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Antibiotics
Volume 14
Issue 7
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Antibiotics, Volume 14, Issue 7 (July 2025) – 110 articles

Cover Story (view full-size image): Platelet concentrates (PCs), used to treat patients with bleeding disorders, are stored at 20–24 °C to maintaining platelet functionality. These conditions also sustain the growth of bacteria such as Staphylococcus aureus, which poses an important safety risk to transfusion patients as it reaches clinically significant levels and produces virulence factors during PC storage. Previous studies have demonstrated that Staphylococcus spp. grown in PCs display upregulation of genes encoding for antimicrobial resistance and virulence. To expand the current knowledge, this study aimed to test whether the increase in the norB efflux pump expression observed in PCs translates into heightened quinolone resistance. Furthermore, the role of the NorB efflux pump on S. aureus virulence was investigated using a Bombyx mori (silkworm) animal model. View this paper
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13 pages, 2744 KiB  
Article
Preliminary Evaluation of the Synergistic Antibacterial Effects of Selected Commercial Essential Oil Compounds Against Methicillin-Resistant Staphylococcus aureus ATCC 43300
by Kacper Hartman, Maja Świerczyńska, Amelia Wieczorek, Piotr Baszuk, Iwona Wojciechowska-Koszko, Katarzyna Garbacz, Monika Sienkiewicz and Paweł Kwiatkowski
Antibiotics 2025, 14(7), 733; https://doi.org/10.3390/antibiotics14070733 - 21 Jul 2025
Viewed by 858
Abstract
Background/Objectives: Growing antibiotic resistance is one of the most significant problems of current medicine. Various research efforts are focused on the search for new substances and their combinations as potential solutions to this problem. Essential oil compounds (EOCs) are considered promising candidates [...] Read more.
Background/Objectives: Growing antibiotic resistance is one of the most significant problems of current medicine. Various research efforts are focused on the search for new substances and their combinations as potential solutions to this problem. Essential oil compounds (EOCs) are considered promising candidates in this regard. However, the interactions between these natural compounds remain understudied. This study conducted a preliminary evaluation of the antimicrobial action of various commercial EOCs (1,8-cineole, eugenol, linalyl acetate, (-)-α-pinene, limonene, α-terpineol, DL-menthol, geraniol, farnesol, carvacrol, and myrcene) alone and in combination (n = 56) against methicillin-resistant Staphylococcus aureus strain (ATCC 43300). Methods: The following parameters were studied: antibacterial activity of EOCs alone and in combination using microdilution and checkerboard assays. Results: After the initial screening, geraniol, farnesol, linalyl acetate, carvacrol, (−)-α-pinene, α-terpineol, 1,8-cineole, and eugenol exhibited antibacterial activity against the tested strain and were, therefore, selected for further evaluation in the checkerboard assay. The checkerboard assay revealed 10 synergistic interactions, with farnesol demonstrating the highest number of synergistic combinations among the tested compounds. The results highlighted its high synergistic potential in combination with eugenol, linalyl acetate, (-)-α-pinene, α-terpineol, geraniol, and carvacrol. Conclusions: In conclusion, the results help elucidate the different interactions between EOCs and may be helpful in further applications of natural compounds as antimicrobial agents in wound dressings. Overall, the most promising compound was found to be farnesol. Full article
(This article belongs to the Section Mechanism and Evolution of Antibiotic Resistance)
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16 pages, 673 KiB  
Article
Genotypic and Phenotypic Methods in the Detection of MDR-TB and Evolution to XDR-TB
by Natalia Zaporojan, Ramona Hodișan, Carmen Pantiș, Andrei Nicolae Csep, Claudiu Zaporojan and Dana Carmen Zaha
Antibiotics 2025, 14(7), 732; https://doi.org/10.3390/antibiotics14070732 - 21 Jul 2025
Viewed by 435
Abstract
Background: Accurate and rapid diagnosis of drug-resistant tuberculosis is essential for initiating appropriate treatment and preventing the transmission of these strains. This study compares phenotypic and genotypic methods of drug susceptibility testing for Mycobacterium tuberculosis (M. tuberculosis). Methods: Resistance to [...] Read more.
Background: Accurate and rapid diagnosis of drug-resistant tuberculosis is essential for initiating appropriate treatment and preventing the transmission of these strains. This study compares phenotypic and genotypic methods of drug susceptibility testing for Mycobacterium tuberculosis (M. tuberculosis). Methods: Resistance to first-line drugs, as well as resistance to second-line drugs (fluoroquinolones and aminoglycosides), was assessed using the Löwenstein–Jensen medium phenotypic method and the GenoType MTBDRplus genotypic method and analyzed. Results: The phenotypic resistance rate was 84.85% for INH (n = 56), 46.97% for RIF (n = 31), 48.48% for STR (n = 32), and 30.30% for EMB (n = 20). Of the MDR-TB isolates (n = 29), 41.37% were resistant to fluoroquinolones (n = 12) and 31.03% were resistant to both fluoroquinolones and injectable aminoglycosides, being classified as XDR-TB (n = 9). In addition, 22.73% of the MDR-TB isolates were resistant to all four first-line drugs (n = 15). The overall concordance between the line probe assay method and phenotypic testing was 94.74% for RIF and 95.16% for INH. Discordances were identified in three cases for RIF and two cases for INH, where isolates were reported as susceptible by GenoType MTBDRplus, but phenotypically resistant. Conclusions: Genotypic testing using GenoType MTBDRplus provides rapid and accurate results, but some cases of phenotypic resistance are not detected by this method. The results highlight the importance of using combined phenotypic and genotypic methods for accurate diagnosis of MDR-TB, as well as the need to integrate genomic sequencing to improve diagnostic accuracy. Full article
(This article belongs to the Special Issue Epidemiological Data on Antibiotic Resistance)
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17 pages, 2176 KiB  
Article
Growth-Phase-Dependent Modulation of Quorum Sensing and Virulence Factors in Pseudomonas aeruginosa ATCC 27853 by Sub-MICs of Antibiotics
by Ahmed Noby Amer, Nancy Attia, Daniel Baecker, Rasha Emad Mansour and Ingy El-Soudany
Antibiotics 2025, 14(7), 731; https://doi.org/10.3390/antibiotics14070731 - 21 Jul 2025
Viewed by 634
Abstract
Background: Antibiotics at sub-inhibitory concentrations can rewire bacterial regulatory networks, impacting virulence. Objective: The way that exposure to selected antibiotics (ciprofloxacin, amikacin, azithromycin, ceftazidime, and meropenem) below their minimum inhibitory concentration (sub-MIC) modulates the physiology of Pseudomonas aeruginosa is examined in [...] Read more.
Background: Antibiotics at sub-inhibitory concentrations can rewire bacterial regulatory networks, impacting virulence. Objective: The way that exposure to selected antibiotics (ciprofloxacin, amikacin, azithromycin, ceftazidime, and meropenem) below their minimum inhibitory concentration (sub-MIC) modulates the physiology of Pseudomonas aeruginosa is examined in this study using growth-phase-resolved analysis. Methods: Standard P. aeruginosa strain cultures were exposed to ¼ and ½ MIC to determine the growth kinetics under antibiotic stress. The study measured protease and pyocyanin production and the expression level of important quorum sensing and virulence genes (lasI/R, rhlI/R, pqsR/A, and phzA) at different growth phases. Results: Meropenem produced the most noticeable growth suppression at ½ MIC. Sub-MIC antibiotics did not completely stop growth, but caused distinct, dose-dependent changes. Azithromycin eliminated protease activity in all phases and had a biphasic effect on pyocyanin. Ciprofloxacin consistently inhibited both pyocyanin and protease in all phases. The effects of amikacin varied by phase and dose, while β-lactams markedly increased pyocyanin production during the log phase. In contrast to the plateau phase, when expression was often downregulated or unchanged, most quorum-sensing- and virulence-associated genes showed significant upregulation during the death phase under sub-MIC exposure. Conclusions: These findings indicate that sub-MIC antibiotics act as biochemical signal modulators, preserving stress-adapted sub-populations that, in late growth phases, activate quorum sensing and stress tolerance pathways. Full article
(This article belongs to the Special Issue Advancing and Standardising Antimicrobial Susceptibility and Resistance Detection Methodology)
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11 pages, 1036 KiB  
Article
The Re-Emergence of Pediatric Pertussis: Insights from a Regional Romanian Hospital
by Ioana Rosca, Alina Turenschi, Alexandru Dinulescu and Victoria Lichii
Antibiotics 2025, 14(7), 730; https://doi.org/10.3390/antibiotics14070730 - 21 Jul 2025
Viewed by 475
Abstract
Introduction: Pertussis, a vaccine-preventable disease caused by Bordetella pertussis, is resurging globally due to declining immunization rates. This study explores the clinical and epidemiological features of pediatric pertussis cases in a regional Romanian hospital amid growing vaccine hesitancy. Methods: We conducted a retrospective [...] Read more.
Introduction: Pertussis, a vaccine-preventable disease caused by Bordetella pertussis, is resurging globally due to declining immunization rates. This study explores the clinical and epidemiological features of pediatric pertussis cases in a regional Romanian hospital amid growing vaccine hesitancy. Methods: We conducted a retrospective cohort study on 99 children diagnosed with pertussis and admitted to Ploiești Pediatric Hospital between January 2024 and January 2025. Demographic, clinical, laboratory, and radiological data were analyzed using SPSS 25.0. Results: The median age was 11 months (IQR 4–25), with 12.1% under two months, and ineligible for the first DTaP dose. Notably, 72.7% of children were unvaccinated; 59.4% had missed scheduled doses. None of the mothers received the DTaP vaccination during pregnancy. Most cases (55.6%) had bilaterally accentuated interstitial patterns on chest X-ray, significantly associated with vaccination status (p = 0.019). The leukocyte count was higher in children with alveolar infiltrates (p = 0.028), and as the number of vaccine doses increased, the leukocyte count tended to slightly decrease (p = 0.022, R = −0.229). PCR confirmation was obtained after a mean of 2.2 days, with 12.1% of cases confirmed post-discharge. Azithromycin was used in 74.7% of cases, with good tolerability. Conclusions: Low pediatric and maternal vaccine uptake was a major contributor to pertussis resurgence in this cohort. Radiological severity correlated with vaccination status, suggesting that vaccination may confer protection not only against infection but also against severe pulmonary involvement. These findings support urgent public health efforts to restore vaccine confidence and coverage, particularly among vulnerable infant populations and expectant mothers. Full article
(This article belongs to the Special Issue Epidemiology, Clinical Microbiology and Antimicrobial Therapy: A Shared Effort against Infectious Diseases)
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20 pages, 6178 KiB  
Article
Time Evolution of Bacterial Resistance Observed with Principal Component Analysis
by Claudia P. Barrera Patiño, Mitchell Bonner, Andrew Ramos Borsatto, Jennifer M. Soares, Kate C. Blanco and Vanderlei S. Bagnato
Antibiotics 2025, 14(7), 729; https://doi.org/10.3390/antibiotics14070729 - 20 Jul 2025
Cited by 1 | Viewed by 542
Abstract
Background/Objectives: In recent work, we have demonstrated that principal component analysis (PCA) and Fourier Transformation Infrared (FTIR) spectra are powerful tools for analyzing the changes in microorganisms at the biomolecular level to detect changes in bacteria with resistance to antibiotics. Here biochemical [...] Read more.
Background/Objectives: In recent work, we have demonstrated that principal component analysis (PCA) and Fourier Transformation Infrared (FTIR) spectra are powerful tools for analyzing the changes in microorganisms at the biomolecular level to detect changes in bacteria with resistance to antibiotics. Here biochemical structural changes in Staphylococcus aureus were analyzed over exposure time with the goal of identifying trends inside the samples that have been exposed to antibiotics for increasing amounts of time and developed resistance. Methods: All studied data was obtained from FTIR spectra of samples with induced antibiotic resistance to either Azithromycin, Oxacillin, or Trimethoprim/Sulfamethoxazole following the evolution of this development over four increasing antibiotic exposure periods. Results: The processing and data analysis with machine learning algorithms performed on this FTIR spectral database allowed for the identification of patterns across minimum inhibitory concentration (MIC) values associated with different exposure times and both clusters from hierarchical classification and PCA. Conclusions: The results enable the observation of resistance development pathways for the sake of knowing the present stage of resistance of a bacterial sample. This is carried out via machine learning methods for the purpose of faster and more effective infection treatment in healthcare settings. Full article
(This article belongs to the Section Mechanism and Evolution of Antibiotic Resistance)
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30 pages, 874 KiB  
Review
Liposome-Encapsulated Antibiotics for the Therapy of Mycobacterial Infections
by Metin Yıldırım and Nejat Düzgüneş
Antibiotics 2025, 14(7), 728; https://doi.org/10.3390/antibiotics14070728 - 20 Jul 2025
Viewed by 704
Abstract
About a quarter of the world’s population is infected with Mycobacterium tuberculosis. Growing antibiotic resistance by this microorganism is a major problem in the therapy of the disease. M. avium-M. intracellulare that emerged as a major opportunistic infection of HIV/AIDS continues to [...] Read more.
About a quarter of the world’s population is infected with Mycobacterium tuberculosis. Growing antibiotic resistance by this microorganism is a major problem in the therapy of the disease. M. avium-M. intracellulare that emerged as a major opportunistic infection of HIV/AIDS continues to afflict immunocompromised individuals. We describe the use of liposome-encapsulated antibiotics in the experimental and clinical therapy of mycobacterial infections, as well as recent experimental liposomal vaccines against tuberculosis. Liposome-mediated intravenous or inhalational delivery of antibiotics enhances the antibacterial effects of the drugs, particularly for infections of resident macrophages, where the liposomes are passively targeted. Despite experimental successes of liposomal antibiotics in the treatment of mycobacterial and other bacterial infections, applications of this method to the clinic have been lagging. This review underscores the significance of liposomes in the treatment of mycobacterial infections, encompassing their synthesis methods, limitations, and both preclinical and clinical studies, providing guidance for the development of future therapeutic approaches and innovative antimicrobial strategies. Full article
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18 pages, 586 KiB  
Review
The Changing Landscape of Antibiotic Treatment: Reevaluating Treatment Length in the Age of New Agents
by Francesca Serapide, Salvatore Rotundo, Luca Gallelli, Caterina Palleria, Manuela Colosimo, Sara Palma Gullì, Gianmarco Marcianò and Alessandro Russo
Antibiotics 2025, 14(7), 727; https://doi.org/10.3390/antibiotics14070727 - 20 Jul 2025
Viewed by 649
Abstract
Background: The landscape of antimicrobial therapy is undergoing a profound transformation; the contemporary arsenal of antimicrobials, particularly those with extended half-lives and enhanced tissue penetration, necessitates critically reassessing these traditional paradigms. The growing emphasis on antimicrobial stewardship programs has underscored the importance of [...] Read more.
Background: The landscape of antimicrobial therapy is undergoing a profound transformation; the contemporary arsenal of antimicrobials, particularly those with extended half-lives and enhanced tissue penetration, necessitates critically reassessing these traditional paradigms. The growing emphasis on antimicrobial stewardship programs has underscored the importance of optimizing antimicrobial agents to minimize the development and spread of resistance. Shorter treatment durations, when clinically appropriate, represent a key strategy in this endeavor. Methods: This narrative review provides a comprehensive synthesis of current evidence on the duration of antimicrobial therapy, with a particular focus on the clinical and pharmacological implications of novel agents, including long-acting formulations. Results: We critically examine the pharmacokinetic and pharmacodynamic properties of these agents, evaluate the opportunities and limitations associated with treatment shortening strategies, and underscore the pivotal role of antimicrobial stewardship in optimizing therapeutic outcomes within an increasingly complex and evolving landscape. Conclusions: The future of antimicrobial therapy lies in a personalized approach, where treatment decisions are tailored to the individual patient, but detailed clinical trials are necessary to evaluate these approaches. Full article
(This article belongs to the Special Issue Antimicrobial Resistance and Epidemiological Study of Clinically Relevant Pathogens)
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16 pages, 694 KiB  
Article
Direct Disk Diffusion Testing and Antimicrobial Stewardship for Gram-Negative Bacteremia in the Context of High Multidrug Resistance
by Wantin Sribenjalux, Pawarit Kulwongroj, Waewta Kuwatjanakul, Lumyai Wonglakorn, Kanuengnit Srisak, Natapong Manomaiwong and Atibordee Meesing
Antibiotics 2025, 14(7), 726; https://doi.org/10.3390/antibiotics14070726 - 19 Jul 2025
Viewed by 619
Abstract
Background: Combining direct disk diffusion (DD) testing with antimicrobial stewardship (AMS) may optimize antibiotic use and improve outcomes in patients with Gram-negative bloodstream infections (GNBSIs). Methods: This quasi-experimental study was conducted at Srinagarind Hospital, Khon Kaen University, between 13 September 2022 and 11 [...] Read more.
Background: Combining direct disk diffusion (DD) testing with antimicrobial stewardship (AMS) may optimize antibiotic use and improve outcomes in patients with Gram-negative bloodstream infections (GNBSIs). Methods: This quasi-experimental study was conducted at Srinagarind Hospital, Khon Kaen University, between 13 September 2022 and 11 April 2023. Patients with GNBSIs were enrolled during two phases: a standard care phase (13 September 2022–2 January 2023) and an intervention phase (16 January 2023–11 April 2023), during which therapy adjustments were guided by DD results interpreted by infectious disease specialists. Results: Among the 141 patients included (68 in the standard care group and 73 in the intervention group), the mean age was 61.7 years, and 60.2% were male. Escherichia coli (36.5%) and Klebsiella pneumoniae (27.6%) were the most frequently isolated pathogens, with intra-abdominal and urinary tract infections being the most common sources. Multidrug-resistant (MDR) organisms were identified in 48.9% of cases. Compared to standard care, the intervention group had a significantly shorter median time to optimal therapy (40.0 vs. 59.1 h, p = 0.037) and a higher proportion of patients receiving optimal therapy within 72 h (86.2% vs. 62.3%, p = 0.002). While 30-day mortality did not differ significantly between groups (17.2% vs. 16.7%, p = 0.98), MDR bacteremia and ICU admission were associated with increased mortality. In contrast, receiving optimal therapy within 72 h was associated with reduced mortality. Conclusion: Direct DD testing combined with AMS significantly reduced the time to optimal antibiotic therapy and decreased inappropriate antibiotic use in GNBSI patients. Achieving optimal therapy within 72 h was associated with a trend toward reduced mortality. Full article
(This article belongs to the Section Antibiotics Use and Antimicrobial Stewardship)
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16 pages, 298 KiB  
Article
Antimicrobial-Resistant Staphylococcus spp. Harbored by Hedgehogs (Erinaceus europaeus) in Central Italy
by Fabrizio Bertelloni, Francesca Pauselli, Giulia Cagnoli, Roberto Biscontri, Renato Ceccherelli and Valentina Virginia Ebani
Antibiotics 2025, 14(7), 725; https://doi.org/10.3390/antibiotics14070725 - 18 Jul 2025
Viewed by 423
Abstract
Background/Objectives: European hedgehogs (Erinaceus europaeus) are present in areas where there is human activity; therefore, they can be a source of pathogens for other animals and humans. Methods: Eighteen hedgehog carcasses were collected and analyzed for Staphylococcus spp. Isolated strains were [...] Read more.
Background/Objectives: European hedgehogs (Erinaceus europaeus) are present in areas where there is human activity; therefore, they can be a source of pathogens for other animals and humans. Methods: Eighteen hedgehog carcasses were collected and analyzed for Staphylococcus spp. Isolated strains were typed and analyzed for exfoliative toxins genes and the phenotypic and genotypic characteristics of antimicrobial resistance. Results: A total of 54 strains were isolated and typed as S. aureus, S. xylosus, S. sciuri, S. pseudintermedius, S. simulans, S. chromogenes, S. epidermidis, S. hyicus, and S. lentus. No strains had the eta and etb genes coding for exfoliative toxins. Overall, 39/54 (72.20%) isolates showed phenotypic resistance to at least one antimicrobial and 21/54 (38.80%) showed more than one resistance. The lowest efficacy was observed for erythromycin, with 40/54 (74.08%) strains classified as intermediate and 6/54 (11.11%) classified as resistant. Among the 29 isolates shown to be penicillin-resistant, 11 (37.93%) were oxacillin-resistant, with a minimum inhibitory concentration (MIC). Among the 54 staphylococcal strains, 2 (3.70%) were resistant to vancomycin, both with an MIC value equal to the maximum concentration of the antibiotic tested (256 μg/mL) and 2 (3.70%) had an intermediate resistance profile with an 8 μg/mL MIC value. No strains had the genes vanA and vanB. Two of the 29 (6.90%) penicillin-resistant strains had the blaZ gene; 8 (27.13%) strains had the mecA gene. Overall, 2/54 (3.70%) isolates were classified as extensively drug-resistant (XDR) and 9/54 (16.66%) were classified as multidrug-resistant (MDR). Conclusions: Hedgehogs can harbor antimicrobial-resistant staphylococci and can be sources of these bacteria for other animals and humans. They can also serve as bioindicators of the pathogens and antimicrobial-resistant bacteria circulating in a given habitat. Full article
(This article belongs to the Collection Staphylococcus— Molecular Pathogenesis, Virulence Regulation and Antibiotics Resistance)
14 pages, 1973 KiB  
Article
Exploring the Microbiome of Diabetic Foot Ulcers: A Focus on Cases with a Clinical Worse Outcome
by Laura Soldevila-Boixader, Anna Carrera-Salinas, Isabel Mur, Laura Morata, Alba Rivera, Jordi Bosch, Abelardo Montero-Saez, Jéssica Martínez Castillejo, Natividad Benito, Sara Martí and Oscar Murillo
Antibiotics 2025, 14(7), 724; https://doi.org/10.3390/antibiotics14070724 - 18 Jul 2025
Viewed by 479
Abstract
Background/Objectives: We evaluated the diabetic foot ulcer (DFU) microbiome in clinical situations identified as risk factors for a worse outcome and explored the roles of the most abundant microorganisms. Methods: A prospective multicenter cohort of diabetic patients with DFU were followed [...] Read more.
Background/Objectives: We evaluated the diabetic foot ulcer (DFU) microbiome in clinical situations identified as risk factors for a worse outcome and explored the roles of the most abundant microorganisms. Methods: A prospective multicenter cohort of diabetic patients with DFU were followed up for 6 months. We obtained a DFU tissue biopsy for microbiome analysis at the baseline visit. Genomic DNA was extracted (QIAamp DNA Mini Kit, Qiagen, Hilden, Germany) and quantified (QuantiFluor dsDNA System, Promega, Madison, WI, USA), with analysis of bacterial communities focusing on relative abundances (RA) and on alpha and beta diversity. Results: Overall, 59 DFUs were analyzed. DFUs of long duration (≥4 weeks) presented a higher RA of Gammaproteobacteria compared with ulcers of short duration (p = 0.02). Non-infected DFUs had a higher proportion of Actinobacteriota phyla than infected DFUs and, particularly, a higher RA of Corynebacterium genera (means ± SD: 0.063 ± 0.14 vs. 0.028 ± 0.13, respectively; p = 0.03). Regarding the pathogenic role of Staphylococcus aureus, DFUs with low S. aureus bacterial loads (<106 CFU/mL) compared with those with high loads (≥106 CFU/mL) showed a higher Corynebacterium RA (0.045 ± 0.08 vs. 0.003 ± 0.01, respectively; p = 0.01). Conclusions: In clinical situations associated with poor DFU outcomes, we observed a predominance of Gammaproteobacteria in the microbiome of long-duration ulcers and a higher RA of Corynebacterium in non-infected DFUs. An inverse relationship between the predominance of Corynebacterium and the S. aureus bacterial load in DFUs was also noted, which may suggest these commensals have a modulatory role. Further studies should explore the clinical utility of microbiome analysis for DFUs. Full article
(This article belongs to the Special Issue Bone and Joint Infections: The Challenges of Prevention, Diagnosis and Treatment and Opportunities for Future Research)
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21 pages, 594 KiB  
Article
Trends in Positive Urine Culture Rates and Antimicrobial Resistance in Non-Hospitalized Children from Western Romania: A Retrospective Observational Study
by Constantin Catalin Marc, Maria Daniela Mot, Monica Licker, Delia Muntean, Daniela Teodora Marti, Ana Alexandra Ardelean, Alina Ciceu, Sergiu Adrian Sprintar, Daniela Adriana Oatis, Alin Gabriel Mihu and Tudor Rares Olariu
Antibiotics 2025, 14(7), 723; https://doi.org/10.3390/antibiotics14070723 - 18 Jul 2025
Viewed by 537
Abstract
Background: Urinary tract infections (UTIs) are among the most common types of infections during childhood. Limited data are available on the prevalence of UTI in children from Romania, with most being available for hospitalized children. For this reason, we conducted a retrospective observational [...] Read more.
Background: Urinary tract infections (UTIs) are among the most common types of infections during childhood. Limited data are available on the prevalence of UTI in children from Romania, with most being available for hospitalized children. For this reason, we conducted a retrospective observational study in consecutive non-hospitalized children to assess the number of positive UTI samples and the antibacterial resistance of causative pathogens. Methods: This study included 7222 consecutive urine cultures collected from children aged 1 to 18 years who are residents of Arad County, Western Romania. Urine samples were analyzed for leukocyturia and cultures for the presence of monomorphic bacteria. Results: The overall number of positive UTI samples was 10.44%. A higher number of positive UTI samples was observed in females when compared to males and in children aged 6–12 and 12 to 18 years when compared to those aged 1–5 years. The antibiotic susceptibility testing of E. coli isolates revealed high sensitivity to most tested antibacterials. Near-complete susceptibility was observed for fosfomycin (99.71%) and nitrofurantoin (96.01%), while high susceptibility rates were also observed for ciprofloxacin (85.43%) and amoxicillin–clavulanic acid (75.05%). In contrast, high resistance was found for ampicillin (62.28% resistant) and trimethoprim–sulfamethoxazole (36.53% resistant). Conclusions: Given the clinical risks associated with UTI in children, our findings underscore the urgent need for the continued monitoring of multidrug-resistant strains. Our study provides important epidemiological and resistance data to guide empirical treatment and strengthen pediatric antimicrobial resistance surveillance. Future studies should focus on different regions and regularly update resistance patterns to keep treatment and prevention strategies aligned with local conditions. Full article
(This article belongs to the Special Issue Prevalence, Treatment and Antibacterial Resistance of Urinary Tract Infections)
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9 pages, 234 KiB  
Article
Should Cefoxitin Non-Susceptibility in Ceftriaxone-Susceptible E. coli and K. pneumoniae Prompt Concerns Regarding Plasmid-Mediated AmpC Resistance? A Genomic Characterization and Summary of Treatment Challenges in Singapore
by Jonathan Jinpeng Foo, Ying Ying Ong, Clement Kin Ming Tsui, David C. Lye, De Partha Pratim, Nurhidayah Binte Mohamed Yazid, Swaine L. Chen, Shawn Vasoo and Tat Ming Ng
Antibiotics 2025, 14(7), 722; https://doi.org/10.3390/antibiotics14070722 - 18 Jul 2025
Viewed by 540
Abstract
Objectives: Plasmid-mediated AmpC beta-lactamases represent a growing clinical concern in Enterobacterales, with challenges in diagnostic approaches, limited data on clinical outcomes, and our incomplete understanding of their regulatory mechanisms warranting the need for further investigation. Methods: This retrospective study examined the genomic [...] Read more.
Objectives: Plasmid-mediated AmpC beta-lactamases represent a growing clinical concern in Enterobacterales, with challenges in diagnostic approaches, limited data on clinical outcomes, and our incomplete understanding of their regulatory mechanisms warranting the need for further investigation. Methods: This retrospective study examined the genomic and clinical characteristics of cefoxitin-non-susceptible, ceftriaxone-susceptible Escherichia coli and Klebsiella pneumoniae bloodstream isolates collected from a tertiary hospital in Singapore. Whole-genome sequencing was performed to detect ampC genes, subtypes, and associated regulatory elements. Results: Among 108 cefoxitin-non-susceptible isolates, only 15 (13.9%) harboured plasmid-mediated ampC, suggesting that cefoxitin non-susceptibility alone in ceftriaxone susceptible isolates was not predictive of ampC carriage. All plasmid-ampC isolates were from the blaDHA-1 subtype and carried ampR, a known transcriptional regulator of inducible beta-lactamase expression. Notably, five non-ampC carrying Klebsiella isolates displayed truncations in ompK35 and ompK36, which could potentially contribute to reduced cefoxitin susceptibility via porin loss. Conclusions: These findings underscore the limited diagnostic utility of cefoxitin susceptibility testing for detecting plasmid-mediated ampC producers and highlight the clinical relevance of regulatory genes such as ampR in mediating inducible resistance. The routine incorporation of molecular diagnostics or genome sequencing may be necessary to improve detection accuracy and inform antimicrobial stewardship strategies. Full article
(This article belongs to the Special Issue Strategies for Combatting Multidrug-Resistant and Extensively Drug-Resistant Bacteria, 2nd Edition)
13 pages, 1371 KiB  
Article
Multisite Infections Caused by Carbapenem-Resistant Klebsiella Pneumoniae: Unveiling the Clinical Characteristics and Risk Factors
by Jing Li, Shunjun Wu, Huanhuan Zhang, Xingxing Guo, Wanting Meng, Heng Zhao and Liqiang Song
Antibiotics 2025, 14(7), 721; https://doi.org/10.3390/antibiotics14070721 - 18 Jul 2025
Viewed by 551
Abstract
Objectives: There is a scarcity of studies on multisite infections (MSIs) caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). The primary objectives of this research were to determine the clinical characteristics of CRKP MSI, and the risk factors of infection and mortality. Methods: [...] Read more.
Objectives: There is a scarcity of studies on multisite infections (MSIs) caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). The primary objectives of this research were to determine the clinical characteristics of CRKP MSI, and the risk factors of infection and mortality. Methods: Patients with a CRKP bloodstream infection (BSI) were enrolled retrospectively between January 2017 and December 2021 in Xijing Hospital, China. The risk factors for CRKP MSI and mortality were evaluated. The demographic data, clinical and microbiological characteristics, therapy and outcomes were analyzed. Results: Among 101 patients, 74.3% (75/101) had a diagnosis of CRKP MSI, while 25.7% (26/101) of CRKP non-MSI. The overall case fatality rate was 42.6% (43/101). Multivariate analysis indicated that previous surgery (OR 3.971, 95% CI 1.504–10.480, p = 0.005) and ICU admission (OR 3.322, 95% CI 1.252–8.816, p = 0.016) were independent risk factors for CRKP MSI. ICU admission (OR 4.765, 95% CI 1.192–19.054, p = 0.027), a Pitt bacteremia score (PBS) > 4 (OR 3.820, 95% CI 1.218–11.983, p = 0.022) and thrombocytopenia (OR 8.650, 95% CI 2.573–29.007, p < 0.001) were independent risk factors for mortality due to CRKP MSI. Conclusions: Our findings confirmed that CRKP MSIs were associated with poorer outcomes. To improve prognosis, early screening of individuals at the highest risk is vital. 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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21 pages, 1088 KiB  
Review
Veterinary Clinics as Reservoirs for Pseudomonas aeruginosa: A Neglected Pathway in One Health Surveillance
by George Cosmin Nadăş, Alice Mathilde Manchon, Cosmina Maria Bouari and Nicodim Iosif Fiț
Antibiotics 2025, 14(7), 720; https://doi.org/10.3390/antibiotics14070720 - 17 Jul 2025
Viewed by 718
Abstract
Pseudomonas aeruginosa is a highly adaptable opportunistic pathogen with significant clinical relevance in both human and veterinary medicine. Despite its well-documented role in hospital-acquired infections in human healthcare settings, its persistence and transmission within veterinary clinics remain underexplored. This review highlights the overlooked [...] Read more.
Pseudomonas aeruginosa is a highly adaptable opportunistic pathogen with significant clinical relevance in both human and veterinary medicine. Despite its well-documented role in hospital-acquired infections in human healthcare settings, its persistence and transmission within veterinary clinics remain underexplored. This review highlights the overlooked status of veterinary facilities as environmental reservoirs and amplification points for multidrug-resistant (MDR) P. aeruginosa, emphasizing their relevance to One Health surveillance. We examine the bacterium’s environmental survival strategies, including biofilm formation, resistance to disinfectants, and tolerance to nutrient-poor conditions that facilitate the long-term colonization of moist surfaces, drains, medical equipment, and plumbing systems. Common transmission vectors are identified, including asymptomatic animal carriers, contaminated instruments, and the hands of veterinary staff. The review synthesizes current data on antimicrobial resistance in environmental isolates, revealing frequent expression of efflux pumps and mobile resistance genes, and documents the potential for zoonotic transmission to staff and pet owners. Key gaps in environmental monitoring, infection control protocols, and genomic surveillance are identified, with a call for standardized approaches tailored to the veterinary context. Control strategies, including mechanical biofilm disruption, disinfectant cycling, effluent monitoring, and staff hygiene training, are evaluated for feasibility and impact. The article concludes with a One Health framework outlining cross-species and environmental transmission pathways. It advocates for harmonized surveillance, infrastructure improvements, and intersectoral collaboration to reduce the risk posed by MDR P. aeruginosa within veterinary clinical environments and beyond. By addressing these blind spots, veterinary facilities can become proactive partners in antimicrobial stewardship and global resistance mitigation. Full article
(This article belongs to the Special Issue Veterinary Microbiology and Antimicrobial Resistance—the One Health Approach)
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13 pages, 239 KiB  
Article
Extended-Spectrum Beta-Lactamase Production and Carbapenem Resistance in Elderly Urinary Tract Infection Patients: A Multicenter Retrospective Study from Turkey
by Çiğdem Yıldırım, Sema Sarı, Ayşe Merve Parmaksızoğlu Aydın, Aysin Kilinç Toker, Ayşe Turunç Özdemir, Esra Erdem Kıvrak, Sinan Mermer, Hasip Kahraman, Orçun Soysal, Hasan Çağrı Yıldırım and Meltem Isikgoz Tasbakan
Antibiotics 2025, 14(7), 719; https://doi.org/10.3390/antibiotics14070719 - 17 Jul 2025
Viewed by 519
Abstract
Introduction: Urinary tract infections (UTIs) remain a significant public health issue worldwide, particularly affecting the geriatric population with increased morbidity and mortality. Aging-related immune changes, comorbidities, and urogenital abnormalities contribute to the higher incidence and complexity of UTIs in elderly patients. Antimicrobial resistance, [...] Read more.
Introduction: Urinary tract infections (UTIs) remain a significant public health issue worldwide, particularly affecting the geriatric population with increased morbidity and mortality. Aging-related immune changes, comorbidities, and urogenital abnormalities contribute to the higher incidence and complexity of UTIs in elderly patients. Antimicrobial resistance, especially extended-spectrum beta-lactamase (ESBL) production and carbapenem resistance, poses a major challenge in managing UTIs in this group. Methods: This retrospective, multicenter study included 776 patients aged 65 and older, hospitalized with a diagnosis of urinary tract infection between January 2019 and August 2024. Clinical, laboratory, and microbiological data were collected and analyzed. Urine samples were obtained under sterile conditions and pathogens identified using conventional and automated systems. Antibiotic susceptibility testing was performed according to CLSI standards. Logistic regression analyses were conducted to identify factors associated with ESBL production, carbapenem resistance, and mortality. Results: Among the patients, the median age was 78.9 years, with 45.5% female. ESBL production was detected in 56.8% of E. coli isolates and carbapenem resistance in 1.2%. Klebsiella species exhibited higher carbapenem resistance (37.8%). Independent predictors of ESBL production included the presence of urogenital cancer and antibiotic use within the past three months. Carbapenem resistance was associated with recent hospitalization, absence of kidney stones, and infection with non-E. coli pathogens. Mortality was independently associated with intensive care admission at presentation, altered mental status, Gram-positive infections, and comorbidities such as chronic obstructive pulmonary disease and urinary incontinence. Discussion: Our findings suggest that urinary pathogens and resistance patterns in elderly patients are similar to those in younger adults reported in the literature, highlighting the need for age-specific awareness in empiric therapy. The identification of risk factors for multidrug-resistant organisms emphasizes the importance of targeted antibiotic stewardship, especially in high-risk geriatric populations. Multicenter data contribute to regional understanding of resistance trends, aiding clinicians in optimizing management strategies for elderly patients with UTIs. Conclusions: This study highlights that E. coli and Klebsiella species are the primary causes of UTIs in the elderly, with resistance patterns similar to those seen in younger adults. The findings also contribute important data on risk factors for ESBL production and carbapenem resistance, supported by a robust patient sample. Full article
32 pages, 2479 KiB  
Review
Fungal Biofilm: An Overview of the Latest Nano-Strategies
by Andrea Giammarino, Laura Verdolini, Giovanna Simonetti and Letizia Angiolella
Antibiotics 2025, 14(7), 718; https://doi.org/10.3390/antibiotics14070718 - 17 Jul 2025
Viewed by 917
Abstract
Background/Objectives: There is an increasing incidence of fungal infections in conjunction with the rise in resistance to medical treatment. Antimicrobial resistance is frequently associated with virulence factors such as adherence and the capacity of biofilm formation, which facilitates the evasion of the [...] Read more.
Background/Objectives: There is an increasing incidence of fungal infections in conjunction with the rise in resistance to medical treatment. Antimicrobial resistance is frequently associated with virulence factors such as adherence and the capacity of biofilm formation, which facilitates the evasion of the host immune response and resistance to drug action. Novel therapeutic strategies have been developed to overcome antimicrobial resistance, including the use of different type of nanomaterials: metallic (Au, Ag, Fe3O4 and ZnO), organic (e.g., chitosan, liposomes and lactic acid) or carbon-based (e.g., quantum dots, nanotubes and graphene) materials. The objective of this study was to evaluate the action of nanoparticles of different synthesis and with different coatings on fungi of medical interest. Methods: Literature research was conducted using PubMed and Google Scholar databases, and the following terms were employed in articles published up to June 2025: ‘nanoparticles’ in combination with ‘fungal biofilm’, ‘Candida biofilm’, ‘Aspergillus biofilm’, ‘Cryptococcus biofilm’, ‘Fusarium biofilm’ and ‘dermatophytes biofilm’. Results: The utilization of nanoparticles was found to exert a substantial impact on the reduction in fungal biofilm, despite the presence of substantial variability in minimum inhibitory concentration (MIC) values attributable to variations in nanoparticle type and the presence of capping agents. It was observed that the MIC values were lower for metallic nanoparticles, particularly silver, and for those synthesized with polylactic acid compared to the others. Conclusions: Despite the limited availability of data concerning the stability and biocompatibility of nanoparticles employed in the treatment of fungal biofilms, it can be posited that these results constitute a significant initial step. Full article
(This article belongs to the Special Issue Methods for Preventing Biofilm Formation and Treat the Infections Caused by Biofilm Formed on Biotics or Abiotic Surfaces)
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15 pages, 636 KiB  
Article
High Prevalence of Multidrug-Resistant Bacterial Colonization Among Patients and Healthcare Workers in a Rural Ethiopian Hospital
by Elena Hidalgo, Teresa Alvaredo-Carrillo, Josefina-Marina Gil-Belda, Clara Portela-Pino, Clara Bares-Moreno, Sara Jareño-Moreno, Paula de la Fuente, Lucía Platero and Ramón Pérez-Tanoira
Antibiotics 2025, 14(7), 717; https://doi.org/10.3390/antibiotics14070717 - 17 Jul 2025
Viewed by 503
Abstract
Background/Objectives: Multidrug-resistant (MDR) bacterial colonization poses a significant risk for subsequent infections, especially within hospital environments. Healthcare workers can inadvertently transmit these MDR bacteria to vulnerable patients, exacerbating the problem. This study aimed to determine the colonization rates of MDR bacteria among patients [...] Read more.
Background/Objectives: Multidrug-resistant (MDR) bacterial colonization poses a significant risk for subsequent infections, especially within hospital environments. Healthcare workers can inadvertently transmit these MDR bacteria to vulnerable patients, exacerbating the problem. This study aimed to determine the colonization rates of MDR bacteria among patients and healthcare workers in a rural Ethiopian hospital with limited resources. Methods: Between 26 May and 6 June 2024, nasal, rectal, vagino-rectal exudate, and stool samples were collected from patients (n = 78) and healthcare workers (n = 11) at Gambo General Hospital (Oromia Region, Ethiopia). Samples were cultured on chromogenic media selective for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), and carbapenemase-producing Enterobacteriaceae (CPE). Bacterial identification was performed using MALDI-TOF mass spectrometry (Bruker), antimicrobial susceptibility testing using the MicroScan WalkAway system (Beckman Coulter), and genotypic characterization with the MDR Direct Flow Chip kit (Vitro). Results: MRSA nasal colonization was detected in 43.3% of patients (13/30; 95% CI: 27.4–60.8%) and 27.3% of healthcare workers (3/11; 95% CI: 6.0–61.0%) (p = 0.73). Rectal (or stool) colonization by MDR bacteria was significantly higher in pediatric patients (85.0%, 17/20; 95% CI: 62.1–96.8%) than in adults (14.3%, 4/28; 95% CI: 5.7–31.5%) (p < 0.001). Notably, a high proportion of pediatric patients harbored Escherichia coli strains co-producing NDM carbapenemase and CTX-M ESBL, and VRE strains were also predominantly isolated in this group. Conclusions: This study reveals a concerningly high prevalence of MRSA and MDR Enterobacteriaceae, especially among children at Gambo Hospital. The VRE prevalence was also substantially elevated compared to other studies. These findings underscore the urgent need for strengthened infection control measures and antimicrobial stewardship programs within the hospital setting. Full article
(This article belongs to the Special Issue Gram-Negative Multidrug-Resistant Pathogens and Their Treatment, 2nd Edition)
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11 pages, 511 KiB  
Article
Effects of Antibiotic De-Escalation on Outcomes in Severe Community-Acquired Pneumonia: An Inverse Propensity Score-Weighted Analysis
by Diego Viasus, Gabriela Abelenda-Alonso, Juan Bolivar-Areiza, Carlota Gudiol and Jordi Carratalà
Antibiotics 2025, 14(7), 716; https://doi.org/10.3390/antibiotics14070716 - 17 Jul 2025
Viewed by 603
Abstract
Objective: This study aimed to assess the effect of antibiotic de-escalation on 30-day mortality, duration of intravenous (IV) antibiotic therapy and length of hospital stay (LOS) in severe community-acquired pneumonia (sCAP). Methods: We performed a retrospective analysis of prospectively collected data [...] Read more.
Objective: This study aimed to assess the effect of antibiotic de-escalation on 30-day mortality, duration of intravenous (IV) antibiotic therapy and length of hospital stay (LOS) in severe community-acquired pneumonia (sCAP). Methods: We performed a retrospective analysis of prospectively collected data from a cohort of adults diagnosed with sCAP and microbiologically confirmed etiology between 1995 to 2022. Two distinct time points of the de-escalation were analyzed: 3 and 6 days post-admission, corresponding, respectively, to the availability of microbiological results and the median time to clinical stability. Inverse propensity score-weighted binary logistic regression was used to adjust for potential confounders. Results: A total of 398 consecutive cases of sCAP were analyzed. No significant differences were observed between the de-escalation and non-de-escalation groups in terms of age, sex, comorbidities, or severity-related variables (such as impaired consciousness, shock, respiratory failure, or multilobar pneumonia). Patients in the de-escalation group had lower rates of leukopenia, bacteremia and empyema, and less need for mechanical ventilation, with variations depending on the timing of de-escalation. After adjusting for confounding factors in an inverse propensity score-weighted analysis, de-escalation within 3 or 6 days after admission was not associated with increased mortality risk (adjusted odds ratio [aOR] 1.48, 95% confidence interval [CI] 0.29–7.4; p = 0.63, and aOR 0.57, 95% CI 0.14–2.31, p = 0.43, respectively). Similar findings were observed for prolonged LOS. However, antibiotic de-escalation was related to a lower risk of prolonged IV antibiotic. Conclusions: Antibiotic de-escalation in microbiologically confirmed sCAP did not negatively impact clinical outcomes, supporting the safety of this strategy for optimizing antibiotic use in this serious infection. 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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11 pages, 809 KiB  
Article
Antimicrobial Behavior of Surface-Treated Commercially Pure Titanium (CpTi) for Dental Implants in Artificial Saliva—In Vitro Study
by Roshni Bopanna, Neetha J. Shetty, Ashith M. Varadaraj, Himani Kotian, Sameep Shetty and Simran Genescia
Antibiotics 2025, 14(7), 715; https://doi.org/10.3390/antibiotics14070715 - 16 Jul 2025
Viewed by 383
Abstract
Background/Objectives:Titanium implant surface modifications enhance osseointegration and prevent microbial colonization, improving implant longevity. Antimicrobial coatings, particularly cerium- and bismuth-doped hydroxyapatite (CeHAp and BiHAp), have gained attention for reducing infection-related complications. This study evaluates the antimicrobial activity of CeHAp and BiHAp coatings on [...] Read more.
Background/Objectives:Titanium implant surface modifications enhance osseointegration and prevent microbial colonization, improving implant longevity. Antimicrobial coatings, particularly cerium- and bismuth-doped hydroxyapatite (CeHAp and BiHAp), have gained attention for reducing infection-related complications. This study evaluates the antimicrobial activity of CeHAp and BiHAp coatings on CpTi compared to untreated CpTi in artificial saliva at pH levels of 4.5, 6.5, and 8. Methods: Antibacterial efficacy against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Candida albicans (C. albicans) was assessed using the broth dilution method. Titanium rods coated with test compounds were incubated in inoculated nutrient broth, and microbial inhibition was determined via optical density at 600 nm. A statistical analysis was performed using the Kruskal–Wallis ANOVA test, the median and Interquartile Range were determined for the variables, and a Dwass–Steel–Critchlow–Fligner intergroup pairwise comparison was conducted. Results: The results showed that both the CeHAp and BiHAp coatings demonstrated significant antimicrobial activity against S. aureus (OD = 0.01) at pH 6.5, which was more pronounced than the activity observed against E. coli (OD = 0.05), with the difference being statistically significant (p = 0.001). The least antimicrobial activity was observed against C. albicans (0.21) at pH 8 (p = 0.001). Conclusion: These findings highlight the pH-dependent effectiveness of BiHAp and CeHAp coatings in inhibiting microbial growth. Their application on titanium implants may enhance antimicrobial properties, contributing to improved dental implant success and broader biomedical applications. Full article
(This article belongs to the Section Antimicrobial Materials and Surfaces)
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11 pages, 2797 KiB  
Article
Illuminating the Invisible: Green Fluorescent Protein as a Beacon for Antibiotic-Induced Phage Activity in Escherichia coli
by Maria João Silva, Tim Van Den Bossche, Mattias Collin and Rolf Lood
Antibiotics 2025, 14(7), 714; https://doi.org/10.3390/antibiotics14070714 - 16 Jul 2025
Viewed by 369
Abstract
Background/Objectives: Antibiotic resistance presents an urgent public health threat. By developing a streamlined and effective method for studying bacteriophage induction, this research marks a step further in understanding how antibiotic-resistant genes might spread across different environments. This knowledge is essential for creating strategies [...] Read more.
Background/Objectives: Antibiotic resistance presents an urgent public health threat. By developing a streamlined and effective method for studying bacteriophage induction, this research marks a step further in understanding how antibiotic-resistant genes might spread across different environments. This knowledge is essential for creating strategies to reduce the spread of antimicrobial resistance (AMR), particularly from a One Health perspective. In this study, we develop and validate a Green Fluorescent Protein (GFP)-based method as a proxy for bacteriophage induction. This method screens compounds for their potential to promote bacteriophage induction. Methods: This study utilized a recA-GFP construct in Escherichia coli to measure fluorescence as an indicator of SOS response activation. The experiments involved treating E. coli cultures with varying concentrations of the DNA-damaging chemical mitomycin C and measuring fluorescence over time. Additionally, droplet digital PCR (ddPCR) quantified bacteriophage induction in a lambda phage-carrying E. coli strain, allowing for correlation analysis between the two methods. Results: The recA-driven SOS response depended on both dose and time, with increasing concentrations of mitomycin C leading to higher fluorescence. ddPCR analysis confirmed that mitomycin C induced prophage activation, with gene ratios increasing at higher drug concentrations over time. A strong Spearman correlation (>0.7) was noted between fluorescence and ddPCR results at elevated concentrations and relevant time points, indicating the validity of the GFP-based model as a proxy for bacteriophage induction. Conclusions: The findings demonstrate a strong association between the two methods of measuring phage induction, suggesting that the GFP-based E. coli model is a reliable, cost-effective, and efficient tool for studying phage induction and its potential role in AMR spread. This method could facilitate the screening of environmental samples and specific drugs to evaluate their impact on bacteriophage induction, which opens the door for applications such as screening for antibiotic resistance dissemination. Full article
(This article belongs to the Section Bacteriophages)
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22 pages, 3103 KiB  
Article
Genomic and Metabolomic Analysis of the Endophytic Fungus Alternaria alstroemeriae S6 Isolated from Veronica acinifolia: Identification of Anti-Bacterial Properties and Production of Succinic Acid
by Farkhod Eshboev, Alex X. Gao, Akhror Abdurashidov, Kamila Mardieva, Asadali Baymirzaev, Mirzatimur Musakhanov, Elvira Yusupova, Shengying Lin, Meixia Yang, Tina T. X. Dong, Shamansur Sagdullaev, Shakhnoz Azimova and Karl W. K. Tsim
Antibiotics 2025, 14(7), 713; https://doi.org/10.3390/antibiotics14070713 - 16 Jul 2025
Viewed by 582
Abstract
Background: Endophytic fungi are prolific sources of bioactive metabolites with potential in pharmaceutical and biotechnological applications. Methods: Here, the endophytic fungus, Alternaria alstroemeriae S6, was isolated from Veronica acinifolia (speedwell), and conducted its anti-microbial activities, whole-genome sequencing and metabolome analysis. Results: The ethyl [...] Read more.
Background: Endophytic fungi are prolific sources of bioactive metabolites with potential in pharmaceutical and biotechnological applications. Methods: Here, the endophytic fungus, Alternaria alstroemeriae S6, was isolated from Veronica acinifolia (speedwell), and conducted its anti-microbial activities, whole-genome sequencing and metabolome analysis. Results: The ethyl acetate extract of this fungus exhibited strong anti-bacterial activity and the inhibition zones, induced by the fungal extract at 20 mg/mL, reached 16.25 ± 0.5 mm and 26.5 ± 0.5 mm against Gram-positive and Gram-negative bacteria. To unravel the biosynthetic potential for anti-bacterial compounds, whole-genome sequencing was conducted on A. alstroemeriae S6, resulting in a high-quality assembly of 42.93 Mb encoding 13,885 protein-coding genes. Comprehensive functional genome annotation analyses, including gene ontology (GO) terms, clusters of orthologous groups (COGs), Kyoto encyclopedia of genes and genomes (KEGG), carbohydrate-active enzymes (CAZymes), and antibiotics and secondary metabolites analysis shell (antiSMASH) analyses, were performed. According to the antiSMASH analysis, 58 biosynthetic gene clusters (BGCs), including 16 non-ribosomal peptide synthetases (NRPSs), 21 terpene synthases, 12 polyketide synthetases (PKSs), and 9 hybrids, were identified. In addition, succinic acid was identified as the major metabolite within the fungal extract, while 20 minor bioactive compounds were identified through LC-MS/MS-based molecular networking on a GNPS database. Conclusions: These findings support the biotechnological potential of A. alstroemeriae S6 as an alternative producer of succinic acid, as well as novel anti-bacterial agents. Full article
(This article belongs to the Section Fungi and Their Metabolites)
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11 pages, 869 KiB  
Article
Species Distribution, Characterization, and Antifungal Susceptibility Patterns of Candida Isolates Causing Oral and Vulvovaginal Candidiasis in Chile
by Francisca Nahuelcura and Eduardo Álvarez Duarte
Antibiotics 2025, 14(7), 712; https://doi.org/10.3390/antibiotics14070712 - 16 Jul 2025
Viewed by 443
Abstract
Background: Oral candidiasis (OC) and vulvovaginal candidiasis (VVC) are infections caused by species belonging to the genus Candida. In Chile, epidemiological studies on OC/VVC are scarce, leading to an overestimation of the prevalence of C. albicans. Additionally, awareness of the prevalence [...] Read more.
Background: Oral candidiasis (OC) and vulvovaginal candidiasis (VVC) are infections caused by species belonging to the genus Candida. In Chile, epidemiological studies on OC/VVC are scarce, leading to an overestimation of the prevalence of C. albicans. Additionally, awareness of the prevalence of species phenotypically and genotypically similar to C. albicans is lacking. The clinical impact of non-albicans species in cases of OC/VVC is also often underestimated. This study aims to determine the distribution of Candida species, their phenotypic and molecular characteristics, and their antifungal susceptibility patterns in incidents of oral and vulvovaginal candidiasis in Chile. Methods: A descriptive analysis was conducted on 101 isolates of Candida spp. obtained from OC/VVC cases. The identification of Candida species was performed using both phenotypic and molecular techniques. Antifungal susceptibility testing was carried out using the Sensititre YeastOne system. Results: Among the analyzed isolates, 89.1% were identified as C. albicans, while 10.9% were categorized as non-albicans species, including C. dubliniensis, C. glabrata sensu stricto, C. bracarensis, C. tropicalis, C. lusitaniae, and C. parapsilosis sensu stricto. The susceptibility pattern was predominantly susceptible, with only 10.9% of the total strains demonstrating resistance, and low antifungal activity in vitro was observed for Fluconazole, Voriconazole, and Posaconazole. Conclusions: The most prevalent species causing OC/VVC in Chile is C. albicans. This study also presents the first report of C. lusitaniae as a causal agent of VVC in the country. The identification of azole-resistant strains emphasizes the critical role of laboratory diagnosis in VVC cases, thereby preventing potential treatment failures. No resistance was observed in the strains associated with OC. Full article
(This article belongs to the Special Issue Epidemiology, Antifungal Resistance and Therapy in Fungal Infection)
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16 pages, 1988 KiB  
Article
Epidemiological Surveillance, Variability, and Evolution of Isolates Belonging to the Spanish Clone of the 4,[5],12:i:- Monophasic Variant of Salmonella enterica Serovar Typhimurium
by Xenia Vázquez, Patricia García, Javier Fernández, Víctor Ladero, Carlos Rodríguez-Lucas, Jürgen J. Heinisch, Rosaura Rodicio and M. Rosario Rodicio
Antibiotics 2025, 14(7), 711; https://doi.org/10.3390/antibiotics14070711 - 16 Jul 2025
Viewed by 372
Abstract
Background/Objective: The present study focused on the analysis of the Spanish clone belonging to the successful 4,[5],12:i:- monophasic variant of Salmonella enterica serovar Typhimurium. Methods: All isolates of the clone recovered in a Spanish region from human clinical samples between 2008 and 2018 [...] Read more.
Background/Objective: The present study focused on the analysis of the Spanish clone belonging to the successful 4,[5],12:i:- monophasic variant of Salmonella enterica serovar Typhimurium. Methods: All isolates of the clone recovered in a Spanish region from human clinical samples between 2008 and 2018 (N = 14) were investigated using microbiological approaches and genome sequence analysis. In addition, they were compared with isolates from the years 2000 to 2003 (N = 21), which were previously characterized but had not yet been sequenced. Results: Phylogenetic analyses indicate that all isolates are closely related (differing by 1 to 103 SNPs) but belong to two clades termed A and B. With few exceptions, clade A comprised isolates of the first period, also including two “older” control strains, LSP 389/97 and LSP 272/98. Clade B only contained isolates from the second period. Isolates from both periods were resistant to antibiotics and biocides, with almost all resistance genes located on large IncC plasmids, additionally carrying pSLT-derived virulence genes. The number of resistance genes was highly variable, resulting in a total of 22 ABR (antibiotic biocide resistance) profiles. The number of antibiotic resistance genes, but not that of biocide resistance genes, was considerably lower in isolates from the second than from the first period (with averages of 5.5 versus 9.6 genes). Importantly, IS26, which resides in multiple copies within these plasmids, appears to be playing a crucial role in the evolution of resistance, and it was also responsible for the monophasic phenotype, which was associated with four different deletions eliminating the fljAB region. Conclusions: the observed reduction in the number of antibiotic resistance genes could correlate with the loss of adaptive advantage originating from the ban on the use of antibiotics as feed additives implemented in the European Union since 2006, facilitated by the intrinsic instability of the IncC plasmids. Two consecutive IS26 transposition events, which can explain both the clonal relationship of the isolates and their variability, may account for the observed fljAB deletions. Full article
(This article belongs to the Special Issue Genomic Analysis of Antimicrobial Drug-Resistant Bacteria)
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2 pages, 133 KiB  
Correction
Correction: Honegger et al. Antimicrobial Efficacy of Five Wound Irrigation Solutions in the Biofilm Microenvironment In Vitro and Ex Vivo. Antibiotics 2025, 14, 25
by Anja L. Honegger, Tiziano A. Schweizer, Yvonne Achermann and Philipp P. Bosshard
Antibiotics 2025, 14(7), 710; https://doi.org/10.3390/antibiotics14070710 - 16 Jul 2025
Viewed by 219
Abstract
There was an error in the original publication [...] Full article
19 pages, 368 KiB  
Article
Barriers to Compliance with National Guidelines Among Children Hospitalized with Community-Acquired Pneumonia in Vietnam and the Implications
by Thuy Thi Phuong Nguyen, Huong Thi Thu Vu, Anh Minh Hoang, An Minh Ho, Israel Abebrese Sefah, Brian Godman and Johanna C. Meyer
Antibiotics 2025, 14(7), 709; https://doi.org/10.3390/antibiotics14070709 - 15 Jul 2025
Cited by 1 | Viewed by 892
Abstract
Background: Community-acquired pneumonia (CAP) is the leading cause of death in infants aged 1–59 months. Concurrent with this, there is a need to prescribe antibiotics wisely in Vietnam due to concerns with rising antimicrobial resistance (AMR). Consequently, an urgent need has arisen [...] Read more.
Background: Community-acquired pneumonia (CAP) is the leading cause of death in infants aged 1–59 months. Concurrent with this, there is a need to prescribe antibiotics wisely in Vietnam due to concerns with rising antimicrobial resistance (AMR). Consequently, an urgent need has arisen to treat patients according to agreed guidelines. The aim of this study was to investigate the current management of infants under five years old with CAP in Vietnam as well as identify possible obstacles to adhering to national guidelines. Methods: A mixed-method approach was used incorporating both quantitative and qualitative data analysis in a leading hospital in Vietnam, which influences others. Data from 108 pediatric patient records were collected and analyzed. Subsequently, in-depth interviews were conducted with pediatric doctors treating these patients to ascertain possible reasons for non-adherence to guidelines. Results: The mean age of children diagnosed with CAP was 27.94 ± 12.99 months, with 82.4% having non-severe CAP, and 41.7% of children had previously used antibiotics before hospitalization. The median length of hospital stay was 7 days. All children were prescribed antibiotics, 91.4% of children received these initially intravenously, with third-generation cephalosporins being the most (91.7%) commonly prescribed. Cefoperazone/sulbactam was the most frequently prescribed (48.2%) antibiotic. However, on 96.1% of occasions cefoperazone/sulbactam was given at higher doses than the label instructions. Overall, 73.3% of antibiotics prescribed were “Watch” antibiotics. In addition, the proportion of initial antibiotic regimens that were consistent with current national guidelines was only 4.63%. Conclusions: There were considerable concerns with low adherence rates to current guidelines alongside high rates of prescribing of injectable third-generation cephalosporins due to various internal and external barriers. Antimicrobial stewardship programs with updated national guidelines are urgently needed in Vietnamese hospitals to treat CAP in children as part of ongoing measures to reduce increasing AMR rates. Such activities should also help improve antibiotic use in the community following improved education of trainee ambulatory care physicians regarding appropriate management of children with CAP. Full article
(This article belongs to the Special Issue Antibiotic Resistance: From the Bench to Patients, 2nd Edition)
15 pages, 633 KiB  
Article
Performance of Early Sepsis Screening Tools for Timely Diagnosis and Antibiotic Stewardship in a Resource-Limited Thai Community Hospital
by Wisanu Wanlumkhao, Duangduan Rattanamongkolgul and Chatchai Ekpanyaskul
Antibiotics 2025, 14(7), 708; https://doi.org/10.3390/antibiotics14070708 - 15 Jul 2025
Viewed by 1016
Abstract
Background: Early identification of sepsis is critical for improving outcomes, particularly in low-resource emergency settings. In Thai community hospitals, where physicians may not always be available, triage is often nurse-led. Selecting accurate and practical sepsis screening tools is essential not only for timely [...] Read more.
Background: Early identification of sepsis is critical for improving outcomes, particularly in low-resource emergency settings. In Thai community hospitals, where physicians may not always be available, triage is often nurse-led. Selecting accurate and practical sepsis screening tools is essential not only for timely clinical decision-making but also for timely diagnosis and promoting appropriate antibiotic use. Methods: This cross-sectional study analyzed 475 adult patients with suspected sepsis who presented to the emergency department of a Thai community hospital, using retrospective data from January 2021 to December 2022. Six screening tools were evaluated: Systemic Inflammatory Response Syndrome (SIRS), Quick Sequential Organ Failure Assessment (qSOFA), Modified Early Warning Score (MEWS), National Early Warning Score (NEWS), National Early Warning Score version 2 (NEWS2), and Search Out Severity (SOS). Diagnostic accuracy was assessed using International Classification of Diseases, Tenth Revision (ICD-10) codes as the reference standard. Performance metrics included sensitivity, specificity, predictive values, likelihood ratios, and the area under the receiver operating characteristic (AUROC) curve, all reported with 95% confidence intervals. Results: SIRS had the highest sensitivity (84%), while qSOFA demonstrated the highest specificity (91%). NEWS2, NEWS, and MEWS showed moderate and balanced diagnostic accuracy. SOS also demonstrated moderate accuracy. Conclusions: A two-step screening approach—using SIRS for initial triage followed by NEWS2 for confirmation—is recommended. This strategy enhances nurse-led screening and optimizes limited resources in emergency care. Early sepsis detection through accurate screening tools constitutes a feasible public health intervention to support appropriate antibiotic use and mitigate antimicrobial resistance, especially in resource-limited community hospital settings. Full article
(This article belongs to the Special Issue Antimicrobial Prescribing, Population Use and Resistance, Impact in Global Health, 3rd Edition)
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14 pages, 1574 KiB  
Article
Antimicrobial Efficacy of Impregnated Human Acellular Dermal Substitutes in Burn Wound Models
by Marianna Hajská, Elena Kurin, Silvia Bittner Fialová, Marian Vidiščák and Arpád Panyko
Antibiotics 2025, 14(7), 707; https://doi.org/10.3390/antibiotics14070707 - 14 Jul 2025
Viewed by 440
Abstract
Burn wound infections remain a major clinical challenge due to delayed healing, scarring, and the risk of sepsis, especially when complicated by multidrug-resistant (MDR) Gram-negative pathogens and biofilm formation. Acellular dermal matrices (ADMs) are widely used in reconstructive and burn surgery, yet they [...] Read more.
Burn wound infections remain a major clinical challenge due to delayed healing, scarring, and the risk of sepsis, especially when complicated by multidrug-resistant (MDR) Gram-negative pathogens and biofilm formation. Acellular dermal matrices (ADMs) are widely used in reconstructive and burn surgery, yet they lack intrinsic antimicrobial activity, necessitating their combination with topical agents. Background/Objectives: This study investigates the antimicrobial and cytocompatibility profiles of ADMs impregnated with various antimicrobial agents, using in vitro planktonic and biofilm burn wound models. While the incorporation of antimicrobials into scaffolds has been previously explored, this study is, to our knowledge, the first to directly compare seven clinically relevant antimicrobial agents after they were impregnated into an ADM in a standardized in vitro model. Methods: Seven topical antimicrobials were tested against MDR Pseudomonas aeruginosa and Acinetobacter baumannii from burn patients. Results: The ADM with 1% acetic acid (AA) showed superior antimicrobial activity, achieving > 7 log10 reductions in planktonic assays and complete inhibition of P. aeruginosa biofilms. In NIH 3T3 fibroblast cytotoxicity assays, the 1% AA ADM maintained cell viability at control levels, indicating excellent biocompatibility. Compared with agents such as Betadine®, Octenilin®, and colistin, which showed cytotoxicity, and Prontosan®, which showed low efficacy, 1% AA uniquely combined potent antibacterial effects with minimal toxicity. Conclusions: Among the seven antimicrobial agents impregnated into ADMs, 1% AA demonstrated a unique efficacy and safety profile, supporting its potential for clinical application in integrated wound dressings and implantable biomaterials for infection control in burn care. Full article
(This article belongs to the Special Issue Antimicrobial Resistance and Therapy in Intensive Care Unit)
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15 pages, 2742 KiB  
Article
Resistome and Phylogenomics of Escherichia coli Strains Obtained from Diverse Sources in Jimma, Ethiopia
by Mulatu Gashaw, Esayas Kebede Gudina, Guenter Froeschl, Ralph Matar, Solomon Ali, Liegl Gabriele, Amelie Hohensee, Thomas Seeholzer, Arne Kroidl and Andreas Wieser
Antibiotics 2025, 14(7), 706; https://doi.org/10.3390/antibiotics14070706 - 14 Jul 2025
Viewed by 444
Abstract
Introduction: In recent years, antimicrobial resistance (AMR) rates have increased significantly in bacterial pathogens, particularly extended beta-lactam resistance. This study aimed to investigate resistome and phylogenomics of Escherichia coli (E. coli) strains isolated from various sources in Jimma, Ethiopia. Methods [...] Read more.
Introduction: In recent years, antimicrobial resistance (AMR) rates have increased significantly in bacterial pathogens, particularly extended beta-lactam resistance. This study aimed to investigate resistome and phylogenomics of Escherichia coli (E. coli) strains isolated from various sources in Jimma, Ethiopia. Methods: Phenotypic antibiotic resistance patterns of E. coli isolates were determined using automated Kirby–Bauer disc diffusion and minimum inhibitory concentration (MIC). Isolates exhibiting phenotypic resistance to beta-lactam antibiotics were further analyzed with a DNA microarray to confirm the presence of resistance-encoding genes. Additionally, multilocus sequence typing (MLST) of seven housekeeping genes was conducted using PCR and Oxford Nanopore-Technology (ONT) to assess the phylogenetic relationships among the E. coli isolates. Results: A total of 611 E. coli isolates from human, animal, and environmental sources were analyzed. Of these, 41.6% (254) showed phenotypic resistance to at least one of the tested beta-lactams, 96.1% (244) thereof were confirmed genotypically. More than half of the isolates (53.3%) had two or more resistance genes present. The most frequent ESBL-encoding gene was CTX-M-15 (74.2%; 181), followed by TEM (59.4%; 145) and CTX-M-9 (4.1%; 10). The predominant carbapenemase gene was NDM-1, detected in 80% (12 out of 15) of carbapenem-resistant isolates. A phylogenetic analysis revealed clonality among the strains obtained from various sources, with international high-risk clones such as ST131, ST648, ST38, ST73, and ST405 identified across various niches. Conclusions: The high prevalence of CTX-M-15 and NDM-1 in multidrug-resistant E. coli isolates indicates the growing threat of AMR in Ethiopia. The discovery of these high-risk clones in various niches shows possible routes of transmission and highlights the necessity of a One Health approach to intervention and surveillance. Strengthening antimicrobial stewardship, infection prevention, and control measures are crucial to mitigate the spread of these resistant strains. Full article
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18 pages, 333 KiB  
Review
Antibiotic Elution from Cement Spacers and Its Influencing Factors
by Bernd Fink and Kevin D. Tetsworth
Antibiotics 2025, 14(7), 705; https://doi.org/10.3390/antibiotics14070705 - 14 Jul 2025
Viewed by 801
Abstract
Antibiotic-loaded cement spacers play a crucial role in two-stage revision arthroplasty of infected total hip and knee prostheses. There is still controversy regarding whether the elution from antibiotic-loaded cement spacers is greater than the MIC for a prolonged time between stages. Therefore, the [...] Read more.
Antibiotic-loaded cement spacers play a crucial role in two-stage revision arthroplasty of infected total hip and knee prostheses. There is still controversy regarding whether the elution from antibiotic-loaded cement spacers is greater than the MIC for a prolonged time between stages. Therefore, the aim of the current review was to determine how long spacers elute antibiotics above the MIC for most causative microorganisms, as well as to evaluate what factors influence that elution. Independent of methodological differences and weaknesses of the studies themselves, several study results indicate that after an early peak of antibiotic release from the spacer in the first 1 to 2 days (followed by a gradual decline), a sufficient release above the MIC for most causative bacteria continues for 6 to 12 weeks. Full article
(This article belongs to the Special Issue Diagnostics, Antibiotic Usage and Surgery Related Techniques in Prevention and Treatment of Prosthetic Joint and Implant Related Infections)
13 pages, 1556 KiB  
Article
Investigation of WQ-3810, a Fluoroquinolone with a High Potential Against Fluoroquinolone-Resistant Mycobacterium avium
by Sasini Jayaweera, Pondpan Suwanthada, David Atomanyi Barnes, Charlotte Poussier, Tomoyasu Nishimura, Naoki Hasegawa, Yukiko Nishiuchi, Jeewan Thapa, Stephen V. Gordon, Hyun Kim, Chie Nakajima and Yasuhiko Suzuki
Antibiotics 2025, 14(7), 704; https://doi.org/10.3390/antibiotics14070704 - 14 Jul 2025
Viewed by 453
Abstract
Background/Objectives: Mycobacterium avium, a member of Mycobacterium avium complex (MAC), is an emerging opportunistic pathogen causing MAC-pulmonary disease (PD). Fluoroquinolones (FQs), along with ethambutol (EMB) and rifampicin, are recommended for macrolide-resistant MAC-PD; however, FQ-resistant M. avium have been reported worldwide. WQ-3810 [...] Read more.
Background/Objectives: Mycobacterium avium, a member of Mycobacterium avium complex (MAC), is an emerging opportunistic pathogen causing MAC-pulmonary disease (PD). Fluoroquinolones (FQs), along with ethambutol (EMB) and rifampicin, are recommended for macrolide-resistant MAC-PD; however, FQ-resistant M. avium have been reported worldwide. WQ-3810 is an FQ with high potency against FQ-resistant pathogens; however, its activity against M. avium has not yet been studied. Methods: In this study, we conducted a DNA supercoiling inhibitory assay to evaluate the inhibitory effect of WQ-3810 on recombinant wild-type (WT) and four mutant DNA gyrases of M. avium and compared the IC50s of WQ-3810 with those of ciprofloxacin (CIP), levofloxacin (LVX), and moxifloxacin (MXF). In addition, we examined WQ-3810’s antimicrobial activity against 11 M. avium clinical isolates, including FQ-resistant isolates, with that of other FQs. Furthermore, we assessed the synergistic action of WQ-3810 with the combination of either EMB or isoniazid (INH). Results: In a DNA supercoiling inhibitory assay, WQ-3810 showed 1.8 to 13.7-fold higher efficacy than LVX and CIP. In the MIC assay, WQ-3810 showed 4 to 8-fold, 2 to 16-fold, and 2 to 4-fold higher antimicrobial activity against FQ-resistant isolates than CIP, LVX, and MXF, respectively. The combination of WQ-3810 and INH exhibited a synergistic relationship. Conclusions: The overall characteristics of WQ-3810 demonstrated greater effectiveness than three other FQs, suggesting that it is a promising option for treating FQ-resistant M. avium infections. Full article
(This article belongs to the Special Issue Genomic Characterization of Antimicrobial Resistance and Evolution Mechanism of Bacteria)
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