Search Results (7,848)

The emergence of multidrug-resistant Pseudomonas strains poses a serious threat to public health. Essential oil components, such as thymol (TH), exhibit potent antibacterial activity. However, the effects of continuous sublethal TH exposure and resulting changes to antibiotic susceptibility remain poorly understood. Here, we investigated a multi-resistant Pseudomonas psychrophila strain after TH adaptation using an integrated transcriptomic and metabolomic approach. Treatment with TH caused a significant decrease in MIC values for aminoglycosides (streptomycin, gentamicin, kanamycin) and tetracycline and increased susceptibility to five other antibiotics. Multi-omics analyses revealed coordinated changes in fatty acid metabolism (FabI downregulation and accumulation of unsaturated fatty acids), lipid A biosynthesis (LpxC downregulation), peptidoglycan synthesis (Mur genes downregulated, accompanied by increased spermine levels), and stress response pathways (such as GABA, GadA, maltose, and MalK). These results suggest that metabolic alterations and envelope remodeling potentially affect cell wall integrity and growth, which could, in turn, contribute to increased antibiotic susceptibility and re-sensitization. Overall, our findings highlight the potential of TH-mediated sensitization as a complementary strategy to restore antibiotic efficacy. Full article

Salmonella enterica remains a major threat to animal and human health because of its broad host range, increasing antimicrobial resistance (AMR), and capacity to form biofilms. Biofilm formation enhances bacterial persistence in host tissues, farm environments, food-processing systems, and clinical reservoirs, while also contributing to their tolerance against antibiotics, disinfectants, and other stresses. However, biofilm capacity is not uniform across serovars and is influenced by host adaptation, niche specialization, and accessory genome content. This review synthesizes current knowledge on the relationship between biofilm formation, AMR, and serovar-specific adaptation in Salmonella. It examines biofilm-associated traits across various hosts (e.g., gastrointestinal tract and gallbladder, and environmental (e.g., food-production and clinical) niches, and discusses comparative evidence from genomic, transcriptomic, proteomic, and metabolomic studies. Particular attention is given to the emerging concept of comparative biofilmomics, which integrates phenotypic and multi-omics data across diverse serovars and host sources to identify conserved and niche-specific determinants of persistence. This framework may help define high-risk lineages that couple multidrug resistance (MDR) with enhanced biofilm-forming capacity. A better understanding of these linked traits will support the development of more targeted interventions for controlling persistent Salmonella in veterinary, food production, and public health settings. Full article

Genetically modified (GM) lactic acid bacteria (LAB) are gaining attention as tools for innovation in the food sector, health applications, and industrial processes. LAB have long been used safely due to their GRAS/QPS status, making them suitable for improving fermentation and synthesizing specific and beneficial metabolites. Advances in genomics and gene editing have significantly expanded the available tools, ranging from classical mutagenesis to site-specific recombination, homologous recombination in non-coding regions, CRISPR-based systems, and food-grade chromosomal integration. These approaches enable the insertion of desired genes and the development of engineered strains with tailored functionalities. GM-LAB are also being studied as live delivery systems for therapeutic molecules, including cytokines, hormones, antimicrobial peptides, and vaccine antigens. Engineered strains of Lactococcus lactis and Lactobacillus spp. have yielded promising outcomes in applications such as mucosal immunization, modulation of inflammatory and metabolic responses, and inhibition of pathogenic microorganisms, including multidrug-resistant bacteria. From an industrial perspective, several studies highlight their potential for cost-effective recombinant protein production and the synthesis of high-value metabolites through fermentation. However, within the European Union, their use is subject to stringent regulatory oversight, requiring comprehensive molecular and environmental risk assessments, careful evaluation of horizontal gene transfer, and a preference for markerless chromosomal integrations. Despite these constraints, GM-LAB offer significant potential to improve food quality, sustainability, and human health. Full article

Staphylococcus aureus is a high-priority pathogen causing skin and soft tissue infections (SSTIs). The frequent resistance to anti-staphylococcal agents exhibited by this underscores the need for accurate diagnostics to guide effective therapy. Therefore, this study aimed to compare phenotypic and genotypic resistance in S. aureus isolates from nasal carriers and SSTIs and to elucidate gene-silencing mechanisms. In total, 355 S. aureus isolates (256 isolated from carriers and 79 from SSTIs) were studied for their phenotypic and genotypic resistance to β-lactams, macrolides, tetracyclines, aminoglycosides, and mupirocin. The silenced mupA gene (low prevalence: 0.6%; 2/335), linked to mupirocin resistance, was sequenced, and expression was assessed via reverse transcription qualitative PCR (RT-qPCR) in all mupA-positive isolates. SSTI isolates showed significantly higher resistance to erythromycin, gentamicin, and mupirocin, along with a higher prevalence of multidrug-resistant strains and ermC and tetM genes. Sequencing revealed multiple mutations in silent mupA, including a critical frameshift (c.372 delA) in a poly(A) tract that brings about premature truncation. RT-qPCR indicated upregulation of silent mupA variants and high variability in functional strains, suggesting that frameshift alone prevents resistance. These findings highlight silent resistance genes as key targets for advancing S. aureus surveillance and for combating emerging threats. Full article

Selective inhibition of the tumour-associated carbonic anhydrase (CA) isoforms IX and XII, which are overexpressed in hypoxic tumours, has emerged as a promising strategy for the development of novel anticancer agents. Among the diverse CA inhibitors reported to date, coumarins have attracted particular attention. These chromenone derivatives, widely distributed in phytochemicals, display a broad range of biological activities and are known to act as suicide inhibitors of CAs. Following the tail approach, we designed a series of hybrid compounds combining a coumarin core with an N-arylthioureido scaffold located at the C-7 position and investigated how structural variations—including substituents on the coumarin and aromatic moieties, tether length, and urea/thiourea isosterism—influence their biological properties (CA inhibition and antiproliferative activity). Substituted coumarins at C-3 and C-4 were efficiently prepared via Pechmann condensation, while the thioureido motif was introduced using various aryl isothiocyanates as key synthetic intermediates. The lead compound, featuring a dimethylated coumarin, a pentyl linker, and an N-(p-tolyl)thioureido residue, inhibited the target enzymes in the low- to mid-nanomolar range (K_i = 6.0 and 49.9 nM, respectively), displaying selectivity indexes (S.I.s) surpassing those of the reference drug acetazolamide (AAZ). Moreover, it exhibited potent antiproliferative activity, with GI₅₀ values in the low micromolar range (1.9–3.5 µM) against both drug-sensitive and multidrug-resistant cancer cell lines. Label-free three-dimensional holotomographic microscopy revealed that this compound triggers slow apoptosis, leading to cell death after approximately 20 h of exposure. Full article

Multidrug (MDR) resistances against various classes of antibiotics used in S. aureus and MRSA infections have emerged. With limited options for novel antibacterial compounds, there is a strong focus on finding agents against MDR phenomenon, namely causative efflux pumps. We synthesised novel benzo-annelated 1,4-dihydropyridines with various substitution patterns both at the 4- and N-alkyl substituents and, additionally, at the annelated aromatic residues. MDR efflux pump-inhibiting activity was evaluated in S. aureus strains including MRSA and was measured in a fluorescent assay system using ethidium bromide as the overall substrate of S. aureus efflux pumps. Favourable substituents for inhibiting efflux pump activity in S. aureus have been 4-methoxy and 4- and 3-chloro at the 4-phenyl position of the 1,4-dihydropyridine ring combined with an N-benzyl residue. The most favourable substituents for the activity inMRSA strains have been those 4-phenyl chloro substituents combined with additional pyrido residues attached to the benzo substituent at the 1,4-dihydropyridine core. Benzo-annelated 1,4-dihydropyridines are a novel class of inhibitors of MDR relevant efflux pumps in S. aureus strains including MRSA. Full article

Candidozyma auris (C. auris) is an emerging healthcare-associated yeast of major epidemiological concern because of its multidrug resistance and outbreak potential. We report the recovery of a single C. auris isolate from a used face mask collected in May 2025 during a blinded dental medicine quality-control programme assessing microbial contamination in the working environment. To contextualise this finding, we analysed routine diagnostic laboratory data from 2017 to 2025. The isolate underwent whole-genome sequencing for molecular characterisation, including analysis of the ERG11 gene, and antifungal susceptibility testing by EUCAST broth microdilution. In addition, 53,802 patient-related Candida spp. isolates collected between 2017 and 2025 were reviewed retrospectively; species identification had been performed by MALDI-TOF. The environmental isolate belonged to clade III and carried the V125A/F126L substitutions in ERG11, consistent with African clade isolates and associated with intrinsically high fluconazole minimum inhibitory concentrations. No C. auris was detected in routine patient specimens during the study period, whereas Candida albicans remained the predominant species in clinical samples. These findings provide no evidence of ongoing C. auris transmission at the Medical University of Innsbruck, but highlight the need for continued vigilance and robust infection-prevention measures to limit the risk posed by isolated introductions. Full article

Background/Objectives: Multidrug-resistant (MDR) Enterobacter spp. are critical pathogens within the ESKAPE group, frequently exhibiting resistance to carbapenems. Antimicrobial photodynamic therapy (aPDT) represents a promising non-antibiotic strategy to circumvent these resistance mechanisms. This scoping review aims to map the current evidence regarding the efficacy of aPDT in inactivating Enterobacter spp., identifying the most effective photosensitizers (PS), light parameters, and existing research gaps. Methods: A systematic search was performed across PubMed, Scopus, and Google Scholar (2013–2025) following PRISMA-ScR guidelines and registered on OSF. Studies were included if they evaluated aPDT against Enterobacter spp. (in vitro or in vivo) and provided quantitative data on microbial reduction. Data was extracted using a standardized charting form covering bacterial strains, PS type, light source, and viability reduction. The results from the eligible sources of evidence were synthesized narratively to address the review objectives. Results: Despite the clinical priority of Enterobacter, only seven studies met the eligibility criteria. Methylene Blue remains the most frequently studied PS, achieving reductions of 3–8 log₁₀. Emerging evidence highlights the synergistic efficacy of monocationic chlorins and graphene-based nanomaterials in enhancing the bactericidal effect of light-based treatments. Notably, aPDT demonstrated the ability to inactivate carbapenemases, the bacterial enzymes responsible for carbapenem resistance. However, only two studies evaluated in vivo applications, primarily within dental settings. Conclusions: aPDT is a promising method against MDR Enterobacter spp. and bypasses traditional resistance mechanisms. However, the limited number of studies indicates a significant knowledge gap. Future research should focus on standardized in vivo protocols and the synergy between aPDT and conventional antibiotics to support clinical translation. Full article

Genetic diversity and antifungal susceptibility profiles of Aspergillus fumigatus are critical for understanding the evolution of resistance in clinical and environmental settings. We performed comprehensive genomic characterization of A. fumigatus isolates using whole-genome sequencing combined with phenotypic susceptibility assays. SnpEff-based variant annotation identified 76,079 single-nucleotide polymorphisms, revealing a high proportion of mutations (78.8%) in upstream and downstream regulatory regions, whereas high-impact coding variants remained rare (0.083%). Several key mutations were identified, including the well-established cyp51A M220V and HMG1 S212P/Y564H mutations. Moreover, a diverse array of peripheral cyp51A polymorphisms (M39I, E402D, N248K, and K372N) was detected, although these variants did not correlate with the resistant phenotypes. Our comparative genomic analysis identified a novel A586T substitution in the FKS1 gene in an isolate with an elevated minimum effective concentration of caspofungin, suggesting its possible association with reduced susceptibility, although functional validation is required. In isolates lacking canonical target-site mutations, the high frequency of regulatory-region variants indicated the involvement of non–target-site mechanisms. This study provides a detailed map of the genomic landscape of A. fumigatus and identifies candidate loci for future functional validation. Our results demonstrate the utility of high-throughput genomic surveillance for monitoring emerging resistance trends and characterizing the genetic background of clinical fungal pathogens. Full article

Linezolid represents a critical last-resort treatment for severe multidrug-resistant (MDR) Gram-positive bacterial infections. Rising linezolid resistance in Enterococcus isolates threatens its efficacy; this study characterized the molecular features and transfer potential of plasmid-encoded linezolid resistance genes optrA and poxtA in a linezolid-resistant Enterococcus asini isolate from chickens. An E. asini strain was isolated during a surveillance program focusing on drug-resistant Gram-positive bacteria in poultry. PCR screened linezolid resistance genes, conjugation and plasmid stability assays evaluated gene transferability and stability, and whole-genome sequencing (WGS) was performed using both the Illumina and Nanopore platforms. We present the first detection of optrA and poxtA genes in E. asini recovered from chicken feces in China. Sequence analysis of the complete genome showed that poxtA and optrA were situated on two distinct plasmids. The poxtA positive plasmid, pHNGXN23C145Ea-1, also carried multiple resistance genes, including tet(S), fexB, erm(B), ant(6)-Ia, aph(3′)-III. Furthermore, the poxtA gene was flanked by IS1216E mobile elements. The optrA bearing plasmid, pHNGXN23C145Ea-2, harbours a common genetic array of ‘IS1216E fexA-optrA-erm(A)-IS1216E’. Conjugation experiments indicated that neither the poxtA- nor the optrA-bearing plasmid was transferred to recipient strains, which was consistent with sequence analysis showing that both plasmids lacked intact conjugative transfer regions. Stability assays confirmed that poxtA and optrA remained highly stable in the absence of selective pressure. Notably, this discovery was made in a livestock sample, despite the non-use of linezolid in food animals, suggesting that such niches may act as silent reservoirs for resistance genes, which could persist and potentially transfer to clinically relevant MDR pathogens. Full article

Background: Resistance to first-line anti-tuberculosis drugs in Mycobacterium tuberculosis represents a significant public health challenge, particularly in high-burden tuberculosis (TB) settings such as Pakistan, where multidrug-resistant (MDR) forms further complicate disease control efforts. Drug resistance is primarily associated with mutations in rpoB, inhA, katG, embA, embB, embC, and pncA. The emergence of novel, region-specific variants underscores the urgent need for integrating genomic surveillance into routine TB diagnostics and regional control programs. This study aimed to identify the spectrum of mutations contributing to first-line drug resistance in MDR-TB isolates from Khyber Pakhtunkhwa, Pakistan. Methods: Whole-genome sequencing was performed on 16 clinical isolates (12 MDR and 4 drug-susceptible) to identify resistance-associated mutations in rpoB, inhA, katG, embA, embB, embC, and pncA. Detected variants were interpreted using the World Health Organization (WHO) mutation catalogue to determine their association with drug resistance. Phylogenetic relationships were inferred using the Bacterial and Viral Bioinformatics Resource Center (BV-BRC) platform. Results: A total of 16 M. tuberculosis isolates were analyzed to evaluate resistance to first-line anti-tuberculosis drugs. In rpoB, 76 distinct variants were identified, including canonical mutations such as Ser450Leu and His445Arg, as well as a potentially novel substitution, Ser431Phe, predicted to confer high-level rifampicin resistance. The katG and inhA genes harbored 24 and 27 mutations, respectively, including well-characterized substitutions such as Ser315Thr and Ala114Glu, which are strongly associated with isoniazid resistance. Mutations in embA and embB were linked to ethambutol resistance, with several variants localized within conserved transmembrane domains critical for drug interaction. Phylogenetic analysis revealed substantial genetic diversity and evidence of local transmission among MDR-TB isolates. Conclusions: This study suggests that the genetic landscape of drug resistance in M. tuberculosis is highly dynamic in endemic regions. The findings highlight the importance of integrating region-specific mutation profiles into molecular diagnostic frameworks to enhance early detection, guide individualized therapeutic interventions, and strengthen strategies aimed at controlling the transmission of MDR-TB. Full article

The gut microbiota is a central regulator of metabolic function, and its disruption by a high-fat diet (HFD) is strongly linked to obesity and metabolic impairment. This study evaluated the potential of heat-killed Lactiplantibacillus plantarum beLP1 (beLP1^®) in alleviating HFD-induced metabolic and microbial imbalances in mice. Male C57BL/6N mice were fed an HFD for 10 weeks, with or without daily oral supplementation of beLP1 (≥3 × 10¹⁰ cells). Compared with untreated HFD mice, beLP1 supplementation reduced serum triglycerides by 35% and lowered liver enzymes AST and ALT by 17% and 36%, respectively. Blood glucose levels remained similar to the HFD group throughout the study period. Shotgun metagenomic analysis revealed that beLP1 restored gut microbial diversity, increased beneficial taxa such as Akkermansia and Faecalibaculum high. and reduced pro-inflammatory species including Streptococcus sp., Mucispirillum schaedleri and Clostridium cocleatum. These microbial changes were associated with partial normalization of the Firmicutes/Bacteroidota ratio and improvements in antibiotic resistance gene (ARG) profiles. Specifically, in silico analysis of the short-chain fatty acid (SCFA) synthesis pathways indicated that the potential for acetate and propionate production was maximized in the beLP1 group, resulting in the highest relative abundance among all groups. This functional enhancement directly correlated with the enrichment of key SCFA-producing taxa, particularly Akkermansia muciniphila, confirming that increased bacterial abundance suggests an enhanced functional potential for SCFA production. Furthermore, beLP1^® induced a selective modulation of gut ARGs, significantly reducing specific subtypes such as tetracycline and multidrug efflux genes, despite a slight increase in vancomycin resistance markers. Overall, our findings suggest that beLP1^® attenuated the rate of body weight gain during the initial weeks of HFD exposure and significantly improved markers of hepatic stress and lipid metabolism. Full article

Background/Objectives: Multidrug resistance (MDR) remains a major pathophysiological barrier to effective chemotherapy based on anthracyclines, including daunorubicin (DNR), in the treatment of leukemia. However, conventional population-level measurements of drug uptake do not resolve variability in uptake kinetics among individual leukemia cells, which may influence intracellular drug accumulation and therapeutic response. Methods: In this study, real-time DNR uptake was quantified at the single-cell level using a microfluidic biochip that enabled long-term cellular retention and continuous monitoring. Both wild-type drug-sensitive leukemia cells and a multidrug-resistant mutant overexpressing the P-glycoprotein (P-gp) efflux pump were examined. Results: Kinetic analysis revealed that DNR uptake in drug-sensitive cells was well described by a single dominant uptake process, whereas uptake in MDR cells required a model incorporating two kinetically distinct processes. In both cell populations, pronounced cell-to-cell variation was observed in uptake rates and intracellular drug retention, indicating substantial functional heterogeneity within phenotypically similar cells. This variability persisted following the treatment with an MDR inhibitor and obscured the differences between inhibitor-treated and untreated cells when the uptake was compared across different single cells. To overcome this limitation, a same-single-cell analysis (SASCA) approach was employed, enabling direct comparison of DNR uptake in the same individual cell before and after inhibitor exposure, thereby revealing enhanced intracellular DNR retention and accelerated uptake kinetics following inhibition. Conclusions: Together, these results demonstrate that real-time single-cell kinetic analysis reveals functionally relevant heterogeneity in multidrug-resistant leukemia cells and provides insight into the pathophysiology of MDR that cannot be obtained from population-averaged measurements. Full article

Background: Eravaycline is a novel fully synthetic fluorocycline that is currently approved for complicated intra-abdominal infections. However, it is sometimes also used off-label in tertiary care centers for other infection sites as an antibiotic of last resort due to its broad spectrum of activity and efficacy against Enterobacterales, including multidrug-resistant pathogens like extended spectrum β-lactamase (ESBL) producers or carbapenem-resistant Enterobacterales, as well as all Gram-positive organisms including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin- and linezolid-resistant Enterococcus faecium (VRE). Methods: We retrospectively included a total of 78 patients from Austria and Udine who received eravacycline between April 2023 and August 2024 to evaluate the real-world efficacy of eravacycline in various infection sites and pathogens using descriptive statistics. Results: Eravacycline was most commonly used in intra-abdominal infections (44.9%), followed by pneumonia (12.8%) and infections of unknown origin (7.7%). Escherichia coli, including ESBL producers, was the most common pathogen (24.4%), followed by Enterococcus spp. (12.8%) and Klebsiella pneumoniae (12.8%). Clinical cure was achieved in 65% of patients, whereas microbiological cure was documented in 46%; source control was attained in 48.7%, and 16.7% died within 30 days. A total of 48% of patients required intensive care. Conclusions: Eravacycline represents a possible therapeutic option for a wide range of pathogens, but its use must be evaluated in the context of infection site and severity. Full article

Candida albicans (C. albicans) is an opportunistic fungal pathogen capable of causing a wide range of infections, including mucosal and systemic candidiasis. In the oral cavity, fungi represent a minor component of the microbiome but can significantly contribute to morbidity, particularly under conditions of dysbiosis or immunosuppression. Treatment remains challenging due to increasing multidrug resistance. This study investigates the in vitro antifungal potential of Viroelixir, a standardized polyphenol blend derived from green tea and pomegranate and enriched in catechins (including epigallocatechin gallate, EGCG), ellagitannins (notably punicalagin), ellagic acid, and flavonoids, with particular focus on its potential anti-virulence mechanisms. Methods: The effect of Viroelixir on C. albicans growth was assessed using MTT assay, optical density measurements, colony formation, carbohydrate quantification, and pH variation analysis. Biofilm formation, morphological transition, ROS production, necrosis, virulence gene expression, adhesion, and host immune responses were also evaluated. Results: Viroelixir significantly inhibited C. albicans growth and reduced colony formation compared with untreated controls. The formulation also inhibited biofilm formation and markedly reduced pseudohyphal development, reaching up to 94% reduction under specific treatment conditions. Flow cytometry analysis showed an increase in dead fungal cells, reaching approximately 88% following exposure to Viroelixir at the highest tested concentration. In addition, Viroelixir reduced the transcript levels of several virulence-associated genes, including SAP1–SAP9 and EAP1. In epithelial cell co-culture models, pre-treatment of C. albicans with Viroelixir reduced fungal adhesion and attenuated epithelial inflammatory responses, including IL-6, IL-8, and hBD-2 production, and was associated with reduced activation of the TLR4-NF-κB signaling pathway. Conclusions: These findings suggest that the antifungal and anti-virulence effects observed may be associated with the polyphenolic compounds present in the Viroelixir formulation, highlighting its potential as a promising in vitro antifungal candidate against C. albicans. Full article