Biofilm最新文献

{"title":"Formation of CO2-dependent small-colony variants (SCVs) in methicillin-resistant Staphylococcus aureus mediated by a single point mutation in mpsB","authors":"Sisi Chen ,&nbsp;Wanyang Dong ,&nbsp;Song Li ,&nbsp;Tian Zhong ,&nbsp;Xiping Qian ,&nbsp;Yi Cai ,&nbsp;Yanrui Ye ,&nbsp;Junyan Liu ,&nbsp;Zhenbo Xu ,&nbsp;Wenchang Yuan","doi":"10.1016/j.bioflm.2025.100320","DOIUrl":"10.1016/j.bioflm.2025.100320","url":null,"abstract":"<div><h3>Introduction</h3><div><em>Staphylococcus aureus</em> is a major human pathogen and the emergence of small colony variants (SCVs) makes the treatment of <em>S. aureus</em> infections more challenging. The mechanism of CO₂-dependent SCVs (CO₂-SCVs) remains inadequately explored.</div></div><div><h3>Methods</h3><div>In this study, a clinical CO₂-SCV strain (GY8) and a normal strain (GY9) were characterized from a patient with long-term infection. Through whole-genome sequencing, we detected a point mutation (H607Y) in the <em>mpsB</em> gene associated with the SCV phenotype. Transcriptomic profiling of both strains was performed to identify key genes or pathways closely related to SCV formation, followed by functional validation.</div></div><div><h3>Results</h3><div>The <em>mpsB</em> (H607Y) mutant exhibited typical SCV characteristics, including reduced growth rate, decreased pigmentation, and increased aminoglycoside resistance. Compared to GY9, the SCV strain GY8 showed attenuated virulence but enhanced intracellular persistence, facilitating chronic infection. Additionally, the mutant displayed heightened sensitivity to Triton X-100 induced cell lysis, though electron microscopy revealed significant changes in cell wall thickness.under ambient air. Finally, protein structure prediction and molecular docking analysis revealed that the H607 residue likely serves as the active center of MpsB, providing new mechanistic insights into the formation of CO₂-SCVs.</div></div><div><h3>Conclusion</h3><div>Our findings demonstrate that a single mpsB mutation drives SCV emergence, highlighting its role in persistent infections and providing potential targets for therapeutic intervention.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100320"},"PeriodicalIF":4.9,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145264887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Legionella affects biofilm structural response to detachment upon shear stress increase","authors":"Ana Rosa Silva ,&nbsp;C. William Keevil ,&nbsp;Ana Pereira","doi":"10.1016/j.bioflm.2025.100323","DOIUrl":"10.1016/j.bioflm.2025.100323","url":null,"abstract":"<div><div>Poor hydraulic management at water systems is associated with an increased risk of Legionnaires' disease caused by <em>Legionella</em>. Stagnation periods, followed by sudden water flow, can promote biofilm detachment and the release of <em>Legionella</em> into the bulk water. Regardless of its importance, the simultaneous effects of shear stress on biofilm detachment and <em>Legionella</em> release into the bulk water remain poorly understood. This study investigates how shear stress affects biofilms containing <em>Legionella pneumophila</em> in terms of: a) biofilm detachment, b) release of <em>L. pneumophila</em> into the bulk phase, and c) shifting of <em>L. pneumophila</em> into the viable but nonculturable (VBNC) state. <em>Pseudomonas fluorescens</em> biofilms were formed in a Center for Disease Control (CDC) biofilm reactor at 125 RPM and spiked with <em>L. pneumophila</em>. After 6 days, the system was set for 48 h to stagnation before flow was resumed at rotational velocities of 125, 225, and 400 RPM, corresponding to turbulent regimes with Reynolds numbers of 1552, 2794 and 4966, respectively. Biofilm properties, <em>L. pneumophila</em> viability, culturability, and spatial distribution were monitored. Results show that biofilms containing <em>L. pneumophila</em> maintained a similar basal thickness (12 μm) despite the detachment of the upper layers under different shear stresses. <em>L. pneumophila</em>, located at the bottom of the biofilm, remains surface-attached after biofilm detachment and seems to enhance the cohesiveness of these layers compared to <em>P. fluorescens</em> biofilms. On the contrary, when <em>Legionella</em> is not present, biofilm detachment increases with the increase of applied shear forces. All tested rotational velocities triggered <em>L. pneumophila</em> to enter the VBNC state in the bulk phase, while biofilm-associated VBNC cells were only observed at 400 RPM.</div><div>Finally, the contribution of the present work to <em>Legionella</em> control practices in water systems is discussed, highlighting the important insights that biofilms can provide in this context.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100323"},"PeriodicalIF":4.9,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145264886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluorene derivatives as potent antifungal and antibiofilm agents against fluconazole-resistant Candida albicans","authors":"Oluwatosin Oluwaseun Faleye ,&nbsp;Amra Yunus ,&nbsp;Jin-Hyung Lee,&nbsp;Jintae Lee","doi":"10.1016/j.bioflm.2025.100319","DOIUrl":"10.1016/j.bioflm.2025.100319","url":null,"abstract":"<div><div><em>Candida albicans</em> ranks as one of the most common causes of fungal sepsis in hospitalized patients around the world with an increasing mortality rate. The current antifungal drugs in use face several limitations including fungal resistance due to biofilm formation. This has complicated the treatment landscape, necessitating the need for continued search for effective therapeutic options against drug-resistant <em>C. albicans</em> threats. Therefore, this study investigated eighteen fluorene derivatives for their antifungal and antibiofilm potential against <em>C. albicans</em>. Two fluorene derivatives namely: 9,9-bis(4-hydroxyphenyl) fluorene (BHPF) and fluorene-9-acetic acid (FAA) were identified as potential inhibitors of <em>Candida</em> biofilms, achieving 97 % and 89 % inhibition at 10 μg/mL. Microscopic studies also confirmed their antibiofilm efficacy, with BHPF demonstrating activities comparable to amphotericin B. Furthermore, BHPF inhibited planktonic cell growth at concentration as low as 5 μg/mL. Both BHPF and FAA exhibited fungicidal activity and also inhibited <em>C. albicans</em> virulence factors such as cell aggregation and hyphal formation. Notably, neither compound showed propensity for resistance development over 15 passages. Additionally, toxicity evaluations in both plant and <em>Caenorhabditis elegans</em> model revealed non-to mild toxicity, and the ADMET prediction also satisfied the criteria for drug-likeliness. The results of this multifaceted investigation highlight the potential of BHPF and FAA as novel antifungal agents targeting <em>C. albicans</em> infections and biofilm-related challenges.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100319"},"PeriodicalIF":4.9,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic visualization of extracellular matrix components in S. aureus colony biofilms reveals functional amyloids leading to the formation of cap-like structures","authors":"Tianqi Zhang ,&nbsp;Julian Bär ,&nbsp;Lovisa Risberg ,&nbsp;Alejandro Gómez Mejia ,&nbsp;Hugo Hammar ,&nbsp;Susanne Löffler ,&nbsp;Daniel Erik Otzen ,&nbsp;Maria Andreasen ,&nbsp;Rikke Louise Meyer ,&nbsp;Keira Melican ,&nbsp;Annelies S. Zinkernagel ,&nbsp;Agneta Richter-Dahlfors","doi":"10.1016/j.bioflm.2025.100318","DOIUrl":"10.1016/j.bioflm.2025.100318","url":null,"abstract":"<div><div><em>Staphylococcus aureus</em> infections represent a clinical challenge due to their propensity to form biofilms and the increasing prevalence of antibiotic resistance. The ability of <em>S. aureus</em> to form biofilm affects clinical outcome, but techniques to study extracellular matrix (ECM) in <em>S. aureus</em> biofilms are lacking. Here, we present an agar-based method in which the optotracer EbbaBiolight 680 (Ebba680) is used to visualize ECM formation alongside evaluation of colony growth dynamics in agar colonies. As models for colony biofilms, we use drop inoculation for macrocolony formation or spread-plating for single-cell derived colonies. Kinetic fluorescence spectroscopy combined with time-lapse microscopy showed bright fluorescence signals, revealing different spatial-temporal appearance of ECM in macrocolonies versus single-cell derived colonies. In contrast, the microstructure was conserved between the two types of colonies. Detailed characterization of the biofilm microstructures by confocal microscopy revealed Ebba680 binding targets interspersed between cells as well as in a cap-like structure formed on the outer surface of the biofilm. Accessory gene regulator (<em>agr</em>) controlled expression of Ebba680 binding target(s) and the binding of Ebba680 to synthetic fibrillated phenol soluble modulins (fPSMs) suggests these functional amyloids act as targets for Ebba680 in the biofilm ECM. By upgrading ColTapp, an application developed for colony radius quantification, to also analyze fluorescence images, concurrent analysis of Ebba680-stained ECM and colony growth was achieved. This provided a new dimension to the assessment of colony biofilms. Detailed phenotypic characterization of clinical isolates is critical for treatment decision making, and enhanced screening which includes ECM as presented here has potential to facilitate treatment decisions in problematic staphylococcal infections.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100318"},"PeriodicalIF":4.9,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145157322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Farnesol emulsion for elimination of Pseudomonas aeruginosa biofilm in a 3D airway model of cystic fibrosis","authors":"Li Tan ,&nbsp;Khiry Sutton ,&nbsp;Sean V. Murphy ,&nbsp;Nicole Levi","doi":"10.1016/j.bioflm.2025.100317","DOIUrl":"10.1016/j.bioflm.2025.100317","url":null,"abstract":"<div><div>Cystic fibrosis (CF), a life-shortening genetic disease, is hallmarked by mucus obstruction, respiratory deficiency, and chronic bacterial infections. <em>Pseudomonas aeruginosa</em> is the most common virulent respiratory pathogen that is detrimental to the overall survival of CF patients. Here we evaluate the efficacy of farnesol emulsion, a broad-spectrum agent recently used to combat <em>P. aeruginosa</em> biofilm infections, for reducing <em>P. aeruginosa</em> infections in CF using a three-dimensional (3D) airway “organ tissue equivalent” (OTE) model. OTEs are fabricated using cells derived from human primary cells sourced from CF donors (CF-OTEs), which accurately recapitulate multiple key traits of human CF airways, including increased mucin accumulation and lower cilium beating frequency, compared to OTEs derived from normal donors (N-OTEs). The OTE model closely approximates the native CF condition to provide a platform where both mucoid and nonmucoid <em>P. aeruginosa</em> establish biofilms. Luminescence quantification and viable bacterial enumeration demonstrated that more <em>P. aeruginosa</em> biofilm mass developed upon CF-OTEs compared to non-CF (normal) OTEs. The capability to establish infection and biofilm formation, without acute tissue toxicity, allows for rapid discrimination of therapeutic efficacy in an accurate, human <em>in vitro</em> model. Farnesol emulsion disrupted <em>P. aeruginosa</em> biofilms <em>in situ</em> and also protected OTE lung cell viability. We propose that the 3D airway OTE infection model is a reliable preclinical tool for CF drug screening, with farnesol emulsion being a prospective drug candidate to treat <em>P. aeruginosa</em> biofilm infections in CF.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100317"},"PeriodicalIF":4.9,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145121175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accurate quantitation of antibiotic penetration through staphylococcal biofilms","authors":"Lou Bin ,&nbsp;David McGiffin ,&nbsp;Thuy Nguyen ,&nbsp;Lv Wang ,&nbsp;Yao Sun ,&nbsp;Lumei Ye ,&nbsp;Meiling Han ,&nbsp;Chengju Sheng ,&nbsp;Tzong-Hsien Lee ,&nbsp;Marie-Isabel Aguilar ,&nbsp;Anton Y. Peleg ,&nbsp;Yue Qu","doi":"10.1016/j.bioflm.2025.100316","DOIUrl":"10.1016/j.bioflm.2025.100316","url":null,"abstract":"<div><h3>Objectives</h3><div>Limited antimicrobial penetration is an important mechanism underlying antimicrobial resistance of biofilms and has often been incorrectly quantitated. We adopted a rationalized antibiotic agar-diffusion model to accurately interpret experimental results of a widely-accepted biofilm penetration assay, and to determine drug-related physiochemical properties impacting antimicrobial biofilm penetration.</div></div><div><h3>Methods</h3><div>Staphylococcal reference strains and eight conventional antibiotics were selected for this study. A well-established biofilm penetration assay based on disk diffusion and colony biofilms was used. Sizes of the zone of inhibition (ZOI) were converted to concentrations of antibiotics, using linear regressions of squared radii of the ZOI on the natural logarithm of antibiotic concentrations. Biofilm penetration ratios were calculated by comparing concentrations of antibiotics reaching the agar surface with or without biofilm barriers. Multiple regression analysis was performed to assess the impact of antibiotic physicochemical properties, such as surface charge, on their biofilm penetration.</div></div><div><h3>Results</h3><div>Ciprofloxacin and oxacillin showed great capacities in penetrating staphylococcal biofilms. Rifampicin penetrated biofilms at low rates of ∼20 %. Aminoglycosides showed strain- and agent-specific penetration ratios, with tobramycin showing the least penetration (17.8 % for <em>Staphylococcus aureus</em> and 35.6 % for <em>Staphylococcus epidermidis</em>) and kanamycin presenting good penetration (∼82.3 %) against <em>S. aureus</em> biofilms. Surface charges of antibiotics at neutral and acidic conditions were important for their biofilm penetration.</div></div><div><h3>Conclusions</h3><div>Accurate quantitation of antibiotic biofilm penetration can be achieved using the transformed linear regression between the ZOI and antibiotic concentrations. Mathematical evidence was provided to support the importance of surface charge of antimicrobials on their biofilm penetration.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100316"},"PeriodicalIF":4.9,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ambroxol hydrochloride as an antibiofilm agent synergizes with tetracycline antibiotics against mature biofilms of multidrug-resistant Klebsiella pneumoniae","authors":"TengLi Zhang ,&nbsp;XunQin Gao ,&nbsp;MengTing Liu ,&nbsp;Chun Wen ,&nbsp;Peng Jin ,&nbsp;Hong Yao ,&nbsp;XiWang Liu ,&nbsp;YingLan Yu ,&nbsp;Hao Shao ,&nbsp;Lei Luo","doi":"10.1016/j.bioflm.2025.100315","DOIUrl":"10.1016/j.bioflm.2025.100315","url":null,"abstract":"<div><div>Multidrug-resistant <em>Klebsiella pneumoniae</em> (MDR-KP) is a major pathogen responsible for hospital-acquired infections, associated with high morbidity and mortality. Biofilm formation plays a key role in the pathogenicity of MDR-KP and contributes significantly to its antibiotic resistance, substantially impairing the effectiveness of antimicrobial therapies. To enhance the efficacy of existing antibiotics, this study investigates a biofilm-targeting synergistic strategy inspired by the structural similarity between sputum and biofilm matrices. In this study, 87 clinical isolates of MDR-KP were initially screened for biofilm-forming capacity, and strong biofilm producers were selected to establish an <em>in vitro</em> model for systematic evaluation of the anti-biofilm efficacy of six mucolytic agents. Ambroxol hydrochloride (ABH) emerges as the optimal effective, disrupting biofilm structure at 0.7 mg/mL and achieving 50 % clearance within 8 h. ABH enhanced the anti-biofilm activity of tetracycline and doxycycline <em>in vitro</em>, reducing their IC₅₀ values by 98.9 % and 98.6 %, respectively, against preformed biofilms of MDR-KP compared to monotherapy. Additionally, the excellent physical and chemical compatibility between ABH and tetracycline or doxycycline provides a stable basis for <em>in vivo</em> co-administration. <em>In vivo</em>, the combination alleviates pulmonary inflammation, reduces bacterial load and inflammatory factor levels, and shows no tissue toxicity. In conclusion, ABH combined with tetracycline antimicrobials enhanced their efficacy against MDR-KP infections, especially biofilm-associated infections, in both <em>in vitro</em> and <em>in vivo</em> models, and possessed a favorable physicochemical compatibility and safety profile. These findings suggested that ABH-tetracycline therapy could represent a translationally promising and effective strategy for combating clinical MDR-KP infections.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100315"},"PeriodicalIF":4.9,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144922454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Potassium iodide enhances the antimicrobial activity of plasma-activated water","authors":"Laura A. McClenaghan ,&nbsp;Thomas P. Thompson ,&nbsp;Akash Shambharkar ,&nbsp;Ross M. Duncan ,&nbsp;Paula Bourke ,&nbsp;Timofey Skvortsov ,&nbsp;Brendan F. Gilmore","doi":"10.1016/j.bioflm.2025.100313","DOIUrl":"10.1016/j.bioflm.2025.100313","url":null,"abstract":"<div><div>Plasma-activated water (PAW) is a promising disinfection strategy that generates a complex mixture of reactive oxygen and nitrogen species (ROS/RNS), including hydrogen peroxide (H₂O₂), nitrate (NO₃⁻), and transient oxidants, in an acidic aqueous environment. These reactive species contribute to both immediate and extended antimicrobial activity. This study investigates how the addition of low concentrations (&lt;100 μM) of potassium iodide (KI) enhances the bactericidal properties of spark-generated PAW by enabling the in-situ generation of reactive iodine species (RIS), particularly hypoiodous acid (HIO), under acidic conditions.</div><div>KI addition (10–100 μM) led to a counterintuitive, dose-dependent increase in H₂O₂ concentrations, from ∼1.2 mM in PAW alone to ∼1.8 mM at 30 μM KI, possibly due to iodine-mediated catalytic effects or reduced H₂O₂ degradation. NO₃⁻ levels also increased by ∼17 % with increasing KI. Equivalent concentrations of H₂O₂ + KI failed to replicate the rapid antimicrobial activity observed in PAW + KI, which achieved complete inactivation of <em>Escherichia coli</em> and <em>Listeria monocytogenes</em> planktonic cells within 3 min, compared to over 10 min for PAW alone, indicating the involvement of additional reactive species in KI-enhanced antimicrobial activity of PAW. However, <em>Salmonella enterica planktonic cells</em> exhibited only partial inactivation even with KI, indicating species-specific tolerance under these conditions. 24h biofilms of <em>L. monocytogenes</em> and <em>E. coli</em> were eradicated with PAW + KI in 10 min, whereas <em>S. enterica</em> showed only a 2-log reduction.</div><div>Scavenger assays revealed that both longer-lived species (H₂O₂) and shorter-lived oxidants such as singlet oxygen are essential for this enhanced killing, while ozone and superoxide appeared dispensable. These findings support a multi-step antimicrobial mechanism: (1) plasma treatment creates a low pH, H₂O₂-rich solution; (2) iodide is oxidised to RIS such as I₃⁻ and HIO; (3) additional PAW-derived oxidants potentiate RIS chemistry; and (4) unionised HIO diffuses across bacterial membranes to induce oxidative damage.</div><div>PAW-KI remained stable for at least 14 days at 4 °C, with sustained RIS activity and minimal loss of H₂O₂ or NO₃⁻, suggesting preserved antimicrobial capacity over time. The antimicrobial mechanism likely proceeds through a four-step pathway: plasma-mediated generation of H₂O₂ and NO₃⁻; oxidation of I⁻ to I₂ and HIO; potentiation of RIS via PAW-derived ROS/RNS; and subsequent microbial inactivation via membrane damage.</div><div>Together, these results demonstrate that PAW + KI f","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100313"},"PeriodicalIF":4.9,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A fully automated model to form “dry surface biofilms” under optimal dehydration conditions. application to Enterobacteriaceae in healthcare settings","authors":"Nicolas Jean-Marie ,&nbsp;Talyssa Lebielle ,&nbsp;Myriam Louisin ,&nbsp;Claude Olive ,&nbsp;Karine Marion-Sanchez","doi":"10.1016/j.bioflm.2025.100312","DOIUrl":"10.1016/j.bioflm.2025.100312","url":null,"abstract":"<div><div>Over ten years ago, bacteria attached to surfaces and surrounded by extracellular polymeric substances were observed on dry surfaces in intensive care units. These structures were named \"dry surface biofilms\" (DSBs). Most in vitro models used to study “DSBs” alternate long hydration phases with short periods of desiccation, producing \"semi-dehydrated DSBs\" that differ from the conditions in healthcare settings.</div><div>Our aim was to create a model that could produce \"DSBs\" under optimal dehydration conditions and apply it to Enterobacteriaceae. These bacteria are commonly responsible for healthcare-associated infections in our hospital, yet they have received little attention in the context of \"DSBs.\" We developed a fully automated model that mimics the splashing of respiratory secretions by repeatedly nebulizing an inoculum of contaminated artificial saliva. Hydration phases lasted 2 s every 6 h. We investigated the microscopic aspect, mean surface coverage, bacterial culturability and membrane integrity.</div><div>After validating the model with methicillin-resistant <em>Staphylococcus aureus</em> (MRSA), we tested wild-type <em>Enterobacter cloacae</em>, wild-type <em>Klebsiella pneumonia</em><em>e</em> and extensively drug-resistant (XDR) <em>Klebsiella pneumoniae</em>. The latter formed compact dried inocula with the highest surface coverage (29.7 %), containing curled-up bacteria alongside a low number of culturable cells (3 log₁₀). Conversely, dried <em>S. aureus</em> inocula covered a lower surface (10.9 %) but contained more culturable cells (6 log₁₀), which persisted for more than two months. After several weeks of storage, even the samples containing no more culturable bacteria showed bacteria with intact membranes. Subsequent studies must further assess in depth the composition of these deposits and the viability of the bacteria they contain.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100312"},"PeriodicalIF":4.9,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dual red and near-infrared LED therapy inhibits MRSA biofilm in otitis media","authors":"Yoo-Seung Ko,&nbsp;Eun-Ji Gi,&nbsp;Sungsu Lee,&nbsp;Hong-Chan Kim,&nbsp;Hyong-Ho Cho","doi":"10.1016/j.bioflm.2025.100314","DOIUrl":"10.1016/j.bioflm.2025.100314","url":null,"abstract":"<div><div>Otitis media (OM), particularly when caused by methicillin-resistant <em>Staphylococcus aureus</em> (MRSA), can become refractory due to biofilm formation, which contributes to resistance against conventional antimicrobial treatments. Photobiomodulation using light-emitting diode (LED) therapy has recently emerged as a promising non-antibiotic strategy for managing refractory infections by targeting biofilm-associated pathology. However, especially in the context of MRSA-induced OM, its therapeutic efficacy and underlying mechanisms remain incompletely elucidated. In this study, we established a rat model of OM by inoculating MRSA (5 × 10⁸ CFUs) into the middle ear via the tympanic membrane. Red and near-infrared (NIR) LED irradiation (655/842 nm; 163.2 W/m²; 30 min/day for 5 days) was administered 1 week after infection. Scanning electron microscopy revealed a marked reduction in MRSA biofilm structures, and biofilm biomass was significantly decreased, as assessed by crystal violet staining. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis demonstrated significant downregulation of <em>fib</em>, <em>icaB</em>, <em>icaC</em>, and <em>icaD</em>, key genes crucial for bacterial adhesion and biofilm development. Histological assessment further showed decreased mucosal thickening and macrophage infiltration, supported by reduced ionized calcium-binding adapter molecule 1 (Iba1) expression. These findings suggest that dual red and NIR LED therapy effectively suppresses MRSA biofilm formation and inflammation in OM, indicating its potential as a novel non-antibiotic therapy for biofilm-associated OM that may help manage persistent or treatment-resistant cases in clinical settings.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100314"},"PeriodicalIF":4.9,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144902573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}