Search Results (583)

Streptococcus uberis is a bovine mastitis pathogen with a demonstrated ability to form biofilms. However, the dynamics of this process remain poorly characterized. This study aimed to comprehensively characterize biofilm formation in four S. uberis strains that differed in their biofilm-forming capacity, from weak to strong producers, and in the presence of key virulence-associated genes, such as sua, hasA and hasC. To achieve this, we integrated structural, biochemical, physiological and transcriptional analyses using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), spectral flow cytometry and qRT-PCR. The multi-faceted analysis revealed a coordinated maturation peak at 48 h, characterized by a structured architecture with water channels, a distinct biochemical signature rich in polysaccharides and proteins, and a predominantly viable bacterial population. This peak coincided with a marked upregulation of key virulence-associated genes, with sua expression increasing 2.5-fold and hasA increasing 3-fold at 48 h. This mature biofilm conferred high tolerance to antibiotics, with eradication concentrations (>256 µg/mL) exceeding planktonic MICs, although tetracycline was notably effective. At 72 h, the biofilm entered a dispersion phase characterized by structural collapse and reduced viability. These findings establish S. uberis biofilm maturation as a highly coordinated process, providing new insights into the biofilm lifecycle of this important pathogen and identifying key temporal and molecular targets for future interventions. Full article

The growing global threat of antimicrobial resistance (AMR), particularly in cutaneous wound infections, represents a significant clinical and economic challenge. Biofilm formation by multidrug-resistant pathogens, such as Acinetobacter baumannii, often complicates healing and leads to therapeutic failure. Antimicrobial peptides (AMPs) are a promising alternative to conventional antibiotics due to their potent membrane-disrupting mechanism of action and lower propensity to induce resistance. Background/Objectives: This study aimed to evaluate the antibacterial, antibiofilm, and in vivo efficacy of four snake venom-derived cathelicidin-like peptides—Btn (15-34) and BotrAMP14 from Bothrops atrox, and Ctn (15-34) and CrotAMP14 from Crotalus durissus—against multidrug-resistant A. baumannii, Escherichia coli, and Pseudomonas aeruginosa clinical isolates from skin infections, with emphasis on A. baumannii, a WHO priority pathogen. Methods: Minimal Inhibitory Concentration (MIC), Minimal Bactericidal Concentration (MBC), and Minimal Biofilm Inhibitory Concentration (MBIC) were determined against A. baumannii, Escherichia coli, and Pseudomonas aeruginosa. Time-kill kinetics, hemolytic activity, and cytotoxicity assays were performed. A murine skin wound infection model was established to evaluate in vivo antibacterial efficacy and safety. Results: MIC/MBC values ranged from 0.78 to 25 µM against planktonic cells. In comparison, MBIC ranged from 1.56 to 12.5 µM against biofilms. BotrAMP14 eradicated A. baumannii within 4 min, while CrotAMP14 achieved bactericidal action in 20 min at 1.56 µM. Both peptides exhibited no hemolytic activity up to 128 µM and low cytotoxicity (IC₅₀ > 128 µM). In vivo, BotrAMP14 and CrotAMP14 demonstrated significant antibacterial activity at 24 h and 48 h post-infection, respectively, surpassing that of meropenem. Conclusions: These findings suggest that BotrAMP14 and CrotAMP14 are promising topical antimicrobial agents for managing multidrug-resistant skin infections and may help address the urgent need for alternative therapies against antibiotic-resistant pathogens. Full article

Background: This research aimed to investigate the antifungal and antibiofilm action of Lavandula angustifolia essential oil (LaEO) against certain Candida species and its toxicity on human keratinocytes. Methods: The minimum inhibitory concentration (MIC) and sessile minimum inhibitory concentration (SMIC) of LaEO were both determined by broth microdilution assays. The influence of LaEO treatment on the ultrastructural morphology of the biofilm and germ tubes was evaluated by scanning electron microscopy (SEM) and light microscopy. In vitro cytotoxicity studies were conducted using human HaCaT epidermal keratinocytes. Results: LaEO showed fungicidal action for all Candida species (125–4000 μg/mL). The SMIC_>90 (C. albicans) ranged between 10,000 and 20,000 μg/mL and resulted in quantitative and qualitative cellular changes. LaEO also inhibited the developmental germ tube kinetics of C. albicans. The 50% cytotoxic concentration (CI₅₀) for HaCaT cells was estimated at 420 μg/mL of LaEO, resulting in a selectivity index (SI) of 0.376 to 5.753 for planktonic cells and 0.056 to 0.321 for biofilm phases. Conclusions: LaEO was found to have antifungal action against Candida species and inhibited the pathogenic morphology of C. albicans. Its antibiofilm effects are comparable to the antifungal agent nystatin, and it can become an important component for the development of natural products applicable to alternative and complementary medicine and dentistry. Full article

The impact of nitrogen on harmful algal blooms (HABs) and functions of biota in marine ecosystems under eutrophication is a topical issue of growing importance. The article aimed at describing the diversity of planktonic bloom-forming dinoflagellates in the SW Baltic Sea coastal waters under variable eutrophication. The analysis of 44 year-long database revealed 82 dinoflagellate species and demonstrated diversity patterns of ten common bloom-forming species, including seven mixotrophs from the genera Prorocentrum, Dinophysis, and Ceratium, under variable eutrophication evaluated using total nitrogen (TN) content in water. Based on the Intermediate Disturbance Hypothesis (IDH), we presumed those coastal waters with total nitrogen concentrations that are optimal to dinoflagellates to host greater taxonomic diversity compared to areas with non-optimum TN content. The results showed that the highest dinoflagellate species richness was associated with much lower TN concentrations than the optimum values for these species. Thus, our findings disagreed with the IDH. We suggested and discussed possible reasons of this inconsistency, including algal growth rates and disturbance frequency. We also updated the classification of eutrophication levels in the Baltic Sea based on the distribution of TN content and diversity of HAB-forming dinoflagellates. The results can contribute to predictive assessment of HABs under growing eutrophication. Full article

This review synthesizes current knowledge on the biology and ecology of the small cyclopoid copepod Oithona similis, a prevalent planktonic species in the Barents Sea, during the period of Arctic warming since the early 2000s. The region serves as an effective model system for examining the influence of different water masses on Arctic zooplankton dynamics. The highest abundances and biomass of Oithona similis are observed in Murmansk Coastal Waters (MCW) and Arctic Waters (ArW). Although its contribution to total zooplankton biomass is generally lower than that of higher copepod taxa, it can account for up to 27–35% seasonally and regionally. Ovigerous females are most abundant in Novaya Zemlya Waters (NZW) and ArW. Egg production rates exhibit a decreasing trend from south to north across the sea. Morphometric analyses reveal an increase in prosome length for both sexes, while relative antenna size diminishes from the south (MCW) to the north (ArW). The highest mortality rates occur during summer, coinciding with peak abundances of Oithona similis, its predators, and parasites, as well as increased interspecific competition. Based on morphological and reproductive parameters, three distinct populations are delineated within the Barents Sea: southern (MCW), central (Atlantic Water/Barents Sea Water), and northern/eastern (ArW/NZW), with respective life cycle durations of 11–12, 9–10, and 11 months, and typically one to two generations per year. The primary environmental drivers influencing population abundance, biomass, size, and reproduction are temperature and salinity, while chlorophyll a concentration predominantly affects mortality rates. Full article

Background/Objectives: Stenotrophomonas maltophilia (SM) is a significant cause of hospital-acquired infections in immunocompromised and critical care patients. This study investigates the impact of combining ceftazidime/avibactam (CZA) with conventional antibiotics on SM obtained from various sources in planktonic and biofilm cell cultures. Methods: Using broth microdilution, the MICs of different antibiotics, including CZA, were determined on 37 SM strains. CZA’s bactericidal and synergistic effectiveness were examined through in vitro time–kill curve tests with tigecycline (TGC), chloramphenicol (CHL), levofloxacin (LVX), colistin (CS), and amikacin (AMK). In addition, synergistic activity was investigated against SM biofilm cell cultures, and antibiotic Mutant Prevention Concentrations (MPCs) were tested against SM isolates. Results: Compared to ceftazidime (CAZ), CZA was four times more efficient against 37 SM strains. Unlike TGC and CHL, CS, AMK, and CZA had 2–4 times higher MBCs than MICs. All studied antibiotics were bactericidal at 1× or 4× MIC doses against SM bacteria, except for CZA. The combinations of CZA with LVX and CZA with AMK or CS demonstrated synergistic effects in four out of seven (57%) strains and in three out of seven (43%) strains, respectively, when tested at doses equivalent to the MIC. Moreover, all antibiotic combinations with CZA showed a synergistic effect at dosages four times the MIC. Additionally, CZA and the tested drugs synergistically inhibited SM biofilm formation, and MPC values were 8–16 times the MIC. Conclusions: The results of this study indicate that combining CZA with LVX and CS was more effective against SM strains. These combinations might provide alternatives for treating SM pathogens in both planktonic and biofilm cell cultures. Full article

Background: Antibiotic-loaded bone cement (ALBC) is widely used for local antibiotic delivery in joint arthroplasty to prevent and treat prosthetic joint infections (PJIs). In this study, we evaluated the efficacy of cemented Kirschner (K)-wires coated with various ALBC formulations using a Galleria mellonella infection model against multidrug-resistant (MDR) Staphylococcus aureus and Enterococcus faecalis. Methods: We tested commercially available bone cements, including gentamicin-only formulations (PALACOS R+G) and dual-antibiotic formulations, combining gentamicin with either clindamycin (COPAL G+C) or vancomycin (COPAL G+V), alongside an antibiotic-free control (PALACOS R). In vitro assays—including minimum inhibitory/bactericidal concentration (MIC/MBC) determination, antibiotic release kinetics, agar diffusion, and antibiofilm evaluations—demonstrated effective antibiotic release and significant antimicrobial activity against both planktonic and biofilm-associated bacteria. Results: In vivo, ALBC-coated K-wires were well tolerated in G. mellonella and significantly protected the larvae from S. aureus infection compared to controls. Notably, dual-antibiotic formulations provided superior protection, correlating with substantial reductions in bacterial colonisation on implant surfaces and in surrounding tissues. Conclusions: These findings support the utility of the G. mellonella model as a high-throughput, cost-effective platform for the preclinical evaluation of antimicrobial strategies to prevent and treat PJIs and further demonstrate the effectiveness of dual-loaded ALBC against multidrug-resistant bacteria. Full article

Background: Porphyromonas gingivalis is one of the most prevalent periodontal pathogens, involved in the development of periodontitis, deep caries, pulpitis, endodontic infections, and peri-implantitis. Antiseptics are commonly used in the treatment of oral diseases, but their effectiveness against P. gingivalis remains only partially understood. This preliminary study investigated antimicrobial and antibiofilm activity of eight pure antiseptics: boric acid (BA), chlorhexidine (CHX), ethacridine lactate (ET), hydrogen peroxide (H₂O₂), octenidine (OCT), polyhexanide (PHMB), potassium permanganate (KMnO₄), and sodium hypochlorite (NaOCl), as well as five commercial rinses containing these agents, against periopathogen P. gingivalis ATCC 33277. Methods: Minimal inhibitory concentrations (MICs) were determined using the broth microdilution method. The Clinical Efficiency of MIC (CEMIC) was subsequently calculated. Antibiofilm activity was evaluated using the crystal violet method, LIVE/DEAD fluorescence assay and by measuring biofilm thickness with digital microscopy in combination with the author’s Python-based application Biofilm Thickness Analyzer. Results: OCT, CHX, PHMB and ET showed the strongest activity against P. gingivalis, in both its planktonic and biofilm forms. H₂O₂ and BA had variable MIC efficacy and moderate antibiofilm activity. In contrast, NaOCl and KMnO₄ demonstrated the weakest activity or no significant effect against P. gingivalis. Conclusions: The results have a translational dimension, supporting the potential clinical relevance of the selected compounds. However, this study was conducted strictly in vitro on a single strain under monomicrobial biofilm conditions. Therefore, while the findings suggest that mouthwashes containing OCT, CHX, and PHMB may be effective against P. gingivalis, their actual clinical efficacy in the treatment and prevention of oral diseases remains to be confirmed in in vivo studies. Full article

Managing bacterial infections and the spread of microbial resistance is one of the most critical and complex tasks of modern healthcare infrastructures. Antiseptics and disinfectants such as biocides play a significant role in controlling microbial resistance by reducing the microbial load on surfaces, skin, and environments, thereby limiting the opportunity for pathogens to proliferate and develop resistance. Herein, we tested the different interactions of quaternary ammonium compound (QAC)-based biocide compositions in pursuit of a better antimicrobial performance. An extensive microbiological analysis was conducted for 12 selected compositions of various combinations of mono-QACs, bis-QACs, and alcohols on 17 strains of bacteria of the ESKAPEE group and fungi, including 11 clinical highly resistant varieties, highlighting synergistic or additive dynamics. The evaluation showed noticeable improvements in activity, with up to 16-fold MBC and 32-fold MBEC reductions for alcohol-based compositions of lead QAC. Moreover, synergistic interactions were detected and confirmed via an optimized checkerboard assay for pyridinium QAC combinations against planktonic Gram-positive S. aureus with a fractional inhibitory concentration index (FICI) and fractional bactericidal concentration index (FBCI) of 0.39–0.5 and Gram-negative A. baumannii biofilms. The studied biocides demonstrated the long-term preservation of antimicrobial efficiency without resistance development during a 40-day period and do not induce QAC-associated cross-resistance for four commercially available antibiotics with similar mechanisms of action. Full article

A biofilm is a self-protective material formed by microorganisms to resist adverse environments. As an important group of microorganisms in the food industry and the human intestine, lactic acid bacteria (LAB) demonstrate enhanced probiotic activity in their biofilm state. In this study, a total of 90 LAB isolates from various traditional fermented foods across China were evaluated for their biofilm-forming capacity using the crystal violet staining method. Of these, eight isolates showed strong biofilm-forming capacity. These eight isolates were further evaluated for environmental stress responses, including tolerance to high acid and high bile salt concentrations, resistance to simulated gastrointestinal conditions, and adherence to Caco-2 cells. Four isolates with strong resistance to these stresses and adhesion to Caco-2 cells were selected for comparison between their planktonic and biofilm forms. Among these, the two isolates demonstrating the highest biofilm production capacity were AQ-4 and SY1-3, which were isolated from fermented pear juice and apple juice, respectively. Isolate AQ-4 was then identified as Lactiplantibacillus plantarum based on 16S rDNA sequencing. By integrating biofilm-forming capacity with key biological properties, including stress tolerance and epithelial adhesion, this study focuses on L. plantarum AQ-4, which exhibits distinct microstructural differences between planktonic and biofilm states, as revealed by scanning electron microscopy. The findings suggest that L. plantarum AQ-4 could be used to investigate the differential mechanisms in the planktonic and biofilm states and to act as the theoretical basis for the application of LAB biofilms in the food industry. Full article

Cannabinoids have been shown to have effective antibacterial applications. With the limitations of current intracanal endodontic medicaments and the rise of bacterial resistance, it is important to investigate novel treatment strategies for endodontic infections. The aim of this study was to test the antibacterial efficacy of cannabinoids on bacteria in persistent endodontic infections: Enterococcus faecalis, Streptococcus mutans, and Fusobacterium nucleatum. Planktonic bacteria were exposed to a negative control (no exposure), a positive control (3% NaOCl), and the experimental groups Cannabidiol (CBD), Cannabinol (CBN), and Tetrahydrocannabinol (THC). The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were also investigated. Biofilms were cultured and treated with cannabinoids. A crystal violet assay (CVA) and live/dead analysis assessed the biofilm degradation and inhibition, respectively. A statistical analysis was performed using an ANOVA. CBD, CBN, and THC reached a MIC for both E. faecalis and S. mutans in planktonic forms. The MBC was found for the tested cannabinoids on planktonic E. faecalis. No MBC was found for S. mutans. The live/dead analysis of E. faecalis and S. mutans biofilms showed a decrease in the viability of the biofilm with an increased cannabinoid concentration. The CVA revealed that cannabinoids only degrade the E. faecalis biofilm. Planktonic F. nucleatum had no MIC for tested cannabinoids. Cannabinoids have inhibitory effects on E. faecalis and S. mutans in the planktonic and biofilm states. No inhibitory effects of F. nucleatum were found at tested concentrations of all three cannabinoids. The findings suggest that cannabinoids have distinct antibacterial effects on certain pathogens associated with persistent endodontic infections. Full article

This study synthesizes novel photosensitizer calcination betaine hydrochloride carbon dots (CBCDs) to address the critical challenge of Enterococcus faecalis (E. faecalis) biofilms, a major cause of root canal treatment failure. To this end, this study investigates the effective elimination via reactive oxygen species (ROS) mediated by these CBCDs. CBCDs were prepared by calcining betaine hydrochloride and rigorously characterized for their structural and chemical properties using transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Their optical characteristics were also thoroughly analyzed through UV-Vis and fluorescence spectroscopy. The RNO-ID assay was performed to explicitly confirm ROS production, particularly verifying significant singlet oxygen (¹O₂) generation. Bactericidal efficacy of the CBCDs was comprehensively evaluated against planktonic E. faecalis and its formed biofilms. Live/dead staining was subsequently performed to observe their state after treatment. As a result, TEM confirmed nanosized CBCDs, and FTIR/XPS analyses identified crucial functional groups. Colony Forming Unit (CFU) assays revealed a dose-dependent reduction in E. faecalis viability, achieving complete eradication at 200 mg/L under light irradiation. Complete cell death and inactivation of the formed biofilms with increasing CBCD concentrations were also strongly evidenced by red fluorescence. The obtained results underscore CBCDs as highly effective photodynamic agents for the robust elimination of E. faecalis biofilms, offering a promising new strategy to combat persistent oral infections. Full article

Natural compound-based strategies have gained attention as alternatives to conventional antifungal therapies, particularly in the management of Candida infections affecting the oral cavity, such as denture stomatitis. Our aim was to investigate the antifungal activity of the polyphenol pterostilbene (PTE) on clinical Candida isolates and microcosm biofilms from denture stomatitis, as well as to evaluate its toxicity and therapeutic efficacy in Galleria mellonella. PTE exhibited fungicidal effects against Candida albicans and Candida dubliniensis at 32 µg/mL. Time-kill assays demonstrated complete inhibition of viability for both strains within 8 h of exposure. In addition, PTE exhibited broad-spectrum antimicrobial activity, significantly reducing the counts of streptococci, mutans streptococci, staphylococci, and yeasts within microcosm biofilms. In vivo, PTE showed no signs of toxicity in G. mellonella at concentrations up to 20× MIC. Prophylactic treatment with PTE enhanced larval survival in experimental candidiasis caused by both C. albicans and C. dubliniensis. Moreover, prophylactic treatment decreased the fungal burden of C. albicans in the G. mellonella hemolymph, while the recruitment of hemocytes involved in host defense mechanisms remained unaltered. In summary, PTE demonstrated antimicrobial activity against Candida planktonic cells and complex biofilms associated with denture stomatitis, exhibiting favorable biocompatibility and in vivo antifungal efficacy in G. mellonella model. Full article

Reservoirs are hotspots for the coupling of nutrients and heavy metals, and they substantially modify the compositions and spatiotemporal distributions of microorganisms in fluvial systems. However, relatively few studies have been performed that investigate the microbial mechanisms driving interactions among heavy metals and nutrients in reservoirs. The Goupitan Reservoir, a seasonal stratified reservoir located within the Wujiang River catchment, was chosen as the research subject. The temporal and spatial variations in heavy metals and nutrients, and the metagenomic composition of the reservoir water were analyzed in January, April, July, and October 2019. The results revealed that As, Ni, Co, and Mn were derived primarily from mine wastewater, whereas Zn, Pb, Cd, and Cr were related to domestic and agricultural wastewater discharge. The study area was dominated by Proteobacteria, Actinobacteria, Cyanobacteria, and Bacteroidetes, with the proportion of dominant phyla reaching 90%. Decreases in the dissolved oxygen (DO) concentration and pH in the bottom water during July and October were conducive to increases in the abundance of the anaerobic bacterial groups Planctomycetes and Acidobacteria. The functional genes norBC and nosZ associated with denitrification (DNF), the key gene nrfAH involved in the dissimilatory nitrate reduction to ammonium (DNRA) process, the functional genes aprAB and dsrAB responsible for sulfate reduction/sulfide oxidation, as well as the thiosulfate oxidation complex enzyme system SOX, all exhibit high abundance in hypoxic water bodies and peak in the redoxcline, highlighting the significance of related nitrogen (N) and sulfur (S) metabolic processes. In addition, the concentrations of heavy metals significantly affected the spatial differentiation of the planktonic bacterial community structure, with Mn, Co, Fe, Ni, As, and Cu making relatively high individual contributions (p < 0.01). This study is important for elucidating the sources and microbiological mechanisms influencing heavy metals and nutrients in seasonally stratified subtropical reservoirs. Full article

Microplastic pollution poses growing risks to aquatic zooplankton, yet its impact on Daphnia magna life history remains incompletely understood. This study explored the influences of micro/nanoplastics (MPs/NPs) on D. magna by exposing organisms to size- and concentration-varied microplastics, tracking microplastic distribution via fluorescence imaging. Results demonstrated significant microplastic-induced impairments in growth and reproduction. Gut microbiota analysis revealed microplastic-altered microbial communities, with functional prediction identifying disrupted glucose metabolism as a key driver of life-history changes. Intestinal structure observations further showed microplastic-accelerated aging. Collectively, our findings highlight that microplastic accumulation in D. magna disrupts gut microbiota and tissue integrity, ultimately impairing life-history traits. These alterations in growth and gut characteristics of D. magna may further propagate through the aquatic food web, potentially damaging the intestinal structure and function of plankton communities. Given the pivotal role of zooplankton in nutrient cycling and energy transfer, our findings underscore that microplastic-induced disruptions in key species like D. magna could threaten the stability and sustainability of aquatic ecosystems. Full article