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Microbial Biofilms and Antibiofilm Agents

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Microbiology".

Deadline for manuscript submissions: closed (30 December 2020) | Viewed by 44904

Special Issue Editors


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Guest Editor
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
Interests: biofilm; biofilm-associated infections; antimicrobial peptides; new antimicrobial agents; host–pathogen interactions; virulence factors; Pseudomonas aeruginosa; Staphylococcus aureus
Special Issues, Collections and Topics in MDPI journals
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56123 Pisa, Italy
Interests: macrophage; bacteria; flow cytometry; immunology of infectious diseases; innate immunity; cell culture; immunity; antimicrobials; cytokines; infection
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56123 Pisa, Italy
Interests: antimicrobial peptides; bacterial cells; antimicrobials; antibacterial activity; antibiotics; antibacterials; biofilm formation; bacterial antibiotic resistance; quorum sensing; bacteriocins
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Although the intense basic research on biofilms that has been carried out in recent decades has improved our capacity to design original and efficient therapeutic approaches to specifically target biofilm-related infections, most of these approaches are still at a developmental stage, and treatment of biofilm infections currently represents a challenging task for microbiologists and clinicians. Several mechanisms are responsible for the recalcitrance of biofilms to conventional antimicrobial treatments. These include, among others, reduced diffusion or sequestration of antibiotics through biofilm layers, generation of subsets of persistent bacteria, elevated rate of exchange of mobile genetic elements carrying resistance determinants, and establishment of environmental niches unfavorable to antibiotic action. To increase the translational potential of novel antibiofilm approaches, much work still needs to be done. For instance, even if in vitro biofilm susceptibility testing is a mandatory first step in evaluating new antibiofilm agents, molecules identified in vitro should be validated in models mimicking, as much as possible, in vivo physiological conditions and tested also for pharmacokinetics and absence of toxicity. Moreover, the increasing awareness of the polymicrobial nature of biofilms should lead to the development of dedicated approaches to study bacteria–bacteria or bacteria–fungi interactions and their consequences on biofilm pathogenesis or tolerance towards antibiotics.

This Special issue aims to gather a collection of papers focused on biofilm infections and new strategies to target them, with special interest at the molecular mechanisms involved in antibiofilm action. We hope that this Special issue may contribute to disclose new promising approaches that could improve our ability to prevent or eradicate bacterial biofilms in medical settings.

Prof. Dr. Giovanna Batoni
Dr. Semih Esin
Dr. Giuseppantonio Maisetta
Guest Editors

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Keywords

  • biofilm
  • antibiofilm agents
  • antibiofilm strategies
  • antiadhesive materials
  • biofilm-related infections
  • quorum sensing
  • persisters
  • ex vivo models
  • in vivo models
  • wound infections
  • lung infections

Published Papers (14 papers)

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Research

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15 pages, 2937 KiB  
Article
Contribution of Drugs Interfering with Protein and Cell Wall Synthesis to the Persistence of Pseudomonas aeruginosa Biofilms: An In Vitro Model
by Gianmarco Mangiaterra, Elisa Carotti, Salvatore Vaiasicca, Nicholas Cedraro, Barbara Citterio, Anna La Teana and Francesca Biavasco
Int. J. Mol. Sci. 2021, 22(4), 1628; https://doi.org/10.3390/ijms22041628 - 05 Feb 2021
Cited by 2 | Viewed by 2319
Abstract
The occurrence of Pseudomonas aeruginosa (PA) persisters, including viable but non-culturable (VBNC) forms, subpopulations of tolerant cells that can survive high antibiotic doses, is the main reason for PA lung infections failed eradication and recurrence in Cystic Fibrosis (CF) patients, subjected to life-long, [...] Read more.
The occurrence of Pseudomonas aeruginosa (PA) persisters, including viable but non-culturable (VBNC) forms, subpopulations of tolerant cells that can survive high antibiotic doses, is the main reason for PA lung infections failed eradication and recurrence in Cystic Fibrosis (CF) patients, subjected to life-long, cyclic antibiotic treatments. In this paper, we investigated the role of subinhibitory concentrations of different anti-pseudomonas antibiotics in the maintenance of persistent (including VBNC) PA cells in in vitro biofilms. Persisters were firstly selected by exposure to high doses of antibiotics and their abundance over time evaluated, using a combination of cultural, qPCR and flow cytometry assays. Two engineered GFP-producing PA strains were used. The obtained results demonstrated a major involvement of tobramycin and bacterial cell wall-targeting antibiotics in the resilience to starvation of VBNC forms, while the presence of ciprofloxacin and ceftazidime/avibactam lead to their complete loss. Moreover, a positive correlation between tobramycin exposure, biofilm production and c-di-GMP levels was observed. The presented data could allow a deeper understanding of bacterial population dynamics during the treatment of recurrent PA infections and provide a reliable evaluation of the real efficacy of the antibiotic treatments against the bacterial population within the CF lung. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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15 pages, 1980 KiB  
Article
Sodium Salicylate Influences the Pseudomonas aeruginosa Biofilm Structure and Susceptibility Towards Silver
by Erik Gerner, Sofia Almqvist, Peter Thomsen, Maria Werthén and Margarita Trobos
Int. J. Mol. Sci. 2021, 22(3), 1060; https://doi.org/10.3390/ijms22031060 - 21 Jan 2021
Cited by 6 | Viewed by 2944
Abstract
Hard-to-heal wounds are typically infected with biofilm-producing microorganisms, such as Pseudomonas aeruginosa, which strongly contribute to delayed healing. Due to the global challenge of antimicrobial resistance, alternative treatment strategies are needed. Here, we investigated whether inhibition of quorum sensing (QS) by sodium salicylate [...] Read more.
Hard-to-heal wounds are typically infected with biofilm-producing microorganisms, such as Pseudomonas aeruginosa, which strongly contribute to delayed healing. Due to the global challenge of antimicrobial resistance, alternative treatment strategies are needed. Here, we investigated whether inhibition of quorum sensing (QS) by sodium salicylate in different P. aeruginosa strains (QS-competent, QS-mutant, and chronic wound strains) influences biofilm formation and tolerance to silver. Biofilm formation was evaluated in simulated serum-containing wound fluid in the presence or absence of sodium salicylate (NaSa). Biofilms were established using a 3D collagen-based biofilm model, collagen coated glass, and the Calgary biofilm device. Furthermore, the susceptibility of 48-h-old biofilms formed by laboratory and clinical strains in the presence or absence of NaSa towards silver was evaluated by assessing cell viability. Biofilms formed in the presence of NaSa were more susceptible to silver and contained reduced levels of virulence factors associated with biofilm development than those formed in the absence of NaSa. Biofilm aggregates formed by the wild-type but not the QS mutant strain, were smaller and less heterogenous in size when grown in cultures with NaSa compared to control. These data suggest that NaSa, via a reduction of cell aggregation in biofilms, allows the antiseptic to become more readily available to cells. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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21 pages, 3535 KiB  
Article
Microstructured Lipid Carriers (MLC) Based on N-Acetylcysteine and Chitosan Preventing Pseudomonas aeruginosa Biofilm
by Marta Guerini, Pietro Grisoli, Cristina Pane and Paola Perugini
Int. J. Mol. Sci. 2021, 22(2), 891; https://doi.org/10.3390/ijms22020891 - 17 Jan 2021
Cited by 6 | Viewed by 2310
Abstract
The aim of this work was the development of microstructured lipid carriers (MLC) based on chitosan (CH) and containing N-acetylcysteine (NAC), a mucolytic and antioxidant agent, to inhibit the formation of Pseudomonas aeruginosa biofilm. MLC were prepared using the high shear homogenization technique. [...] Read more.
The aim of this work was the development of microstructured lipid carriers (MLC) based on chitosan (CH) and containing N-acetylcysteine (NAC), a mucolytic and antioxidant agent, to inhibit the formation of Pseudomonas aeruginosa biofilm. MLC were prepared using the high shear homogenization technique. The MLC were characterized for morphology, particle size, Z potential, encapsulation efficiency and drug release. The antioxidant properties of NAC-loaded microstructured carriers were evaluated through an in vitro spectrophotometer assay. Finally, the activity of NAC-CH-MLC on biofilm production by Pseudomonas aeruginosa was also evaluated. Results obtained from this study highlighted that the use of chitosan into the inner aqueous phase permitted to obtain microstructured particles with a narrow size range and with good encapsulation efficiency. NAC-loaded MLC showed higher antioxidant activity than the free molecule, demonstrating how encapsulation increases the antioxidant effect of the molecule. Furthermore, the reduction of biofilm growth resulted extremely high with MLC being 64.74% ± 6.2% and 83.74% ± 9.95%, respectively, at 0.5 mg/mL and 2 mg/mL. In conclusion, this work represents a favorable technological strategy against diseases in which bacterial biofilm is relevant, such as cystic fibrosis. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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12 pages, 4195 KiB  
Article
Effect of Polyhexamethylene Biguanide in Combination with Undecylenamidopropyl Betaine or PslG on Biofilm Clearance
by Yaqian Zheng, Di Wang and Luyan Z. Ma
Int. J. Mol. Sci. 2021, 22(2), 768; https://doi.org/10.3390/ijms22020768 - 14 Jan 2021
Cited by 16 | Viewed by 2461
Abstract
Hospital-acquired infection is a great challenge for clinical treatment due to pathogens’ biofilm formation and their antibiotic resistance. Here, we investigate the effect of antiseptic agent polyhexamethylene biguanide (PHMB) and undecylenamidopropyl betaine (UB) against biofilms of four pathogens that are often found in [...] Read more.
Hospital-acquired infection is a great challenge for clinical treatment due to pathogens’ biofilm formation and their antibiotic resistance. Here, we investigate the effect of antiseptic agent polyhexamethylene biguanide (PHMB) and undecylenamidopropyl betaine (UB) against biofilms of four pathogens that are often found in hospitals, including Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli, Gram-positive bacteria Staphylococcus aureus, and pathogenic fungus, Candida albicans. We show that 0.02% PHMB, which is 10-fold lower than the concentration of commercial products, has a strong inhibitory effect on the growth, initial attachment, and biofilm formation of all tested pathogens. PHMB can also disrupt the preformed biofilms of these pathogens. In contrast, 0.1% UB exhibits a mild inhibitory effect on biofilm formation of the four pathogens. This concentration inhibits the growth of S. aureus and C. albicans yet has no growth effect on P. aeruginosa or E. coli. UB only slightly enhances the anti-biofilm efficacy of PHMB on P. aeruginosa biofilms. However, pretreatment with PslG, a glycosyl hydrolase that can efficiently inhibit and disrupt P. aeruginosa biofilm, highly enhances the clearance effect of PHMB on P. aeruginosa biofilms. Meanwhile, PslG can also disassemble the preformed biofilms of the other three pathogens within 30 min to a similar extent as UB treatment for 24 h. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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15 pages, 3425 KiB  
Article
2-(2-Methyl-2-nitrovinyl)furan but Not Furvina Interfere with Staphylococcus aureus Agr Quorum-Sensing System and Potentiate the Action of Fusidic Acid against Biofilms
by Diana Oliveira, Anabela Borges, Reinaldo Molina Ruiz, Zenaida Rodríguez Negrín, Simona Distinto, Fernanda Borges and Manuel Simões
Int. J. Mol. Sci. 2021, 22(2), 613; https://doi.org/10.3390/ijms22020613 - 09 Jan 2021
Cited by 6 | Viewed by 2487
Abstract
Quorum sensing (QS) plays an essential role in the production of virulence factors, in biofilm formation and antimicrobial resistance. Consequently, inhibiting QS is being considered a promising target for antipathogenic/anti-virulence therapies. This study aims to screen 2-nitrovinylfuran derivatives structurally related to Furvina (a [...] Read more.
Quorum sensing (QS) plays an essential role in the production of virulence factors, in biofilm formation and antimicrobial resistance. Consequently, inhibiting QS is being considered a promising target for antipathogenic/anti-virulence therapies. This study aims to screen 2-nitrovinylfuran derivatives structurally related to Furvina (a broad-spectrum antibiotic already used for therapeutic purposes) for their effects on QS and in biofilm prevention/control. Furvina and four 2-nitrovinylfuran derivatives (compounds 14) were tested to assess the ability to interfere with QS of Staphylococcus aureus using bioreporter strains (S. aureus ALC1742 and ALC1743). The activity of Furvina and the most promising quorum-sensing inhibitor (QSI) was evaluated in biofilm prevention and in biofilm control (combined with fusidic acid). The biofilms were further characterized in terms of biofilm mass, viability and membrane integrity. Compound 2 caused the most significant QS inhibition with reductions between 60% and 80%. Molecular docking simulations indicate that this compound interacts preferentially with the protein hydrophobic cleft in the LytTR domain of AgrA pocket. Metabolic inactivations of 40% for S. aureus ALC1742 and 20% for S. aureus ALC1743 were reached. A 24 h-old biofilm formed in the presence of the QSI increased the metabolic inactivation by fusidic acid to 80%, for both strains. The overall results highlight the effects of compound 2 as well as the potential of combining QSI with in-use antibiotics for the management of skin and soft tissues infections. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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13 pages, 3603 KiB  
Article
Durable Oral Biofilm Resistance of 3D-Printed Dental Base Polymers Containing Zwitterionic Materials
by Jae-Sung Kwon, Ji-Yeong Kim, Utkarsh Mangal, Ji-Young Seo, Myung-Jin Lee, Jie Jin, Jae-Hun Yu and Sung-Hwan Choi
Int. J. Mol. Sci. 2021, 22(1), 417; https://doi.org/10.3390/ijms22010417 - 03 Jan 2021
Cited by 30 | Viewed by 3266
Abstract
Poly(methyl methacralyate) (PMMA) has long been used in dentistry as a base polymer for dentures, and it is recently being used for the 3D printing of dental materials. Despite its many advantages, its susceptibility to microbial colonization remains to be overcome. In this [...] Read more.
Poly(methyl methacralyate) (PMMA) has long been used in dentistry as a base polymer for dentures, and it is recently being used for the 3D printing of dental materials. Despite its many advantages, its susceptibility to microbial colonization remains to be overcome. In this study, the interface between 3D-printed PMMA specimens and oral salivary biofilm was studied following the addition of zwitterionic materials, 2-methacryloyloxyethyl phosphorylcholine (MPC) or sulfobetaine methacrylate (SB). A significant reduction in bacterial and biofilm adhesions was observed following the addition of MPC or SB, owing to their protein-repellent properties, and there were no significant differences between the two test materials. Although the mechanical properties of the tested materials were degraded, the statistical value of the reduction was minimal and all the properties fulfilled the requirements set by the International Standard, ISO 20795-2. Additionally, both the test materials maintained their resistance to biofilm when subjected to hydrothermal fatigue, with no further deterioration of the mechanical properties. Thus, novel 3D-printable PMMA incorporated with MPC or SB shows durable oral salivary biofilm resistance with maintenance of the physical and mechanical properties. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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14 pages, 1796 KiB  
Article
A Label-Free Cellular Proteomics Approach to Decipher the Antifungal Action of DiMIQ, a Potent Indolo[2,3-b]Quinoline Agent, against Candida albicans Biofilms
by Robert Zarnowski, Anna Jaromin, Agnieszka Zagórska, Eddie G. Dominguez, Katarzyna Sidoryk, Jerzy Gubernator and David R. Andes
Int. J. Mol. Sci. 2021, 22(1), 108; https://doi.org/10.3390/ijms22010108 - 24 Dec 2020
Cited by 4 | Viewed by 2211
Abstract
Candida albicans forms extremely drug-resistant biofilms, which present a serious threat to public health globally. Biofilm-based infections are difficult to treat due to the lack of efficient antifungal therapeutics, resulting in an urgent demand for the development of novel antibiofilm strategies. In this [...] Read more.
Candida albicans forms extremely drug-resistant biofilms, which present a serious threat to public health globally. Biofilm-based infections are difficult to treat due to the lack of efficient antifungal therapeutics, resulting in an urgent demand for the development of novel antibiofilm strategies. In this study, the antibiofilm activity of DiMIQ (5,11-dimethyl-5H-indolo[2,3-b]quinoline) was evaluated against C. albicans biofilms. DiMIQ is a synthetic derivative of indoquinoline alkaloid neocryptolepine isolated from a medicinal African plant, Cryptolepis sanguinolenta. Antifungal activity of DiMIQ was determined using the XTT assay, followed by cell wall and extracellular matrix profiling and cellular proteomes. Here, we demonstrated that DiMIQ inhibited C. albicans biofilm formation and altered fungal cell walls and the extracellular matrix. Cellular proteomics revealed inhibitory action against numerous translation-involved ribosomal proteins, enzymes involved in general energy producing processes and select amino acid metabolic pathways including alanine, aspartate, glutamate, valine, leucine and isoleucine. DiMIQ also stimulated pathways of cellular oxidation, metabolism of carbohydrates, amino acids (glycine, serine, threonine, arginine, phenylalanine, tyrosine, tryptophan) and nucleic acids (aminoacyl-tRNA biosynthesis, RNA transport, nucleotide metabolism). Our findings suggest that DiMIQ inhibits C. albicans biofilms by arresting translation and multidirectional pathway reshaping of cellular metabolism. Overall, this agent may provide a potent alternative to treating biofilm-associated Candida infections. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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14 pages, 2600 KiB  
Article
A Celecoxib Derivative Eradicates Antibiotic-Resistant Staphylococcus aureus and Biofilms by Targeting YidC2 Translocase
by Shiou-Ru Tzeng, Yi-Wei Huang, Yao-Qing Zhang, Ching-Yi Yang, Han-Sheng Chien, Yi-Ru Chen, Sung-Liang Yu, Ching S. Chen and Hao-Chieh Chiu
Int. J. Mol. Sci. 2020, 21(23), 9312; https://doi.org/10.3390/ijms21239312 - 07 Dec 2020
Cited by 5 | Viewed by 2816
Abstract
The treatment of Staphylococcus aureus infections is impeded by the prevalence of MRSA and the formation of persisters and biofilms. Previously, we identified two celecoxib derivatives, Cpd36 and Cpd46, to eradicate MRSA and other staphylococci. Through whole-genome resequencing, we obtained several lines of [...] Read more.
The treatment of Staphylococcus aureus infections is impeded by the prevalence of MRSA and the formation of persisters and biofilms. Previously, we identified two celecoxib derivatives, Cpd36 and Cpd46, to eradicate MRSA and other staphylococci. Through whole-genome resequencing, we obtained several lines of evidence that these compounds might act by targeting the membrane protein translocase YidC2. Our data showed that ectopic expression of YidC2 in S. aureus decreased the bacterial susceptibility to Cpd36 and Cpd46, and that the YidC2-mediated tolerance to environmental stresses was suppressed by both compounds. Moreover, the membrane translocation of ATP synthase subunit c, a substrate of YidC2, was blocked by Cpd46, leading to a reduction in bacterial ATP production. Furthermore, we found that the thermal stability of bacterial YidC2 was enhanced, and introducing point mutations into the substrate-interacting cavity of YidC2 had a dramatic effect on Cpd36 binding via surface plasmon resonance assays. Finally, we demonstrated that these YidC2 inhibitors could effectively eradicate MRSA persisters and biofilms. Our findings highlight the potential of impeding YidC2-mediated translocation of membrane proteins as a new strategy for the treatment of bacterial infections. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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20 pages, 5872 KiB  
Article
Essential Oils Biofilm Modulation Activity, Chemical and Machine Learning Analysis—Application on Staphylococcus aureus Isolates from Cystic Fibrosis Patients
by Rosanna Papa, Stefania Garzoli, Gianluca Vrenna, Manuela Sabatino, Filippo Sapienza, Michela Relucenti, Orlando Donfrancesco, Ersilia Vita Fiscarelli, Marco Artini, Laura Selan and Rino Ragno
Int. J. Mol. Sci. 2020, 21(23), 9258; https://doi.org/10.3390/ijms21239258 - 04 Dec 2020
Cited by 17 | Viewed by 2475
Abstract
Bacterial biofilm plays a pivotal role in chronic Staphylococcus aureus (S. aureus) infection and its inhibition may represent an important strategy to develop novel therapeutic agents. The scientific community is continuously searching for natural and “green alternatives” to chemotherapeutic drugs, including [...] Read more.
Bacterial biofilm plays a pivotal role in chronic Staphylococcus aureus (S. aureus) infection and its inhibition may represent an important strategy to develop novel therapeutic agents. The scientific community is continuously searching for natural and “green alternatives” to chemotherapeutic drugs, including essential oils (EOs), assuming the latter not able to select resistant strains, likely due to their multicomponent nature and, hence, multitarget action. Here it is reported the biofilm production modulation exerted by 61 EOs, also investigated for their antibacterial activity on S. aureus strains, including reference and cystic fibrosis patients’ isolated strains. The EOs biofilm modulation was assessed by Christensen method on five S. aureus strains. Chemical composition, investigated by GC/MS analysis, of the tested EOs allowed a correlation between biofilm modulation potency and putative active components by means of machine learning algorithms application. Some EOs inhibited biofilm growth at 1.00% concentration, although lower concentrations revealed different biological profile. Experimental data led to select antibiofilm EOs based on their ability to inhibit S. aureus biofilm growth, which were characterized for their ability to alter the biofilm organization by means of SEM studies. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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17 pages, 3375 KiB  
Article
Antibiofilm Properties of Temporin-L on Pseudomonas fluorescens in Static and In-Flow Conditions
by Angela Di Somma, Federica Recupido, Arianna Cirillo, Alessia Romano, Alessandra Romanelli, Sergio Caserta, Stefano Guido and Angela Duilio
Int. J. Mol. Sci. 2020, 21(22), 8526; https://doi.org/10.3390/ijms21228526 - 12 Nov 2020
Cited by 19 | Viewed by 3435
Abstract
Biofilms consist of a complex microbial community adhering to biotic or abiotic surfaces and enclosed within a protein/polysaccharide self-produced matrix. The formation of this structure represents the most important adaptive mechanism that leads to antibacterial resistance, and therefore, closely connected to pathogenicity. Antimicrobial [...] Read more.
Biofilms consist of a complex microbial community adhering to biotic or abiotic surfaces and enclosed within a protein/polysaccharide self-produced matrix. The formation of this structure represents the most important adaptive mechanism that leads to antibacterial resistance, and therefore, closely connected to pathogenicity. Antimicrobial peptides (AMPs) could represent attractive candidates for the design of new antibiotics because of their specific characteristics. AMPs show a broad activity spectrum, a relative selectivity towards their targets (microbial membranes), the ability to act on both proliferative and quiescent cells, a rapid mechanism of action, and above all, a low propensity for developing resistance. This article investigates the effect at subMIC concentrations of Temporin-L (TL) on biofilm formation in Pseudomonas fluorescens (P. fluorescens) both in static and dynamic conditions, showing that TL displays antibiofilm properties. Biofilm formation in static conditions was analyzed by the Crystal Violet assay. Investigation of biofilms in dynamic conditions was performed in a commercial microfluidic device consisting of a microflow chamber to simulate real flow conditions in the human body. Biofilm morphology was examined using Confocal Laser Scanning Microscopy and quantified via image analysis. The investigation of TL effects on P. fluorescens showed that when subMIC concentrations of this peptide were added during bacterial growth, TL exerted antibiofilm activity, impairing biofilm formation both in static and dynamic conditions. Moreover, TL also affects mature biofilm as confocal microscopy analyses showed that a large portion of preformed biofilm architecture was clearly perturbed by the peptide addition with a significative decrease of all the biofilm surface properties and the overall biomass. Finally, in these conditions, TL did not affect bacterial cells as the live/dead cell ratio remained unchanged without any increase in damaged cells, confirming an actual antibiofilm activity of the peptide. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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14 pages, 2694 KiB  
Article
Surface Wiping Test to Study Biocide -Cinnamaldehyde Combination to Improve Efficiency in Surface Disinfection
by Joana F. Malheiro, Catarina Oliveira, Fernando Cagide, Fernanda Borges, Manuel Simões and Jean-Yves Maillard
Int. J. Mol. Sci. 2020, 21(21), 7852; https://doi.org/10.3390/ijms21217852 - 23 Oct 2020
Cited by 5 | Viewed by 2689
Abstract
Disinfection is crucial to control and prevent microbial pathogens on surfaces. Nonetheless, disinfectants misuse in routine disinfection has increased the concern on their impact on bacterial resistance and cross-resistance. This work aims to develop a formulation for surface disinfection based on the combination [...] Read more.
Disinfection is crucial to control and prevent microbial pathogens on surfaces. Nonetheless, disinfectants misuse in routine disinfection has increased the concern on their impact on bacterial resistance and cross-resistance. This work aims to develop a formulation for surface disinfection based on the combination of a natural product, cinnamaldehyde, and a widely used biocide, cetyltrimethylammonium bromide. The wiping method was based on the Wiperator test (ASTM E2967−15) and the efficacy evaluation of surface disinfection wipes test (EN 16615:2015). After formulation optimization, the wiping of a contaminated surface with 6.24 log10 colony-forming units (CFU) of Escherichia coli or 7.10 log10 CFU of Staphylococcus aureus led to a reduction of 4.35 log10 CFU and 4.27 log10 CFU when the wipe was impregnated with the formulation in comparison with 2.45 log10 CFU and 1.50 log10 CFU as a result of mechanical action only for E. coli and S. aureus, respectively. Furthermore, the formulation prevented the transfer of bacteria to clean surfaces. The work presented highlights the potential of a combinatorial approach of a classic biocide with a phytochemical for the development of disinfectant formulations, with the advantage of reducing the concentration of synthetic biocides, which reduces the potentially negative environmental and public health impacts from their routine use. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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Review

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24 pages, 4554 KiB  
Review
Therapeutic Potential of Antimicrobial Peptides in Polymicrobial Biofilm-Associated Infections
by Giovanna Batoni, Giuseppantonio Maisetta and Semih Esin
Int. J. Mol. Sci. 2021, 22(2), 482; https://doi.org/10.3390/ijms22020482 - 06 Jan 2021
Cited by 46 | Viewed by 6317
Abstract
It is widely recognized that many chronic infections of the human body have a polymicrobial etiology. These include diabetic foot ulcer infections, lung infections in cystic fibrosis patients, periodontitis, otitis, urinary tract infections and even a proportion of systemic infections. The treatment of [...] Read more.
It is widely recognized that many chronic infections of the human body have a polymicrobial etiology. These include diabetic foot ulcer infections, lung infections in cystic fibrosis patients, periodontitis, otitis, urinary tract infections and even a proportion of systemic infections. The treatment of mixed infections poses serious challenges in the clinic. First, polymicrobial communities of microorganisms often organize themselves as biofilms that are notoriously recalcitrant to antimicrobial therapy and clearance by the host immune system. Secondly, a plethora of interactions among community members may affect the expression of virulence factors and the susceptibility to antimicrobials of individual species in the community. Therefore, new strategies able to target multiple pathogens in mixed populations need to be urgently developed and evaluated. In this regard, antimicrobial or host defense peptides (AMPs) deserve particular attention as they are endowed with many favorable features that may serve to this end. The aim of the present review is to offer a comprehensive and updated overview of studies addressing the therapeutic potential of AMPs in mixed infections, highlighting the opportunities offered by this class of antimicrobials in the fight against polymicrobial infections, but also the limits that may arise in their use for this type of application. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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21 pages, 4545 KiB  
Review
Bio-Interactive Zwitterionic Dental Biomaterials for Improving Biofilm Resistance: Characteristics and Applications
by Utkarsh Mangal, Jae-Sung Kwon and Sung-Hwan Choi
Int. J. Mol. Sci. 2020, 21(23), 9087; https://doi.org/10.3390/ijms21239087 - 29 Nov 2020
Cited by 16 | Viewed by 2977
Abstract
Biofilms are formed on surfaces inside the oral cavity covered by the acquired pellicle and develop into a complex, dynamic, microbial environment. Oral biofilm is a causative factor of dental and periodontal diseases. Accordingly, novel materials that can resist biofilm formation have attracted [...] Read more.
Biofilms are formed on surfaces inside the oral cavity covered by the acquired pellicle and develop into a complex, dynamic, microbial environment. Oral biofilm is a causative factor of dental and periodontal diseases. Accordingly, novel materials that can resist biofilm formation have attracted significant attention. Zwitterionic polymers (ZPs) have unique features that resist protein adhesion and prevent biofilm formation while maintaining biocompatibility. Recent literature has reflected a rapid increase in the application of ZPs as coatings and additives with promising outcomes. In this review, we briefly introduce ZPs and their mechanism of antifouling action, properties of human oral biofilms, and present trends in anti-biofouling, zwitterionic, dental materials. Furthermore, we highlight the existing challenges in the standardization of biofilm research and the future of antifouling, zwitterated, dental materials. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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33 pages, 1073 KiB  
Review
Combination Therapy to Treat Fungal Biofilm-Based Infections
by Jana Tits, Bruno P. A. Cammue and Karin Thevissen
Int. J. Mol. Sci. 2020, 21(22), 8873; https://doi.org/10.3390/ijms21228873 - 23 Nov 2020
Cited by 31 | Viewed by 4312
Abstract
An increasing number of people is affected by fungal biofilm-based infections, which are resistant to the majority of currently-used antifungal drugs. Such infections are often caused by species from the genera Candida, Aspergillus or Cryptococcus. Only a few antifungal drugs, including echinocandins and [...] Read more.
An increasing number of people is affected by fungal biofilm-based infections, which are resistant to the majority of currently-used antifungal drugs. Such infections are often caused by species from the genera Candida, Aspergillus or Cryptococcus. Only a few antifungal drugs, including echinocandins and liposomal formulations of amphotericin B, are available to treat such biofilm-based fungal infections. This review discusses combination therapy as a novel antibiofilm strategy. More specifically, in vitro methods to discover new antibiofilm combinations will be discussed. Furthermore, an overview of the main modes of action of promising antibiofilm combination treatments will be provided as this knowledge may facilitate the optimization of existing antibiofilm combinations or the development of new ones with a similar mode of action. Full article
(This article belongs to the Special Issue Microbial Biofilms and Antibiofilm Agents)
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