Search Results (830)

Background: Biofilms consist of complex microbial communities embedded in an extracellular matrix which confer resistance to the most used antimicrobial agents. Chronic wounds are often associated with burns, trauma, surgery, diabetes and peripheral vascular disease. They are characterized by a marked delay in wound healing favoring the development of microbial biofilms, which in turn further delay tissue regeneration. Staphylococcus aureus, Staphylococcus epidermidis, and methicillin-resistant staphylococci biofilms are found in chronic wounds, seriously hindering wound treatment. Vitreoscilla filiformis, a Gram-negative non-pathogenic filamentous bacterium, has been shown to improve atopic dermatitis by reducing S. aureus colonization and inducing antioxidant responses in the skin. Objectives: The aim of the present study was to evaluate the antimicrobial, anti-inflammatory, and regenerative activities of the V. filiformis supernatant (VFS). Methods: The effect of VFS on bacteria growth was assessed by microbial growth kinetics and biofilm formation and dispersal. Antioxidant potential was determined by DPPH-scavenging ability and reduction in intracellular reactive oxygen species (ROS). The regenerative properties were assessed by scratch assay. Results: V. filiformis VFS holds strong anti-biofilm activity against S. aureus, S. epidermidis and methicillin-resistant S. aureus (MRSA), acting during both biofilm formation and dispersion. The decrease in biofilm mass is accompanied by a significant increase in the planktonic form compared to the untreated cells. Moreover, VFS is characterized by an interesting antioxidant activity, as demonstrated by a cell-free DPPH assay and a neutrophil-based in vitro assay. In addition, VFS can stimulate tissue regeneration in human dermal fibroblasts and keratinocytes. Conclusions: The demonstration of anti-biofilm, antioxidant and regenerative properties of V. filiformis supernatant could be exploited for the treatment of biofilm-associated wound infections. Full article

Gram-positive bacteria covalently anchor specific proteins to the peptidoglycan cell wall via sortase, a cysteine transpeptidase that targets proteins with a cell wall sorting signal. Sortase enzymes are critical for bacterial pathogenesis, and their inhibitors have become promising therapeutic targets for infection management. Filifactor alocis, a Gram-positive anaerobic bacterium, is now proposed as a diagnostic indicator of periodontal disease. Unlike other bacteria, F. alocis encodes a single putative sortase, FA1364. In this study, we functionally characterized the putative sortase FA1364 and found that it belongs to the class A family (SrtA). The SrtA-anchored surface proteins (FA1006, FA1336, FA1424, and FA1750) were identified, and MS/MS analysis confirmed that SrtA is required for their cell-surface localization. The recombinant SrtA protein could recognize and cleave the LPKTG sorting motif with cysteine 191 and arginine 200 as essential catalytic residues. F. alocis FLL101 (ΔFA1364::ermF) showed reduced ability to coaggregate and form biofilm, along with decreased collagen binding and survival in epithelial cells. Additionally, the FA1364-defective mutant exhibited increased sensitivity to air exposure. Collectively, these results suggest that the F. alocis SrtA protein is an important virulence factor and may represent a novel therapeutic target for the control of periodontal diseases. Full article

This study highlights the strong ability of a new bacterial strain, Hafnia paralvei UUNT_MP29, isolated from the gastrointestinal tract (GIT) of common carp (Cyprinus carpio), to break down polystyrene (PS). As an omnivorous bottom feeder, C. carpio is constantly exposed to microplastics, creating a unique environment that favors the evolution of specialized microbiota capable of degrading polymers. Genomic analysis of the isolate identified key homologs involved in xenobiotic breakdown, including alcohol dehydrogenase (Adh), 3-hydroxybutyrate dehydrogenase (HDH), and a small glutamine-rich tetratricopeptide repeat-containing protein (SGTA), showing a strong metabolic system for processing long-chain hydrocarbons. Growth experiments showed the strain quickly adapted, reaching maximum cell density and forming mature biofilms by Day 16. Gravimetric analysis confirmed that H. paralvei UUNT_MP29 uses PS as its primary carbon source, with a significant weight loss of 16.76% over 16 days. Kinetic modeling indicated the degradation follows first-order kinetics (R² = 0.9243) with a high degradation rate constant (k) of 0.2078 day⁻¹. Surface analyses using FTIR and SEM confirmed extensive oxidative changes, as evidenced by the rising Carbonyl Index and surface erosion. TGA also showed reduced thermal stability of the treated polymer, suggesting microbial chain scission. These findings demonstrate the strong degradative ability of H. paralvei UUNT_MP29 and highlight the GIT of plastic-exposed aquatic animals as a promising area for discovering powerful biocatalysts for microplastic cleanup. Full article

Candida albicans is the causal agent of invasive candidiasis, which might be lethal in immunocompromised patients. Biofilm formation is considered a key virulence factor of C. albicans and is associated with its elevated resistance to antifungals. C. albicans and bacteria like E. coli are frequently found to form mixed biofilms on biotic or abiotic surfaces, rendering them more refractory to existing antifungals. To investigate how E. coli endogenous indole interplaying with exogenous IAA exerts modulatory effects on dual-species biofilm with C. albicans, an E. coli strain deficient in the indole biosynthetic gene tnaA was constructed, and the enzyme TnaA inhibitor was administered to block the indole production in E. coli monoculture and/or E. coli–C. albicans dual culture. Phenotypic assay revealed that indole deficiency attenuated E. coli mono-species biofilm by 12% (tnaA∆ versus WT E. coli), and the lack of indole in the E. coli cell-free culture filtrate abolished the ability to promote C. albicans biofilms, evidenced by the fact that the treatment with WT E. coli culture supernatants exhibited a 1.7-fold promotive effect, while treatment with tnaA∆ displayed no significant difference from the broth control towards C. albicans biofilms. Furthermore, impaired E. coli indole production might disrupt E. coli–C. albicans biofilm, as examined by confocal laser scanning microscopy (CLSM). Moreover, indole-3-acetic acid (IAA) was found to exhibit more potent biofilm-modulatory activity than indole by CLSM imaging with dual biofilms of WT E. coli–C. albicans, in contrast to those of E. coli tnaA∆–C. albicans post-supplemented with exogenous IAA. This study provides evidence for indole as a signaling molecule mediating bacterial–fungal communication during mixed-biofilm formation. Indole and its derivatives, particularly in combination with existing antifungals, have potential in the development of anti-biofilm strategies to eradicate refractory fungal infections. Full article

Background: Candida tropicalis is a pathogenic yeast species responsible for infections within the Candida genus and is identified as the most virulent species after C. albicans, partly due to its ability to form biofilms. Objective: This study analyzes the antifungal efficacy of a newly synthesized dendron, BD132 dendron, against C. tropicalis. Results: The compound showed a strong antifungal activity with promising minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC) values. Combination therapy with AgNO₃ and amphotericin B showed additive and synergistic effects, respectively, enhancing antifungal efficacy and potentially reducing cytotoxicity. The dendron did not alter key enzyme activities, and scanning electron microscopy revealed significant morphological alterations, including increased cell size and surface damage, indicating membrane disruption. In addition, the BD132 dendron did not induce resistance, and stability studies indicated a slight MIC decrease at 4 °C and −20 °C after 15 days, with stable minimum fungicidal concentration (MFC), suggesting potential for long-term use. Conclusions: These findings highlight the potential of this dendron in combination therapies to treat C. tropicalis infections. Full article

Salmonella enterica is a significant Gram-negative bacterium possessing over 2500 serovars capable of affecting both animals and humans and disseminating widely due to its adaptability, genetic diversity, and ability to form biofilms. Different serovars, such as S. enterica Typhimurium (ST), Enteritidis (SE), and Infantis (SI), display varying traits and survival strategies in harsh environments. Biofilms, composed of proteins, lipids, and DNA, enable bacteria to survive stresses such as pH changes, nutrient shortages, temperature fluctuations, and disinfectants. Evaluating disinfectants on inert surfaces is crucial for understanding their effectiveness and impact on poultry. This study assessed the efficacy of chlorine dioxide (ClO₂) disinfectant against ST, SE, and SI growth, biofilm formation, and biofilm removal at varying concentrations in vitro. Results showed serotype-dependent and condition-specific responses, with SE and SI being more affected than ST, which may be associated with differences in oxidative stress response mechanisms, highlighting the need for tailored disinfection protocols. 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

Enterococci are found not only in warm-blooded animals but also as a resident population of water and an indicator of fecal pollution. The species Enterococcus haemoperoxidus and E. moraviensis are relatively new, having been detected in water. Strains with genes for biofilm formation can serve as reservoirs for gene transfer. The aim and novelty of this study were to determine whether the postbiotic substance (PS) of proteinaceous character (Durancin-like) produced by our strain Enterococcus durans ED26E/7 can inhibit in vitro the growth of biofilm-forming E. haemoperoxidus and E. moraviensis isolated from water sources. E. haemoperoxidus and E. moraviensis lacked the biofilm-forming genes ica, bap, ace, and fsrA. The bopD gene was found only in three strains of E. haemoperoxidus. The srtA gene was present in two strains of E. haemoperoxidus and E. moraviensis. Using the quantitative test, three strains showed low-grade biofilm-forming ability. They exhibited ɤ-hemolysis, and they were mostly susceptible to antibiotics. However, they were susceptible to PS Durancin-like ED26E/7. E. haemoperoxidus, the strains EHae466 and EMo494, showed the highest susceptibility to Durancin-like ED26E/7. Full article

Background: Respiratory tract infections remain among the most common indications for antibiotic therapy and represent a major driver of antimicrobial resistance. The ability of respiratory pathogens to form biofilms further contributes to treatment failure and recurrence. This study aimed to evaluate the antibiotic adjuvant potential of selected essential oil components against clinically relevant respiratory bacteria and to determine whether planktonic synergistic interactions translate into early-stage antibiofilm efficacy. Thymol, eugenol, trans-cinnamaldehyde, and terpinen-4-ol were tested against Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa. Methods: Minimum inhibitory concentrations were determined by broth microdilution. Synergistic interactions with clinically relevant antibiotics were assessed using the checkerboard method and fractional inhibitory concentration index (FICI) analysis. Selected combinations were further evaluated in a 6 h crystal violet-based early-stage biofilm model. Gram-positive strains generally exhibited higher susceptibility to the tested components than Gram-negative bacteria. Results: Synergistic interactions (FICI ≤ 0.5) were most frequently observed between β-lactam antibiotics and phenolic components, particularly thymol and trans-cinnamaldehyde. Strong synergy was detected for vancomycin-eugenol against MRSA and for amoxicillin/clavulanic acid–cinnamaldehyde against M. catarrhalis. Importantly, synergistic combinations translated into significantly enhanced inhibition of early biofilm formation, increasing inhibition rates by 15–40% compared to antibiotic monotherapy (p < 0.05). Selected essential oil components enhanced the antibacterial activity of clinically relevant antibiotics and effectively potentiated early-stage biofilm inhibition. Conclusions: These findings support further investigation of phytochemical-antibiotic combinations as potential adjunct strategies in respiratory infection management. Full article

Uropathogenic Escherichia coli (UPEC) is a leading cause of urinary tract infections (UTIs) in companion animals. This study characterized 42 UPEC isolates recovered from dogs and cats at the University of Florida, College of Veterinary Medicine Diagnostic Laboratories between 2023 and 2024, focusing on antimicrobial resistance (AMR), virulence gene profiles, biofilm-forming ability, and phylogroup distribution of the isolates. Antimicrobial susceptibility testing (AST) showed that 40.48% of the isolates were resistant to at least one of the tested antibiotics, and 9.52% exhibited multidrug resistance (MDR). Phylogroup B2 was predominant (69.05%), and 61.90% of isolates demonstrated strong biofilm formation in artificial human urine. Virulence gene analysis revealed the presence of genes mediating adhesion (fim, pap, sfa), iron acquisition (fyuA, iro), biofilm formation (csg, bcs, pga, ycg/ymg), motility (fli, mot, flh), and stress response (oxyR, soxR/S, kat). Multiple plasmids carrying AMR and virulence determinants were also identified. The co-occurrence of the traits underscores the potential for persistent and recurrent infections, which can complicate therapeutic outcomes and facilitate horizontal gene transfer (HGT). The detection of antimicrobial-resistant, highly virulent UPEC strains possessing human UPEC traits in companion animals suggests the risk of zoonotic and reverse-zoonotic transmission, particularly in households with close pet–owner interactions. These findings emphasize the importance of judicious antimicrobial use, routine molecular surveillance, and integrated One Health strategies to mitigate the veterinary and public health threats associated with UPEC infections in companion animals. Full article

The objective of this study is to evaluate the efficiency of surgical instruments’ manual cleaning versus automated cleaning in an ultrasonic cleaner for the removal of biofilms on surgical forceps contaminated with Staphylococcus epidermidis and Pseudomonas aeruginosa. Subsequently, the residual microbial load was quantified through microbiological culture, aiming to evaluate the effectiveness of biofilm removal under different reprocessing conditions. Cleaning is an essential step in the processing of surgical instruments to ensure the effective removal of dirt and microorganisms. Through adhesion, microorganisms can attach to surfaces and form biofilms, organized structures surrounded by an extracellular matrix consisting of various components, which favor metabolic exchanges, adaptation, resistance, and bacterial dispersion. These biofilms increase the pathogenic potential of microorganisms, contributing to the occurrence of Healthcare-Associated Infections, and to avoid these, it is essential that preventive measures aimed at microbial reduction are adopted. Automated cleaning proved more effective than manual cleaning, and the combined approach achieved the greatest microbial reduction, though persistent contamination was still observed. The ability of adhesion and biofilm formation on the surfaces of surgical instruments is regarded as a challenge for complete microbial removal. These findings enhance the need for more rigorous reprocessing protocols and complementary strategies to ensure greater safety in the use of reusable instruments in clinical practice. Full article

Objective: The objective of this study is to evaluate the ability of silver oxide nanoparticle (Ag₂ONP)-functionalized high-efficiency particulate air (HEPA) filters and colloidal Ag₂ONP suspensions to inhibit biofilm formation by major respiratory pathogens causing infections at operating rooms. Background: Respiratory infections caused by bacterial pathogens such as Streptococcus pneumoniae, Pseudomonas aeruginosa and Staphylococcus species are often associated with the formation of biofilms, which confer increased resistance to antibiotics and host immune responses. Effective strategies to prevent biofilm formation on biological surfaces and in air filtration systems are urgently needed in clinical settings. Methods: The biofilm-forming ability of each bacterial strain was assessed by crystal violet microplate assay, viable count or confocal microscopy after prior incubation of the culture medium with Ag₂ONP-coated HEPA filter material or colloidal Ag₂ONP suspension. Results: Both silver-functionalized filters and silver nanoparticle suspensions significantly inhibited biofilm formation by S. pneumoniae and P. aeruginosa, with near-complete suppression observed. In the case of S. aureus and S. epidermidis, the silver nanoparticle suspension showed partial inhibition of biofilm development. Conclusions: Ag₂ONP-functionalized HEPA filters and colloidal Ag₂ONP suspensions effectively prevent biofilm formation by major respiratory pathogens, for both Gram-negative and Gram-positive bacteria. These materials show promise for integration with air filtration and surface coating systems to reduce microbial load and transmission in healthcare environments such as operating room facilities. Full article

Immunosuppressive therapies increase the risk of infection, but there is little information regarding their effects on cellular antimycobacterial activity. In this context, the aim was to evaluate in vitro the impact of commonly used immunosuppressive drugs on the ability of peripheral blood mononuclear cells (PBMCs), neutrophils (polymorphonuclear cells, PMNs), and monocyte-derived macrophages (MDMs) to control Mycobacterium abscessus. Biofilm formation was assessed by quantifying bacterial colonies in cellular cultures (BCCCs) and bacterial viability by colony-forming units (CFUs). BCCCs showed significant differences among treatment conditions in PBMCs. The median (interquartile range) BCCC values for tacrolimus (TAC) 16.5 (41), everolimus (EVE) 11 (33), methotrexate (MTX) 12.5 (22) and leflunomide (LEF) 11 (29) were all significantly higher than the negative control (DMSO) 5 (14), indicating that these immunosuppressants impaired the ability of PBMCs to restrict BCCC formation. Log-transformed CFUs also varied across treatments in PMNs. Mycophenolic acid (MPA) 5.98 (2.61) and EVE 5.85 (2.77) increased LogCFU recovery compared with DMSO 5.58 (2.63), whereas MTX 5.18 (2.74) decreased it. In contrast, immunosuppressants had no significant overall effect in MDM cultures. Interestingly, 6-mercaptopurine (6MP) affected the size of colonies. Prednisolone, as expected, but also MTX and LEF, inhibited the expression in infected PBMCs of IL-1β, IL-1Ra, IL-6, CCL3, CCL5, CXCL8 and TIMP-2, whereas IL-10, CCL2 and CXCL7 expression remained essentially unchanged. Unexpectedly, methotrexate promoted CXCL8 expression, a chemokine for PMNs. These results show that commonly used immunosuppressive drugs can differentially modulate the antimycobacterial activity of PBMCs and innate immune cells, affecting both mycobacterial viability and biofilm formation. Full article

Streptococcus mutans is a primary contributor to dental caries due to its ability to form biofilms rich in extracellular polysaccharides (EPS). While erythritol has been recognized for its anti-cariogenic effects, the molecular pathways involved have remained unclear. In this study, we combined phenotypic and transcriptomic approaches to uncover the mechanism by which erythritol inhibits EPS synthesis. We found that erythritol treatment significantly reduces EPS production and biofilm density, and that these changes are accompanied by marked downregulation of the phosphotransferase system (PTS), particularly the celB gene. Functional validation through gene deletion demonstrated that loss of celB mimics the effects of erythritol, resulting in reduced bacterial growth, impaired biofilm formation and decreased EPS production. Our results establish celB as a key mediator of erythritol-induced biofilm inhibition and suggest that targeting carbohydrate transport systems could offer a novel approach to caries prevention. Full article

Candidozyma auris (formerly Candida auris) is an emerging multidrug-resistant pathogenic fungus with an increased ability to cause outbreaks in healthcare facilities, leading to poor patient outcomes. Since its initial discovery in 2009, C. auris has spread rapidly across continents and is now classified by both the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) as a critical-priority pathogen. This review summarizes current knowledge on the origin, taxonomy, microbiology, and virulence mechanisms of C. auris, emphasizing its thermotolerance, osmotolerance, and biofilm-forming capacity on biotic and abiotic surfaces, as well as aspects related to its antifungal drug resistance and management. These features, together with its genomic plasticity, contribute to persistence, transmission, and drug resistance. Emerging evidence also supports a potential link between climate change and C. auris evolution, highlighting environmental adaptation as a driver of pathogenicity. Combating C. auris will require multidisciplinary efforts to mitigate its expanding global impact. Full article