Pub Date : 2025-08-29DOI: 10.1016/j.bioflm.2025.100315
TengLi Zhang , XunQin Gao , MengTing Liu , Chun Wen , Peng Jin , Hong Yao , XiWang Liu , YingLan Yu , Hao Shao , Lei Luo
Multidrug-resistant Klebsiella pneumoniae (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 in vitro 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 in vitro, 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 in vivo co-administration. In vivo, 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 in vitro and in vivo 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.
{"title":"Ambroxol hydrochloride as an antibiofilm agent synergizes with tetracycline antibiotics against mature biofilms of multidrug-resistant Klebsiella pneumoniae","authors":"TengLi Zhang , XunQin Gao , MengTing Liu , Chun Wen , Peng Jin , Hong Yao , XiWang Liu , YingLan Yu , Hao Shao , 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 IC<sub>50</sub> 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}
Pub Date : 2025-08-22DOI: 10.1016/j.bioflm.2025.100313
Laura A. McClenaghan , Thomas P. Thompson , Akash Shambharkar , Ross M. Duncan , Paula Bourke , Timofey Skvortsov , Brendan F. Gilmore
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 (<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.
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 Escherichia coli and Listeria monocytogenes 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, Salmonella enterica planktonic cells exhibited only partial inactivation even with KI, indicating species-specific tolerance under these conditions. 24h biofilms of L. monocytogenes and E. coli were eradicated with PAW + KI in 10 min, whereas S. enterica showed only a 2-log reduction.
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.
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.
Together, these results demonstrate that PAW + KI f
{"title":"Potassium iodide enhances the antimicrobial activity of plasma-activated water","authors":"Laura A. McClenaghan , Thomas P. Thompson , Akash Shambharkar , Ross M. Duncan , Paula Bourke , Timofey Skvortsov , 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 (H<sub>2</sub>O<sub>2</sub>), nitrate (NO<sub>3</sub><sup>−</sup>), 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 (<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 H<sub>2</sub>O<sub>2</sub> 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 H<sub>2</sub>O<sub>2</sub> degradation. NO<sub>3</sub><sup>−</sup> levels also increased by ∼17 % with increasing KI. Equivalent concentrations of H<sub>2</sub>O<sub>2</sub> + 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 (H<sub>2</sub>O<sub>2</sub>) 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, H<sub>2</sub>O<sub>2</sub>-rich solution; (2) iodide is oxidised to RIS such as I<sub>3</sub><sup>−</sup> 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 H<sub>2</sub>O<sub>2</sub> or NO<sub>3</sub><sup>−</sup>, suggesting preserved antimicrobial capacity over time. The antimicrobial mechanism likely proceeds through a four-step pathway: plasma-mediated generation of H<sub>2</sub>O<sub>2</sub> and NO<sub>3</sub><sup>−</sup>; oxidation of I<sup>−</sup> to I<sub>2</sub> 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}
Pub Date : 2025-08-21DOI: 10.1016/j.bioflm.2025.100312
Nicolas Jean-Marie , Talyssa Lebielle , Myriam Louisin , Claude Olive , Karine Marion-Sanchez
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.
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.
After validating the model with methicillin-resistant Staphylococcus aureus (MRSA), we tested wild-type Enterobacter cloacae, wild-type Klebsiella pneumoniae and extensively drug-resistant (XDR) Klebsiella pneumoniae. 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 S. aureus 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.
{"title":"A fully automated model to form “dry surface biofilms” under optimal dehydration conditions. application to Enterobacteriaceae in healthcare settings","authors":"Nicolas Jean-Marie , Talyssa Lebielle , Myriam Louisin , Claude Olive , 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 log<sub>10</sub>). Conversely, dried <em>S. aureus</em> inocula covered a lower surface (10.9 %) but contained more culturable cells (6 log<sub>10</sub>), 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}
Pub Date : 2025-08-21DOI: 10.1016/j.bioflm.2025.100314
Yoo-Seung Ko, Eun-Ji Gi, Sungsu Lee, Hong-Chan Kim, Hyong-Ho Cho
Otitis media (OM), particularly when caused by methicillin-resistant Staphylococcus aureus (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 fib, icaB, icaC, and icaD, 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.
{"title":"Dual red and near-infrared LED therapy inhibits MRSA biofilm in otitis media","authors":"Yoo-Seung Ko, Eun-Ji Gi, Sungsu Lee, Hong-Chan Kim, 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 × 10<sup>8</sup> CFUs) into the middle ear via the tympanic membrane. Red and near-infrared (NIR) LED irradiation (655/842 nm; 163.2 W/m<sup>2</sup>; 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}
Pub Date : 2025-08-07DOI: 10.1016/j.bioflm.2025.100311
Linglu Hong , Karin Hjort , Dan I. Andersson , Cecilia Persson
Acrylic bone cement is widely used in vertebroplasty to treat osteoporosis-induced vertebral compression fractures. However, infection after vertebroplasty is problematic and previous work has suggested loading the bone cement with an antibiotic for prophylaxis. Linoleic acid (LA) has been investigated as a promising additive to improve the mechanical properties of bone cement for vertebroplasty, but LA could potentially also have an antibacterial effect. In this study, we evaluated the antibacterial properties of LA-loaded bone cement by comparing its antibiofilm properties with that of original bone cement through quantification of bacterial growth using viable cell count and scanning electron microscopy. The released monomer (MMA) concentration and the monomer minimum inhibitory concentration were determined to clarify the monomer's potential role in inhibiting bacterial growth. The LA release profile was measured, and a checkerboard assay was done to determine any synergistic effects of LA and the commonly used antibiotic gentamicin. Results show that LA-loaded bone cement could significantly inhibit Staphylococcus aureus biofilm formation, including gentamicin-resistant strains, but with limited effect on Escherichia coli. Furthermore, the released MMA did not have a significant influence on bacterial growth. The checkerboard assay results show that the LA and gentamicin combination could broaden the antibacterial spectrum and increase gentamicin efficacy. In conclusion, LA merits further investigation as an antibacterial agent in bone cement, alone or in combination with antibiotics.
{"title":"Linoleic acid addition prevents Staphylococcus aureus biofilm formation on PMMA bone cement","authors":"Linglu Hong , Karin Hjort , Dan I. Andersson , Cecilia Persson","doi":"10.1016/j.bioflm.2025.100311","DOIUrl":"10.1016/j.bioflm.2025.100311","url":null,"abstract":"<div><div>Acrylic bone cement is widely used in vertebroplasty to treat osteoporosis-induced vertebral compression fractures. However, infection after vertebroplasty is problematic and previous work has suggested loading the bone cement with an antibiotic for prophylaxis. Linoleic acid (LA) has been investigated as a promising additive to improve the mechanical properties of bone cement for vertebroplasty, but LA could potentially also have an antibacterial effect. In this study, we evaluated the antibacterial properties of LA-loaded bone cement by comparing its antibiofilm properties with that of original bone cement through quantification of bacterial growth using viable cell count and scanning electron microscopy. The released monomer (MMA) concentration and the monomer minimum inhibitory concentration were determined to clarify the monomer's potential role in inhibiting bacterial growth. The LA release profile was measured, and a checkerboard assay was done to determine any synergistic effects of LA and the commonly used antibiotic gentamicin. Results show that LA-loaded bone cement could significantly inhibit <em>Staphylococcus aureus</em> biofilm formation, including gentamicin-resistant strains, but with limited effect on <em>Escherichia coli</em>. Furthermore, the released MMA did not have a significant influence on bacterial growth. The checkerboard assay results show that the LA and gentamicin combination could broaden the antibacterial spectrum and increase gentamicin efficacy. In conclusion, LA merits further investigation as an antibacterial agent in bone cement, alone or in combination with antibiotics.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100311"},"PeriodicalIF":4.9,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809573","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}
Sulfate-reducing bacterial (SRB) biofilms are prevalent across diverse environments, playing key roles in biogeochemical sulfur cycling while also contributing to industrial challenges such as biofouling and biocorrosion. Understanding the genetic and physiological adaptations of SRB biofilms to different surfaces is crucial for developing mitigation strategies. This study presents a comparative transcriptomic analysis of Oleidesulfovibrio alaskensis G20 biofilms grown on copper and polycarbonate surfaces, aimed at elucidating their differential responses at the molecular level. RNA sequencing revealed 1255 differentially expressed genes, with copper-grown biofilms exhibiting upregulation of Dde_1570 (flagellin; log2FC 2.31) and Dde_0831 (polysaccharide chain length determinant; log2FC 1.15), highlighting enhanced motility and extracellular polymeric substance production. Conversely, downregulated genes on copper included Dde_0132 (Cu/Zn efflux transporter; log2FC −3.37) and Dde_0369 (methyl-accepting chemotaxis protein; log2FC −1.19), indicating a metabolic shift and stress adaptation to metal exposure. Morphological analysis via SEM revealed denser biofilm clusters with precipitates on copper, whereas biofilms on polycarbonate were more dispersed. AFM analysis showed a 4.6-fold increase in roughness on copper (44.3 ± 3.1 to 205.89 ± 8.7 nm) and a 3.8-fold increase on polycarbonate (521.12 ± 15.2 to 1975.64 ± 52.6 nm), indicating surface erosion and structural modifications. Protein-protein interaction analysis identified tightly regulated clusters associated with ribosomal synthesis, folate metabolism, and quorum sensing, underscoring their role in biofilm resilience. Additionally, functional annotations of uncharacterized genes revealed potential biofilm regulators, such as Dde_4025 (cytochrome-like protein; log2FC 4.18) and Dde_3288 (DMT superfamily permease; log2FC 3.55). These findings provide mechanistic insights into surface-dependent biofilm formation, with implications for designing antifouling materials and controlling microbial-induced corrosion.
{"title":"Comparative transcriptomics analysis of the Oleidesulfovibrio alaskensis G20 biofilms grown on copper and polycarbonate surfaces","authors":"Priya Saxena , Dipayan Samanta , Payal Thakur , Vinoj Gopalakrishnan , Rajesh K. Sani","doi":"10.1016/j.bioflm.2025.100309","DOIUrl":"10.1016/j.bioflm.2025.100309","url":null,"abstract":"<div><div>Sulfate-reducing bacterial (SRB) biofilms are prevalent across diverse environments, playing key roles in biogeochemical sulfur cycling while also contributing to industrial challenges such as biofouling and biocorrosion. Understanding the genetic and physiological adaptations of SRB biofilms to different surfaces is crucial for developing mitigation strategies. This study presents a comparative transcriptomic analysis of <em>Oleidesulfovibrio alaskensis</em> G20 biofilms grown on copper and polycarbonate surfaces, aimed at elucidating their differential responses at the molecular level. RNA sequencing revealed 1255 differentially expressed genes, with copper-grown biofilms exhibiting upregulation of Dde_1570 (flagellin; log2FC 2.31) and Dde_0831 (polysaccharide chain length determinant; log2FC 1.15), highlighting enhanced motility and extracellular polymeric substance production. Conversely, downregulated genes on copper included Dde_0132 (Cu/Zn efflux transporter; log2FC −3.37) and Dde_0369 (methyl-accepting chemotaxis protein; log2FC −1.19), indicating a metabolic shift and stress adaptation to metal exposure. Morphological analysis via SEM revealed denser biofilm clusters with precipitates on copper, whereas biofilms on polycarbonate were more dispersed. AFM analysis showed a 4.6-fold increase in roughness on copper (44.3 ± 3.1 to 205.89 ± 8.7 nm) and a 3.8-fold increase on polycarbonate (521.12 ± 15.2 to 1975.64 ± 52.6 nm), indicating surface erosion and structural modifications. Protein-protein interaction analysis identified tightly regulated clusters associated with ribosomal synthesis, folate metabolism, and quorum sensing, underscoring their role in biofilm resilience. Additionally, functional annotations of uncharacterized genes revealed potential biofilm regulators, such as Dde_4025 (cytochrome-like protein; log2FC 4.18) and Dde_3288 (DMT superfamily permease; log2FC 3.55). These findings provide mechanistic insights into surface-dependent biofilm formation, with implications for designing antifouling materials and controlling microbial-induced corrosion.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100309"},"PeriodicalIF":4.9,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831276","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}
Pub Date : 2025-07-19DOI: 10.1016/j.bioflm.2025.100305
Daniel S. Levin , Camila S. Cué Royo , Denis Johnson , Soumalya Ghosh , Sricharani Rao Balmuri , Huda Usman , Shakira M. Martínez Vásquez , David Kumar Yesudoss , Abdoulaye Djire , Mostafa Bedewy , Tagbo H.R. Niepa
Staphylococcus aureus is the leading cause of skin infections in the U.S., and its rapid evolution and resistance to antibiotics create a barrier to effective treatment. In this study, we engineered a composite membrane with bacterial cellulose and carbon nanotubes (BC-CNT) as an electroactive dressing to rapidly eradicate vancomycin-intermediate S. aureus. Nonpathogenic Komagataeibacter sucrofermentans produced the BC membrane at an air-liquid interface. Then, carboxyl-functionalized multi-walled CNTs were integrated into decellularized BC to create stable and electrically conductive BC-CNT dressings. The electric potential and ionic flux across BC-CNT were modeled and standardized via chronoamperometry for experimental validation. We found that treatment with electroactive BC-CNT increases S. aureus sensitivity to vancomycin and prevents macro-scale biofilm formation. The bactericidal efficacy of the composite membrane is consistent with electrochemical stress caused by voltage mediated with BC-CNT. After a single hour of combinatorial electrical and drug treatment, biofilm-forming capacity was inhibited by nearly 92 %. These results advance applications of electrochemistry in medicine and create a new direction to overcome S. aureus infections on skin and soft tissues.
{"title":"Engineering an electroactive bacterial cellulose-carbon nanotube composite membrane against Staphylococcus aureus","authors":"Daniel S. Levin , Camila S. Cué Royo , Denis Johnson , Soumalya Ghosh , Sricharani Rao Balmuri , Huda Usman , Shakira M. Martínez Vásquez , David Kumar Yesudoss , Abdoulaye Djire , Mostafa Bedewy , Tagbo H.R. Niepa","doi":"10.1016/j.bioflm.2025.100305","DOIUrl":"10.1016/j.bioflm.2025.100305","url":null,"abstract":"<div><div><em>Staphylococcus aureus</em> is the leading cause of skin infections in the U.S., and its rapid evolution and resistance to antibiotics create a barrier to effective treatment. In this study, we engineered a composite membrane with bacterial cellulose and carbon nanotubes (BC-CNT) as an electroactive dressing to rapidly eradicate vancomycin-intermediate <em>S. aureus</em>. Nonpathogenic <em>Komagataeibacter sucrofermentans</em> produced the BC membrane at an air-liquid interface. Then, carboxyl-functionalized multi-walled CNTs were integrated into decellularized BC to create stable and electrically conductive BC-CNT dressings. The electric potential and ionic flux across BC-CNT were modeled and standardized via chronoamperometry for experimental validation. We found that treatment with electroactive BC-CNT increases <em>S. aureus</em> sensitivity to vancomycin and prevents macro-scale biofilm formation. The bactericidal efficacy of the composite membrane is consistent with electrochemical stress caused by voltage mediated with BC-CNT. After a single hour of combinatorial electrical and drug treatment, biofilm-forming capacity was inhibited by nearly 92 %. These results advance applications of electrochemistry in medicine and create a new direction to overcome <em>S. aureus</em> infections on skin and soft tissues.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100305"},"PeriodicalIF":5.9,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694323","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}
Antimicrobial resistance (AMR) is a global concern that undermines microbial disease treatment and prevention. WHO and World Bank's EcoAMR report predicts that AMR could cause 39 million deaths and $3.4 trillion in annual GDP losses by the year 2050. This is particularly critical with S. aureus, a cause of diverse infections like skin abscesses and pneumonia, where antibiotic resistance increases mortality and hinders treatment. Biofilms are one of the major causes of multi-drug resistance in S. aureus, and their inhibition can restore antibiotic sensitivity. In this study, through screening of the LOPAC drug library, we identified several compounds that exhibit biofilm inhibitory properties against multi-drug-resistant S. aureus without affecting its growth. The compound 10058-F4 was found to have the strongest anti-biofilm activity (>70 % inhibition) with minimal antibacterial effects (MIC 256 μg/mL); however, it showed no inhibitory effects on pre-existing biofilm. Further, the 10058-F4 treatment suppressed the expression of sarA, the biofilm master regulator, along with biofilm genes, such as icaA, fnb, nuc, and sspA. Additionally, the results showed that 10058-F4 synergistically enhanced the antibacterial activity of norfloxacin and tetracycline, indicating its potential use as an adjunct to the existing antibiotic treatments. While these findings suggest the potential of 10058-F4 for clinical use, further investigations are necessary to elucidate its mechanism of action and optimize its application in combination therapies.
{"title":"10058-F4 Mediated inhibition of the biofilm formation in multidrug-resistant Staphylococcus aureus","authors":"Hiren Dodia , Suvendu Ojha , Puja Chatterjee , Tushar Kant Beuria","doi":"10.1016/j.bioflm.2025.100307","DOIUrl":"10.1016/j.bioflm.2025.100307","url":null,"abstract":"<div><div>Antimicrobial resistance (AMR) is a global concern that undermines microbial disease treatment and prevention. WHO and World Bank's EcoAMR report predicts that AMR could cause 39 million deaths and $3.4 trillion in annual GDP losses by the year 2050. This is particularly critical with <em>S. aureus</em>, a cause of diverse infections like skin abscesses and pneumonia, where antibiotic resistance increases mortality and hinders treatment. Biofilms are one of the major causes of multi-drug resistance in <em>S. aureus,</em> and their inhibition can restore antibiotic sensitivity. In this study, through screening of the LOPAC drug library, we identified several compounds that exhibit biofilm inhibitory properties against multi-drug-resistant <em>S. aureus</em> without affecting its growth. The compound 10058-F4 was found to have the strongest <em>anti</em>-biofilm activity (>70 % inhibition) with minimal antibacterial effects (MIC 256 μg/mL); however, it showed no inhibitory effects on pre-existing biofilm. Further, the 10058-F4 treatment suppressed the expression of <em>sarA,</em> the biofilm master regulator, along with biofilm genes, such as <em>icaA, fnb, nuc, and sspA</em>. Additionally, the results showed that 10058-F4 synergistically enhanced the antibacterial activity of norfloxacin and tetracycline, indicating its potential use as an adjunct to the existing antibiotic treatments. While these findings suggest the potential of 10058-F4 for clinical use, further investigations are necessary to elucidate its mechanism of action and optimize its application in combination therapies.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100307"},"PeriodicalIF":5.9,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144665824","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}
The ability of yeast cells to adhere to solid surfaces or even penetrate semi-solid surfaces and form multicellular biofilms are critical factors in infection. This study examines the relationship between cell adhesion capability and the ability to create spatially organized biofilms in selected Saccharomyces cerevisiae strains, including clinical isolates, and five Candida species (C. albicans, C. glabrata, C. krusei, C. parapsilosis, and C. tropicalis). We assessed cell adhesion to polystyrene surface in four media varying in source of carbon and other nutrients. Using microscopy of vertical cell arrangement profiles within yeast populations grown at the solid-liquid interface, we evaluated their internal organization to determine whether the populations exhibit typical biofilm characteristics, such as the spatial organization of distinct cell types. Results indicate that well adherent S. cerevisiae strains form spatial biofilms with typical internal organization, highlighting strain-specific responses to media composition and supporting the use of natural S. cerevisiae strains for biofilm research. Among Candida species, biofilm formation did not consistently align with adhesion efficiency to plastic; while C. albicans and C. krusei formed spatially structured biofilms on media where they adhered well, C. tropicalis and C. glabrata exhibited efficient adhesion without biofilm structuring. Interestingly, C. parapsilosis formed a structured biofilm despite minimal adhesion. These findings emphasize the role of media composition, particularly components of yeast extract and defined medium for mammalian cell growth RPMI, which differentially impacted adhesion and biofilm formation in S. cerevisiae and C. albicans.
{"title":"Spatial structure of yeast biofilms and the role of cell adhesion across different media","authors":"Vichi Sicha Irianto , Vítězslav Plocek , Rashim Bharti , Jana Maršíková , Libuše Váchová , Zdena Palková","doi":"10.1016/j.bioflm.2025.100306","DOIUrl":"10.1016/j.bioflm.2025.100306","url":null,"abstract":"<div><div>The ability of yeast cells to adhere to solid surfaces or even penetrate semi-solid surfaces and form multicellular biofilms are critical factors in infection. This study examines the relationship between cell adhesion capability and the ability to create spatially organized biofilms in selected <em>Saccharomyces cerevisiae</em> strains, including clinical isolates, and five <em>Candida</em> species (<em>C. albicans</em>, <em>C. glabrata</em>, <em>C. krusei</em>, <em>C. parapsilosis</em>, and <em>C. tropicalis</em>). We assessed cell adhesion to polystyrene surface in four media varying in source of carbon and other nutrients. Using microscopy of vertical cell arrangement profiles within yeast populations grown at the solid-liquid interface, we evaluated their internal organization to determine whether the populations exhibit typical biofilm characteristics, such as the spatial organization of distinct cell types. Results indicate that well adherent <em>S. cerevisiae</em> strains form spatial biofilms with typical internal organization, highlighting strain-specific responses to media composition and supporting the use of natural <em>S. cerevisiae</em> strains for biofilm research. Among <em>Candida</em> species, biofilm formation did not consistently align with adhesion efficiency to plastic; while <em>C. albicans</em> and <em>C. krusei</em> formed spatially structured biofilms on media where they adhered well, <em>C. tropicalis</em> and <em>C. glabrata</em> exhibited efficient adhesion without biofilm structuring. Interestingly, <em>C. parapsilosis</em> formed a structured biofilm despite minimal adhesion. These findings emphasize the role of media composition, particularly components of yeast extract and defined medium for mammalian cell growth RPMI, which differentially impacted adhesion and biofilm formation in <em>S. cerevisiae</em> and <em>C. albicans</em>.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100306"},"PeriodicalIF":5.9,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144663356","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}
Pub Date : 2025-07-08DOI: 10.1016/j.bioflm.2025.100304
Robert Falconer , Tyler Smith , David Rothberg , Jeremy Gililland , Nicholas Ashton , Dustin Williams
Wound irrigation is routinely performed as part of the DAIR procedure and for hardware infections, yet the most effective irrigation solution for reducing bacterial bioburden is unknown. Clinicians can choose on-label, commercially available irrigation solutions or hand-mix preparations off-label on the operating back table. Current methods for evaluating antiseptic efficacy often do not represent the clinical scenario. Here, we present a proof-of-concept ex vivo setup to evaluate whether on-label, commercially available irrigation solutions were superior at reducing bacterial biofilm burden compared to off-label, hand-mixed irrigation solutions. Staphylococcus aureus ATCC 49525 (Xen36) biofilms were grown on Grade 5 titanium simulated fracture fixation plates and secured to sections of autoclaved bovine femur with cortical bone screws. Fourteen irrigation solutions (three commercial, eleven hand-mixed) and one untreated control group were evaluated by irrigating the biofilm-ridden plates and quantifying the remaining bioburden using a 10-fold dilution series to determine the log10 reduction. None of the fourteen treatments reduced bioburden statistically significantly compared to the untreated control, where no irrigation was performed. Additionally, no treatment achieved the FDA benchmark of a 4 log10 reduction for antibacterial activity. An off-label, hand-mixed 0.472 % w/v chlorhexidine gluconate solution reduced the greatest bioburden overall, with a 1.43 ± 0.20 log10 reduction. On-label irrigation products did not reduce bioburden more than off-label, hand-mixed solutions clinicians often prepare in the operating room. Musculoskeletal infections remain a significant clinical challenge and contribute to increasing healthcare costs. The antimicrobial efficacy of irrigation products should be assessed using clinically relevant models.
{"title":"Antimicrobial efficacy of on-label vs. hand-mixed irrigation solutions against S. aureus biofilms","authors":"Robert Falconer , Tyler Smith , David Rothberg , Jeremy Gililland , Nicholas Ashton , Dustin Williams","doi":"10.1016/j.bioflm.2025.100304","DOIUrl":"10.1016/j.bioflm.2025.100304","url":null,"abstract":"<div><div>Wound irrigation is routinely performed as part of the DAIR procedure and for hardware infections, yet the most effective irrigation solution for reducing bacterial bioburden is unknown. Clinicians can choose on-label, commercially available irrigation solutions or hand-mix preparations off-label on the operating back table. Current methods for evaluating antiseptic efficacy often do not represent the clinical scenario. Here, we present a proof-of-concept <em>ex vivo</em> setup to evaluate whether on-label, commercially available irrigation solutions were superior at reducing bacterial biofilm burden compared to off-label, hand-mixed irrigation solutions. <em>Staphylococcus aureus</em> ATCC 49525 (Xen36) biofilms were grown on Grade 5 titanium simulated fracture fixation plates and secured to sections of autoclaved bovine femur with cortical bone screws. Fourteen irrigation solutions (three commercial, eleven hand-mixed) and one untreated control group were evaluated by irrigating the biofilm-ridden plates and quantifying the remaining bioburden using a 10-fold dilution series to determine the log<sub>10</sub> reduction. None of the fourteen treatments reduced bioburden statistically significantly compared to the untreated control, where no irrigation was performed. Additionally, no treatment achieved the FDA benchmark of a 4 log<sub>10</sub> reduction for antibacterial activity. An off-label, hand-mixed 0.472 % w/v chlorhexidine gluconate solution reduced the greatest bioburden overall, with a 1.43 ± 0.20 log<sub>10</sub> reduction. On-label irrigation products did not reduce bioburden more than off-label, hand-mixed solutions clinicians often prepare in the operating room. Musculoskeletal infections remain a significant clinical challenge and contribute to increasing healthcare costs. The antimicrobial efficacy of irrigation products should be assessed using clinically relevant models.</div></div>","PeriodicalId":55844,"journal":{"name":"Biofilm","volume":"10 ","pages":"Article 100304"},"PeriodicalIF":5.9,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144606034","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号