Antibiotics

21 pages, 7339 KiB

Open AccessArticle

In Vitro Analysis of Interactions Between Staphylococcus aureus and Pseudomonas aeruginosa During Biofilm Formation

by Julia Scaffo, Rayssa Durães Lima, Cameron Dobrotka, Tainara A. N. Ribeiro, Renata F. A. Pereira, Daniela Sachs, Rosana B. R. Ferreira and Fabio Aguiar-Alves

Antibiotics 2025, 14(5), 504; https://doi.org/10.3390/antibiotics14050504 - 14 May 2025

Abstract

Staphylococcus aureus and Pseudomonas aeruginosa are classified as ESKAPE pathogens that present a significant challenge to treatment due to their increased resistance to a considerable number of antimicrobial agents. Background/Objective: Biofilms exacerbate treatment challenges by providing enhanced antimicrobial and environmental protection. Mixed-species [...] Read more.

Staphylococcus aureus and Pseudomonas aeruginosa are classified as ESKAPE pathogens that present a significant challenge to treatment due to their increased resistance to a considerable number of antimicrobial agents. Background/Objective: Biofilms exacerbate treatment challenges by providing enhanced antimicrobial and environmental protection. Mixed-species biofilms further complicate treatment options through numerous complex interspecies interactions, leading to potentially severe adverse clinical outcomes. Methods: This study assessed the interaction between clinical S. aureus and P. aeruginosa isolates during biofilm formation using microplate biofilm formation assays, scanning electron microscopy, and confocal microscopy. Results: We identified a competitive relationship between P. aeruginosa and S. aureus, where both pathogens exhibited a reduction in biofilm formation during mixed-species biofilms compared with monocultures, although P. aeruginosa outcompeted S. aureus. Furthermore, we found that the cell-free conditioned media (CFCM) of P. aeruginosa significantly reduced the S. aureus biofilms. Using fractioned CFCM, we identified that the anti-staphylococcal activity of the >10 kDa fraction was almost identical to the non-fractioned CFCM. Our confocal microscopy results suggest that P. aeruginosa CFCM depolarize S. aureus membranes and reduces the biofilm burden. Conclusions: These findings contribute to our understanding of the mechanisms underlying the interactions between these pathogens, suggesting that there is an antagonistic relationship between S. aureus and P. aeruginosa in a biofilm setting. Full article

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

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34 pages, 708 KiB

Open AccessReview

Essential Oils for Biofilm Control: Mechanisms, Synergies, and Translational Challenges in the Era of Antimicrobial Resistance

by Abdelaziz Touati, Assia Mairi, Nasir Adam Ibrahim and Takfarinas Idres

Antibiotics 2025, 14(5), 503; https://doi.org/10.3390/antibiotics14050503 - 13 May 2025

Abstract

Biofilms, structured microbial consortia embedded in self-produced extracellular matrices, pose significant challenges across the medical, industrial, and environmental sectors due to their resistance to antimicrobial therapies and ability to evade the immune system. Their resilience is driven by multifaceted mechanisms, including matrix-mediated drug [...] Read more.

Biofilms, structured microbial consortia embedded in self-produced extracellular matrices, pose significant challenges across the medical, industrial, and environmental sectors due to their resistance to antimicrobial therapies and ability to evade the immune system. Their resilience is driven by multifaceted mechanisms, including matrix-mediated drug sequestration, metabolic dormancy, and quorum sensing (QS)-regulated virulence, which collectively sustain persistent infections and contribute to the amplification of antimicrobial resistance (AMR). This review critically examines the potential of plant-derived essential oils (EOs) as innovative agents for biofilm control. EOs exhibit broad-spectrum antibiofilm activity through multi-target mechanisms, including disrupting initial microbial adhesion, degrading extracellular polymeric substances (EPSs), suppressing QS pathways, and compromising membrane integrity. Their ability to act synergistically with conventional antimicrobials at sub-inhibitory concentrations enhances therapeutic efficacy while reducing the selection pressure for resistance. Despite their potential, EO applications face technical challenges, such as compositional variability due to botanical sources, formulation stability issues, and difficulties in standardization for large-scale production. Clinical translation is further complicated by biofilm stage- and strain-dependent efficacy, insufficient in vivo validation of therapeutic outcomes, and potential cytotoxicity at higher doses. These limitations underscore the need for optimized delivery systems, such as nanoencapsulation, to enhance bioavailability and mitigate adverse effects. Future strategies should include combinatorial approaches with antibiotics or EPS-degrading enzymes, advanced formulation technologies, and standardized protocols to bridge laboratory findings to clinical practice. By addressing these challenges, EOs hold transformative potential to mitigate biofilm-associated AMR, offering sustainable, multi-target alternatives for infection management and biofilm prevention in diverse contexts. Full article

(This article belongs to the Special Issue Essential Oil of the Plants: Chemical Composition, Antimicrobial Activity, and Biological Applications)

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25 pages, 1114 KiB

Open AccessArticle

Molecular Detection of Antibiotic Resistance Genes Using Respiratory Sample from Pneumonia Patients

by Eman Abdullah Alsuof, Ahmad R. Alsayed, Manar Saleh Zraikat, Heba A. Khader, Luai Z. Hasoun, Mamoon Zihlif, Osama Abu Ata, Malek A. Zihlif, Mahmoud Abu-Samak and Mohammed Al Maqbali

Antibiotics 2025, 14(5), 502; https://doi.org/10.3390/antibiotics14050502 - 13 May 2025

Abstract

Introduction/Objectives: Antibiotic resistance makes the treatment of pneumonia challenging. Effective management depends on accurate diagnostic techniques to identify resistance genes and customize drugs. This study primarily aimed to identify antibiotic resistance genes in respiratory samples from patients with pneumonia using polymerase chain reaction [...] Read more.

Introduction/Objectives: Antibiotic resistance makes the treatment of pneumonia challenging. Effective management depends on accurate diagnostic techniques to identify resistance genes and customize drugs. This study primarily aimed to identify antibiotic resistance genes in respiratory samples from patients with pneumonia using polymerase chain reaction (PCR) to determine the prevalence of specific resistance genes and analyze clinical factors contributing to antibiotic resistance, as well as to provide actionable insights into resistance patterns in Jordan and support efforts to improve pneumonia management. Methods: This retrospective observational study included 114 patients who were diagnosed with pneumonia. Clinical data, including prior antibiotic exposure and treatment history, were collected. PCR diagnostics were used to detect resistance genes in respiratory samples. In this study, we evaluated 14 antibiotic resistance genes in pneumonia pathogens, highlighting their diverse resistance mechanisms. Results: Mec A was the most frequently detected gene, appearing in 87 samples (77.3%). Additionally, Tem in 80 samples (70.2%), Oxa-48-like in 15 samples (13.2%), and Ctx-M-1 in 38 samples (33.3%) were among the most commonly detected genes. In contrast, Oxa-40-like (7.0%), Vim (8.8%), and Imp (4.4%) genes exhibited a lower prevalence. The Oxa-51-like gene showed the only significant association with ertapenem resistance (p-value = 0.046). Further analysis revealed statistically significant associations between Mec A and methicillin resistance (p < 0.001), underscoring its critical role. However, other genes, such as Oxa-40-like and Oxa-48-like, showed no significant correlation with the antibiotic resistance patterns of imipenem and meropenem (p > 0.05). Conclusions: This study demonstrates the utility of PCR-based diagnostics for detecting resistance genes and highlights the critical clinical factors associated with antibiotic resistance in patients with pneumonia. These findings underscore the importance of integrating molecular diagnostics into routine care to improve treatment outcomes and combat the growing threat of antibiotic resistance in Jordan. This highlights PCR’s value in guiding effective treatment strategies and addressing multidrug-resistant pneumonia. Full article

(This article belongs to the Special Issue Epidemiology and Mechanism of Bacterial Resistance to Antibiotics)

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16 pages, 1794 KiB

Open AccessArticle

Dose-Dependent Physiological Response to Transient Bioaccumulation of Tetracycline in Kimchi Cabbage (Brassica campestris L.)

by Hadjer Chohra, Keum-Ah Lee, Hyeonji Choe, Ju Young Cho, Vimalraj Kantharaj, Mi Sun Cheong, Young-Nam Kim and Yong Bok Lee

Antibiotics 2025, 14(5), 501; https://doi.org/10.3390/antibiotics14050501 - 13 May 2025

Abstract

Background/Objectives: Globally, antibiotic contamination has become an emerging issue in agricultural lands. The presence of antibiotic residues in farmlands, especially through the application of manure fertilizers containing veterinary antibiotics, e.g., tetracycline (TC), can cause severe toxicity, which inhibits crop growth and performance, subsequently [...] Read more.

Background/Objectives: Globally, antibiotic contamination has become an emerging issue in agricultural lands. The presence of antibiotic residues in farmlands, especially through the application of manure fertilizers containing veterinary antibiotics, e.g., tetracycline (TC), can cause severe toxicity, which inhibits crop growth and performance, subsequently threatening human health via consumption of contaminated products. This study was conducted to evaluate the phytotoxicity of TC on Kimchi cabbage (Brassica campestris L.) during seed germination, seedling, and vegetative growth stages, along with its physiological responses and bioaccumulation under TC stress. Methods: The responses of cabbage plants to TC stress were assessed through a germination test and a pot experiment, conducted for three days and six weeks, respectively, under different doses of TC (0, 5, 10, 25, and 50 mg/L). Results: As a result of the germination test, higher TC doses (25 and 50 mg/L) tended to delay seed germination, but all treatments achieved a 100% germination percentage by Day 3 after sowing. Eight days after sowing, the length of shoots and roots of seedlings exhibited a TC dose-dependent decline, specifically under 50 mg TC/L, showing a considerable decrease of 24% and 77%, respectively, compared to control. Similar results were observed in the plants transitioning from the seedling to vegetative stages in the pot experiment. Four and six weeks after sowing, the 50 mg TC/L dose showed the strongest phytotoxicity in cabbage plants with physiological parameters, such as the maximum photosystem II quantum yield (F_v/F_m), pigment content (chlorophyll and carotenoid), biomass, and leaf number, significantly reduced by 26 to 60% compared to control. Interestingly, at lower TC doses (5 and 10 mg/L), a hormesis effect was observed in the phenotype and biomass of the plants. In addition, the degree of TC accumulation in the plants was highly dose-dependent at Week 4 and Week 6, but a temporal decline in TC accumulation was noted between these time points in all TC treatments. This phenomenon might affect the value of the bio-concentration factor (BCF) as an indicator of the plant’s tendency to uptake TC. That is, in Week 6, the dose-dependent reduction in BCF for TC in the plants was likely attributed to a dilution effect caused by plant biomass increase or a degradation mechanism within the plant. Conclusions: Overall, our findings suggest that tetracycline toxicity induces seed germination delay and influences seedling elongation and photosynthetic functions, ultimately impairing crop growth and performance. Also, the antibiotic dynamics related to accumulation and degradation in plants were identified. These results will not only suggest the toxicity threshold of TC for cabbage but also provide insights into effective soil management strategies for food production safety and agroecosystem sustainability in antibiotic-contaminated soils. Full article

(This article belongs to the Special Issue Environmental Fate and Effects of Antibiotics and Antibiotic Resistance Genes, 2nd Edition)

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11 pages, 998 KiB

Open AccessArticle

Multiple Copies of Tigecycline Gene Cluster tmexC6D6-toprJ1b in Pseudomonas mendocina in a Swine Farm

by Renjie Wu, Yongliang Che, Longbai Wang, Qiuyong Chen, Bing He, Jingli Qiu, Xuemin Wu, Rujing Chen, Yutao Liu and Lunjiang Zhou

Antibiotics 2025, 14(5), 500; https://doi.org/10.3390/antibiotics14050500 - 13 May 2025

Abstract

Background/Objectives: The emergence and transmission of the tigecycline resistance efflux pump gene cluster tmexCD-toprJ among humans, animals and the environment have posed a serious threat to public health. The objective of this study was to characterize Pseudomonas strains carrying multiple copies of tmexC6D6-toprJ1b [...] Read more.

Background/Objectives: The emergence and transmission of the tigecycline resistance efflux pump gene cluster tmexCD-toprJ among humans, animals and the environment have posed a serious threat to public health. The objective of this study was to characterize Pseudomonas strains carrying multiple copies of tmexC6D6-toprJ1b from a pig farm and illustrate the genetic context of tmexC6D6-toprJ1b in the NCBI database. Methods: The characterization of Pseudomonas strains FJFQ21PNM23 and FJFQ21PNM24 was determined by antimicrobial susceptibility testing, whole-genome sequencing, and RT-qPCR. Results: The tmexCD-toprJ-positive P. mendocina strains FJFQ21PNM23 and FJFQ21PNM24 were isolated from nasal swabs in a pig farm. Sequence analysis showed that the two P. mendocina strains harbored multiple antimicrobial resistance genes, including tigecycline resistance gene tmexC6D6-toprJ1b. WGS analysis indicated that tmexC6D6-toprJ1b gene was located on a classical transferable module (int1-int2-hp1-hp2-tnfxB-tmexCD-toprJ) and a multiresistance region in FJFQ21PNM24 and FJFQ21PNM23, respectively. Further analysis revealed that 39 additional tmexC6D6-toprJ1b genes in the NCBI database were all identified in Pseudomonas spp., and the genetic features of tmexC6D6-toprJ1b were summarized into three distinct structures. Conclusions: This study is the first to identify and report the tigecycline resistance gene tmexCD-toprJ in a swine farm. Our findings summarize the three structures in the genetic context of tmexC6D6-toprJ1b and reveal that Pseudomonas serves as the only known reservoir of tmexC6D6-toprJ1b. Full article

(This article belongs to the Special Issue Antimicrobial Susceptibility of Veterinary Origin Bacteria)

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14 pages, 3408 KiB

Open AccessArticle

Antifungal Effects of the Phloroglucinol Derivative DPPG Against Pathogenic Aspergillus fumigatus

by Liyang Wang, Junying He, Hanzhong Feng, Qian Li, Meirong Song, Haoran Gou, Yongxing He and Kui Zhu

Antibiotics 2025, 14(5), 499; https://doi.org/10.3390/antibiotics14050499 - 13 May 2025

Abstract

Background: Fungal infections pose an increasingly predominant threat to human and animal health. Modified compounds derived from chemo-diverse natural products offer enhanced therapeutic efficacies and promising approaches to combat life-threatening fungal pathogens. Methods: We performed biosynthetic gene clusters analysis of 2,4-diacetylchloroglucoside (DAPG) in [...] Read more.

Background: Fungal infections pose an increasingly predominant threat to human and animal health. Modified compounds derived from chemo-diverse natural products offer enhanced therapeutic efficacies and promising approaches to combat life-threatening fungal pathogens. Methods: We performed biosynthetic gene clusters analysis of 2,4-diacetylchloroglucoside (DAPG) in 4292 shotgun metagenomes samples from the healthy and diseased skin. Then, we assessed the antifungal activity of DAPG and the derivative 2,4-diproylphloroglucinol (DPPG) against pathogenic fungi by minimum inhibitory concentrations. The inhibitory effects of DPPG were measured using hyphal growth assay and spore germination assay. Concurrently, the mechanism of DPPG on Aspergillus fumigatus was investigated in membrane permeability and fluidity. The therapeutic efficacy was evaluated in a Galleria mellonella infection model. Results: We observed a significantly higher abundance of bacteria harboring DAPG biosynthetic clusters on healthy skin compared to diseased skin. Further, we designed and synthesized a series of phloroglucinol derivatives based on DAPG and obtained an antifungal candidate DPPG. DPPG not only exhibited robust antifungal activity against Aspergillus spp. and Candida spp. but also impaired hyphal growth and spore germination of A. fumigatus in vitro. A mechanism study showed that DPPG reduced membrane fluidity and increased the leakage of cellular contents, resulting in membrane perturbation and fungal death. Lastly, the therapeutic efficacy of DPPG was confirmed in a G. mellonella infection model. Conclusions: Our study demonstrates that DPPG is a potent scaffold to combat invasive fungal infections. Full article

(This article belongs to the Special Issue Discovery and Development of Novel Antibacterial Agents—2nd Edition)

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11 pages, 3006 KiB

Open AccessArticle

A Pilot Study in Humans on the Urinary Tract Excretion of the FimH Inhibitor 1-Deoxymannose

by Hiromi Hayashi, Naoto Miyazaki, Takuya Kawakami, Shusaku Izumi and Kazuhiro Yoshinaga

Antibiotics 2025, 14(5), 498; https://doi.org/10.3390/antibiotics14050498 - 13 May 2025

Abstract

Background: FimH inhibitors are anticipated to serve as preventive therapeutics against urinary tract infections. Consequently, multiple inhibitors—predominantly D-mannose derivatives—have been synthesized, and their binding affinities (determined by dissociation coefficient; K_D) to FimH have been examined in vitro. Nevertheless, the amounts [...] Read more.

Background: FimH inhibitors are anticipated to serve as preventive therapeutics against urinary tract infections. Consequently, multiple inhibitors—predominantly D-mannose derivatives—have been synthesized, and their binding affinities (determined by dissociation coefficient; K_D) to FimH have been examined in vitro. Nevertheless, the amounts of most of these synthetic compounds that reach the urinary tract after oral administration in humans have not been investigated. D-mannose (Man) and its analog, 1-Deoxymannose (DM), have already been reported to show K_D values against FimH. Therefore, this study aimed to estimate the post-oral ingestion of FimH inhibitory potentials of DM and Man in the urinary tract. Methods: Six participants were given single 1 g doses of DM and Man in a crossover test. The sample concentrations in urine were measured 8 h after ingestion. Results: DM levels increased rapidly after oral intake; contrarily, Man was detected in the urine before administration, with no notable increase post-ingestion. The peak concentration ranges of Man and DM in urine were 2.15–22.9 μg/mL and 665–57,804 μg/mL, respectively, which are 66.3–707 and 3600–31,200 times that of K_D, respectively. Conclusions: These results indicate that DM as a supplement is an orally active FimH inhibitor in the human urinary tract. Conversely, d-mannose is expected to exert comparatively milder inhibition. Full article

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11 pages, 1691 KiB

Open AccessArticle

Evaluation of Adjunctive Aminoglycoside Therapy Compared to β-Lactam Monotherapy in Critically Ill Patients with Gram-Negative Bloodstream Infections

by Joshua Eudy, Aaron M. Chase, Divisha Sharma, Zoheb Irshad Sulaiman, August Anderson, Ashley Huggett, Lucy Gloe and Daniel T. Anderson

Antibiotics 2025, 14(5), 497; https://doi.org/10.3390/antibiotics14050497 - 13 May 2025

Abstract

Background/Objectives: Gram-negative bloodstream infections (GN-BSIs) in the critically ill carry significant mortality, which is exacerbated by delays in appropriate therapy. To improve the time to effective therapy, aminoglycosides are often recommended as empiric adjunctive antimicrobials. However, there is a paucity of clinical [...] Read more.

Background/Objectives: Gram-negative bloodstream infections (GN-BSIs) in the critically ill carry significant mortality, which is exacerbated by delays in appropriate therapy. To improve the time to effective therapy, aminoglycosides are often recommended as empiric adjunctive antimicrobials. However, there is a paucity of clinical data supporting this practice. This study’s objective was to evaluate the safety and efficacy of adjunctive aminoglycosides compared to β-lactam monotherapy in patients admitted to the intensive care unit (ICU) with GN-BSI. Methods: This was a retrospective, propensity-matched cohort study of critically ill patients with GN-BSI. The primary outcome was 15-day all-cause mortality. The secondary endpoints evaluated included 30-day mortality, ICU-free survival days, 60-day relapse, 30-day readmission, development of acute kidney injury (AKI), and new resistance. Results: A total of 209 propensity-matched patients were included for analysis: 136 received β-lactam monotherapy and 73 received adjunctive aminoglycoside. The primary outcome of 15-day all-cause mortality was not significantly different between groups (17% vs. 21%; p = 0.644). Additional secondary endpoints of 30-day mortality (22% vs. 25%), ICU-free survival (12.1 vs. 12.2 days), 60-day relapse (3.3% vs. 7.4%), and 30-day readmission (23% vs. 18%) did not yield significant differences. The proportion of AKI was higher in the adjunctive aminoglycoside group but was not found to be significantly different (26.5% vs. 37%). Conclusions: The use of adjunctive aminoglycosides for GN-BSI did not affect clinical outcomes in the critically ill. Full article

(This article belongs to the Special Issue Antimicrobial Resistance in Clinical Infection and Antibiotic Stewardship)

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16 pages, 1873 KiB

Open AccessArticle

Antimicrobial Susceptibility Profiles of Staphylococcus aureus and Streptococcus spp. Isolates from Clinical Cases of Waterfowl in Hungary Between 2022 and 2023

by Ádám Kerek, Ábel Szabó and Ákos Jerzsele

Antibiotics 2025, 14(5), 496; https://doi.org/10.3390/antibiotics14050496 - 12 May 2025

Abstract

Background: Antimicrobial resistance (AMR) is an escalating concern in both human and veterinary medicine, particularly in the poultry sector, where antibiotic usage is substantial. Streptococcus spp. and Staphylococcus aureus are important pathogens in waterfowl, causing systemic infections. However, there is a significant [...] Read more.

Background: Antimicrobial resistance (AMR) is an escalating concern in both human and veterinary medicine, particularly in the poultry sector, where antibiotic usage is substantial. Streptococcus spp. and Staphylococcus aureus are important pathogens in waterfowl, causing systemic infections. However, there is a significant lack of data regarding their antimicrobial susceptibility patterns in waterfowl populations. This study aims to address this gap by determining the minimum inhibitory concentrations (MICs) of isolates from Hungarian waterfowl farms and evaluating resistance patterns in clinical isolates. Methods: A total of eight S. aureus and 19 Streptococcus isolates were collected from ducks and geese between 2022 and 2023. Antimicrobial susceptibility testing was performed for 15 antimicrobials using the broth microdilution method. Potential associations between MIC values were analyzed using Spearman’s rank correlation test. Results: High MIC values were observed for tetracyclines, phenicols, and fluoroquinolones, in the case of Streptococcus, with 89.5% of isolates exhibiting resistance to doxycycline, 63.2% to florfenicol, and in the case of S. aureus, 25.0% to enrofloxacin. In the case of Streptococcus, a strong positive correlation was identified between tylosin and tiamulin (0.88, p < 0.001), as well as between tylosin and lincomycin (0.75, p < 0.001). A moderate correlation was observed between doxycycline and spectinomycin (0.72, p = 0.03), suggesting potential co-selection mechanisms. Conclusions: Our findings emphasize the necessity of continuous AMR surveillance in the waterfowl industry, particularly for multidrug-resistant strains. Understanding cross-resistance patterns is crucial for developing targeted control measures, and future studies should incorporate whole-genome sequencing to elucidate resistance determinants and co-selection mechanisms. This study highlights the potential public health and veterinary risks associated with AMR in waterfowl and reinforces the importance of responsible antibiotic use and the development of alternative therapeutic strategies in veterinary practice. Full article

(This article belongs to the Special Issue Virulence, Antimicrobial Resistance and Biofilm Production in Veterinary, Zoonotic and Food-Related Pathogens)

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22 pages, 3117 KiB

Open AccessArticle

New Curcumin Analogue (PAC) Inhibits Candida albicans Virulence, Restricts Its Adhesion Potential, and Relieves Oral Epithelial Cell Inflammation and Defense Mechanisms

by Ghazoua Mezni, Hawraa Issa, Manal Dahdah, Anaïs Poulin, Adam Daïch, Abdulaziz Alamri, Mahmoud Rouabhia and Abdelhabib Semlali

Antibiotics 2025, 14(5), 495; https://doi.org/10.3390/antibiotics14050495 - 12 May 2025

Abstract

Objectives: The oral cavity hosts one of the most complex microbial communities in the body. A disruption of the balance favors the growth of pathogenic species, contributing to oral diseases. The rise in microbial resistance has limited the effectiveness of conventional treatments, shifting [...] Read more.

Objectives: The oral cavity hosts one of the most complex microbial communities in the body. A disruption of the balance favors the growth of pathogenic species, contributing to oral diseases. The rise in microbial resistance has limited the effectiveness of conventional treatments, shifting the interest to natural product-based alternatives. Given its superior bioavailability and bioactivity in other models, this study investigates the antifungal potential of a novel curcumin derivative, PAC (3,5-bis(4-hydroxy-3-methoxybenzylidene)-N-methyl-4-piperidone), and studies its impact on host–pathogen dynamics and host defense mechanisms. Methods: Candida albicans was used as the model organism. Viability, growth kinetics, and colony formation were evaluated using optical density, agar culture, and MTT assay. Biofilm formation was assessed through electron microscopy and total sugar quantification. The morphological transition from hyphae to the less virulent blastospore was monitored using an optical microscope. The gene expression of adhesion factors and host defense markers was analyzed using RT-PCR. Results: PAC impairs C. albicans viability and reduces virulence by compromising biofilm formation and ensuring phenotypic transition to a blastospore form. Also, PAC controls C. albicans growth via necrosis/ROS pathways. As a result, PAC appears to repress host–pathogen interaction by downregulating SAPs, EAP1, and HWP1 adhesion genes, thus relieving the need to activate gingival epithelial cell defense mechanisms. This is highlighted by recording baseline levels of IL-6, IL-8, and IL-1β cytokines and antimicrobial β-defensin peptides in the presence of less virulent candida forms. Conclusions: PAC effectively reduces C. albicans virulence by limiting biofilm formation and adhesion while minimizing inflammatory responses. These findings support its potential as a promising therapeutic agent for infectious disease control. Full article

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33 pages, 1262 KiB

Open AccessSystematic Review

Antimicrobial Activity of Clove (Syzygium aromaticum) Essential Oil in Meat and Meat Products: A Systematic Review

by Eduardo Valarezo, Guicela Ledesma-Monteros, Ximena Jaramillo-Fierro, Matteo Radice and Miguel Angel Meneses

Antibiotics 2025, 14(5), 494; https://doi.org/10.3390/antibiotics14050494 - 11 May 2025

Abstract

Background: Clove (Syzygium aromaticum) essential oil is widely recognized for its potent antimicrobial properties, making it a valuable natural preservative in food products, particularly in meat and meat derivatives, where it helps extend shelf life and enhance food safety. Methods: This [...] Read more.

Background: Clove (Syzygium aromaticum) essential oil is widely recognized for its potent antimicrobial properties, making it a valuable natural preservative in food products, particularly in meat and meat derivatives, where it helps extend shelf life and enhance food safety. Methods: This systematic review aims to evaluate the application of clove essential oil in meat and meat products, following the PRISMA 2020 methodology, to analyze its antimicrobial efficacy and its impact on the preservation of these products. The information search was carried out in the PubMed, ScienceDirect, SCOPUS, and Web of Science databases and included research articles in English published between 1999 and 2024, and 37 studies were confirmed as eligible. Results: Due to the heterogeneity of methodologies and concentrations evaluated, a narrative analysis was chosen, organizing the studies into three categories according to the application of the essential oil: direct addition, use in edible films and coatings, and encapsulation. The analysis included the main components of the essential oil, the activity analysis method, a concentration evaluation, storage conditions, the activities obtained, and a sensory evaluation. However, variability in methodologies and concentrations made direct comparison between studies difficult. Conclusions: Overall, this review confirms the effectiveness of clove essential oil in preserving meat and meat products but highlights the need to standardize its concentration and application conditions to optimize its use in the food industry. Full article

(This article belongs to the Special Issue Antimicrobial Properties of Essential Oils: Activities, Mechanisms, Applications, and Therapeutic Potential)

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18 pages, 786 KiB

Open AccessArticle

Prevalence and Associated Mortality of Infections by Multidrug-Resistant Organisms in Pediatric Intensive Care Units in Argentina (PREV-AR-P)

by Wanda Cornistein, Carina Balasini, Yanina Nuccetelli, Viviana M. Rodriguez, Norma Cudmani, Maria Virginia Roca, Graciela Sadino, Martín Brizuela, Analía Fernández, Soledad González, Damián Águila, Alejandra Macchi, Maria Inés Staneloni and Elisa Estenssoro

Antibiotics 2025, 14(5), 493; https://doi.org/10.3390/antibiotics14050493 - 11 May 2025

Abstract

Background/Objectives: Data on multidrug-resistant organism (MDRO) infections in children are scarce, especially in resource-limited regions. This study aimed to estimate the prevalence of MDRO infections in pediatric intensive care units (PICUs) and characterize their epidemiologic and clinical features. Methods: A national, multicenter, point-prevalence [...] Read more.

Background/Objectives: Data on multidrug-resistant organism (MDRO) infections in children are scarce, especially in resource-limited regions. This study aimed to estimate the prevalence of MDRO infections in pediatric intensive care units (PICUs) and characterize their epidemiologic and clinical features. Methods: A national, multicenter, point-prevalence study was conducted in 50 PICUs in Argentina over 24 h between 24 and 28 November 2023. The primary study outcome was the prevalence of ICU infections caused by MDROs. Secondary outcomes included the prevalence of carbapenemase-producing Enterobacterales (CPE) colonization, ICU mortality, and ICU length of stay (LOS_ICU). Results: 304 patients were included. The overall prevalence of infection was 45.1% (137/304); of these, 50.3% (69/137) were hospital-acquired. Among the 137 patients with reported infections, 49.6% (n = 68) were classified as definite (microbiologically confirmed) and 50.4% (n = 69) as probable (no confirmatory microbiology). Among definite infections, 20.6% (n = 14) were due to MDROs. The overall prevalence of MDRO infections was 4.6% (14/304). Extended-spectrum β-lactamase (ESBL)-producing organisms were the most commonly identified microorganisms (42.9%), followed by CPE (28.6%). Ventilator-associated pneumonia (VAP) was the most frequent location of MDRO infections. The prevalence of CPE colonization was 13.2%. Mortality was low (5.3%) and similar in patients with MDRO and non-MDRO infections. LOS_ICU was longer in patients with MDRO infections compared to patients with non-MDRO infections (81 [22–150] vs. 25 [12–27] days, respectively, p = 0.0007). Conclusions: Among 304 PICU patients, the prevalence of MDRO infections and colonization was relatively low. MDRO infections were not associated with increased mortality but were associated with longer ICU stays, compared to patients with non-MDRO infections. Full article

(This article belongs to the Special Issue Nosocomial Infections and Complications in ICU Settings)

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15 pages, 7498 KiB

Open AccessArticle

Lack of Spontaneous and Adaptive Resistance Development in Staphylococcus aureus Against the Antimicrobial Peptide LTX-109

by Bhupender Singh, Mia Angelique Winkler, Wasifa Kabir, Johanna U Ericson and Arnfinn Sundsfjord

Antibiotics 2025, 14(5), 492; https://doi.org/10.3390/antibiotics14050492 - 11 May 2025

Abstract

Nasal carriage of Staphylococcus aureus and its antibiotic-resistant derivative, methicillin-resistant S. aureus (MRSA), is a risk factor for nosocomial S. aureus infections. Mupirocin is a topical antibiotic and a key in the decolonization of both methicillin-susceptible S. aureus (MSSA) and MRSA carriage in [...] Read more.

Nasal carriage of Staphylococcus aureus and its antibiotic-resistant derivative, methicillin-resistant S. aureus (MRSA), is a risk factor for nosocomial S. aureus infections. Mupirocin is a topical antibiotic and a key in the decolonization of both methicillin-susceptible S. aureus (MSSA) and MRSA carriage in patients and health care personnel. Recent observations have shown a global increase in the prevalence of mupirocin-resistant MSSA and MRSA, reducing the efficacy of mupirocin in decolonization regimens. LTX-109 is a peptidomimetic synthetic compound that has shown broad-spectrum bactericidal antimicrobial activity in vitro and in animal experiments. However, the development of resistance against LTX-109 in clinical isolates of MRSA and MSSA has not been systematically examined. Background/Objectives: Here, we assess the development of spontaneous and adaptive resistance against LTX-109 in genomically diverse MRSA (n = 3) and MSSA (n = 4) strains. Methods: Adaptive and mutational resistance were examined by serial passaging strains over 60 cycles in a range of LTX-109 and mupirocin concentrations. Spontaneous resistance was examined in high-inoculum agar plates with 2–8 times the concentration above MIC. Results: Throughout serial passage, LTX-109 MICs varied less than 4-fold compared to the initial MIC of 4–8 mg/L, while mupirocin MICs increased in all susceptible strains (n = 5) from 0.25 mg/L to 16–512 mg/L. The spontaneous resistance assay demonstrated no resistance development at 4–8× MIC LTX-109 and an inoculum effect at 2× MIC. Conclusions: Our results demonstrate the novelty of LTX-109 as an antimicrobial agent with no detectable in vitro resistance development in selected clinical strains of MRSA and MSSA. Full article

(This article belongs to the Special Issue Strategies for Combatting Multidrug-Resistant and Extensively Drug-Resistant Bacteria, 2nd Edition)

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18 pages, 3148 KiB

Open AccessArticle

Antimicrobial Susceptibility Profiles of Escherichia coli Isolates from Clinical Cases of Ducks in Hungary Between 2022 and 2023

by Ádám Kerek, Ábel Szabó and Ákos Jerzsele

Antibiotics 2025, 14(5), 491; https://doi.org/10.3390/antibiotics14050491 - 10 May 2025

Abstract

Background: Antimicrobial resistance (AMR) poses a growing threat to veterinary medicine and food safety. This study examines Escherichia coli antibiotic resistance patterns in ducks, focusing on multidrug-resistant (MDR) strains. Understanding resistance patterns and predicting MDR occurrence are critical for effective intervention strategies. [...] Read more.

Background: Antimicrobial resistance (AMR) poses a growing threat to veterinary medicine and food safety. This study examines Escherichia coli antibiotic resistance patterns in ducks, focusing on multidrug-resistant (MDR) strains. Understanding resistance patterns and predicting MDR occurrence are critical for effective intervention strategies. Methods: E. coli isolates were collected from duck samples across multiple regions. Descriptive statistics and resistance frequency analyses were conducted. A decision tree classifier and a neural network were trained to predict MDR status. Cross-resistance relationships were visualized using graph-based models, and Monte Carlo simulations estimated MDR prevalence variations. Results: Monte Carlo simulations estimated an average MDR prevalence of 79.6% (95% CI: 73.1–86.1%). Key predictors in MDR classification models were enrofloxacin, neomycin, amoxicillin, and florfenicol. Strong cross-resistance associations were detected between neomycin and spectinomycin, as well as amoxicillin and doxycycline. Conclusions: The high prevalence of MDR strains underscores the urgent need to revise antibiotic usage guidelines in veterinary settings. The effectiveness of predictive models suggests that machine learning tools can aid in the early detection of MDR, contributing to the optimization of treatment strategies and the mitigation of resistance spread. The alarming MDR prevalence in E. coli isolates from ducks reinforces the importance of targeted surveillance and antimicrobial stewardship. Predictive models, including decision trees and neural networks, provide valuable insights into resistance trends, while Monte Carlo simulations further validate these findings, emphasizing the need for proactive antimicrobial management. Full article

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

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10 pages, 767 KiB

Open AccessArticle

Prevalence of Acinetobacter baumannii Multidrug Resistance in University Hospital Environment

by Francesco Foglia, Annalisa Ambrosino, Shahab Bashir, Emiliana Finamore, Carla Zannella, Giovanna Donnarumma, Anna De Filippis and Massimiliano Galdiero

Antibiotics 2025, 14(5), 490; https://doi.org/10.3390/antibiotics14050490 - 10 May 2025

Abstract

Background: Acinetobacter baumannii is a significant pathogen and a major contributor to healthcare-associated infections, particularly in intensive care units. Its high potential for developing multiple drug resistance (MDR) makes it a challenging pathogen to manage. This study investigates the prevalence and resistance [...] Read more.

Background: Acinetobacter baumannii is a significant pathogen and a major contributor to healthcare-associated infections, particularly in intensive care units. Its high potential for developing multiple drug resistance (MDR) makes it a challenging pathogen to manage. This study investigates the prevalence and resistance patterns of MDR A. baumannii isolates over a six-year period at a university hospital in Southern Italy. Objective: The aims of this study are to evaluate recent trends in the prevalence of MDR A. baumannii, analyze resistance patterns, and assess the impact of the antimicrobial diagnostic stewardship program implemented in 2018. Methods: This retrospective cohort study was conducted at the University Hospital of Campania “Luigi Vanvitelli” from 2018 to 2023. A total of 191 A. baumannii isolates from blood, urine, and wound samples were analyzed. Antimicrobial susceptibility testing was performed following EUCAST guidelines. The prevalence of MDR strains was assessed across three periods: pre-pandemic (2018–2019), during the pandemic (2020–2021), and post-pandemic (2022–2023) Results: Among the 191 isolates, 89.5% were classified as MDR. The highest number of isolates occurred in 2020, with blood cultures and urine samples increasing by 40.9% and 62.5%, respectively, while wound isolates decreased by 34.2%. The implementation of antimicrobial diagnostic stewardship programs correlated with a reduction in carbapenem resistance in 2020 and 2022. However, resistance to meropenem and colistin persisted. A 60.4% decline in total isolation from 2020 to 2023 suggests effective infection control measures. Conclusions: MDR A. baumannii remains a significant threat to healthcare. Although there have been slight reductions in resistance following antimicrobial stewardship interventions, persistent resistance to last-line antibiotics underscores the urgent need for alternative treatments, enhanced surveillance, and stricter infection control strategies. Full article

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

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23 pages, 3364 KiB

Open AccessArticle

Antimicrobial Resistance and Phylogenetic Analysis of Multidrug-Resistant Non-Typhoidal Salmonella Isolates from Different Sources in Southern Vietnam

by Daria Starkova, Svetlana Egorova, Ludmila Suzhaeva, Truong Quang Nguyen, Lidiia Kaftyreva, Maria Makarova, Samida Zhamborova, Dmitrii Polev, Alina Saitova, Vu Hoang Nguyen, Tram Khac Vo and Long Thanh Nguyen

Antibiotics 2025, 14(5), 489; https://doi.org/10.3390/antibiotics14050489 - 10 May 2025

Abstract

Background/Objectives: Non-typhoidal Salmonella (NTS) is one of the most common causative agents of food poisoning in Vietnam, and contaminated livestock meat poses a major risk to human health. The present study aims to provide the genetic characteristics of NTS with a particular focus [...] Read more.

Background/Objectives: Non-typhoidal Salmonella (NTS) is one of the most common causative agents of food poisoning in Vietnam, and contaminated livestock meat poses a major risk to human health. The present study aims to provide the genetic characteristics of NTS with a particular focus on antimicrobial resistance and determine phylogenetic relationships between isolates from different sources in Southern Vietnam based on whole-genome sequencing (WGS) data. Methods: A total of 49 NTS isolates from pork/broiler meat, pigs, chickens, and humans were collected in Ho Chi Minh City and four provinces of Southern Vietnam. Phenotypic antimicrobial susceptibility testing (AST) and WGS for all isolates were performed. Results: As a result, 14 different serotypes were identified, among which S. Typhimurium and its monophasic variant were the dominant serotypes for human and pig sources. All chicken samples belonged to S. Indiana, whereas S. Infantis predominated in broiler meat. AST results revealed that 98% of isolates were multidrug resistant. NTS strains isolated from poultry and pigs exhibited resistance to the highest priority antimicrobials—quinolones and polymyxin, as well as to β-lactams, aminoglycosides, tetracycline, and sulfonamide, which are considered to be critical for the treatment of severe diseases. Conclusions: The results highlight the utmost importance of issues related to the selection, spreading, and transmission of multi-resistant strains from animals to humans. Full article

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25 pages, 5184 KiB

Open AccessArticle

The Impact of Human Milk Oligosaccharides on Antibiotic-Induced Microbial Dysbiosis and Gut Inflammation in Mice

by Kristine Rothaus Christensen, Torben Sølbeck Rasmussen, Caroline M. Junker Mentzel, Sofie Kaas Lanng, Elena Tina Gabriella Meloni, Hanne Christine Bertram, Camilla Hartmann Friis Hansen and Axel Kornerup Hansen

Antibiotics 2025, 14(5), 488; https://doi.org/10.3390/antibiotics14050488 - 10 May 2025

Abstract

Background/Objectives: Antibiotics have a significant impact on the gut microbiota, and we hypothesized that human milk oligosaccharides may alleviate antibiotic-induced gut microbiota dysbiosis. Methods: Six groups of eight mice were administered drinking water with or without ampicillin for one week. We [...] Read more.

Background/Objectives: Antibiotics have a significant impact on the gut microbiota, and we hypothesized that human milk oligosaccharides may alleviate antibiotic-induced gut microbiota dysbiosis. Methods: Six groups of eight mice were administered drinking water with or without ampicillin for one week. We then introduced the human milk oligosaccharide 2′-fucosyllactose (2′FL), either alone or in combination with difucosyl-lactose (DFL), for two weeks after the termination of ampicillin treatment. Results: Ampicillin reduced microbiota diversity and the abundance of specific bacteria. One week after the termination of ampicillin treatment, the 2′FL + DFL mixture counteracted the ampicillin-induced reduction in diversity, although this effect was not sustained. Over the subsequent two weeks, the 2′FL + DFL mixture had a significant impact on the relative abundances of Lactobacillus spp. and Bacteroides spp. Ampicillin also reduced caecal propionate levels, downregulated the gene Gzmb for Granzyme B, and upregulated the gene Reg3a for Regenerating islet-derived protein 3 alpha, all of which were counteracted by the 2′FL + DFL mixture. Ampicillin had a minor impact on ileal cytokine levels. The 2′FL + DFL mixture showed a cytokine effect indicating reduced adaptive and innate inflammation. Ampicillin reduced water intake and growth in the mice. The oligosaccharides did not affect water intake, but the 2′FL + DFL mixture slightly reduced body weight. Conclusions: The 2′FL + DFL mixture appears to hold potential for counteracting some of the side effects of ampicillin treatment. Full article

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10 pages, 556 KiB

Open AccessPerspective

Virological and Pharmaceutical Properties of Clinically Relevant Phages

by Antonios-Periklis Panagiotopoulos, Antonia P. Sagona, Deny Tsakri, Stefanos Ferous, Cleo Anastassopoulou and Athanasios Tsakris

Antibiotics 2025, 14(5), 487; https://doi.org/10.3390/antibiotics14050487 - 10 May 2025

Abstract

As antimicrobial resistance continues to undermine the efficacy of antibiotics, the global medical community is increasingly turning to alternative treatment modalities. Among these, phage therapy has re-emerged as a promising strategy for managing multidrug-resistant bacterial infections. Herein, we present and briefly discuss eight [...] Read more.

As antimicrobial resistance continues to undermine the efficacy of antibiotics, the global medical community is increasingly turning to alternative treatment modalities. Among these, phage therapy has re-emerged as a promising strategy for managing multidrug-resistant bacterial infections. Herein, we present and briefly discuss eight essential attributes of clinically relevant phages for therapy, which may be categorized broadly into virological and pharmacological characteristics. Virological attributes include a broad host range, a strictly lytic life cycle and the ability to manage the emergence of bacterial resistance to phages. Comprehensive genomic and proteomic characterization forms the foundation for selecting and engineering such candidates, ensuring both safety and predictability. From a pharmacological standpoint, phages should ideally show safety across relevant formulations and routes of administration, favorable pharmacokinetics, stability during storage and scalability in manufacturing. Advances in genomic analysis, artificial intelligence-driven phage selection and formulation technologies have further accelerated the translational potential of phage therapy. By systematically addressing each of these critical attributes, this work aims to inform the rational selection and development of therapeutic phages suitable for integration into the clinical practice. Full article

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15 pages, 1311 KiB

Open AccessArticle

In Vitro Activity of Imipenem/Relebactam Alone and in Combination Against Cystic Fibrosis Isolates of Mycobacterium abscessus

by Madeline Sanders, Sun Woo Kim, Aditi Shinde, Danielle Fletcher-Williams, Eric Quach and Paul Beringer

Antibiotics 2025, 14(5), 486; https://doi.org/10.3390/antibiotics14050486 - 10 May 2025

Abstract

Background: Mycobacterium abscessus (MABS) is an opportunistic pathogen that causes chronic, difficult-to-treat pulmonary infections, particularly in people with cystic fibrosis (PwCF), leading to rapid lung function decline and increased morbidity and mortality. Treatment is particularly challenging due to the pathogen’s resistance mechanisms and [...] Read more.

Background: Mycobacterium abscessus (MABS) is an opportunistic pathogen that causes chronic, difficult-to-treat pulmonary infections, particularly in people with cystic fibrosis (PwCF), leading to rapid lung function decline and increased morbidity and mortality. Treatment is particularly challenging due to the pathogen’s resistance mechanisms and the need for prolonged multidrug therapy, which is characterized by poor clinical outcomes and highlights the urgent need for novel therapeutic strategies. Imipenem/relebactam, a novel β-lactam-β-lactamase inhibitor combination, demonstrates in vitro activity against resistant MABS strains and effective pulmonary penetration. Prior research indicates synergistic activity of imipenem with various antibiotics against M. abscessus. Objectives: This study aims to evaluate the in vitro activity of imipenem/relebactam, alone and in combination with various antibiotics, against MABS clinical isolates from PwCF (n = 28). Methods: Susceptibility and synergy were assessed using broth microdilution and checkerboard assays. Extracellular time-kill assays were performed to evaluate the bactericidal activity of synergistic three-drug combinations containing imipenem/relebactam. Results: Imipenem/relebactam demonstrated potent in vitro activity against clinical MABS isolates, exhibiting substantial synergy with cefuroxime, cefdinir, amoxicillin, and cefoxitin. Rifabutin, azithromycin, moxifloxacin, clofazimine, and minocycline also demonstrated additive effects with imipenem/relebactam. Extracellular time-kill assays identified imipenem/relebactam + cefoxitin + rifabutin and imipenem/relebactam + cefoxitin + moxifloxacin as the most effective combinations. Conclusions: These findings suggest that imipenem/relebactam may offer a significant advancement in the management of MABS infections in PwCF. The promising efficacy of multidrug regimens combining imipenem/relebactam with agents like cefoxitin, azithromycin, moxifloxacin, clofazimine, and rifabutin highlights potential therapeutic strategies. Full article

(This article belongs to the Special Issue Antimicrobial Prescribing, Population Use and Resistance, Impact in Global Health, 2nd Edition)

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