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15 pages, 492 KiB  
Article
Head-to-Head Comparison of Etest, MICRONAUT-AM EUCAST and Reference Broth Microdilution-Based CLSI Results for Candida kefyr Antifungal Susceptibility Testing: Implications for Detection of Reduced Susceptibility to Amphotericin B
by Mohammad Asadzadeh, Suhail Ahmad, Jacques F. Meis, Josie E. Parker and Wadha Alfouzan
J. Fungi 2025, 11(8), 570; https://doi.org/10.3390/jof11080570 - 30 Jul 2025
Viewed by 158
Abstract
Invasive infections with rare yeasts are increasing worldwide and are associated with higher mortality rates due to their resistance to antifungal drugs. Accurate antifungal susceptibility testing (AFST) is crucial for proper management of rare yeast infections. We performed AFST of 74 Candida kefyr [...] Read more.
Invasive infections with rare yeasts are increasing worldwide and are associated with higher mortality rates due to their resistance to antifungal drugs. Accurate antifungal susceptibility testing (AFST) is crucial for proper management of rare yeast infections. We performed AFST of 74 Candida kefyr isolates by Etest, EUCAST-based MICRONAUT-AM assay (MCN-AM) and reference Clinical and Laboratory Standards Institute broth microdilution method (CLSI). Essential agreement (EA, ±1 two-fold dilution), categorical agreement (CA), major errors (MEs) and very-major errors (VmEs) were determined using epidemiological cut-off values of ≤1.0 µg/mL, ≤0.03 µg/mL, ≤0.5 µg/mL and ≤1 µg/mL, defining wild-type isolates for fluconazole, voriconazole, micafungin and amphotericin B (AMB), respectively. Results for AMB susceptibility were correlated with ERG2/ERG3 mutations and total-cell sterols. CA of ≥97% was recorded between any two methods while EA varied between 72 and 82%, 87 and 92%, and 49 and 76% for fluconazole, voriconazole and micafungin, respectively. For AMB, CAs between CLSI and Etest; CLSI and MCN-AM; MCN-AM and Etest were 95% (4 ME, 0 VmE), 96% (3 ME, 0 VmE) and 99%, respectively, while EA varied from 32% to 69%. Non-synonymous ERG2/ERG3 mutations and no ergosterol were found in seven of eight isolates of non-wild types for AMB by Etest. Our data show that Etest, CLSI and MCN-AM methods are suitable for AFST of C. kefyr for fluconazole, voriconazole and micafungin. Excellent CAs for AMB between Etest and MCN-AM with concordant sterol profiles but not with CLSI suggest that Etest is also an excellent alternative for the detection of C. kefyr isolates with reduced susceptibility to AMB. Full article
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22 pages, 1531 KiB  
Article
Evaluation of the Biological Properties and Antibacterial Activities of the Natural Food Supplement “Epavin” for Liver Detoxification and Protection
by Alexia Barbarossa, Maria Pia Argentieri, Maria Valeria Diella, Anita Caforio, Antonio Carrieri, Filomena Corbo, Antonio Rosato and Alessia Carocci
Foods 2025, 14(15), 2600; https://doi.org/10.3390/foods14152600 - 24 Jul 2025
Viewed by 366
Abstract
Background/Objectives: The liver, the body’s primary detoxifying organ, is often affected by various inflammatory diseases, including hepatitis, cirrhosis, and non-alcoholic fatty liver disease (NAFLD), many of which can be exacerbated by secondary infections such as spontaneous bacterial peritonitis, bacteremia, and sepsis—particularly in patients [...] Read more.
Background/Objectives: The liver, the body’s primary detoxifying organ, is often affected by various inflammatory diseases, including hepatitis, cirrhosis, and non-alcoholic fatty liver disease (NAFLD), many of which can be exacerbated by secondary infections such as spontaneous bacterial peritonitis, bacteremia, and sepsis—particularly in patients with advanced liver dysfunction. The global rise in these conditions underscores the need for effective interventions. Natural products have attracted attention for their potential to support liver health, particularly through synergistic combinations of plant extracts. Epavin, a dietary supplement from Erbenobili S.r.l., formulated with plant extracts like Taraxacum officinale (L.), Silybum marianum (L.) Gaertn., and Cynara scolymus (L.), known for their liver-supporting properties, has been proposed as adjuvant for liver functions. The aim of this work was to evaluate of Epavin’s antioxidant, anti-inflammatory, and protective effects against heavy metal-induced toxicity. In addition, the antibacterial effect of Epavin against a panel of bacterial strains responsible for infections associated with liver injuries has been evaluated. Methods: The protection against oxidative stress induced by H2O2 was evaluated in HepG2 and BALB/3T3 cells using the dichlorofluorescein diacetate (DCFH-DA) assay. Its anti-inflammatory activity was investigated by measuring the reduction in nitric oxide (NO) production in LPS-stimulated RAW 264.7 macrophages using the Griess assay. Additionally, the cytoprotecting of Epavin against heavy metal-induced toxicity and oxidative stress were evaluated in HepG2 cells using the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] (MTT) and DCFH-DA assays. The antibacterial activity of Epavin was assessed by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) against Gram-positive (Enterococcus faecalis ATCC 29212, and BS, Staphylococcus aureus 25923, 29213, 43300, and BS) and Gram-negative (Escherichia coli 25922, and BS, Klebsiella pneumoniae 13883, 70063, and BS) bacterial strains using the microdilution method in broth, following the Clinical and Laboratory Standards Institute’s (CLSI) guidelines. Results: Epavin effectively reduced oxidative stress in HepG2 and BALB/3T3 cells and decreased NO production in LPS-stimulated RAW 264.7 macrophages. Moreover, Epavin demonstrated a protective effect against heavy metal-induced toxicity and oxidative damage in HepG2 cells. Finally, it exhibited significant antibacterial activity against both Gram-positive and Gram-negative bacterial strains, with MIC values ranging from 1.5 to 6.0 mg/mL. Conclusions: The interesting results obtained suggest that Epavin may serve as a valuable natural adjuvant for liver health by enhancing detoxification processes, reducing inflammation, and exerting antibacterial effects that could be beneficial in the context of liver-associated infections. Full article
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27 pages, 4093 KiB  
Article
Antimicrobial Resistance in Commensal Bacteria from Large-Scale Chicken Flocks in the Dél-Alföld Region of Hungary
by Ádám Kerek, Ábel Szabó, Franciska Barnácz, Bence Csirmaz, László Kovács and Ákos Jerzsele
Vet. Sci. 2025, 12(8), 691; https://doi.org/10.3390/vetsci12080691 - 24 Jul 2025
Viewed by 471
Abstract
Background: Antimicrobial resistance (AMR) is increasingly acknowledged as a critical global challenge, posing serious risks to human and animal health and potentially disrupting poultry production systems. Commensal bacteria such as Staphylococcus spp., Enterococcus spp., and Escherichia coli may serve as important reservoirs [...] Read more.
Background: Antimicrobial resistance (AMR) is increasingly acknowledged as a critical global challenge, posing serious risks to human and animal health and potentially disrupting poultry production systems. Commensal bacteria such as Staphylococcus spp., Enterococcus spp., and Escherichia coli may serve as important reservoirs and vectors of resistance genes. Objectives: This study aimed to assess the AMR profiles of bacterial strains isolated from industrial chicken farms in the Dél-Alföld region of Hungary, providing region-specific insights into resistance dynamics. Methods: A total of 145 isolates, including Staphylococcus spp., Enterococcus spp., and E. coli isolates, were subjected to minimum inhibitory concentration (MIC) testing against 15 antimicrobial agents, following Clinical and Laboratory Standards Institute (CLSI) guidelines. Advanced multivariate statistics, machine learning algorithms, and network-based approaches were employed to analyze resistance patterns and co-resistance associations. Results Multidrug resistance (MDR) was identified in 43.9% of Staphylococcus spp. isolates, 28.8% of Enterococcus spp. isolates, and 75.6% of E. coli isolates. High levels of resistance to florfenicol, enrofloxacin, and potentiated sulfonamides were observed, whereas susceptibility to critical antimicrobials such as imipenem and vancomycin remained largely preserved. Discussion: Our findings underscore the necessity of implementing region-specific AMR monitoring programs and strengthening multidisciplinary collaboration within the “One Health” framework with proper animal hygiene and biosecurity measures to limit the spread of antimicrobial resistance and protect both animal and human health. Full article
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19 pages, 5670 KiB  
Article
Significant Impact of Growth Medium on Itraconazole Susceptibility in Azole-Resistant Versus Wild-Type Trichophyton indotineae, rubrum, and quinckeanum Isolates
by Luisa Krauße, Anke Burmester, Silke Uhrlaß, Mario Fabri, Pietro Nenoff, Jörg Tittelbach and Cornelia Wiegand
Int. J. Mol. Sci. 2025, 26(15), 7090; https://doi.org/10.3390/ijms26157090 - 23 Jul 2025
Viewed by 139
Abstract
Azole resistance in dermatophytes, particularly Trichophyton indotineae, has become a growing global concern. Current antifungal susceptibility testing protocols (EUCAST, CLSI) have limitations in reproducibility and sensitivity. This study aimed to evaluate how medium composition, incubation temperature, and spore concentration influence itraconazole susceptibility [...] Read more.
Azole resistance in dermatophytes, particularly Trichophyton indotineae, has become a growing global concern. Current antifungal susceptibility testing protocols (EUCAST, CLSI) have limitations in reproducibility and sensitivity. This study aimed to evaluate how medium composition, incubation temperature, and spore concentration influence itraconazole susceptibility testing across various dermatophyte species. Thirty-eight clinical isolates representing Trichophyton, Microsporum, and Epidermophyton species were tested using a microplate laser nephelometry system (MLN). IC50 values for itraconazole were determined in three different media (Sabouraud glucose (SG), RPMI-based (RG), and RG supplemented with casein (RGC)) at 28 °C and 34 °C. Effects of spore concentration on growth dynamics and lag phase were also analyzed. SG medium provided clear phenotypic separation between resistant and sensitive isolates. In contrast, RG and RGC showed overlapping IC50 values. Lower spore concentrations revealed underlying growth differences, which were masked at higher inoculum levels. Temperature and media composition significantly affected IC50 outcomes. Genotypic analysis confirmed resistance-associated Erg11B point mutations and genomic amplifications in T. indotineae, particularly in combination with Erg1 mutations, forming distinct subpopulations. SG medium combined with reduced spore concentrations offered improved differentiation of resistant versus sensitive strains. These findings support the development of more accurate susceptibility testing protocols and highlight the need to establish species-specific ECOFF values for dermatophytes. Full article
(This article belongs to the Special Issue Advances in Research on Antifungal Resistance)
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18 pages, 1178 KiB  
Article
Prevalence and Antimicrobial Resistance of Gram-Negative ESKAPE Pathogens Isolated from Tertiary Care Hospital in Eastern India
by Paramjyoti Rana, Sweta Padma Routray, Surajit De Mandal, Rajashree Panigrahy, Anjan Kumar Sahoo and Enketeswara Subudhi
Appl. Sci. 2025, 15(15), 8171; https://doi.org/10.3390/app15158171 - 23 Jul 2025
Viewed by 254
Abstract
Gram-negative ESKAPE pathogens pose major challenges to global public health due to their multidrug resistance and virulence. The present study aimed to study the prevalence and resistance of Gram-negative ESKAPE pathogens at a tertiary care hospital in Eastern India. A retrospective analysis was [...] Read more.
Gram-negative ESKAPE pathogens pose major challenges to global public health due to their multidrug resistance and virulence. The present study aimed to study the prevalence and resistance of Gram-negative ESKAPE pathogens at a tertiary care hospital in Eastern India. A retrospective analysis was conducted on 7343 non-duplicate isolates collected between January 2023 and December 2024. The bacterial isolates and their antibiotic susceptibility testing were identified using Kirby–Bauer disk diffusion techniques and the VITEK 2 Compact system, adhering to CLSI 2025 and EUCAST 2024 guidelines. Our findings indicate that Klebsiella pneumoniae was the most common isolate, followed by Pseudomonas aeruginosa, Acinetobacter baumannii complex, and Enterobacter cloacae complex, predominantly affecting male patients aged 18–64 years. Importantly, most of these isolates exhibit increased multidrug resistance (MDR) to several key antibiotics, including β-lactams and carbapenems, which further complicates the treatment process. The analysis of seasonal dynamics revealed an increased abundance of infections in monsoon and post-monsoon periods. These findings will be useful in understanding AMR in hospital environments and in developing strategies to prevent the occurrence and spread of antimicrobial resistance among pathogens. Full article
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21 pages, 1808 KiB  
Article
The Effect of Semiorganic Iodine-Containing Compounds on the Antibiotic Susceptibility of Pathogenic Microorganisms
by Sabina T. Kenesheva, Seitzhan Turganbay, Ardak B. Jumagaziyeva, Gaukhar Askhatkyzy, Dana A. Askarova, Amir A. Azembayev, Alexandr I. Ilin, Oleg N. Reva and Tatyana A. Karpenyuk
Biomedicines 2025, 13(8), 1790; https://doi.org/10.3390/biomedicines13081790 - 22 Jul 2025
Viewed by 289
Abstract
Objectives: The global rise in multidrug resistance underscores the urgent need for the development of novel and effective antimicrobial agents. Semi-organic iodine-containing complexes, owing to their unique properties, low likelihood of resistance development, and stability under various conditions, represent a promising avenue for [...] Read more.
Objectives: The global rise in multidrug resistance underscores the urgent need for the development of novel and effective antimicrobial agents. Semi-organic iodine-containing complexes, owing to their unique properties, low likelihood of resistance development, and stability under various conditions, represent a promising avenue for the design of new therapeutic strategies. This study describes the synthesis of semi-organic iodine-containing complexes and the in vitro evaluation of their impact on antibiotic susceptibility modulation in the multidrug-resistant pathogenic microorganisms S. aureus and E. coli. Methods: The physicochemical properties of the semiorganic compounds were characterized using UV-Vis spectroscopy, potentiometric, and titrimetric methods. Evaluation of antimicrobial activity was obtained according to CLSI protocols. The impact of semiorganic compounds on the in vitro susceptibility of MDR strains was evaluated by the disk diffusion method. Results: This study evaluated the effects of iodine-containing complexes KC-270 and KC-271 on the antibiotic susceptibility of Staphylococcus aureus BAA-39 and Escherichia coli BAA-196. The most pronounced effect was observed with KC-270 applied during the lag phase, which enhanced the activity of several antibiotics and, in some cases, restored susceptibility. KC-271 exhibited a weaker and more limited impact. The findings suggest that KC-270 has potential as a modulator of antibiotic susceptibility, particularly when administered at early stages of bacterial growth. Conclusions: The results support the ability of amino acid-based iodine coordination compounds to influence the antibiotic susceptibility of pathogenic bacteria, highlighting their potential as adjuvant agents to improve the effectiveness of current antimicrobial therapies. However, although changes in susceptibility were detected, neither compound fully eliminated resistance in the multidrug-resistant strains, indicating the necessity for further research into their mechanisms of action and possible synergistic interactions with antibiotics. Full article
(This article belongs to the Section Microbiology in Human Health and Disease)
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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 342
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
12 pages, 1380 KiB  
Article
Halicin: A New Approach to Antibacterial Therapy, a Promising Avenue for the Post-Antibiotic Era
by Imane El Belghiti, Omayma Hammani, Fatima Moustaoui, Mohamed Aghrouch, Zohra Lemkhente, Fatima Boubrik and Ahmed Belmouden
Antibiotics 2025, 14(7), 698; https://doi.org/10.3390/antibiotics14070698 - 11 Jul 2025
Viewed by 678
Abstract
Background: The global spread of antibiotic-resistant bacteria presents a major public health challenge and necessitates the development of innovative antimicrobial agents. Artificial intelligence (AI)-driven drug discovery has recently enabled the repurposing of existing compounds with novel therapeutic potential. Halicin, originally developed as an [...] Read more.
Background: The global spread of antibiotic-resistant bacteria presents a major public health challenge and necessitates the development of innovative antimicrobial agents. Artificial intelligence (AI)-driven drug discovery has recently enabled the repurposing of existing compounds with novel therapeutic potential. Halicin, originally developed as an anti-diabetic molecule, has been identified through AI screening as a promising antibiotic candidate due to its broad-spectrum activity, including efficacy against multidrug-resistant pathogens. Methods: In this study, the antibacterial activity of halicin was evaluated against a range of clinically relevant multidrug-resistant bacterial strains. Bacterial isolates were first characterized using the agar disk diffusion method with a panel of 22 conventional antibiotics to confirm resistance profiles. The minimum inhibitory concentration (MIC) of halicin was then determined for selected isolates, including Escherichia coli ATCC® 25922™ and Staphylococcus aureus ATCC® 29213™, using broth microdilution according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: Halicin demonstrated notable antibacterial activity, with MIC values of 16 μg/mL and 32 μg/mL against E. coli ATCC® 25922™ and S. aureus ATCC® 29213™, respectively. A dose-dependent inhibition of bacterial growth was observed for the majority of tested isolates, except for Pseudomonas aeruginosa, which exhibited intrinsic resistance. This lack of susceptibility is likely related to reduced outer membrane permeability, limiting the intracellular accumulation of halicin. Conclusions: Our findings support the potential of halicin as a novel antimicrobial agent for the treatment of infections caused by antibiotic-resistant bacteria. However, further investigations, including pharmacokinetic, pharmacodynamic, and toxicity studies, are essential to assess its clinical safety and therapeutic applicability. Full article
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21 pages, 3409 KiB  
Article
Mapping the AMR Infection Landscape in Bihar: Implications for Strengthening Policy and Clinical Practice
by Vinay Modgil, Sundeep Sahay, Neelam Taneja, Burhanuddin Qayyumi, Ravikant Singh, Arunima Mukherjee, Bibekananda Bhoi and Gitika Arora
Antibiotics 2025, 14(7), 684; https://doi.org/10.3390/antibiotics14070684 - 5 Jul 2025
Viewed by 979
Abstract
Background: Antimicrobial resistance (AMR) poses a significant threat to public health, especially in low- and middle-income countries (LMICs), where surveillance infrastructure is underdeveloped. Bihar, India’s third most populous state and one of its least-resourced states, has remained largely absent from national AMR monitoring [...] Read more.
Background: Antimicrobial resistance (AMR) poses a significant threat to public health, especially in low- and middle-income countries (LMICs), where surveillance infrastructure is underdeveloped. Bihar, India’s third most populous state and one of its least-resourced states, has remained largely absent from national AMR monitoring initiatives. Methods: This study aimed to characterize the AMR infection landscape across five public tertiary care hospitals in Bihar over three years (2022–2024) and to assess the feasibility of integrating digital workflows for real-time microbiological reporting. Standardized antimicrobial susceptibility testing (AST) was performed on >48,000 urine, pus, and blood samples using CLSI guidelines. Facility-level data were digitized into an open-source AMR reporting system, enabling automated antibiogram generation. Results: The findings revealed substantial resistance: high resistance to beta-lactams, carbapenems, and fluoroquinolones across pathogens. For instance, E. coli sensitivity to nitrofurantoin varied from 86.5% at NMCH (Patna) to 44.7% at JLNMCH (Bhagalpur), while cephalosporin sensitivity in Klebsiella spp. dropped below 2% in several hospitals. MRSA prevalence exceeded 65% in two facilities, far above the national average of 47.8%. Digital integration led to a four-fold increase in culture testing in all facilities and improved data completeness and turnaround times. Spatial analysis and microbiology laboratory assessment revealed significant geographic disparities in diagnostic access, with facilities in remote districts facing delays of over four hours for basic testing. Conclusions: Our study is the first study from India to create such a broad, facility-associated AMR picture over time at a state level. Policy implications include the need for a state-level AMR surveillance dashboard, alignment of procurement with facility-specific resistance patterns, and routine stewardship audits. Clinically, this study demonstrates the utility of localized antibiograms for guiding empirical therapy in resource-limited settings. This study provides a scalable framework for embedding AMR surveillance into routine health system workflows in LMICs. Full article
(This article belongs to the Special Issue Antibiotic Stewardship Implementation Strategies)
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15 pages, 695 KiB  
Article
In Vitro Susceptibility to Imipenem/Relebactam and Comparators in a Multicentre Collection of Mycobacterium abscessus Complex Isolates
by Alejandro Seoane-Estévez, Pablo Aja-Macaya, Andrea Garcia-Pose, Paula López-Roa, Alba Ruedas-López, Verónica Gonzalez-Galán, Jaime Esteban, Jorge Arca-Suárez, Martín Pampín, Alejandro Beceiro, Marina Oviaño, Germán Bou and on behalf of the GEIM-SEIMC Study Group
Antibiotics 2025, 14(7), 682; https://doi.org/10.3390/antibiotics14070682 - 5 Jul 2025
Viewed by 428
Abstract
Background and Objectives: Infections caused by non-tuberculous mycobacteria (NTM), including Mycobacterium abscessus complex (MABc), are increasing globally and are notoriously difficult to treat due to the intrinsic resistance of these bacteria to many common antibiotics. The aims of this study were to demonstrate [...] Read more.
Background and Objectives: Infections caused by non-tuberculous mycobacteria (NTM), including Mycobacterium abscessus complex (MABc), are increasing globally and are notoriously difficult to treat due to the intrinsic resistance of these bacteria to many common antibiotics. The aims of this study were to demonstrate the in vitro activity of imipenem/relebactam against MABc clinical isolates and to determine any in vitro synergism between imipenem/relebactam and other antimicrobials. Methods: A nationwide collection of 175 MABc clinical respiratory isolates obtained from 24 hospitals in Spain (August 2022–April 2023) was studied. Fifteen different antimicrobial agents were comprised, including imipenem/relebactam. MICs were determined according to CLSI criteria, and the synergism studies were performed with the selected clinical isolates. Results: Of the 175 isolates obtained, 110 were identified as M. abscessus subsp. abscessus (62.9%), 51 as M. abscessus subsp. massiliense (29.1%), and 14 as M. abscessus subsp. bolleti (8%). The antibiotics yielding the highest susceptibility rates were tigecycline, eravacycline, and omadacycline (100%); followed by imipenem/relebactam and clofazimine (97.6%); and finally amikacin (94.6%). Only four isolates were resistant to imipenem/relebactam, three of which were further characterized by WGS, revealing MABc mutations in BlaMab as well as D,D- and L,D-transpeptidades and mspA porin, which may play an important role in reduced susceptibility to imipenem/relebactam, even though none were previously described or associated with resistance to β-lactams. Conclusions: Our data demonstrate that relebactam improved the anti-MABc activity of imipenem, representing a β-lactam for the treatment of MABc infections. Furthermore, imipenem/relebactam demonstrated in vitro synergism with other anti-MABc treatments, thus supporting its use as part of dual regimens. Full article
(This article belongs to the Section Novel Antimicrobial Agents)
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9 pages, 457 KiB  
Communication
Antimicrobial Susceptibility Testing of the Combination of Aztreonam and Avibactam in NDM-Producing Enterobacterales: A Comparative Evaluation Using the CLSI and EUCAST Methods
by Linda Mei-Wah Chan, Doris Yui Ling Lok, River Chun Wai Wong, Alfred Lok-Hang Lee, Ingrid Yu-Ying Cheung, Christopher Koon-Chi Lai and Viola C. Y. Chow
Antibiotics 2025, 14(7), 675; https://doi.org/10.3390/antibiotics14070675 - 3 Jul 2025
Viewed by 487
Abstract
Background: The combination of aztreonam (ATM) and avibactam (AVI) presents an important therapeutic option for carbapenem-resistant Enterobacterales, particularly the NDM-producing Enterobacterales. In 2024, both the CLSI and EUCAST published their methods in antimicrobial susceptibility testing for this combination of agents. [...] Read more.
Background: The combination of aztreonam (ATM) and avibactam (AVI) presents an important therapeutic option for carbapenem-resistant Enterobacterales, particularly the NDM-producing Enterobacterales. In 2024, both the CLSI and EUCAST published their methods in antimicrobial susceptibility testing for this combination of agents. Materials and Methods: Forty carbapenem-resistant Enterobacterales isolates, including Escherichia coli (n = 35), Enterobacter cloacae complex (n = 2), Klebsiella pneumoniae complex (n = 2), and Citrobacter freundii complex (n = 1) were included in this study. All isolates harbored the NDM carbapenemase except one, which had no known detected carbapenemases. Four antimicrobial susceptibility testing methods of the combination of ATM and AVI were evaluated on these isolates, including the CLSI broth disk elution (BDE) method, the disk diffusion (DD) method of aztreonam–avibactam (AZA) following the EUCAST breakpoints, the MIC test strip (MTS) method of AZA following the EUCAST breakpoints, and the gradient strip stacking (SS) method. BDE was used as the standard of comparison. Results: Using BDE as the standard of comparison, the AZA DD, AZA MTS, and SS methods had 100% categorical agreement (CA), 0% very major error (VME), and 0% major error (ME). The essential agreement (EA) between the AZA MTS and SS method was 57.5%. Conclusions: The AZA DD, AZA MTS, and the SS methods showed complete concordance with the BDE method. However, the MICs obtained from the AZA MTS and SS were not comparable. Full article
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12 pages, 1312 KiB  
Article
Antimicrobial Resistance in the Aconcagua River, Chile: Prevalence and Characterization of Resistant Bacteria in a Watershed Under High Anthropogenic Contamination Pressure
by Nicolás González-Rojas, Diego Lira-Velásquez, Richard Covarrubia-López, Johan Plaza-Sepúlveda, José M. Munita, Mauricio J. Carter and Jorge Olivares-Pacheco
Antibiotics 2025, 14(7), 669; https://doi.org/10.3390/antibiotics14070669 - 2 Jul 2025
Viewed by 448
Abstract
Background: Antimicrobial resistance (AMR) is a growing global health concern, driven in part by the environmental release of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). Aquatic systems, particularly those exposed to urban, agricultural, and industrial activity, are recognized as hotspots for [...] Read more.
Background: Antimicrobial resistance (AMR) is a growing global health concern, driven in part by the environmental release of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). Aquatic systems, particularly those exposed to urban, agricultural, and industrial activity, are recognized as hotspots for AMR evolution and transmission. In Chile, the Aconcagua River—subject to multiple anthropogenic pressures—offers a representative model for studying the environmental dimensions of AMR. Methods: Thirteen surface water samples were collected along the Aconcagua River basin in a single-day campaign to avoid temporal bias. Samples were filtered through 0.22 μm membranes and cultured on MacConkey agar, either unsupplemented or supplemented with ceftazidime (CAZ) or ciprofloxacin (CIP). Isolates were purified and identified using MALDI-TOF mass spectrometry. Antibiotic susceptibility was evaluated using the Kirby–Bauer disk diffusion method in accordance with CLSI guidelines. Carbapenemase activity was assessed using the Blue-Carba test, and PCR was employed for the detection of the blaVIM, blaKPC, blaNDM, and blaIMP genes. Results: A total of 104 bacterial morphotypes were isolated; 80 were identified at the species level, 5 were identified at the genus level, and 19 could not be taxonomically assigned using MALDI-TOF. Pseudomonas (40 isolates) and Aeromonas (25) were the predominant genera. No growth was observed on CIP plates, while 24 isolates were recovered from CAZ-supplemented media, 87.5% of which were resistant to aztreonam. Five isolates exhibited resistance to carbapenems; two tested positive for carbapenemase activity and carried the blaVIM gene. Conclusions: Our results confirm the presence of clinically significant resistance mechanisms, including blaVIM, in environmental Pseudomonas spp. from the Aconcagua River. These findings highlight the need for environmental AMR surveillance and reinforce the importance of adopting a One Health approach to antimicrobial stewardship and wastewater regulation. Full article
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15 pages, 433 KiB  
Article
In Vitro Activity of Novel β-Lactam/β-Lactamase Inhibitors Against Carbapenem-Resistant Pseudomonas aeruginosa and Enterobacterales in Korea
by Seulgi Moon, Jongyoun Yi, Mee Kyung Ko, Yong Ki Sim and Kye-Hyung Kim
Antibiotics 2025, 14(7), 649; https://doi.org/10.3390/antibiotics14070649 - 26 Jun 2025
Viewed by 392
Abstract
Background/Objectives: Carbapenem-resistant Enterobacterales (CRE) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) are challenging multidrug-resistant pathogens. This study evaluated the in vitro susceptibility of CRE and CRPA blood isolates from Korea to novel β-lactam/β-lactamase inhibitor combinations: ceftolozane/tazobactam (C/T), ceftazidime/avibactam (CZA), imipenem/cilastatin/relebactam (IMR), and meropenem/vaborbactam (MEV). Methods: [...] Read more.
Background/Objectives: Carbapenem-resistant Enterobacterales (CRE) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) are challenging multidrug-resistant pathogens. This study evaluated the in vitro susceptibility of CRE and CRPA blood isolates from Korea to novel β-lactam/β-lactamase inhibitor combinations: ceftolozane/tazobactam (C/T), ceftazidime/avibactam (CZA), imipenem/cilastatin/relebactam (IMR), and meropenem/vaborbactam (MEV). Methods: Blood isolates of CRE (n = 55) and CRPA (n = 65) collected between September 2017 and September 2022 in a Korean tertiary hospital were included. Carbapenemase production was determined using phenotypic and molecular methods. In vitro susceptibility to C/T, CZA, IMR, and MEV was determined primarily by broth microdilution using current CLSI/EUCAST breakpoints. Clinical characteristics and in-hospital mortality were retrospectively reviewed. Results: Among non-carbapenemase-producing (non-CP) CRPA isolates (n = 47), susceptibility rates were 83.0% to C/T and 70.2% to CZA. For KPC-producing CRE isolates (n = 28), susceptibility rates were high to CZA (92.9%), IMR (82.1%), and MEV (96.4%). However, non-CP CRE isolates (n = 22) showed low susceptibility to C/T (18.2%) but high susceptibility to CZA (100%), IMR (81.8%), and MEV (95.5%). CRE infections were associated with higher rates of hematologic malignancy, immunosuppression, and in-hospital mortality (63.6% vs. 18.5% for CRPA, p < 0.001). Conclusions: The susceptibility of CRE and CRPA to novel β-lactam/β-lactamase inhibitors varies significantly by species and carbapenemase production. CZA, IMR, and MEV showed promising activity against KPC-producing CRE. These findings can inform empirical therapy and stewardship efforts in Korea. Full article
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11 pages, 694 KiB  
Article
In Vitro Therapeutic Efficacy of Furazolidone for Antimicrobial Susceptibility Testing on Campylobacter
by Jeel Moya-Salazar, Alfonso Terán-Vásquez, Richard Salazar-Hernandez, Víctor Rojas-Zumaran, Eliane A. Goicochea-Palomino, Marcia M. Moya-Salazar and Hans Contreras-Pulache
Antibiotics 2025, 14(7), 636; https://doi.org/10.3390/antibiotics14070636 - 22 Jun 2025
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Abstract
Background: Campylobacter causes gastroenteritis worldwide with increasing antimicrobial resistance. Furazolidone (FZD) shows potential in resource-poor areas but needs further study. We aimed to assess the in vitro susceptibility of Campylobacter spp. to FZD, ciprofloxacin (CIP), and erythromycin (ERY) in a high-risk pediatric [...] Read more.
Background: Campylobacter causes gastroenteritis worldwide with increasing antimicrobial resistance. Furazolidone (FZD) shows potential in resource-poor areas but needs further study. We aimed to assess the in vitro susceptibility of Campylobacter spp. to FZD, ciprofloxacin (CIP), and erythromycin (ERY) in a high-risk pediatric cohort and to evaluate the clinical relevance of resistance patterns using inhibitory quotient (IQ) pharmacodynamics. Methods: A two-phase prospective study (2012–2013, 2014–2015) was conducted at a tertiary pediatric hospital in Lima, Peru. Stool samples from children ≤24 months were cultured on selective media, with Campylobacter isolates identified via conventional bacteriological methods. Antimicrobial susceptibility was determined using Kirby–Bauer disk diffusion and regression-derived minimum inhibitory concentrations (MICs). IQ analysis correlated inhibition zones with therapeutic outcomes. Results: Among 194 Campylobacter isolates (C. jejuni: 28%; C. coli: 72%), resistance to CIP declined from 97.7% (2012–2013) to 83% (2014–2015), while ERY resistance rose from 2.3% to 9.4% (p= 0.002). No FZD resistance was observed, with mean inhibition zones of 52 ± 8 mm (2012–2013) and 43 ± 10.5 mm (2014–2015). MICs for FZD were predominantly <0.125 μg/mL, and all susceptible isolates demonstrated favorable IQ outcomes. Multidrug resistance (≥2 drugs) increased to 6.2% (2014–2015), though all MDR strains retained FZD susceptibility. CLSI and EUCAST breakpoints showed concordance for ERY (p = 0.724) but discordance for CIP (p = 0.022 vs. 0.008). Conclusions: FZD exhibits sustained in vitro efficacy against Campylobacter spp., even among MDR strains, contrasting with escalating fluoroquinolone and macrolide resistance. Full article
(This article belongs to the Section Antibiotics Use and Antimicrobial Stewardship)
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13 pages, 904 KiB  
Article
Species Distribution and Antifungal Susceptibility Patterns of Invasive Candidiasis in a Belgian Tertiary Center: A 7-Year Retrospective Analysis
by Sarah Cugnata, Rosalie Sacheli, Nathalie Layios and Marie-Pierre Hayette
J. Fungi 2025, 11(6), 465; https://doi.org/10.3390/jof11060465 - 19 Jun 2025
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Abstract
Candidiasis is a major fungal infection worldwide, with invasive forms linked to high morbidity and mortality. The emergence of azole resistance in Candida parapsilosis causing candidemia led us to examine the epidemiology and antifungal susceptibility of Candida species at the University Hospital of [...] Read more.
Candidiasis is a major fungal infection worldwide, with invasive forms linked to high morbidity and mortality. The emergence of azole resistance in Candida parapsilosis causing candidemia led us to examine the epidemiology and antifungal susceptibility of Candida species at the University Hospital of Liège between January 2017 and December 2023. A total of 916 isolates from blood or sterile body fluids, tissues, and abscesses were analyzed. Species identification was performed using MALDI-TOF MS and antifungal susceptibility testing via Sensititre YO10 AST was interpreted according to the CLSI guidelines. Candida albicans remained the predominant species (56%), followed by Nakaseomyces glabratus (19%), Candida parapsilosis (8%), and Candida tropicalis (7%). No significant shift toward non-albicans Candida species (NAC) was observed even during the COVID-19 pandemic, supporting the use of narrow-spectrum empirical therapy in selected patients. Fluconazole susceptibility was high in C. albicans (98.8%), whereas N. glabratus and C. tropicalis showed high resistance rates with 10.1% and 16.9%, respectively. C. parapsilosis showed stable fluconazole susceptibility across the study period. Echinocandins demonstrated excellent activity (95.6–100%), and amphotericin B was effective against nearly all isolates. This seven-year surveillance at the University Hospital of Liège confirms that while C. albicans remains the predominant and highly susceptible species, rising azole resistance in non-albicans Candida—particularly N. glabratus and C. tropicalis—highlights the critical need for ongoing local epidemiological monitoring to guide effective and targeted antifungal therapy. Full article
(This article belongs to the Special Issue Personalized Mycology)
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