneity underscores the need for standardized regional surveillance networks and coordinated antimicrobial stewardship initiatives. Full article

(This article belongs to the Special Issue Antimicrobial Resistance and Epidemiological Study of Clinically Relevant Pathogens)

24 pages, 11094 KB

Open AccessArticle

Structure–Activity Relationship and Biosafety of Linear Pentapeptide Analogs Derived from Battacin for Antimicrobial Development

by Haixin Sun, Yujie Zhang, Guoqing Gi and Chen Yao

Antibiotics 2026, 15(2), 208; https://doi.org/10.3390/antibiotics15020208 - 13 Feb 2026

Abstract

Background: Natural antimicrobial peptides (AMPs) present a promising solution to address the global threat of drug-resistant infections; however, their clinical translation is challenged by limitations in stability, cytotoxicity, and production costs. Methods: In the present study, a linear Battacin-derived peptide (DDLFD) was modified [...] Read more.

Background: Natural antimicrobial peptides (AMPs) present a promising solution to address the global threat of drug-resistant infections; however, their clinical translation is challenged by limitations in stability, cytotoxicity, and production costs. Methods: In the present study, a linear Battacin-derived peptide (DDLFD) was modified at the N-terminus with lipid chains, cinnamic acid, or lipoic acid. The lipoic acid-modified variant was further crosslinked by UV irradiation to form stable nanoparticles. The antibacterial performance against planktonic and biofilm bacteria was systematically evaluated in vitro. Results: The results demonstrated that lauric acid-modified pentapeptide (C₁₂-5) and crosslinked lipoic acid-modified pentapeptide (cLA-5) exhibited potent and rapid-acting effects against various pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Moreover, they showed enhanced efficacy in eradicating bacterial biofilms. Biosafety assessments based on hemolysis and cytotoxicity assays indicated favorable biocompatibility profiles of cLA-5. Mechanistic investigations confirmed that the modified pentapeptides retained a membrane-targeting mode of action characteristic of natural AMPs, involving membrane depolarization and increased permeability. This physical mechanism effectively prevented the development of resistance in sequential passaging assays and showed strong synergistic effects with ciprofloxacin against ciprofloxacin-resistant strains, effectively restoring their antibiotic susceptibility. Conclusions: Together, these findings underscore the strategic potential of rational structural modification, especially the crosslinked nanostructure, in advancing engineered AMPs toward clinical application. Full article

(This article belongs to the Special Issue Multitalented Synthetic Antimicrobial Compounds: From Design to Effect)

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19 pages, 805 KB

Open AccessArticle

Trends of Microorganisms and Antibiotic Resistance Isolated from Patients with Bacterial Keratitis from a Tertiary Hospital in Southeastern Korea: A 26-Year Retrospective Medical Record Review

by Chan-Ho Cho, Jong Ho Lee and Sang-Bumm Lee

Antibiotics 2026, 15(2), 207; https://doi.org/10.3390/antibiotics15020207 - 13 Feb 2026

Abstract

Background. The aim of this study is to analyze changing trends in isolated organisms and antibiotic resistance of bacterial keratitis (BK) over 26 years. Methods. A retrospective medical record review included 542 strains isolated from 462 BK patients between 1998 and 2023. We [...] Read more.

Background. The aim of this study is to analyze changing trends in isolated organisms and antibiotic resistance of bacterial keratitis (BK) over 26 years. Methods. A retrospective medical record review included 542 strains isolated from 462 BK patients between 1998 and 2023. We analyzed routinely generated in vitro antibiotic susceptibility testing results recorded in the laboratory information system and did not perform additional susceptibility testing for research purposes. The entire period was divided into two (first half: 1998–2010, 297 isolates from 255 patients; second half: 2011–2023, 245 isolates from 207 patients) and compared. Results. During the entire period, Staphylococcus spp. (32.3%) and Pseudomonas spp. (18.1%) were common isolates, and a significant increase in Acinetobacter spp. (1.3% vs. 10.6%, p < 0.001) was observed. Among Gram-positive bacteria, methicillin resistance rates remained stable between the two periods (52.6% vs. 46.7%, p = 0.525), and an increase in vancomycin-resistant Enterococci (VRE, 0% vs. 26.1%, p = 0.074) was found. Among Gram-negative bacteria (GNB), ciprofloxacin (7.5% vs. 14.4%, p = 0.108) and imipenem (2.9% vs. 6.5%, p = 0.255) resistance increased slightly, resistance to ceftazidime (resistance to ceftazidime (8.3% vs. 8.8%, p > 0.999) was maintained, and resistance to aminoglycosides (17.8% vs. 7.2%, p = 0.010) decreased. Conclusions. Our study suggests that conventional topical fortified antibiotic eye drops (tobramycin, ceftazidime) can still be considered as an empirical treatment option for BK. However, our findings revealed a long-term trend of increasing Acinetobacter spp. and VRE, as well as a slight trend of increasing resistance to ciprofloxacin and imipenem in GNB, which may present future challenges in BK treatment. Full article

(This article belongs to the Collection Antibiotics in Ophthalmology Practice)

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20 pages, 5325 KB

Open AccessReview

Neonatal Listeriosis with Central Nervous System Involvement: A Case Series and Review of the Literature

by Chiara Maddaloni, Ludovica Martini, Domenico Umberto De Rose, Daniela Longo, Alessia Guarnera, Cinzia Auriti, Francesca Campi, Maria Paola Ronchetti and Andrea Dotta

Antibiotics 2026, 15(2), 206; https://doi.org/10.3390/antibiotics15020206 - 13 Feb 2026

Abstract

Background: Listeria monocytogenes infection during pregnancy remains an underrecognized cause of severe neonatal disease, frequently leading to central nervous system (CNS) involvement with high mortality and long-term neurological sequelae. Case presentation: We report a case series of four neonates with confirmed neonatal listeriosis [...] Read more.

Background: Listeria monocytogenes infection during pregnancy remains an underrecognized cause of severe neonatal disease, frequently leading to central nervous system (CNS) involvement with high mortality and long-term neurological sequelae. Case presentation: We report a case series of four neonates with confirmed neonatal listeriosis and neurological complications, managed in a tertiary neonatal intensive care unit (NICU). Clinical features, microbiological findings, neuroimaging, treatments, and outcomes were analyzed. Our cases presented with early-onset disease and severe clinical courses, including sepsis, meningitis, ventriculitis, hydrocephalus, and seizures. Neuroimaging revealed extensive CNS injury, ranging from intraventricular hemorrhage to multiloculated hydrocephalus. Outcomes varied from near-normal neurodevelopment to profound neurological impairment, despite appropriate antimicrobial therapy. A narrative review of previous cases of neonatal listeriosis was also performed to contextualize our findings. Conclusions: Neonatal listeriosis remains associated with severe neurological morbidity. Early recognition, advanced neuroimaging, multidisciplinary management, and preventive maternal strategies are essential to improve outcomes. Full article

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13 pages, 253 KB

Open AccessArticle

Study on the Importance of Hygienic Hand Disinfection of Dental Practitioners and Students as an Infection Control Measure in Dental Practice

by Veselina Kondeva, Velina Stoeva, Yordan Kalchev and Rumyana Stoyanova

Antibiotics 2026, 15(2), 205; https://doi.org/10.3390/antibiotics15020205 - 13 Feb 2026

Abstract

The hands of dental students and practitioners are a key epidemiological factor in the transmission of infections associated with dental care. Strict adherence to the established hand hygiene protocols, combined with regular training and monitoring the quality of the performed hygienic hand disinfection, [...] Read more.

The hands of dental students and practitioners are a key epidemiological factor in the transmission of infections associated with dental care. Strict adherence to the established hand hygiene protocols, combined with regular training and monitoring the quality of the performed hygienic hand disinfection, is crucial for ensuring safe dental practice. Objectives: The aim of the study is to assess the quality of hand antisepsis performed with alcohol-containing preparation among dental students and practicing dentists. Methods: A prospective epidemiological and microbiological study was conducted on 225 people—149 students from the 4th, 5th and 6th year of training at the Faculty of Dental Medicine, Plovdiv, and 76 dentists. The skin antiseptic was applied according to the “six steps” method with alcohol-based antiseptics. The samples were taken with a dry sterile swab. Results: The comparison between students and practicing dental medical doctors shows that the latter have a higher relative share of samples with microbiological growth 12 (15.8%), including coagulase-negative staphylococci (CoNS) above 10⁵ CoNS, compared to students 6 (4.0%), (p = 0.004). Gram-negative microbiological isolates indicate a statistically significant gender dependence (p = 0.016)—15 in men (15.8%), compared to 7 in women (5.4%). Growth of fungi (yeasts and mols) is statistically significant depending on gender (p = 0.015) and is observed only in men. Conclusions: The presence of significant microbial counts of CoNS is an indicator of insufficiently effective hygienic hand disinfection. The recovery of Gram-negative enteric bacteria is unacceptable and suggests serious shortcomings in the hygienic disinfection of some of the samples studied. Students demonstrated superior hand antisepsis performance compared to practicing dentists. Full article

(This article belongs to the Special Issue Evidence-Based Antibiotic Protocols and Digital Innovation in Oral Infection Management: Optimizing Use Through Teledentistry and Modern Diagnostics)

17 pages, 3310 KB

Open AccessArticle

Examining the Effects: Lack of Impact by Endolysin and Phage Treatment on Rotifer and Larvae Microbiota

by Jaime Romero, Carolina Ramírez, Alda Pardo, Marco Medina-Morillo, Luz Hurtado, Rodrigo Rojas and Claudio D. Miranda

Antibiotics 2026, 15(2), 204; https://doi.org/10.3390/antibiotics15020204 - 13 Feb 2026

Abstract

Background: Bacteriophages and phage-derived lytic enzymes are increasingly considered to be targeted antimicrobial tools in aquaculture; however, their compatibility with non-target microbial communities under hatchery-relevant conditions remains insufficiently characterized. Objectives This study evaluates the impact of a lytic phage (CH20) and a phage-derived [...] Read more.

Background: Bacteriophages and phage-derived lytic enzymes are increasingly considered to be targeted antimicrobial tools in aquaculture; however, their compatibility with non-target microbial communities under hatchery-relevant conditions remains insufficiently characterized. Objectives This study evaluates the impact of a lytic phage (CH20) and a phage-derived lysin (LysVp1), applied under previously validated conditions for rapid Vibrio control, on the microbiota associated with seawater, rotifers, and zebrafish larvae challenged with Vibrio alginolyticus GV09. Methods: Treatments were independently applied to each biological matrix using short exposure times representative of hatchery practices, intentionally capturing the critical window during which microbial transfer from live feed to larvae occurs. Microbial communities were analyzed using 16S rRNA gene sequencing, with DNA- and RNA-derived datasets evaluated separately. Results: Alpha diversity indices were compared using appropriate statistical tests, while beta diversity was assessed using Aitchison distance, PERMANOVA, and dispersion analyses, and differential abundance was evaluated using ANCOM-BC2. Alpha diversity metrics showed no significant differences among treatments across all matrices, indicating the preservation of microbial richness and diversity. Beta diversity patterns differed according to the nucleic acid source, with RNA-based analyses revealing treatment-associated shifts in rotifer and water microbiota that were not consistently detected at the DNA level. In zebrafish larvae, neither phage nor lysin treatment significantly altered overall community structure, although dispersion effects reflected limitations related to sample size. Conclusions: Overall, these results indicate that phage CH20 and lysin LysVp1 exert minimal impact on alpha diversity and limited, context-dependent effects on microbial community structure, supporting their microbiota-safe potential for aquaculture applications. Full article

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3 pages, 159 KB

Open AccessEditorial

A 2026 Update on Computational Approaches to the Discovery and Design of Antimicrobial Peptides

by Guillermin Agüero-Chapin, Agostinho Antunes and Yovani Marrero-Ponce

Antibiotics 2026, 15(2), 203; https://doi.org/10.3390/antibiotics15020203 - 13 Feb 2026

Abstract

Antimicrobial resistance (AMR) continues to stand as a critical global healthcare challenge [...] Full article

(This article belongs to the Special Issue Computational Approaches in Discovery and Design of Antimicrobial Peptides—2nd Edition)

14 pages, 1424 KB

Open AccessArticle

Engineering Industrial Strain of Acremonium chrysogenum for Deacetoxycephalosporin C Overproduction Using CRISPR/Cas9

by Zhiping Hou, Mengliu Peng, Xiaozhi Ju, Yaqi Sun, Liping Du, Ye Liang and Shu-Shan Gao

Antibiotics 2026, 15(2), 202; https://doi.org/10.3390/antibiotics15020202 - 12 Feb 2026

Abstract

Background: The fungus Acremonium chrysogenum is crucial for producing cephalosporin antibiotics. While CRISPR/Cas9 has been developed for this species, it has not been applied to first-line industrial strains, to the best of our knowledge. For example, engineering industrial A. chrysogenum for overproducing deacetoxycephalosporin [...] Read more.

Background: The fungus Acremonium chrysogenum is crucial for producing cephalosporin antibiotics. While CRISPR/Cas9 has been developed for this species, it has not been applied to first-line industrial strains, to the best of our knowledge. For example, engineering industrial A. chrysogenum for overproducing deacetoxycephalosporin C (DAOC, an important precursor for clinically used cephalosporin antibiotics) is currently often a multi-step and inefficient process. Methods: Here, we applied CRISPR/Cas9 to create a DAOC overproducer in a single step. Our method uses a donor template to simultaneously delete and overexpress genes, offering a simple, efficient, and time-saving solution. Results: Furthermore, through methodological optimization, the final homozygous multigene-edited strain achieved an industrial-scale DAOC titer of 12.4 ± 0.2 g/L, representing a significant improvement over the initial edited strain (7.2 ± 0.22 g/L). Conclusions: This demonstrates that CRISPR/Cas9 can effectively edit industrial A. chrysogenum, providing a strategy to enhance the production of other cephalosporin precursors. Full article

(This article belongs to the Special Issue Synthetic Biology Brings New Opportunity for Antibiotics Discovery, 2nd Edition)

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15 pages, 3390 KB

Open AccessArticle

Epidemiology of Surgical Site Infections: Incidence and Risk Factors at Jimma University Specialized and Comprehensive Hospital, Ethiopia

by Mulatu Gashaw, Bikila Alemu, Andreas Wieser, Rahel Tamrat, Assefa Legesse Sisay, Kira Elsbernd, Rebecca Kisch, Gemechu Abera, Gersam Abera, Demisew Amenu Sori, Esayas Kebede Gudina and Arne Kroidl

Antibiotics 2026, 15(2), 201; https://doi.org/10.3390/antibiotics15020201 - 12 Feb 2026

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Abstract

Background: Surgical site infections (SSIs) are healthcare-associated infections that can occur following surgical procedures, either at admission or within 30 days post-discharge. This study aimed to assess the incidence and associated risk factors for superficial SSI at a Tertiary Hospital in Ethiopia. [...] Read more.

Background: Surgical site infections (SSIs) are healthcare-associated infections that can occur following surgical procedures, either at admission or within 30 days post-discharge. This study aimed to assess the incidence and associated risk factors for superficial SSI at a Tertiary Hospital in Ethiopia. Methods: A longitudinal study was conducted among patients undergoing surgery at Jimma University Specialized and Comprehensive Hospital (JUSCH) from 1 June to 30 September 2022. Pus, wound swab, or abscess samples were inoculated on Blood and MacConkey Agar for culture. Bacterial isolates were identified using MALDI-TOF, antimicrobial susceptibility testing was performed using the Kirby–Bauer disc diffusion method, and the results were interpreted according to EUCAST 2022 breakpoints. Incidence rates, Kaplan–Meier analysis, extended Cox regression, and violin plots were utilized to analyze and present the findings. Results: Among 1205 participants, 629 (52.2%) were male, and the median age was 27 years (IQR: 16–40). The incidence of SSI was 9.2 per 1000 person-days. Most SSIs occurred during hospitalization (81.1%), and the remaining primarily developed within the first week post-discharge. The culture positivity rate was 72.7%, yielding 252 isolates comprising 36 bacterial species. The most frequently identified organisms were E. coli (22.2%), Acinetobacter (20.2%), and Klebsiella (14.7%). Over 67% of Gram-negative bacteria were ESBL producers. Age, gender, residence, hospital ward, surgery area, emergency surgery, longer hospitalization, and the number of staff attending the surgery were identified as important risk factors. Conclusions: This study revealed a high incidence of SSI during hospitalization, with significant proportion identified post-discharge. The high rates of multidrug-resistant Gram-negative pathogens underscore the urgent need for comprehensive infection prevention and control measures. Full article

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

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2 pages, 137 KB

Open AccessRetraction

RETRACTED: Rahman et al. An Overview of Antimicrobial Stewardship Optimization: The Use of Antibiotics in Humans and Animals to Prevent Resistance. Antibiotics 2022, 11, 667

by Md. Mominur Rahman, Mst. Afroza Alam Tumpa, Mehrukh Zehravi, Md. Taslim Sarker, Md. Yamin, Md. Rezaul Islam, Md. Harun-Or-Rashid, Muniruddin Ahmed, Sarker Ramproshad, Banani Mondal, Abhijit Dey, Fouad Damiri, Mohammed Berrada, Md. Habibur Rahman and Simona Cavalu

Antibiotics 2026, 15(2), 200; https://doi.org/10.3390/antibiotics15020200 - 12 Feb 2026

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Abstract

The journal retracts the article “An Overview of Antimicrobial Stewardship Optimization: The Use of Antibiotics in Humans and Animals to Prevent Resistance” [...] Full article

20 pages, 1151 KB

Open AccessArticle

Wild Fishes as Reservoirs of Gut Bacteria Carrying Antimicrobial Resistance Encoding Genes in Chilean Bays

by Claudio D. Miranda, Christopher Concha, Luz Hurtado, Rodrigo Rojas and Jaime Romero

Antibiotics 2026, 15(2), 199; https://doi.org/10.3390/antibiotics15020199 - 11 Feb 2026

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Abstract

Objective: The main aim of the study was to evaluate the role of wild fishes inhabiting in three anthropogenic-impacted Bays in Chile as reservoirs of antimicrobial resistance genes (ARGs). Methods: A total of 245 antimicrobial-resistant isolates were isolated from fish captured in [...] Read more.

Objective: The main aim of the study was to evaluate the role of wild fishes inhabiting in three anthropogenic-impacted Bays in Chile as reservoirs of antimicrobial resistance genes (ARGs). Methods: A total of 245 antimicrobial-resistant isolates were isolated from fish captured in the Coquimbo (142 isolates), Concepción (44 isolates), and Puerto Montt (59 isolates) Bays, and were identified by 16S rRNA gene sequence analysis, Antimicrobial-resistant isolates were tested for susceptibility to 12 antimicrobials by an agar disk diffusion method, and the carriage of genes encoding for resistance to main antimicrobial classes, such as β-lactams, amphenicols, tetracyclines, and sulfonamides by PCR (Polymerase Chain Reaction). Results: A predominance of the Pseudomonas (37.04%), Vibrio (14.40%), and Shewanella (13.99%) genera. Antimicrobial-resistant isolates were tested for susceptibility to 12 antimicrobials by an agar disk diffusion method, showing highest resistance to streptomycin (82.4%), amoxicillin (67.4%), and furazolidone (63.3%), and lowest resistance to ciprofloxacin (3.7%), meropenem (22.5%), and oxytetracycline (29.8%) and exhibiting a high occurrence of the multi-drug resistance phenotype (76.9%). Furthermore, an important number of isolates recovered from sampled fish species carried plasmids (53.5%), floR gene (36.7%), and tet genes (19.2%), whereas the detection of sul genes and class 1-integron was rare. As an overall result, 10.6% of isolates carried at least one bla gene, encoding an extended-spectrum-β-lactamase, with a high predominance of the bla_CTX-M1 gene (23 isolates), whereas 14 out of 245 isolates (5.7%) were positive for the carriage of carbapenemases encoding genes, which both groups exhibited the β-lactam resistance phenotype. Conclusions: The wide distribution of ARG-carrying bacteria in wild fishes from all sampled Bays provides evidence that wild fish are important reservoirs and drivers of spread of ARGs in the marine environment, prompting the need of a continuous surveillance of these genes in wild fishes inhabiting anthropic impacted coastal marine environments in Chile. Full article

(This article belongs to the Special Issue Antimicrobial Resistance in the Wildlife)

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19 pages, 893 KB

Open AccessArticle

Retrospective Study of Bacteriological Patterns and Antimicrobial Resistance Profiles of Mastitis in the Banat Region of Romania

by Caius Stoichescu, János Degi, Eugenia Dumitrescu, Florin Muselin, Diana Brezovan and Romeo Teodor Cristina

Antibiotics 2026, 15(2), 198; https://doi.org/10.3390/antibiotics15020198 - 11 Feb 2026

Viewed by 171

Abstract

Background: Bovine mastitis is a leading cause of economic loss in dairy farming and is increasingly complicated by antimicrobial resistance (AMR), posing challenges to treatment and public health. Objectives: This study aimed to investigate the prevalence, bacterial etiology, and AMR patterns of mastitis [...] Read more.

Background: Bovine mastitis is a leading cause of economic loss in dairy farming and is increasingly complicated by antimicrobial resistance (AMR), posing challenges to treatment and public health. Objectives: This study aimed to investigate the prevalence, bacterial etiology, and AMR patterns of mastitis pathogens in dairy herds from the Banat region of Romania. Materials and Methods: A retrospective analysis was conducted on 420 dairy cows from five localities. Mastitis diagnosis involved clinical examination, indirect tests (California Mastitis Test (CMT), R-Mastitest), and bacteriological culture. Antimicrobial susceptibility was assessed using the VITEK^® 2 system. Results: Out of 420 cows, 120 (28.6%) were diagnosed with mastitis. The predominant pathogens were Staphylococcus aureus (33.3%) and Streptococcus agalactiae (22.5%). Most infections were monomicrobial (70%) and affected a single under quarter (77.5%). Beta-lactam resistance was widespread among both Gram-positive and Gram-negative isolates, particularly against penicillin and ampicillin. Multidrug-resistant (MDR) strains were identified in 33.3% of all isolates, with 100% of Gram-negative isolates exhibiting MDR profiles. Conclusions: The high prevalence of S. aureus and S. agalactiae, along with widespread beta-lactam resistance and frequent MDR phenotypes, highlights the urgent need for routine AMR surveillance and targeted antimicrobial therapy in bovine mastitis control programs. Full article

(This article belongs to the Special Issue Antimicrobial Resistance in Veterinary Pathogens: Phenotypic Surveillance, Genomic Epidemiology, and Control Measures)

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15 pages, 1954 KB

Open AccessArticle

Molecular Identification, Virulence Factors, and Antifungal Susceptibility Profiles of Candida Isolates from Clinical Samples of Intensive Care Patients

by Zeynep Çelik, İbrahim Halil Kılıç, Semih Tokak and Fatma Esenkaya Taşbent

Antibiotics 2026, 15(2), 197; https://doi.org/10.3390/antibiotics15020197 - 10 Feb 2026

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Abstract

Background/Objectives: Candida infections constitute a significant category of healthcare-associated infections. In studies aiming to develop new antifungal agents against Candida species, the importance of their virulence factors has been emphasized. Methods: This study included 100 Candida isolates obtained from patients hospitalized in [...] Read more.

Background/Objectives: Candida infections constitute a significant category of healthcare-associated infections. In studies aiming to develop new antifungal agents against Candida species, the importance of their virulence factors has been emphasized. Methods: This study included 100 Candida isolates obtained from patients hospitalized in intensive care units. Standard microbiological and molecular methods were employed for species identification. Virulence factors were determined through protease, phospholipase, hemolysis, and biofilm activity assays per-formed on the Candida strains. The EUCAST liquid microdilution method was used to assess antifungal susceptibility. Results: Based on sequencing results, 39 isolates were identified as Candida albicans and 61 as non-albicans Candida species. The accuracy of species identification was found to be 71% for Chromagar Candida and 87% for the MALDI-TOF MS system, compared to sequencing. Protease activity was positive in 52% of the isolates, phospholipase in 42%, hemolytic activity in 77%, and biofilm formation in 48%. Kruskal–Wallis analysis revealed no statistically significant interspecies differences in MIC distributions for amphotericin B, fluconazole, itraconazole, or nystatin (p > 0.05), although species-specific trends were observed, with higher fluconazole MICs in C. albicans and lower MIC values in C. tropicalis. Conclusions: Determining the distribution of Candida species, as well as their virulence factors and antifungal MIC profiles, is of great importance for developing appropriate treatment strategies and reducing related morbidity and mortality. Full article

(This article belongs to the Special Issue Advancing and Standardising Antimicrobial Susceptibility and Resistance Detection Methodology)

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24 pages, 698 KB

Open AccessArticle

Development of AWaRe-Based Quality Indicators to Assess the Appropriateness of Antibiotic Prescribing in Primary Healthcare in South Africa

by Audrey K. Chigome, Johanna C. Meyer, Adrian Brink, Sabiha Essack, Elmien Bronkhorst, Halima Dawood, Yasmina Johnson, Renier Coetzee, Chuma Maphathwana, Moloko Phaho, Phillip Malebaco, Nonhlanhla Nhlapo, Filip Djukic, Annie Heath, Aislinn Cook, Gauri Kumar, Stephen M. Campbell, Brian Godman and Marc Mendelson

Antibiotics 2026, 15(2), 196; https://doi.org/10.3390/antibiotics15020196 - 10 Feb 2026

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Abstract

Background/Objectives: The overuse and misuse of antibiotics contribute to antimicrobial resistance (AMR) globally. The appropriateness of antibiotic prescribing at the primary healthcare (PHC) level must be urgently addressed to reduce high levels of inappropriate antibiotic prescribing and associated AMR. This study aimed [...] Read more.

Background/Objectives: The overuse and misuse of antibiotics contribute to antimicrobial resistance (AMR) globally. The appropriateness of antibiotic prescribing at the primary healthcare (PHC) level must be urgently addressed to reduce high levels of inappropriate antibiotic prescribing and associated AMR. This study aimed to develop quality indicators, based on the World Health Organization (WHO)’s Access, Watch, Reserve (AWaRe) guidance, to assess the appropriateness and quality regarding antibiotic prescribing in public PHC settings in South Africa. Methods: Potential indicators were identified from indicators developed by City St George’s, University of London (SGUL); a review of AWaRe-based indicators; and the results from point prevalence surveys at PHC clinics in South Africa. The indicators were developed using the RAND/UCLA Appropriateness Method. In Round 1, 12 experts individually rated 78 indicators for clarity and appropriateness. In Round 2, 10 experts rated 89 indicators for appropriateness and feasibility during an interactive online meeting. Results: The final set had 61/89 indicators (68.5%) that were rated both appropriate and feasible with agreement. Dental infections (9/9; 100%) alongside skin and soft tissue infections (11/13; 84.6%) had the highest percentage of indicators that were rated appropriate and feasible with agreement. Lower urinary tract infections (6/11; 54.5%) and general (4/8; 50%) categories had the lowest percentage of indicators rated appropriate and feasible with agreement. Conclusions: The process proved valuable in developing potential indicators for use in future antimicrobial stewardship programmes to improve antibiotic prescribing in public sector PHC facilities in South Africa and beyond. Full article

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

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29 pages, 5156 KB

Open AccessArticle

Biochanin A, a Plant Isoflavone, Disrupts Peptidoglycan Biosynthesis by Downregulating femA and femB, and Impairs Cell Wall Integrity in Multidrug-Resistant Staphylococcus aureus

by Jade Joshua R. Teodosio, Kathryn Ann H. Dizon, Julyanna R. Bruna, Jan Vincent N. Sollesta, Zenith M. Villorente, Jonel P. Saludes and Doralyn S. Dalisay

Antibiotics 2026, 15(2), 195; https://doi.org/10.3390/antibiotics15020195 - 10 Feb 2026

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Abstract

Background/Objectives: The global rise in multidrug-resistant Staphylococcus aureus (MDR-SA) threatens the efficacy of existing antibiotics and necessitates alternative antibacterial strategies. Plant-derived isoflavones represent a promising but underexplored source of novel antimicrobials. Biochanin A, isolated from Cajanus cajan seeds, exhibits antibacterial activity and [...] Read more.

Background/Objectives: The global rise in multidrug-resistant Staphylococcus aureus (MDR-SA) threatens the efficacy of existing antibiotics and necessitates alternative antibacterial strategies. Plant-derived isoflavones represent a promising but underexplored source of novel antimicrobials. Biochanin A, isolated from Cajanus cajan seeds, exhibits antibacterial activity and may act via noncanonical mechanisms. This study elucidates the mechanism of action and safety profile of Biochanin A against MDR-SA using integrated experimental and computational approaches. Methods: Antibacterial activity was assessed by minimum inhibitory concentration (MIC) testing. Membrane integrity and morphological alterations were evaluated using flow cytometry and scanning electron microscopy (SEM), respectively. Target gene modulation was analyzed by qRT-PCR, while molecular interactions were examined through in silico docking. Cytotoxicity was evaluated in normal mammalian kidney, liver, and cardiac cells. Results: Biochanin A inhibited MDR-SA with an MIC80 of 64 µg/mL. Flow cytometry showed membrane disruption in 74.46 ± 13.19% of treated cells, and SEM revealed a 20% reduction in cell size (561.95 ± 21.99 nm). Biochanin A markedly downregulated femA (94%) and femB (67%), with minimal effect on femX (10%). Docking analyses supported preferential binding to FemA (−7.7 kcal/mol) and FemB (−7.5 kcal/mol) proteins. No cytotoxic effects were observed in normal mammalian cells. Conclusions: Biochanin A is a promising plant-derived antibacterial candidate against MDR-SA, targeting key cell wall biosynthesis genes while maintaining mammalian safety. These findings position Biochanin A as a viable lead for further biochemical, structural, and in vivo pharmacological validation, highlighting the translational potential of plant-derived isoflavones in combating antibiotic resistance. Full article

(This article belongs to the Special Issue Innovations in Plant-Based Antibiotic and Antiviral Agents)

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16 pages, 335 KB

Open AccessArticle

Pyelonephritis Caused by Multidrug-Resistant Bacteria During Pregnancy: A Case–Control Study

by Gabriel-Ioan Anton, Maria Caliniuc, Carina-Alexandra Bandac, Demetra Gabriela Socolov, Ingrid Andrada Tănasa, Rodica Radu, Radu-Stefan Miftode, Theodor Florin Pantilimonescu, Vlad Ichim, Egidia Gabriela Miftode, Ionela-Larisa Miftode and Viorel Dragoș Radu

Antibiotics 2026, 15(2), 194; https://doi.org/10.3390/antibiotics15020194 - 10 Feb 2026

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Abstract

Background: Pyelonephritis during pregnancy represents a significant maternal–fetal risk, particularly in the context of increasing multidrug-resistant (MDR) bacterial infections. This study aimed to characterize the microbiological profiles and antimicrobial resistance patterns of MDR pathogens causing pyelonephritis in pregnancy. Secondary objectives included the evaluation [...] Read more.

Background: Pyelonephritis during pregnancy represents a significant maternal–fetal risk, particularly in the context of increasing multidrug-resistant (MDR) bacterial infections. This study aimed to characterize the microbiological profiles and antimicrobial resistance patterns of MDR pathogens causing pyelonephritis in pregnancy. Secondary objectives included the evaluation of patient characteristics, associated risk factors, and pregnancy outcomes. Methods: A retrospective comparative study was conducted including 171 pregnant patients hospitalized with acute pyelonephritis between 1 January 2017 and 30 April 2025. Thirty-four patients with MDR bacterial infections were compared with 137 patients with infections caused by pathogens with conserved antibiotic susceptibility (Non-MDR). Results: Patients with MDR pyelonephritis were significantly older than those with Non-MDR infections (mean age 27.76 vs. 25.30 years, p = 0.03). MDR infections were more frequently diagnosed in the third trimester of pregnancy (58.8% vs. 29.9%, p = 0.003) and affected multiparous women more often (44.1% vs. 19.7%, p = 0.006). No statistically significant differences were observed between groups regarding clinical presentation or laboratory parameters (p > 0.05). Prior antibiotic exposure was significantly more common in the MDR group (85.29% vs. 26.61%, p < 0.001), as was a history of urological procedures, including urinary catheterization (29.41% vs. 15.10%, p = 0.009). For multivariate analysis, two factors were predictive for pyelonephritis with MDR pathogens: previous antibiotic treatment—OR 20.37 (95% CI 2.19–189.88) and urological procedures—OR 13.23 (95% CI 2.24-78-22). Escherichia coli was the predominant pathogen in both groups but was isolated more frequently in the Non-MDR cohort (81.75% vs. 58.82%, p = 0.015), followed by Klebsiella pneumoniae, which appeared more frequently in the study group (23.53% vs. 10.22%, p = 0.011). MDR isolates demonstrated significantly higher resistance rates to all tested antibiotics (p < 0.05). Complete resistance to ampicillin was observed in the MDR group (100%), compared with 58.01% in the Non-MDR group, indicating markedly reduced efficacy of this agent. Adverse neonatal outcomes were more frequent in the MDR group, with higher rates of Apgar scores < 7 at admission (23.5% vs. 8.8%, p = 0.01) and increased neonatal intensive care unit admission (20.6% vs. 7.3%, p = 0.02). For multivariate analysis, pyelonephritis with MDR pathogens was predictive for Neonatal Intensive Care Unit (NICU) admission (OR 8.17, 95% CI 2.41–27.67). Conclusions: These findings highlight the need for the periodic revision of empirical antibiotic protocols and risk-adapted therapeutic strategies in pregnant patients in order to reduce maternal and fetal morbidity. Full article

(This article belongs to the Special Issue Urinary Tract Infections: Diagnosis, Etiology, Antibiotic Treatment, and Current Trends in Antimicrobial Resistance)

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18 pages, 784 KB

Open AccessArticle

Retrospective Evaluation of Central Venous Catheter Use for Parenteral Nutrition in Pediatric Intestinal Failure: Infections and Taurolidine Role

by Júlia Vicentin de Souza, Angelica Sczepaniak da Silva, Lucas Gabriel Souza da Silva, Jéssica de Carvalho Inácio, Meire Ellen Pereira, Luíza Siqueira de Lima, Jaqueline de Sousa Fortes, Thaís Muniz Vasconcelos, Libera Maria Dalla Costa, Jocemara Gurmini and Cláudia Sirlene Oliveira

Antibiotics 2026, 15(2), 193; https://doi.org/10.3390/antibiotics15020193 - 10 Feb 2026

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Abstract

Objective: This study aimed to describe the main microorganisms causing catheter-related bloodstream infections (CRBSIs) and to evaluate the effectiveness of taurolidine catheter lock therapy in children with intestinal failure (IF) receiving parenteral nutrition (PN). Study design: This retrospective study included 31 pediatric patients [...] Read more.

Objective: This study aimed to describe the main microorganisms causing catheter-related bloodstream infections (CRBSIs) and to evaluate the effectiveness of taurolidine catheter lock therapy in children with intestinal failure (IF) receiving parenteral nutrition (PN). Study design: This retrospective study included 31 pediatric patients with IF admitted between 2017 and 2022 who received PN via central venous catheters (CVCs). Demographic, clinical, and laboratory data were collected, along with information on PN use, catheter characteristics, and infection episodes, including clinical signs, microbiological cultures, and antimicrobial therapy. Serum C-reactive protein and albumin levels, as well as the use of taurolidine lock therapy, were analyzed. Results: The median age was 54.4 days among patients who developed CRBSI and 154.1 days among those without CRBSI. The median duration of PN was 119 days in patients with CRBSI and 89 days in those without. Nineteen patients experienced CRBSI, accounting for 55 infection episodes confirmed by blood cultures obtained from CVCs. The most frequently isolated microorganisms were Staphylococcus epidermidis, Enterococcus faecalis, and Klebsiella pneumoniae. Taurolidine lock therapy was significantly associated with lower infection rates per 1000 catheter days, with most infected catheters and infection episodes occurring in the absence of taurolidine use. Conclusions: These findings contribute to the characterization of the microbiological profile of CRBSIs in pediatric patients with IF and support the use of advanced preventive strategies, such as taurolidine lock therapy, to reduce infection rates in children receiving long-term PN. Full article

(This article belongs to the Special Issue The Interventions to Prevent and Reduce Healthcare-Associated Infection)

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10 pages, 368 KB

Open AccessArticle

A Computational Approach to Evaluating Empirical Antibiotic Coverage for Gram-Negative Bloodstream Infections in Pediatric Febrile Neutropenia

by Francesca Cappozzo, Marcello Mariani, Emanuela Caci, Roberto Bandettini, Alessio Mesini, Erica Ricci, Carolina Saffioti, Carlo Dufour, Maura Faraci, Alberto Garaventa, Claudia Milanaccio, Francesca Bagnasco, Martina Toto and Elio Castagnola

Antibiotics 2026, 15(2), 192; https://doi.org/10.3390/antibiotics15020192 - 10 Feb 2026

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Abstract

Background: Empirical antibacterial therapy for febrile neutropenia requires adaptation to local epidemiology, a process that is often complex, time-consuming, and prone to human error. This study aims to address this challenge by developing a practical, data-driven tool to efficiently evaluate and adapt [...] Read more.

Background: Empirical antibacterial therapy for febrile neutropenia requires adaptation to local epidemiology, a process that is often complex, time-consuming, and prone to human error. This study aims to address this challenge by developing a practical, data-driven tool to efficiently evaluate and adapt treatment protocols. Methods: We developed a novel, open-source computational script in Python (version 3.10), aided by large language models for code revision, to analyze antibiotic susceptibility data. The script was validated using a retrospective dataset of 237 Gram-negative bloodstream infections (BSIs) from 2015 to 2024 in cancer or hematopoietic stem cell transplant recipients at a tertiary care pediatric hospital in Italy. The script calculates efficacy metrics for both single agents and two-drug combinations. Results: Among the Gram-negative BSI strains analyzed, meropenem monotherapy demonstrated the highest efficacy (median 95.4%). In contrast, piperacillin/tazobactam and cefepime showed lower efficacy (80.3% and 81.8%, respectively). On the contrary, combination therapy, particularly with amikacin, significantly increased the efficacy of beta-lactams, elevating their effectiveness to a level comparable to meropenem. Conclusions: The developed script is a valuable tool for antimicrobial stewardship programs, offering a rapid and accessible method to validate international guidelines against local epidemiological data. While meropenem shows high efficacy, its broad use should be limited to prevent resistance. The combination of piperacillin–tazobactam and amikacin is identified as a robust and effective empirical treatment choice. Full article

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

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15 pages, 2750 KB

Open AccessArticle

Prospective Study of the Relative Abundance of Antimicrobial Resistance Genes in Escherichia coli O157:H7 Obtained from Chicken Carcasses from Local Markets in Lima, Peru

by Daniel Desposorio-Vicente and Oscar Nolasco

Antibiotics 2026, 15(2), 191; https://doi.org/10.3390/antibiotics15020191 - 9 Feb 2026

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Abstract

Objective: This study addresses antimicrobial resistance (AMR), a growing public health threat, by evaluating the role of chicken carcasses as possible vehicle for the spread of Escherichia coli O157:H7 and antimicrobial resistance genes (ARGs), with the aim of analyzing the association between bacterial [...] Read more.

Objective: This study addresses antimicrobial resistance (AMR), a growing public health threat, by evaluating the role of chicken carcasses as possible vehicle for the spread of Escherichia coli O157:H7 and antimicrobial resistance genes (ARGs), with the aim of analyzing the association between bacterial load and the relative abundance of ARGs in samples obtained from an open and an enclosed market in Lima, Peru. Methods: SYBR Green qPCR was used to analyze 28 chicken carcasses from two local markets in the Lima metropolitan area (Enclosed market n = 13, and Open Market n = 15), detecting Escherichia coli O157:H7 and ARGs like bla_CTX-M, bla_TEM, and strA. Results: The bacterial load was higher in the enclosed market (5.062 log CFU/mL) than in the open market (3.875 log CFU/mL). E. coli O157:H7 was detected in 76.9% and 86.6% of samples, with average loads of 1.676 and 1.251 log CFU/mL, respectively. The relative abundance of bla_CTX-M and bla_TEM showed greater dispersion in the open market, whereas strA was more homogeneous in both markets. Significant positive correlation was found between E. coli load and ARGs abundance, stronger in the enclosed market (r = 0.904–0.945) and moderate to high in the open market (r = 0.794–0.920). Conclusions: The results demonstrate a significant correlation between E. coli O157:H7 load and ARGs, highlighting the need for a comprehensive approach within the framework of the “OneHealth” initiative. Full article

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

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16 pages, 1305 KB

Open AccessSystematic Review

Ceftolozane/Tazobactam for Complex and Resistant Infections: Systematic Reviews of Comparative Efficacy Studies

by Ignacio Martin-Loeches, Ryan K. Shields, Emre Yücel, Shalini Bagga, Maesumeh Korei, Hariprasad Esam, Nidhi Sharma and Carolyn Cameron

Antibiotics 2026, 15(2), 190; https://doi.org/10.3390/antibiotics15020190 - 9 Feb 2026

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Abstract

Introduction: The emergence and spread of multidrug-resistant infections has resulted in significant clinical and economic burdens. To address these infections, novel therapy combinations are needed. Ceftolozane/tazobactam is a treatment option that targets multidrug-resistant pathogens and may offer improved patient outcomes compared to traditional [...] Read more.

Introduction: The emergence and spread of multidrug-resistant infections has resulted in significant clinical and economic burdens. To address these infections, novel therapy combinations are needed. Ceftolozane/tazobactam is a treatment option that targets multidrug-resistant pathogens and may offer improved patient outcomes compared to traditional antibiotics that are now often ineffective. Objectives: Our objective was to collate findings from comparative efficacy studies to assess the efficacy of ceftolozane/tazobactam for the indications of complex intra-abdominal infection, complex urinary tract infection, ventilated hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia. Methods: Two systematic literature reviews were conducted, including randomized controlled trials comparing ceftolozane/tazobactam with other interventions for complex intra-abdominal infection, complex urinary tract infection, ventilated hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia indications. The outcomes of interest were mortality, clinical cure and microbiological eradication. Results: Ceftolozane/tazobactam was determined to be non-inferior to comparators for all outcomes of interest. All-cause mortality for ceftolozane/tazobactam displayed non-inferiority to meropenem, with the largest numerical differences in all-cause mortality displayed in susceptible patients, such as those with severe renal impairment. Similarly, the clinical cure and microbiological eradication for ceftolozane/tazobactam demonstrated non-inferiority compared to meropenem or levofloxacin. Conclusions: These reviews support the role of ceftolozane/tazobactam as an alternative option, particularly when MDR pathogens are suspected or documented. Their findings may contribute to the standardization of treatment guidelines, ultimately helping to reduce the clinical and economic burdens associated with these infections. Full article

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12 pages, 1263 KB

Open AccessArticle

Clinical Relevance of Antimicrobial Susceptibility Testing Methods in Carbapenem-Resistant Acinetobacter baumannii Pneumonia: A Secondary Analysis of a Randomized Controlled Trial

by Chutchawan Ungthammakhun, Vasin Vasikasin, Nadia Cheh-Oh, Wichai Santimaleeworagun and Dhitiwat Changpradub

Antibiotics 2026, 15(2), 189; https://doi.org/10.3390/antibiotics15020189 - 9 Feb 2026

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Abstract

Background/Objective: Carbapenem-resistant Acinetobacter baumannii (CRAB) pneumonia has limited treatment options, and sulbactam MIC interpretation varies with the antimicrobial susceptibility testing (AST) method. This study compared sulbactam MICs determined using broth microdilution (BMD) and the E-test and examined their associations with 28-day mortality. [...] Read more.

Background/Objective: Carbapenem-resistant Acinetobacter baumannii (CRAB) pneumonia has limited treatment options, and sulbactam MIC interpretation varies with the antimicrobial susceptibility testing (AST) method. This study compared sulbactam MICs determined using broth microdilution (BMD) and the E-test and examined their associations with 28-day mortality. Methods: This secondary analysis used data from a randomized controlled trial comparing colistin plus sulbactam at 9 g/day versus 12 g/day in adults with CRAB pneumonia. The sulbactam MICs of 134 isolates were determined using BMD and the E-test. The agreement between methods across MIC ranges and associations between MICs, dosing, and 28-day mortality were analyzed. Results: Sulbactam MICs determined using BMD were lower than those obtained with the E-test (MIC50/90: 32/128 µg/mL vs. 96/≥256 µg/mL). Overall, agreement between methods was limited and depended on MIC level, with better agreement at lower MICs and marked discrepancies at higher MICs, where the E-test frequently overestimated the MICs. Using the IDSA breakpoint (MIC ≤ 4 µg/mL), susceptibility was identified in 6% of isolates with BMD and 3% with the E-test. A significant survival benefit with high-dose sulbactam (12 g/day) was observed in patients with BMD-determined MICs ≥ 128 µg/mL (HR 0.27; 95% CI, 0.077–0.956; p = 0.042), whereas no mortality association was seen when MICs were categorized using the E-test results. Conclusions: AST method selection substantially affects sulbactam MIC interpretation in CRAB pneumonia. BMD shows stronger correlation with clinical outcomes than the E-test, particularly at high MIC levels. High-dose sulbactam may benefit patients with highly resistant isolates, underscoring the need for accurate and standardized AST methods. Full article

(This article belongs to the Special Issue Multidrug-Resistant Gram-Negative Bacteria Infections: Current Epidemiology, Prognosis and Treatment Options)

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20 pages, 5843 KB

Open AccessArticle

Zinc-Driven Antibiotic Resistance Gene Dynamics During Vermicomposting: Insights into Co-Contamination Mitigation for Sustainable Manure Management

by Naiyu Wang, Shimei Zheng, Yuanye Zeng and Fengxia Yang

Antibiotics 2026, 15(2), 188; https://doi.org/10.3390/antibiotics15020188 - 9 Feb 2026

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Abstract

Background: The coexistence of antibiotic resistance genes (ARGs) and heavy metals in livestock manure poses critical challenges to vermicomposting technology. Objectives: This study aimed to clarify the zinc (Zn)-driven ARG dynamics over 60-day vermicomposting for livestock manure and provide a reference for taking [...] Read more.

Background: The coexistence of antibiotic resistance genes (ARGs) and heavy metals in livestock manure poses critical challenges to vermicomposting technology. Objectives: This study aimed to clarify the zinc (Zn)-driven ARG dynamics over 60-day vermicomposting for livestock manure and provide a reference for taking appropriate measures to reduce the spread of ARGs in the environment. Methods: In a vermicomposting system using Eisenia fetida and treated with varying concentrations of Zn, high-throughput sequencing was employed to analyze microbial succession, while quantitative real-time PCR (qPCR) was performed to track the fluctuation patterns of ARG (tet-, erm-, qnr-, str-, chl-, bla-, mcr-ARGs) and mobile genetic element (MGE, intI1 and intI2) abundances over the 60-day treatment period. Results: Generally, sul- (10⁻³–10⁻¹ copies/16S rRNA), tet- (10⁻³–10⁻² copies/16S rRNA), and str-ARGs (10⁻³–10⁻² copies/16S rRNA) are dominant in dairy manure. Vermicomposting significantly reduced total ARGs (88.62% removal), but Zn stress triggered concentration-dependent shifts. Low Zn (100–250 mg/kg) elevated tet-, erm-, and chl-ARGs via co-selective pressure and disrupted bacterial succession, while high Zn (500–1000 mg/kg) suppressed qnr- and mcr-ARGs but intensified horizontal transfer via cross-resistance. Conclusions: Vermicomposting maintained a greater ARG removal capacity across the Zn gradient (100–1000 mg/kg) than natural composting, proving an effective approach for reducing the threat of antibiotic resistance in bacteria even under high Zn stress. The link between Zn residues and the increased ARG dissemination risks underscores the challenge of co-contaminants, providing essential insights for developing vermicomposting strategies to mitigate ARG risks and ensure sustainable manure management. Full article

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

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11 pages, 994 KB

Open AccessArticle

The Association Between Antibiotic Use and the Incidence of Third-Generation Cephalosporin-Resistance in Escherichia coli Bloodstream Infections: An Ecological Study

by Adi Cohen, Elizabeth Temkin, Mitchell J. Schwaber, Yehuda Carmeli and BSI Working Group

Antibiotics 2026, 15(2), 187; https://doi.org/10.3390/antibiotics15020187 - 9 Feb 2026

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Abstract

Background/Objectives: The COVID-19 period was marked by changes in antibiotic use and in the incidence of bacterial infections. We examined the association between antibiotic use and the proportion of Escherichia coli bloodstream infections (BSI) that were third-generation cephalosporin-resistant (3GC-R), using the COVID-19 [...] Read more.

Background/Objectives: The COVID-19 period was marked by changes in antibiotic use and in the incidence of bacterial infections. We examined the association between antibiotic use and the proportion of Escherichia coli bloodstream infections (BSI) that were third-generation cephalosporin-resistant (3GC-R), using the COVID-19 period as a natural experiment. Methods: Data for this ecological study came from Israeli national surveillance systems for BSI and antibiotic consumption in 2015–2023. We performed interrupted time series analyses with a 1-year lag to examine the impact of COVID-19 on the proportion of E. coli BSI that were 3GC-R. We used linear regression to test the association between antibiotic use and 3GC resistance. Results: The majority of national antibiotic use was in outpatient settings; it was stable between 2015–2019, dropped by 19.4% in 2020, then increased gradually, but in 2023 remained 10.8% lower than before the pandemic. Incidence of E. coli BSI per 100,000 population increased from 62.6 in 2015 to a peak of 66.0 in 2019, with a small, non-significant change in the proportion of E. coli BSI that were 3GC-R (0.339 in 2015 vs. 0.335 in 2020). In 2020, the incidence of both 3GC-susceptible and 3GC-R E. coli BSI decreased. In 2021, only 3GC-R BSI declined, resulting in the proportion resistant dropping significantly by 0.05 (95% CI: 0.03–0.07). Post-pandemic, BSI incidence rose but remained below the 2019 rate. The proportion resistant after 2021 rose by 0.02 per year relative to the pre-COVID slope (95% CI: 0.02–0.03), such that it was higher in 2023 (0.341) than in 2019 and 2015. There was a significant positive linear relationship between antibiotic use and resistance: the proportion of E. coli BSI that were 3GC-R increased by 0.02 for each increase of one defined daily dose of antibiotic per person (95% CI: 0.001–0.03). Conclusions: Reduced outpatient antibiotic use during COVID-19 was followed by a reduction in the proportion of E. coli BSI that were 3GC-R. Full article

(This article belongs to the Special Issue Prevention and Antimicrobial Surveillance of Hospital-Associated Infections)

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14 pages, 992 KB

Open AccessArticle

Culture and Antimicrobial Consumption: Sector- and Class-Specific Differences in Country-Level Associations Across Europe

by Timo J. Lajunen, Esma Gaygısız, Ümmügülsüm Gaygısız and Mark J. M. Sullman

Antibiotics 2026, 15(2), 186; https://doi.org/10.3390/antibiotics15020186 - 8 Feb 2026

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Abstract

Background: Antimicrobial consumption (AMC) varies widely across European countries, and cross-national studies have linked this variation to cultural values. However, two critical gaps remain: it is unclear whether these associations differ between community and hospital sectors or across antimicrobial classes. This study directly [...] Read more.

Background: Antimicrobial consumption (AMC) varies widely across European countries, and cross-national studies have linked this variation to cultural values. However, two critical gaps remain: it is unclear whether these associations differ between community and hospital sectors or across antimicrobial classes. This study directly tests these differences. Methods: We analysed country-level AMC data from the European Centre for Disease Prevention and Control for EU/EEA countries, combining sector-specific (community, hospital) and Anatomical Therapeutic Chemical (ATC) group-specific data. Spearman’s rank correlation coefficients (ρ) were calculated between Hofstede’s cultural dimensions and AMC. We compared correlations across sectors within ATC groups, and between community antibacterials for systemic use (J01) and other community medicine classes, using differences in correlations (Δρ). Uncertainty was assessed with non-parametric bootstrap 95% confidence intervals and paired-label permutation tests, with false discovery rate control. Sensitivity analyses included leave-one-country-out checks and replication using Kendall’s τ-b. Results: Cultural values, especially Power Distance Index (PDI) and Uncertainty Avoidance Index (UAI), were more strongly associated with community antibiotic use than with hospital antibiotic use or other community medicine groups. PDI and UAI showed significantly stronger correlations with community J01 use than with hospital J01 use and with several other community ATC groups. These patterns were robust in sensitivity analyses. Conclusions: The national cultural context appears more closely related to community antibiotic use than to hospital use or other community medicines, particularly for PDI and UAI. This demonstrates that cultural drivers of AMC are context-specific, necessitating stewardship strategies tailored to community settings to address norms around hierarchy and uncertainty. Full article

(This article belongs to the Special Issue Antibiotic Use and Stewardship in Settings Outside of Acute Hospitals)

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31 pages, 1283 KB

Open AccessReview

Recent Advances in the Development of Selected Triterpenoid-Based Hybrid Molecules and Their Antimicrobial Activities: A Review

by Lihle Mdleleni, Pamela Rungqu and Tobeka Naki

Antibiotics 2026, 15(2), 185; https://doi.org/10.3390/antibiotics15020185 - 8 Feb 2026

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Abstract

Triterpenoids are a diverse class of naturally occurring compounds with a wide range of pharmacological properties, including anticancer, anti-inflammatory, antimicrobial, and antiviral activities. Among them, ursolic acid (UA), oleanolic acid (OA), and betulinic acid (BA) have emerged as key scaffolds due to their [...] Read more.

Triterpenoids are a diverse class of naturally occurring compounds with a wide range of pharmacological properties, including anticancer, anti-inflammatory, antimicrobial, and antiviral activities. Among them, ursolic acid (UA), oleanolic acid (OA), and betulinic acid (BA) have emerged as key scaffolds due to their broad therapeutic potential and structural versatility. However, the clinical application of these compounds is often limited by issues such as poor solubility, bioavailability, and selectivity. To address these challenges, research conducted between 2015 and 2025 increasingly focused on the development of triterpenoid-based hybrid molecules, in which the triterpenoid scaffolds are chemically linked to other bioactive pharmacophores. This approach aims to enhance therapeutic efficacy through synergistic action, improved pharmacokinetics, and multitarget interactions. This comprehensive review explores recent advancements in the design, synthesis, and evaluation of hybrid derivatives of selected triterpenoids, particularly UA, OA, and BA. Emphasis is placed on the structure–activity relationships (SARs), biological evaluations, and mechanisms of action of these hybrid compounds across various disease models. The review also highlights current challenges, research gaps, and future perspectives in the rational development of triterpenoid-based hybrids as potential leading candidates in drug discovery. Full article

(This article belongs to the Special Issue Strategies for the Design of Hybrid-Based Antimicrobial Compounds)

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14 pages, 1971 KB

Open AccessArticle

Knowledge and Attitudes of Community Pharmacists Towards Antibiotic Use and Antimicrobial Resistance in Western Greece

by Maria Sarri, Despoina Gkentzi, Stelios F. Assimakopoulos, Markos Marangos and Maria Lagadinou

Antibiotics 2026, 15(2), 184; https://doi.org/10.3390/antibiotics15020184 - 7 Feb 2026

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Abstract

Background: Antibiotic misuse and overuse remain a critical driver of antimicrobial resistance (AMR), a global health threat associated with increased morbidity, mortality, and healthcare costs. In Greece, where antibiotic consumption and resistance rates are among the highest in Europe, community pharmacists are well-positioned [...] Read more.

Background: Antibiotic misuse and overuse remain a critical driver of antimicrobial resistance (AMR), a global health threat associated with increased morbidity, mortality, and healthcare costs. In Greece, where antibiotic consumption and resistance rates are among the highest in Europe, community pharmacists are well-positioned to contribute to antimicrobial stewardship efforts. Objective: This study aimed to assess the knowledge and attitudes of community pharmacists in Achaia, Western Greece, regarding antibiotic use and AMR, in order to identify knowledge gaps and inform future educational interventions. Methods: A cross-sectional survey was conducted between May and July 2023 among 207 pharmacists using a structured, self-administered questionnaire. The survey assessed demographics, knowledge of antibiotic indications, dispensing practices, and awareness of AMR. Statistical analysis included Chi-square tests and multivariate logistic regression. Results: Pharmacists demonstrated high levels of knowledge regarding appropriate antibiotic use in conditions such as sore throat (95%), bronchitis (76%), influenza (77.5%), and diarrhea (95%). However, knowledge was lower for rhinitis (60%) and sinusitis (56%). Almost all pharmacists (99%) were aware of AMR, and 86% perceived it as a significant public health issue in Greece. Logistic regression showed that pharmacists with 5–10 years of experience were significantly less likely to believe that antibiotics are always effective (OR = 0.08, p = 0.042). Conclusion: Pharmacists in Western Greece are generally well-informed about antibiotic use and AMR, yet misconceptions persist, especially for viral infections. Targeted educational interventions, interprofessional collaboration, and stricter enforcement of prescription regulations are needed to strengthen the role of pharmacists in combating AMR at the community level. Full article

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14 pages, 1872 KB

Open AccessArticle

Emergence of Polymyxin Resistance Driven by a PhoQ Mutation in KPC-2-Producing Klebsiella pneumoniae

by Huijuan Song, Cui Jian, Lu Gong, Ziyong Sun, Zhongju Chen and Yue Wang

Antibiotics 2026, 15(2), 183; https://doi.org/10.3390/antibiotics15020183 - 7 Feb 2026

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Abstract

Background: The emergence of polymyxin-resistant, carbapenem-resistant Klebsiella pneumoniae (CRKP) presents a critical challenge to clinical management. This study aimed to delineate the molecular mechanisms driving the acquisition of polymyxin resistance in CRKP. Methods: We analyzed polymyxin-susceptible and polymyxin-resistant CRKP isolates obtained [...] Read more.

Background: The emergence of polymyxin-resistant, carbapenem-resistant Klebsiella pneumoniae (CRKP) presents a critical challenge to clinical management. This study aimed to delineate the molecular mechanisms driving the acquisition of polymyxin resistance in CRKP. Methods: We analyzed polymyxin-susceptible and polymyxin-resistant CRKP isolates obtained from a single patient. Antimicrobial susceptibility testing was performed to determine the minimum inhibitory concentrations. Whole genome sequencing was employed to identify variations in two-component systems and to screen for mcr genes, which were involved in polymyxin resistance. Differential gene expression was assessed using RNA sequencing and validated by quantitative real-time PCR. Furthermore, site-directed mutagenesis was utilized to confirm the causal role of specific mutations in conferring the resistant phenotype. Results: An L96P mutation in the PhoQ protein was found in the polymyxin-resistant CRKP isolate. Compared with the PhoQ wild-type, this mutation significantly upregulated expression of phoP/Q, pmrD, and arnBCADTEF operon-related genes. A corresponding L96P mutant was subsequently constructed in the polymyxin-susceptible ATCC 13883 strain via site-directed mutagenesis. Antimicrobial susceptibility testing confirmed that the PhoQ L96P mutation elevates the minimal inhibitory concentrations of colistin and polymyxin B to 64 mg/L and >32 mg/L, respectively, from a baseline of 0.5 mg/L. Conclusions: The PhoQ L96P mutation is a pivotal driver of polymyxin resistance in CRKP, primarily mediated through the upregulation of the arnBCADTEF operon. Full article

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

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17 pages, 584 KB

Open AccessArticle

Integrating Syndromic Molecular Assays into Routine Diagnostic Microbiology: Benefits and Challenges

by Sara Comini, Anna Maria Priori, Francesco Coppari, Matteo Sabbatini, Concetta Bruno, Matteo Boattini, Gabriele Bianco and Francesca Brecciaroli

Antibiotics 2026, 15(2), 182; https://doi.org/10.3390/antibiotics15020182 - 7 Feb 2026

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Abstract

Background/Objectives: Rapid pathogen identification is essential to optimize antimicrobial therapy and improve patient outcomes, particularly in severe infections. Syndromic molecular diagnostics have been introduced to overcome the limitations of conventional culture-based methods. This study evaluated the diagnostic performance and real-life implementation of [...] Read more.

Background/Objectives: Rapid pathogen identification is essential to optimize antimicrobial therapy and improve patient outcomes, particularly in severe infections. Syndromic molecular diagnostics have been introduced to overcome the limitations of conventional culture-based methods. This study evaluated the diagnostic performance and real-life implementation of BioFire^® FilmArray^® syndromic panels compared with routine microbiological diagnostics. Methods: A total of 955 clinical specimens collected between 2022 and June 2025 were retrospectively analyzed, including positive blood cultures (n = 400), lower respiratory tract samples (n = 309), cerebrospinal fluid (n = 158) and stool specimens (n = 88). FilmArray^® BCID2, Pneumonia Plus, Meningitis/Encephalitis and Gastrointestinal panels were performed on the Biofire Fimarray^® instrument according to clinical indication and compared with conventional culture-based identification and phenotypic antimicrobial susceptibility testing. Results: Overall diagnostic concordance between BioFire^® FilmArray^® syndromic panels and conventional methods was high across all specimen types, with the highest positive percent agreement (PPA) observed for bloodstream infections (97.7%) and gastrointestinal pathogens (100%). In respiratory samples, the Pneumonia Plus panel detected a considerable number of microorganisms that could not be identified by culture, including viral pathogens and fastidious bacteria. Molecular detection of antimicrobial resistance markers showed excellent concordance with phenotypic profiles, with 100% agreement for CTX-M, carbapenemases (KPC, NDM, OXA-48-like, IMP), and vanA/B, while lower concordance was observed for mecA/C in staphylococci. In parallel, semi-quantitative bacterial loads provided by the Pneumonia Plus panel showed a strong essential agreement with culture-based quantification (97.4%, ±1 log₁₀). Across all panels, syndromic testing significantly reduced diagnostic turnaround time. Conclusions: Syndromic molecular panels provide rapid and reliable simultaneous detection of pathogens, as well as early resistance marker detection, thereby supporting timely antimicrobial optimization and stewardship when integrated with conventional microbiological diagnostics. Full article

(This article belongs to the Special Issue Bacterial Detection, Identification, and Antimicrobial Susceptibility Testing)

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Open AccessArticle

Unbound and Periprostatic Adipose Tissue Cefazolin Pharmacokinetics in Robotic-Assisted Radical Prostatectomy

by Toshiaki Komatsu, Yuki Takahashi, Yoko Takayama, Yuto Akamada, Masaomi Ikeda, Hideyasu Tsumura, Daisuke Ishii, Kazumasa Matsumoto, Masatsugu Iwamura, Hirotsugu Okamoto, Hideaki Hanaki and Katsuya Otori

Antibiotics 2026, 15(2), 181; https://doi.org/10.3390/antibiotics15020181 - 6 Feb 2026

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Abstract

Background/Objectives: This study aimed to describe the population pharmacokinetics of cefazolin (CFZ) using unbound serum and periprostatic adipose tissue concentrations and to optimize dosing regimens for patients undergoing robotic-assisted radical prostatectomy (RARP). Methods: We investigated the population pharmacokinetics of CFZ using 295 unbound [...] Read more.

Background/Objectives: This study aimed to describe the population pharmacokinetics of cefazolin (CFZ) using unbound serum and periprostatic adipose tissue concentrations and to optimize dosing regimens for patients undergoing robotic-assisted radical prostatectomy (RARP). Methods: We investigated the population pharmacokinetics of CFZ using 295 unbound serum and 67 periprostatic adipose tissue samples from 67 individuals. CFZ concentrations were determined in all samples. A nonlinear mixed-effects model was developed. The pharmacodynamic target was defined as maintaining unbound trough and periprostatic adipose tissue concentrations exceeding the minimum inhibitory concentration (MIC) against methicillin-susceptible Staphylococcus aureus (MSSA) for over 90% of the dosing interval (MIC₉₀; 0.5 mg/L). Results: Systemic clearance of unbound CFZ was significantly associated with creatinine clearance (CLcr). In patients with normal renal function, simulations showed that a 1 g CFZ infusion over 15 min maintained unbound concentrations exceeding the MSSA MIC₉₀ for >90% of the 3 h interval after the initial dose. Notably, in patients with mild renal impairment (CLcr ≤ 80 mL/min), a 5 h dosing interval also achieved a >90% probability of maintaining the target CFZ concentration. Conclusions: The simulations demonstrated that the probability of target attainment of >90% was maintained for up to 5 h in patients with mild renal impairment (CLcr ≤ 80 mL/min). These findings provide a pharmacokinetic rationale suggesting that the standard additional dose may not be necessary for this subgroup; however, future clinical studies are needed to validate safety and efficacy. Full article

(This article belongs to the Special Issue Clinical Pharmacokinetics, Pharmacodynamics, and/or TDM of Antimicrobial Agents)

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Antibiotics, Volume 15, Issue 2 (February 2026) – 99 articles

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