Search Results (10,511)

Micro- and nanoplastics (MNPs) have now been detected in human blood, placenta, and arterial tissue, yet the oral cavity has received strikingly little mechanistic attention despite serving as a primary portal of environmental exposure and a local site of polymer generation from dental and oral-care materials. This narrative review addresses that gap from an environmental microbiology perspective, synthesizing recent literature on periodontal disease, chronic low-grade inflammation, oral biofilms, dental materials, microbial–plastic interactions, and systemic chronic disease risk. Unlike prior reviews, we apply an explicit three-tier evidentiary framework (established, plausible, unproven) that distinguishes what is directly demonstrated from what is biologically plausible but unproven, and we situate the periodontal environment specifically as a particle-retention and inflammatory-amplification niche. The strongest direct oral evidence shows that human dental calculus harbors at least 26 microplastic types, dominated by polyamide (41.4%), polyethylene (32.7%), and polyurethane (7.0%). Polyethylene isolated from calculus induces cytotoxicity, apoptosis, impaired migration, NF-κB activation, and upregulation of IL-1β and IL-6 in human gingival fibroblasts. From a microbiological standpoint, oral organisms actively degrade methacrylate dental polymers, and the degradation products of these polymers reciprocally modulate oral bacterial virulence gene expression. Across experimental systems, MNPs activate oxidative stress, inflammasome signaling, macrophage polarization, and barrier dysfunction, pathways that overlap extensively with periodontal pathobiology. Adjacent environmental microbiology demonstrates that plastic-associated biofilms enhance extracellular polymeric substance production, quorum sensing, pathogen persistence, and antibiotic resistance gene transfer, supporting a plausible but not yet validated oral plastisphere within plaque and calculus. We argue that periodontitis should be reconceptualized as a chronically inflamed particle-processing interface that may increase local MNP retention, cellular reactivity, and systemic inflammatory spillover, with implications for cardiovascular, metabolic, and other chronic disease risk pathways. Current evidence does not yet prove that environmental MNP exposure causes human periodontitis, and that evidentiary boundary is maintained throughout. A priority research agenda is proposed, centered on contamination-controlled subgingival biomonitoring stratified by periodontal status, spatially resolved multi-species biofilm models, polymer source attribution, and longitudinal clinical studies linking oral plastic burden to inflammatory and systemic outcomes. Full article

Antibiotics primarily exert their effect on planktonic microbial states, limiting their ability to eradicate biofilms commonly seen in chronic infections. This is because the minimal inhibitory concentration of antibiotics needed to kill microbes in biofilms can be up to 1000 times greater than when microbes are in their planktonic state. Yet up to 70% of all chronic infections are associated with a biofilm component. Consequently, novel therapeutics are needed to aid in the treatment of chronic biofilm infections. One such approach is to repurpose drugs that have demonstrated safety for non-infectious clinical indications. The main advantage of this approach is that the agents have already been shown to be safe for human administration, which can expedite clinical trial development of agents for biofilm infections. Unfortunately, most clinicians are unaware of the antimicrobial properties of some commonly used drugs. Thus, the aim of this Perspective was to discuss the potential of four drugs that have theoretical promise as adjuvants in the treatment of chronic biofilm infections. This was accomplished by providing detailed discussion of each agent with respect to current clinical use, potential mechanisms of antimicrobial activity, and present data to support use as adjuvant biofilm agents. Full article

Objectives: Achieving a smooth tooth surface following periodontal instrumentation is critical for maintaining periodontal health and minimizing plaque and calculus reaccumulation. This narrative review aimed to synthesize preclinical laboratory-based evidence regarding the effects of periodontal instrumentation techniques on enamel and cementum surface roughness and hard-tissue loss. Methods: A focused literature search was conducted using the PubMed database to identify relevant in vitro and in vitro/in vivo hybrid studies published within the last 15 years. This review focused on ultrasonic scaling, hand instrumentation, and air polishing of human teeth during periodontal treatment. Results: Periodontal instrumentation was associated with surface alterations of enamel and cementum, with the extent of these changes depending on instrumentation parameters. Manual instrumentation was generally associated with greater surface irregularities and increased cementum removal, whereas ultrasonic scaling tended to produce more uniform surface characteristics. However, outcomes varied depending on instrumentation parameters. Air-polishing systems were described as less abrasive, particularly in biofilm management. Conclusions: Within the limitations of predominantly in vitro evidence, periodontal instrumentation appears to alter dental hard tissues to varying degrees depending on the technique and application. The clinical relevance of these findings remains uncertain, as the evidence was primarily laboratory-based and may not fully reflect clinical conditions or predict long-term outcomes. Full article

Plaque-disclosing agents are widely used to enhance visualization of dental biofilm. However, their chromogenic components may adhere to enamel surfaces, resulting in transient extrinsic discoloration. This study evaluated the extent and short-term recovery of such discoloration and compared three removal modalities in terms of enamel color change (CIEDE2000, ΔE₀₀), surface roughness (Ra), and gloss (GU). Extracted human anterior teeth with intact buccal enamel were stained using an erythrosine-based disclosing agent and randomly allocated into three groups (n = 15): manual brushing with conventional toothpaste, rubber-cup polishing with a perlite-containing paste (1000 rpm, 5 s), or erythritol-based air-polishing (5 s; 50% power/100% water). ΔE₀₀ was measured at baseline, immediately after cleaning, and after 1 week of storage in artificial saliva. Ra and GU were recorded at baseline and post-cleaning. Data were analyzed using appropriate tests (p < 0.05). All modalities were associated with a reduction in visible discoloration without significantly affecting Ra or GU (p > 0.05). Immediate ΔE₀₀ values remained above commonly reported acceptability thresholds, indicating residual discoloration. Partial color recovery occurred after artificial saliva storage. Within the limitations of this study, the findings indicate no statistically significant differences among the tested procedures, without evidence of superiority of any single modality. Full article

Background/Objectives: The purpose of this study was the chemical design, synthesis, and evaluation of the antimicrobial and antibiofilm potentials of 20 novel thiazolyl-methylthio-thiadiazole hybrid compounds (6a–j and 8a–j). Methods: The compounds were designed as structural analogues of halicin with two points of variation and were synthesized through a process with multiple condensation steps. The compounds were evaluated in vitro through MIC determinations for the antimicrobial activity and percentage of biofilm inhibition, and in silico, respectively, through molecular docking, druggability, and ADMETox prediction. A 2D-QSAR study was conducted for antimicrobial activity using the Free-Wilson model. Results: In terms of antibacterial activity, all compounds displayed important activity on the tested strains (MICs = 15.62–250 μg/mL), except against Staphylococcus aureus. Regarding the antifungal activity, the effect against Candida albicans was similar to fluconazole in most cases (MIC = 15.62 μg/mL). With respect to the antibiofilm activity, the most effective activity was registered against the Pseudomonas aeruginosa biofilm. The in vitro results for the antibacterial activity against Escherichia coli were correlated with the observations drawn in the molecular docking study on the ATPase domain of the GyrB subunit of E. coli. The in silico predictions of the molecular properties concluded that all compounds have good druggability properties, while the ADMETox predictions concluded that the compounds could have low gastrointestinal absorption and blood–brain barrier permeation capacity, but raised safety flags (e.g., hepatotoxicity and high acute oral toxicity). The 2D-QSAR study concluded that the thiazolyl-methylthio-thiadiazole scaffold had the highest contribution to antimicrobial activity in almost all cases. Conclusions: The two series of compounds highlight the impact of structural modulations of the scaffold and its substituents on the investigated biological activities. Full article

Antimicrobial resistance (AMR) represents a major global health threat, largely driven by antibiotic overuse and the protective role of bacterial biofilms. Quorum sensing (QS), a bacterial communication system regulating virulence and biofilm formation, has emerged as a promising therapeutic target. Quorum quenching (QQ), which disrupts QS without directly inhibiting bacterial growth, is considered a potential anti-virulence strategy that may reduce selective pressure for resistance. This review critically evaluates recent advances in QQ research, focusing on its clinical applicability, limitations, and risks. We analyzed studies from the last five years involving natural compounds, synthetic molecules, nanoparticles (NPs), and combination therapies targeting key pathogens such as Pseudomonas aeruginosa and Staphylococcus aureus in models of lung diseases, mainly cystic fibrosis, chronic wounds, burns, and implant-associated infections. While numerous compounds demonstrate significant in vitro anti-biofilm and anti-virulence activity, major challenges remain, including limited in vivo validation, pharmacokinetic constraints, toxicity concerns, microbiome disruption, and the potential development of tolerance or functional resistance. Although QQ offers a promising adjunctive approach to conventional antibiotics, its long-term clinical feasibility requires comprehensive evaluation of evolutionary dynamics, host–microbe interactions, and safety profiles. Full article

The Mycobacterium tuberculosis bacterium encodes two active potassium (K⁺)-uptake transport systems, the Trk and the Kdp. The Trk is the low-affinity K⁺ transporter, consisting of two TrkA proteins, while the Kdp consists of the high-affinity K⁺ transporter KdpFABC and the two-component system KdpDE. Both transporters are utilised by the bacteria for growth and survival. During growth, the bacteria utilise the constitutively expressed Trk and suppress the Kdp, but upregulate both transporters during survival. In the current study, we investigated the interactive effects of these systems on bacterial growth and survival. This was achieved by first constructing a M. tuberculosis mutant strain in which both the Trk and Kdp systems were inactivated by homologous recombination. The mutant was evaluated for its growth kinetics in planktonic cultures, as well as survival in biofilm and macrophage cultures. The constructed M. tuberculosis mutant showed faster growth rates in planktonic cultures, but was attenuated for both biofilm formation and intracellular survival in isolated human monocyte-derived macrophages. These results illustrate that both K⁺-uptake systems are essential to sustain slow rates of bacterial growth, as well as for bacterial persistence in hostile environments via optimisation of biofilm formation, and intracellular survival in macrophages. (Words: 194) Full article

Photodynamic therapy (PDT) is a minimally invasive treatment choice whose clinical success in dermatology relies on the interaction between a photosensitizer, light of an appropriate wavelength, and tissue oxygen, leading to reactive oxygen species generation and selective cytotoxicity. This narrative review summarizes contemporary mechanisms and clinical evidence supporting PDT across neoplastic, inflammatory, infectious, and esthetic indications. A comprehensive literature search included randomized trials when available, systematic reviews, meta-analyses, and guideline and consensus documents, complemented by mechanistic and translational studies relevant to clinical outcomes. In premalignant and neoplastic disease, strongest evidence supports field-directed PDT for actinic keratosis and high efficacy in Bowen’s disease, with favorable cosmetic outcomes and acceptable recurrence patterns. PDT plays a more selective role in basal cell carcinoma, particularly superficial and selected nodular lesions, while its routine use as monotherapy in squamous cell carcinoma remains limited by higher recurrence. Beyond oncology, PDT shows expanding utility in acne via sebomodulatory and immunomodulatory effects, and in infectious dermatoses through broad antimicrobial activity and biofilm disruption with low resistance potential. Cosmetic applications, including photorejuvenation, benefit from protocol tailoring and combination strategies that enhance penetration and remodeling. Overall, PDT is evolving into an adaptable therapeutic framework best positioned within mechanism-oriented, multimodal algorithms. Full article

Microplastics (MPs) are emerging pollutants that affect soil–microbe interactions in paddy ecosystems. Periphytic biofilms (PBs) are complex microbial consortia that ubiquitously distribute at the soil–water interface of paddy ecosystems, playing essential roles in nutrient cycling and pollutant migration. However, whether MPs affect the community composition of PBs remains largely unknown. This microcosm study investigated the effects of three types of MPs (polyacrylonitrile, PAN; polyethylene, PE; and polyethylene terephthalate, PET) on the community characteristics of PBs via high-throughput sequencing (16S/18S rRNA) technology. Results showed that the addition of all MPs significantly increased the biomass and chlorophyll-a content of PBs, with PAN inducing the maximum increase (by 331.9% and 128.6%). However, all MPs had no significant effect on the PB α-diversity of bacterial and eukaryotic communities (p > 0.05). As for PB composition, PAN and PET increased the relative abundance of Cyanobacteria, Proteobacteria and Holozoa, PE increased that of Cyanobacteria, Bacteroidota and Blastocladiomycota, and all MPs decreased the relative abundance of Chloroflexi, Actinobacteriota and Basidiomycota. Furthermore, PET decreased the predicted functional potential of natural polymer degradation (cellulolysis, ligninolysis, xylanolysis, ureolysis), nitrogen fixation and nitrate ammonification, while PE increased predicted potential for plastic degradation, nitrate reduction and denitrification. Co-occurrence network analysis suggested that the PE network showed higher connectivity and lower modularity, while the PAN network showed higher modularity. This study advances our understanding of soil MPs–microbe interactions under high-concentration conditions. It also suggests that PB community characteristics may serve as potential bioindicators for soil MP pollution. Full article

Sensitivity to the bitterness of 6-n-propylthiouracil (PROP) is controlled by variations in the TAS2R38 gene. This phenotype is often used as a marker for individual differences in taste perception. Previous findings show that PROP taster status is associated with differences in the salivary microbiome. It is well known that diet and environmental factors influence the risk of oral disease, but there is far less evidence showing how genetic differences play a role. Forty-seven young, healthy, PROP taster-classified adults rinsed with a cranberry polyphenol extract (CPE) oral rinse (0.75 g/L CPE powder in spring water) twice daily for 11 days. Saliva was collected pre- and post-intervention for microbiome analysis using shotgun metagenomic sequencing. At the same time points, participants evaluated two astringent juices (cranberry and aronia berry) for key attributes. At baseline, PROP taster groups differed in their salivary microbiome compositions, but post-intervention, the groups had more similar bacterial compositions. Post-intervention, non-tasters showed decreases in the relative abundance of 15 bacterial species, including a significant reduction (p = 0.037) in Eikenella corrodens, which is one bacterium, among several others, involved in oral biofilm formation. Additionally, after the intervention, sourness was reduced, and overall liking increased significantly for aronia juice. Oral dysbiosis, a risk factor for oral disease, may be controlled by bactericidal mouthwashes. Our results suggest that CPE, a natural alternative to traditional bactericidal rinses, may selectively target pathobionts while preserving salivary microbiota diversity. CPE might also provide greater benefits to non-tasters, who are at greater risk for oral disease. Full article

Background and Objectives: Halitosis is a common condition with substantial psychosocial impact, frequently driven by intra-oral biofilm, tongue coating, and reduced salivary clearance. This study compared the short-term effectiveness of standardized counseling alone, probiotic lozenges containing Streptococcus salivarius K12, and a zinc-containing mouthrinse in adults with persistent intra-oral halitosis. Materials and Methods: In this 4-week, parallel-group, randomized pragmatic trial, 117 adults with bothersome halitosis for at least 3 months and baseline organoleptic score ≥ 2 were allocated 1:1:1 to standard care, probiotic lozenges, or zinc mouthrinse. All participants received standardized counseling and tongue cleaning instructions. The primary endpoint was change in volatile sulfur compounds (VSCs) measured by portable sulfide monitoring. Secondary outcomes included organoleptic score, Halitosis Associated Life-Quality Test (HALT), Oral Health Impact Profile-14 (OHIP-14), tongue coating, plaque, and salivary Solobacterium moorei quantified by qPCR. Results: Baseline demographic, clinical, and biochemical characteristics were comparable across groups. All interventions improved outcomes over 4 weeks, but improvements followed a consistent gradient favoring zinc mouthrinse, followed by probiotic lozenges, then standard care. Mean VSC reduction was −12.7 ± 33.9 ppb with standard care, −47.3 ± 42.2 ppb with probiotics, and −78.5 ± 36.3 ppb with zinc mouthrinse (p < 0.001). Organoleptic scores improved by −0.2 ± 0.7, −0.8 ± 0.8, and −1.2 ± 0.8, respectively (p < 0.001). HALT and OHIP-14 scores showed parallel reductions, and moderate/severe halitosis at week 4 remained most frequent in the standard care group (58.9%) and least frequent in the zinc group (20.5%; p = 0.004). Conclusions: Both active adjunctive strategies improved intra-oral halitosis beyond standardized counseling alone, but the zinc-containing mouthrinse produced the greatest short-term benefits across objective, clinician-rated, and patient-reported outcomes. These findings support zinc-based rinses as a practical short-term adjunct for managing persistent intra-oral halitosis in outpatient dental care. Durability after discontinuation and potential relapse beyond 4 weeks were not assessed in this trial. Full article

A clinical strain of the opportunistic pathogen Serratia rubidaea, a known contaminant of healthcare environments and an emerging cause of invasive infections, is described. The studied isolate, recovered from a nurse’s hand skin swab during routine screening, exhibits a broad profile of antibiotic resistance combined with reduced susceptibility to several disinfectants. Phenotypic susceptibility testing using a tablet-based microdilution and disk diffusion method was employed to determine the minimum inhibitory concentrations (MICs) of antimicrobial agents from different classes, while broth microdilution assays with disinfectants revealed high-level tolerance to widely used agents, including 70% C₂H₅OH, 3% H₂O₂, 0.05% polyhexamethylene guanidine (PHMG) and others. Whole-genome sequencing identified multiple resistance-associated determinants, such as chromosome-encoded class C $\beta$-lactamase (ampC), several efflux systems (sdeXY, macAB, and emrAB) combined with multicopy tolC, and specific transferases (fos and arnT). Shotgun bottom-up HPLC-MS/MS proteomics confirmed baseline expression of these and other stress-tolerance-related proteins under non-inducing conditions. Taken together, these data underscore the importance of surveillance for Serratia spp. in healthcare facilities to detect strains that combine intrinsic or acquired multidrug resistance with robust survival traits such as disinfectant tolerance and biofilm formation. The present study provides a reference-level phenotypic, genomic, and proteomic characterization of a S. rubidaea clinical isolate, contributing to the understanding of the adaptive potential of this resilient opportunistic pathogen in clinical environments. Full article

Globally, the rise in MDR P. aeruginosa infections poses a serious threat to public health, as these strains frequently exhibit extensive resistance to conventional antibiotics, prompting interest in bacteriophages as alternative treatments. In this study, we isolated and characterized a lytic P. aeruginosa phage, vB_Pae_YuaWU01, from hospital sewage in southern Thailand. Morphological analysis revealed Siphovirus-like characteristics. The phage demonstrated efficient host adsorption, with approximately 85.9% of particles attached within 15 min, and exhibited a latent period of 50 min with a burst size of 17.2 PFU/cell. It showed strong lytic activity, consistently suppressing bacterial growth without no regrowth observed over 72 h. Notably, the phage significantly inhibited biofilm formation by up to 59.9% and reduced pre-established biofilms by 39.78% at the highest tested concentration (10⁹ PFU/mL). Genome analysis revealed a 61,824 bp double-stranded DNA genome with 64.48% GC content and 88 predicted genes. Bioinformatic analysis suggests that the genome is organized into structural, replication, and lysis modules. Importantly, no toxin, antimicrobial resistance, lysogeny, or tRNA genes were identified, suggesting a favorable safety profile. The phage was classified within the genus Yuavirus, showing 97.4% genomic similarity to Sphaerotilus phage SN1, which infects a different host strain. The findings highlight its potential as a genetically safe therapeutic agent; however, its limited host range indicates that it may be best positioned as a strategic component of phage cocktails or as a synergistic partner with antibiotics to maximize therapeutic efficacy. Full article

Background: ESKAPE constitutes a group of six nosocomial bacteria that can evade available antimicrobials due to their great potential to develop multi-drug resistance and biofilm-forming abilities. These pathogens often cause hospital-acquired infections and pose a serious threat to public health. The search for efficient innovative therapeutic strategies to fight ESKAPE bacteria have been intensively investigated topics. One promising approach to fight resistant pathogens and their biofilms is combination therapy, which allows the effectiveness against microorganisms to be increased while reducing the applied concentrations and risks of potential unwanted side effects. Objectives: The object of the study was to determine if there is an interaction of short lipopeptides ((C₁₀)₂-KKKK-NH₂, C₁₆-KK-NH₂) together with erythromycin and tetracycline against pathogens of the ESKAPE group (Acinetobacter baumannii, Enterobacter aerogenes, Enterococcus faecium Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus). Methods: The checkerboard assay was used to examine the activity of compounds applied in combinations against ESKAPE strains in planktonic cells and toward biofilms formed by Staphylococcus aures and Pseudomonas aeruginosa. Results: The lipopeptides demonstrated a great potential of their application as additives to conventional antimicrobials against Gram-negative bacteria, including microorganisms within biofilms. Full article

Diabetic chronic wounds (particularly diabetic foot ulcers) are difficult to heal due to factors such as high glucose levels, infection, and inflammatory imbalance. In severe cases, they can lead to tissue necrosis and amputation. Hydrogel materials, as moist wound dressings, possess high water content, biocompatibility, and tunability, making them an important platform for promoting diabetic wound healing. In recent years, novel smart hydrogels have been developed to integrate multiple functions. They respond to abnormal stimuli in the wound microenvironment—such as acidic pH, high glucose levels, or excessive reactive oxygen species—to trigger the release of drugs, delivering on-demand antimicrobial, antioxidant, and anti-inflammatory effects. Simultaneously, they modulate immune responses (promoting macrophage polarization toward the M2 type) and stimulate angiogenesis, creating a microenvironment conducive to tissue regeneration. Some hydrogels incorporate antimicrobial agents, anti-biofilm components, or photothermal/photodynamic agents to effectively eliminate drug-resistant pathogens and control infections. Others serve as carriers for delivering stem cells and their exosomes, enhancing cell survival rates and releasing growth factors to accelerate wound healing. This review systematically summarizes recent advances in hydrogel strategies for diabetic wound treatment, focusing on stimulus-responsive hydrogels, antimicrobial and immune modulation mechanisms, pro-angiogenic and oxygen-supplying therapies, smart dressings and monitoring technologies, integration of stem cells and exosomes, as well as hydrogel injection, self-healing, and adhesion properties. Based on this, we analyze challenges and prospects for clinical translation of these strategies. Collectively, functionalized hydrogels hold promise as multifunctional therapeutic platforms for diabetic non-healing wounds. They offer a multi-pronged approach to disrupt the vicious cycle of “infection–inflammation–tissue destruction” thereby achieving more efficient wound healing. Full article