Challenges in Discovering Innovations Related to Biofilms: Virulence, Spread, Control Strategies and Treatment

A special issue of Pharmaceuticals (ISSN 1424-8247). This special issue belongs to the section "Pharmacology".

Deadline for manuscript submissions: 25 December 2026 | Viewed by 13105

Special Issue Editor


E-Mail Website
Guest Editor
Institute of Microbiology Bulgarian Academy of Sciences, Sofia, Bulgaria
Interests: microbiology; biofilm formation; biofouling; antibiofilm agents; antimicrobial resistance; quorum sensing; virulence; antimicrobials

Special Issue Information

Dear Colleagues,

The development of a thematic focus on biofilms presents a significant challenge given the vast scope and scientific interest in understanding these complex microbial communities. This Special Issue aims to encourage researchers to publish innovations that could provide deeper insights into the biofilm network. The aim is to highlight current advances in the field of biofilms, with particular attention to virulence mechanisms, biofilm formation and structure, as well as resistance to antimicrobial agents. New developments targeting biofilm dispersion and removal, especially through the application of natural or synthetic inhibitors (such as plant extracts, phytochemicals, nanoparticles, probiotics, biosurfactants, antimicrobial peptides, microbial enzymes, etc.), will also be a key focus of this issue. Additionally, strategies for controlling and treating infectious and environmental biofilms remain an evolving topic that holds significant promise for future research and is also slated for consideration. Addressing these priority scientific questions focused on biofilm research would reveal significant advancements in the field.

Dr. Tsvetelina Paunova-Krasteva
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Pharmaceuticals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • biofilm
  • structure
  • pathogenesis
  • virulence
  • tolerance
  • biofilm infections
  • dispersion
  • control strategies
  • quorum sensing

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • Reprint: MDPI Books provides the opportunity to republish successful Special Issues in book format, both online and in print.

Further information on MDPI's Special Issue policies can be found here.

Published Papers (8 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

19 pages, 1828 KB  
Article
HPMC-ZnO Nanorods Enhance Hydrophilicity and Contact-Killing Activity on Polypropylene Meshes and Sutures
by Sangita Jana, Akshit Malhotra, Honey Mittal, Sambuddha Chakraborty, Manika Khanuja, Gyanendra Singh, Ram Karan, Elvira Rozhina and Ashwini Chauhan
Pharmaceuticals 2026, 19(1), 55; https://doi.org/10.3390/ph19010055 - 26 Dec 2025
Viewed by 797
Abstract
Background: Biomedical device-associated infections pose major challenges in surgical care, particularly in hernia repair where polypropylene (PP) meshes and sutures are prone to bacterial colonization and biofilm formation. The limitations of antibiotic resistance and toxicity warrants the need of developing innovative antibacterial strategies. [...] Read more.
Background: Biomedical device-associated infections pose major challenges in surgical care, particularly in hernia repair where polypropylene (PP) meshes and sutures are prone to bacterial colonization and biofilm formation. The limitations of antibiotic resistance and toxicity warrants the need of developing innovative antibacterial strategies. Methods: We developed a composite coating of hydroxypropyl methylcellulose (HPMC) and zinc oxide nanorods (ZnO NP) synthesized via thermal decomposition. This coating was applied to PP meshes and sutures to enhance anti-adhesive properties. The study evaluated surface hydrophilicity through water contact angles, estimation of Zn2+ ions using inductively coupled plasma–mass spectrometry (ICP-MS), and long-term efficacy over six months. Safety was assessed via systemic toxicity studies in murine models. Results: The ZnO NPs exhibited potent antibacterial efficacy, achieving up to 99.999% killing against Klebsiella pneumoniae. When applied as an HPMC-ZnO coating, PP meshes and sutures demonstrated enhanced hydrophilicity, reducing water contact angles by ~41° and facilitating prevention of bacterial adhesion. The coated meshes inhibited bacterial attachment by 83% (Escherichia coli), 60% (Pseudomonas aeruginosa), 99.6% (K. pneumoniae), and 99% (Staphylococcus aureus). Similarly, coated sutures reduced adhesion by 67–96% across these strains. Long-term storage studies showed retained antibiofilm efficacy for up to six months. In vivo assessments indicated negligible systemic toxicity of ZnO NPs in murine models. Conclusions: Collectively, these findings highlight HPMC-ZnO NPs coatings as a safe, durable, and effective strategy to functionalize PP-based meshes and sutures, reducing the risk of surgical site infections and demonstrating the potential for broader biomedical applications. Full article
Show Figures

Graphical abstract

24 pages, 7480 KB  
Article
Interference of Pseudomonas aeruginosa Virulence Factors by Different Extracts from Inula Species
by Tsvetelina Paunova-Krasteva, Petya D. Dimitrova, Tsvetozara Damyanova, Dayana Borisova, Milena Leseva, Iveta Uzunova, Petya A. Dimitrova, Viktoria Ivanova, Antoaneta Trendafilova, Ralitsa Veleva and Tanya Topouzova-Hristova
Pharmaceuticals 2025, 18(12), 1824; https://doi.org/10.3390/ph18121824 - 29 Nov 2025
Cited by 1 | Viewed by 1373
Abstract
Objectives: Pseudomonas aeruginosa is an opportunistic pathogen of high clinical relevance due to its ability to form biofilms, its inherent virulence regulated by quorum-sensing systems, and its multidrug resistance. In the present study, we evaluated the inhibitory potential of nine extracts from [...] Read more.
Objectives: Pseudomonas aeruginosa is an opportunistic pathogen of high clinical relevance due to its ability to form biofilms, its inherent virulence regulated by quorum-sensing systems, and its multidrug resistance. In the present study, we evaluated the inhibitory potential of nine extracts from Inula species (chloroform and methanolic fractions, including a sesquiterpene lactone-enriched fraction) against biofilm formation and virulence-associated traits of P. aeruginosa PAO1 and three multidrug-resistant clinical isolates, as well as their cytotoxicity, biocompatibility, and ability to affect cytokine and nitric oxide production in infected skin explants. Methods: The following methods were applied: fractionation and extraction of plant extracts; cytotoxicity assessment on HFF cells; crystal violet assay for determining antibiofilm activity; fluorescence microscopy for evaluating biofilm viability; electron microscopy for assessing the 3D structure of biofilms and morphological alterations; inhibition assays of pyocyanin pigment, protease activity, bacterial motility, interleukin-17, and nitric oxide production; histological analysis of mouse skin explants. Results: Quantitative analyses of antibiofilm activity revealed that five of the tested extracts inhibited biofilm formation by more than 50%. Structural and functional analyses using confocal laser scanning microscopy and scanning electron microscopy demonstrated a substantial reduction in biofilm thickness, exfoliation of biofilm biomass, the presence of isolated bacterial clusters, metabolically inactive cell populations, and morphological abnormalities associated with cell elongation, invaginations, and polar deformations as a consequence of treatment. In addition, the plant extracts strongly affected virulence factors regulated by quorum sensing. The methanolic fractions from I. britannica and I. bifrons significantly suppressed pyocyanin synthesis. In contrast, the chloroform fractions from I. helenium and I. spiraeifolia produced the largest inhibition zones in assays for extracellular protease activity. Furthermore, all chloroform extracts suppressed bacterial motility, with the lowest swarming diameter observed for the chloroform and lactone-enriched fractions from I. britannica. The chloroform extracts of I. helenium and I. bifrons, methanolic extracts of I. britannica, and chloroform and methanolic extracts of I. spiraeifolia showed relatively low toxicity to normal diploid human fibroblasts. Methanolic and chloroform fractions from I. britannica disrupted biofilm integrity and reduced IL-17A and nitric oxide production in infected skin explants. Conclusions: All these findings indicate a possible synergistic action of the chemical constituents within the fractions on quorum-sensing regulation, biofilm formation, cellular viability, and modulation of host inflammatory responses. Full article
Show Figures

Graphical abstract

14 pages, 3857 KB  
Article
Coating Doyle Nasal Silicone Splints with a Sustained Release Varnish Containing Antibiotics Provides Long-Term Protection from Staphylococcus aureus: An In Vitro Study
by Ahmad Siag, Ronit Vogt Sionov, Irith Gati, Michael Friedman, Doron Steinberg and Menachem Gross
Pharmaceuticals 2025, 18(11), 1746; https://doi.org/10.3390/ph18111746 - 17 Nov 2025
Viewed by 1453
Abstract
Background/Objectives: Doyle nasal silicone splints are commonly used in nasal surgeries to maintain the shape of the nasal passage and prevent scar tissue formation. However, these implants are prone to bacterial colonization, particularly by Staphylococcus aureus, which is associated with severely [...] Read more.
Background/Objectives: Doyle nasal silicone splints are commonly used in nasal surgeries to maintain the shape of the nasal passage and prevent scar tissue formation. However, these implants are prone to bacterial colonization, particularly by Staphylococcus aureus, which is associated with severely recurrent and recalcitrant cases of infected sinonasal cavities. The aim of this study was to develop a sustained-release varnish (SRV) with antibacterial properties that can be applied to Doyle splints to provide an antibacterial environment for an extended period. Methods: Doyle nasal splints (1 cm × 1 cm segments) were coated with SRV containing one of the three antibiotics: augmentin, ciprofloxacin, or chloramphenicol. A placebo varnish without antibiotics served as a control. The coated splints were exposed daily to a fresh culture of S. aureus, and antibacterial activity was assessed by monitoring bacterial growth. Antibiofilm activity was determined using an MTT metabolic assay. Antibacterial activity was further studied by the kinetic disk diffusion assay, where the stents were transferred daily to new, freshly coated S. aureus plates. Biofilm formation on the coated splints was visualized by high-resolution scanning electron microscopy (HR-SEM). Results: Doyle segments coated with augmentin, ciprofloxacin, or chloramphenicol effectively inhibited S. aureus planktonic growth for 9 ± 1, 18 ± 1, and 21 ± 1 days, respectively. Biofilm formation was prevented for 10 ± 1, 18 ± 1, and 21 ± 1 days, and bacterial clearance occurred for 14 ± 1, 52 ± 1, and >65 days, respectively. HR-SEM images showed the prevention of biofilm formation on the coated segments. Conclusions: Our findings demonstrate that coating Doyle nasal silicon splints with SRV containing augmentin, ciprofloxacin, or chloramphenicol provides long-term antibacterial and antibiofilm activity, with SRV–chloramphenicol being superior. Further studies are needed to confirm the in vivo efficacy of this approach. Full article
Show Figures

Graphical abstract

19 pages, 2009 KB  
Article
Quinazoline-Derivatives of Imino-1,2,3-Dithiazoles Promote Biofilm Dispersion of Pseudomonas aeruginosa
by Mathieu Gonzalez, Anne-Sophie Tareau, Daphnée de Crozals, Corentin Layec, Nathan Broudic, Magalie Barreau, Adrien Forge, Olivier Lesouhaitier, Corinne Fruit, Sylvie Chevalier, Thierry Besson and Ali Tahrioui
Pharmaceuticals 2025, 18(11), 1733; https://doi.org/10.3390/ph18111733 - 14 Nov 2025
Viewed by 779
Abstract
Background/Objectives: Biofilm-associated infections pose a major clinical challenge since bacteria within biofilms exhibit highly antibiotic tolerance. Pseudomonas aeruginosa forms persistent biofilms that cause chronic infections in vulnerable patients, including those with cystic fibrosis, burns, or medical implants. Such biofilm-associated chronic infections require prolonged [...] Read more.
Background/Objectives: Biofilm-associated infections pose a major clinical challenge since bacteria within biofilms exhibit highly antibiotic tolerance. Pseudomonas aeruginosa forms persistent biofilms that cause chronic infections in vulnerable patients, including those with cystic fibrosis, burns, or medical implants. Such biofilm-associated chronic infections require prolonged treatments that promote antimicrobial resistance. To address this, recent strategies focus on enhancing biofilm dispersion. Methods: Thirty-six N-arylimino-1,2,3-dithiazoles were screened for their biofilm dispersal activity using a crystal violet assay. Their cytotoxicity was assessed on A549 and HaCat eukaryotic cells. Moreover, their influence on bacterial growth and virulence was investigated. Lastly, fluorescence anisotropy was used to measure membrane fluidity to obtain the first insights on the mechanism of action of these chemicals. Results: Our results showed that quinazoline-derivatives of imino-1,2,3-dithiazoles display biofilm dispersion activity. These compounds do not increase virulence through pyocyanin production, do not modify the growth kinetics of P. aeruginosa, and do not show cytotoxicity towards eucaryotic cells. Conclusions: These findings highlight the potential use of N-arylimino-1,2,3-dithiazole-derived compounds as safe and effective dispersal agents of P. aeruginosa biofilms. Full article
Show Figures

Graphical abstract

Review

Jump to: Research

33 pages, 6027 KB  
Review
Metal-Functionalized Nanozymes in Antibacterial Wound Management: Recent Advances and Future Perspectives
by Selvam Sathiyavimal, Devaraj Bharathi and Ezhaveni Sathiyamoorthi
Pharmaceuticals 2026, 19(2), 333; https://doi.org/10.3390/ph19020333 - 19 Feb 2026
Viewed by 1493
Abstract
Chronic and infected wounds continue to pose significant clinical challenges due to microbial infections, biofilm development, inflammation, and poor tissue regeneration. Traditional antibiotics medications often show low efficacy and lack stability. The demand for new therapeutic approaches is increasing due to bacterial resistance. [...] Read more.
Chronic and infected wounds continue to pose significant clinical challenges due to microbial infections, biofilm development, inflammation, and poor tissue regeneration. Traditional antibiotics medications often show low efficacy and lack stability. The demand for new therapeutic approaches is increasing due to bacterial resistance. Metal-based nanozymes have intrinsic enzyme-like catalytic activity and emerged as a promising class of antibacterial agents for wound-healing applications. The functionalization with metals such as silver (Ag), copper (Cu), iron (Fe), manganese (Mn), cerium (Ce), platinum (Pt) and gold (Au) enhances peroxidase (POD)-, oxidase (OXD)-, and catalase (CAT)-like biomimetic activities. This improvement enables efficient reactive oxygen species (ROS) production, biofilm inhibition, and microenvironment-responsive antibacterial activity. These metal-nanozymes also alter the immune response, increase angiogenesis, and promote extracellular matrix remodeling when combined with metals and also polysaccharides. This review summarizes recent advances in metal-incorporated antibacterial nanozymes including their design, catalytic mechanisms, structure–activity relationships, and integration into hydrogels, films, and fibers for wound healing. Key challenges such as biosafety, metal ion release, the inflammatory balance, and clinical translation are critically discussed. Emerging directions such as single-atom nanozymes, cascade enzyme systems, and stimuli-responsive platforms are highlighted as promising routes for next-generation wound therapeutics. Overall, this review underscores the clinical potential of metal-functionalized nanozymes for infected wound management; however, concerns regarding ion leakage and long-term safety persist emphasizing the need for controlled designs and biocompatible systems to enable safe translation. Full article
Show Figures

Graphical abstract

25 pages, 1342 KB  
Review
Salmonellosis as a One Health–One Biofilm Challenge: Biofilm Formation by Salmonella and Alternative Eradication Strategies in the Post-Antibiotic Era
by Michał Małaszczuk, Aleksandra Pawlak and Paweł Krzyżek
Pharmaceuticals 2026, 19(1), 61; https://doi.org/10.3390/ph19010061 - 27 Dec 2025
Cited by 1 | Viewed by 1325
Abstract
Non-typhoidal Salmonella (NTS) are globally distributed zoonotic pathogens of major concern within the One Health–One Biofilm framework. Fluoroquinolone-resistant Salmonella strains are included by the World Health Organization (WHO) in the Bacterial Priority Pathogens List as high-risk agents. A key virulence determinant of Salmonella [...] Read more.
Non-typhoidal Salmonella (NTS) are globally distributed zoonotic pathogens of major concern within the One Health–One Biofilm framework. Fluoroquinolone-resistant Salmonella strains are included by the World Health Organization (WHO) in the Bacterial Priority Pathogens List as high-risk agents. A key virulence determinant of Salmonella is its ability to form biofilms, which may display multidrug-resistant (MDR) characteristics and contribute to bacterial persistence and treatment failure. Animals, particularly poultry and reptiles, represent important reservoirs of Salmonella, and reptile-associated salmonellosis (RAS) may manifest as extraintestinal infections in humans. In the post-antibiotic era, there is an urgent need to identify effective alternatives to conventional therapies. This review summarizes current knowledge on Salmonella biofilms, with particular attention to their MDR potential, and discusses possible strategies for their prevention and eradication, including specific immunoprophylaxis, bacteriophage therapy, and alternative antimicrobials. The promising antimicrobials include plant-based compounds/extracts, bacteriocins, fatty acids, and synthetic/semi-synthetic substances. The integration of vaccination, phage therapy, and novel anti-biofilm compounds may provide a sustainable alternative to antibiotics in controlling Salmonella infections and aligns with the principles of the One Health approach. Full article
Show Figures

Graphical abstract

27 pages, 1688 KB  
Review
Bacteriophages and Their Enzymes: Allies Against Microbial Biofilms
by Fohad Mabood Husain, Andaleeb Zahra, Asghar Ali, Mohan Kamthan, Nasser A. Al-Shabib, Zeba Farooqui, Naved Ahmad, Thamer Albalawi, Pravej Alam and Nayla Munawar
Pharmaceuticals 2025, 18(12), 1771; https://doi.org/10.3390/ph18121771 - 21 Nov 2025
Cited by 4 | Viewed by 2017
Abstract
Bacterial biofilms pose a substantial challenge in healthcare and industrial and environmental settings because of their resilience and antibiotic resistance. Biofilm formation is a complex process involving microbial communities encased in an extracellular matrix that contributes to increased resistance and persistent infections. This [...] Read more.
Bacterial biofilms pose a substantial challenge in healthcare and industrial and environmental settings because of their resilience and antibiotic resistance. Biofilm formation is a complex process involving microbial communities encased in an extracellular matrix that contributes to increased resistance and persistent infections. This review explores the emerging roles of bacteriophages and their derived enzymes as promising alternatives or adjunct therapies to combat bacterial biofilms. Bacteriophages, viruses that infect bacteria, exhibit marked specificity and diverse mechanisms for targeting and lysing bacterial cells within biofilms. Enzymes, including endolysins and depolymerases, have demonstrated efficacy in disrupting biofilm matrices. Moreover, the potential synergy between bacteriophages and antibiotics enhances their antimicrobial activity, providing a multifaceted approach for combating biofilm-associated infections. This review critically evaluates the current research, highlighting the successes and limitations of bacteriophage-based strategies in biofilm control, and underscores the potential of these alternatives in shaping future therapeutic interventions against biofilm-related bacterial infections. Full article
Show Figures

Figure 1

37 pages, 4016 KB  
Review
Recent Trends in Bioinspired Metal Nanoparticles for Targeting Drug-Resistant Biofilms
by Devaraj Bharathi and Jintae Lee
Pharmaceuticals 2025, 18(7), 1006; https://doi.org/10.3390/ph18071006 - 5 Jul 2025
Cited by 5 | Viewed by 3064
Abstract
Multidrug-resistant (MDR) biofilm infections characterized by densely packed microbial communities encased in protective extracellular matrices pose a formidable challenge to conventional antimicrobial therapies and are a major contributor to chronic, recurrent and device-associated infections. These biofilms significantly reduce antibiotic penetration, facilitate the survival [...] Read more.
Multidrug-resistant (MDR) biofilm infections characterized by densely packed microbial communities encased in protective extracellular matrices pose a formidable challenge to conventional antimicrobial therapies and are a major contributor to chronic, recurrent and device-associated infections. These biofilms significantly reduce antibiotic penetration, facilitate the survival of dormant persister cells and promote horizontal gene transfer, all of which contribute to the emergence and persistence of MDR pathogens. Metal nanoparticles (MNPs) have emerged as promising alternatives due to their potent antibiofilm properties. However, conventional synthesis methods are associated with high costs, complexity, inefficiency and negative environmental impacts. To overcome these limitations there has been a global push toward the development of sustainable and eco-friendly synthesis approaches. Recent advancements have demonstrated the successful use of various plant extracts, microbial cultures, and biomolecules for the green synthesis of MNPs, which offers biocompatibility, scalability, and environmental safety. This review provides a comprehensive overview of recent trends and the latest progress in the green synthesis of MNPs including silver (Ag), gold (Au), platinum (Pt), and selenium (Se), and also explores the mechanistic pathways and characterization techniques. Furthermore, it highlights the antibiofilm applications of these MNPs emphasizing their roles in disrupting biofilms and restoring the efficacy of existing antimicrobial strategies. Full article
Show Figures

Figure 1

Back to TopTop