Antimicrobial resistance (AMR) is an emerging global health threat responsible for antibiotics being ineffective, leading to persistent infections, increased mortality, and healthcare costs. ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens have a higher priority worldwide for the development of therapeutic approaches other than traditional antibiotics. Quorum sensing (QS) links population-dependent gene expression with a mechanistic understanding of bacterial communication, virulence regulation, and biofilm-associated persistence. Major QS systems across ESKAPE pathogens are Agr and accessory gene regulator networks in Gram-positive bacteria; LuxS/AI-2 signaling; the LuxI/LuxR-family systems in Gram-negative bacteria; the Las, Rhl, and Pseudomonas quinolone signal (PQS) networks in P. aeruginosa; and the AbaI/AbaR system in A. baumannii. This review focuses on QS regulatory mechanisms in ESKAPE pathogens and discusses the novel approaches to target QS-associated virulence and biofilm formation. A review of the literature on QS signaling pathways, biofilm regulation, and anti-QS therapies was performed with special focus on combating strategies like plant-derived phytochemicals, synthetic QS inhibitors, enzymatic quorum quenching, probiotics, and combinations of QS-targeted agents with conventional antibiotics. QS systems are involved in virulence regulation, adhesion, biofilm maturation, and bacterial persistence. Plant-based compounds such as flavonoids, alkaloids, terpenoids, and polyphenols have been shown to have potential to interfere with QS-related processes. Synthetic inhibitors, quorum-quenching enzymes, probiotics, and antibiotic combination strategies are also promising approaches. By integrating QS regulation with virulence, biofilm biology, and antimicrobial response across ESKAPE pathogens, this review provides a comparative framework to guide future target prioritization, diagnostic development, and evaluation of adjunctive anti-virulence strategies. Mechanistic validation, standardized cross-pathogen comparisons, and long-term resistance-evolution studies are needed to establish the therapeutic readiness and clinical value of these approaches.
Biological nitrogen fixation occupies a paramount position in sustainable agriculture. The present study elucidates the genomic diversity and symbiotic capabilities of Bradyrhizobium ottawaense focusing on the commercial B. ottawaense strain RCAM0104 to decipher the genetic bases of plant-bacterial interactions and the evolutionary adaptability of these microorganisms. Experimental assessments of symbiotic compatibility revealed that RCAM0104 effectively nodulates Arachis hypogaea, Glycine soja, and Vigna unguiculata, but is ineffective on Glycine max. Histological examinations confirmed successful infection processes in most host plants, with the exception of white nodules observed on cultivated soybean. Prediction of type III effectors in the RCAM0104 genome identified effector proteins potentially involved in its promiscuous symbiotic phenotype. These findings highlight the genetic flexibility of B. ottawaense and its capacity to adapt to diverse host plants. The observed host-specific nodulation patterns correlate with specific variations in the accessory genome, suggesting their potential role in determining symbiotic compatibility, potentially through gene transfer from local strains. This research contributes significantly to our understanding of the evolutionary dynamics and ecological plasticity of rhizobia in symbiosis with legumes, providing insights into the mechanisms regulating plant-microbe interactions. Based on these results, we hypothesize an evolutionary trade-off, where a loss of compatibility with one host may have occurred concurrently with the putative acquisition in compatibility with another.
The aim of this work was to characterize the pathogenic potential of Shiga toxin-producing Escherichia coli (STEC) circulating in environmental and animal reservoirs. To achieve this, 225 genomes were analyzed: four genomes were obtained from bovine mastitis isolates, and 221 were obtained from the NCBI Pathogen Detection database originating from surface water and animal fecal samples. All genomes were analyzed to identify virulence-associated factors and antimicrobial resistance profiles in strains collected from surface water and animal samples. Virulence analysis revealed that stx1 and stx2 were detected in 32
Non-phototrophic bacteria do not use light for energy, yet many detect visible radiation and reorganise gene expression accordingly. Two routes are involved: dedicated photoreceptors (flavin-binding BLUF and LOV domains, biliverdin-binding bacteriophytochromes and cobalamin-binding CarH/LitR regulators), and reactive oxygen species (ROS) generated when endogenous porphyrins and flavins absorb light, which trigger an oxidative-stress programme without any photosensory protein. This scoping review maps which genes change expression under visible light (400–700 nm) and how responses vary with wavelength, dose and context. We searched Elicit, PubMed/MEDLINE and Europe PMC, performed citation chasing, and charted 70 core primary studies. Blue light (400–470 nm) is reported to produce the largest transcriptional changes in most direct comparisons. Blue-light responses are frequently but not universally characterised by induction of oxidative-stress defences and repression of carbohydrate metabolism, virulence determinants and quorum-sensing systems; important exceptions exist, including up-regulation of type III secretion genes in Pseudomonas syringae. Red and far-red light (620–760 nm) elicits substantial change chiefly in species encoding bacteriophytochromes. Temperature determines whether photoreceptor-dependent regulation occurs at all: in Listeria monocytogenes and Acinetobacter baumannii it operates at environmental temperatures and is attenuated or reversed at 37 °C. Dose–response data and functional validation are scarce, and dosimetry is reported in incompatible units; standardised dosimetry, time-resolved designs and phenotypic confirmation are the principal needs.
The increasing prevalence of multidrug-resistant (MDR) bacteria isolated from dogs with external otitis presents a major therapeutic challenge in veterinary medicine, and antimicrobial photodynamic therapy has emerged as a promising alternative. Meso-tetra-pyridyl porphyrins bearing peripheral platinum(II) (3-PtTPyP) and palladium(II) (3-PdTPyP) complexes have shown activity against clinically relevant Gram-positive bacteria and may represent effective photosensitizers for otitis-associated MDR pathogens. Therefore, this study evaluated the antimicrobial activity and effects on bacterial morphology and adhesive properties of 3-PtTPyP and 3-PdTPyP on MDR isolates of Corynebacterium auriscanis, Enterococcus faecalis, Staphylococcus epidermidis, and Streptococcus canis obtained from dogs with otitis. Antibacterial activity was investigated by determining the minimum inhibitory and bactericidal concentrations (MBC) and by bacterial time-kill assay under white-light irradiation for 120 min. Alterations in bacterial morphology and nanomechanical properties were investigated using atomic force microscopy (AFM). Both porphyrins promoted a marked reduction in bacterial concentrations under white-light irradiation using MBC, although their bactericidal effects varied depending on the bacterial species and porphyrin. The 3-PtTPyP exhibited a more consistent photodynamic response against E. faecalis e C. auricanis, whereas 3-PdTPyP displayed greater effected against S. canis e S. epidermidis. AFM revealed pronounced changes in surface topography and nanomechanical properties after treatment with both porphyrins. Overall, these results demonstrate that 3-PtTPyP and 3-PdTPyP are promising photosensitizers for the inactivation of MDR Gram-positive bacteria associated with canine otitis externa, and the performance against the MDR Gram-positive bacteria was dependent of species.
