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Molecular Mechanism of Biofilm Infections and the Combat Strategies

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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 June 2023) | Viewed by 13081

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Dr. Honghua Hu

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Guest Editor

Surgical Infection Research Group, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney 2109, Australia
Interests: biofilms; decontamination; disinfection; medical devices; infection control; chronic infection
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Special Issue Information

Dear Colleagues,

Microbial biofilms are the most important drivers of chronic and recurrent infections. Biofilms are associated with more than 80% of persistent infectious diseases such as surgical implant infections, chronic wound infections, diabetic foot infections, periodontitis, chronic sinusitis, recurrent urinary tract infections, endocarditis, and chronic bronchitis pneumonia. The resistance of microbial cells in biofilms to the host immune system, antibiotics and antimicrobial agents has increased hundreds of times compared to the same cells in a planktonic state.

The microbial biofilm community causing chronic infections could be a single species or multiple species; could be bacteria, viruses, yeast and fungi, or a mix of bacteria, viruses, yeast and fungi.

Despite their clinical and scientific importance, the mechanisms of biofilm infections are still poorly understood, and the diagnosis and treatment of biofilm infections are still a challenge.

This special research topic aims to better understand the molecular basis of biofilm infections, the microbial community and their virulence and pathogenicity of biofilms, host–pathogen interactions in biofilm infections and to facilitate early intervention and targeted therapeutic strategies to combat biofilm infections.

This research topic will cover but is not limited to the following aspects:

Microbial community/diversity of biofilm infections;
Microbial interaction in biofilm infections;
Host–pathogen interaction in biofilm infections;
Molecular mechanism/basis/insight of biofilm infections;
Virulence factors;
Pathogenicity;
Antibiotic resistance;
Antibiofilm agents;
Strategies/practices/technologies for prevention, identification, and combat biofilm infections.

Dr. Honghua Hu
Guest Editor

Manuscript Submission Information

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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. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. 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 infection
molecular mechanism
antibiofilm agent
prevent biofilm infections
identify biofilm infections
combat biofilm infections

Published Papers (6 papers)

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Research

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26 pages, 5851 KiB

Open AccessArticle

Anti-Bacterial and Anti-Biofilm Activities of Anandamide against the Cariogenic Streptococcus mutans

by Goldie Wolfson, Ronit Vogt Sionov, Reem Smoum, Maya Korem, Itzhack Polacheck and Doron Steinberg

Int. J. Mol. Sci. 2023, 24(7), 6177; https://doi.org/10.3390/ijms24076177 - 24 Mar 2023

Cited by 2 | Viewed by 2254

Abstract

Streptococcus mutans is a cariogenic bacterium in the oral cavity involved in plaque formation and dental caries. The endocannabinoid anandamide (AEA), a naturally occurring bioactive lipid, has been shown to have anti-bacterial and anti-biofilm activities against Staphylococcus aureus. We aimed here to study its effects on S. mutans viability, biofilm formation and extracellular polysaccharide substance (EPS) production. S. mutans were cultivated in the absence or presence of various concentrations of AEA, and the planktonic growth was followed by changes in optical density (OD) and colony-forming units (CFU). The resulting biofilms were examined by MTT metabolic assay, Crystal Violet (CV) staining, spinning disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM). The EPS production was determined by Congo Red and fluorescent dextran staining. Membrane potential and membrane permeability were determined by diethyloxacarbocyanine iodide (DiOC2(3)) and SYTO 9/propidium iodide (PI) staining, respectively, using flow cytometry. We observed that AEA was bactericidal to S. mutans at 12.5 µg/mL and prevented biofilm formation at the same concentration. AEA reduced the biofilm thickness and biomass with concomitant reduction in total EPS production, although there was a net increase in EPS per bacterium. Preformed biofilms were significantly affected at 50 µg/mL AEA. We further show that AEA increased the membrane permeability and induced membrane hyperpolarization of these bacteria. AEA caused S. mutans to become elongated at the minimum inhibitory concentration (MIC). Gene expression studies showed a significant increase in the cell division gene ftsZ. The concentrations of AEA needed for the anti-bacterial effects were below the cytotoxic concentration for normal Vero epithelial cells. Altogether, our data show that AEA has anti-bacterial and anti-biofilm activities against S. mutans and may have a potential role in preventing biofilms as a therapeutic measure. Full article

(This article belongs to the Special Issue Molecular Mechanism of Biofilm Infections and the Combat Strategies)

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16 pages, 7318 KiB

Open AccessArticle

Staphylococcus aureus Cell Wall Phenotypic Changes Associated with Biofilm Maturation and Water Availability: A Key Contributing Factor for Chlorine Resistance

by Farhana Parvin, Md. Arifur Rahman, Anand K. Deva, Karen Vickery and Honghua Hu

Int. J. Mol. Sci. 2023, 24(5), 4983; https://doi.org/10.3390/ijms24054983 - 05 Mar 2023

Cited by 3 | Viewed by 1968

Abstract

Staphylococcus aureus biofilms are resistant to both antibiotics and disinfectants. As Staphylococci cell walls are an important defence mechanism, we sought to examine changes to the bacterial cell wall under different growth conditions. Cell walls of S. aureus grown as 3-day hydrated biofilm, 12-day hydrated biofilm, and 12-day dry surface biofilm (DSB) were compared to cell walls of planktonic organisms. Additionally, proteomic analysis using high-throughput tandem mass tag-based mass spectrometry was performed. Proteins involved in cell wall synthesis in biofilms were upregulated in comparison to planktonic growth. Bacterial cell wall width (measured by transmission electron microscopy) and peptidoglycan production (detected using a silkworm larva plasma system) increased with biofilm culture duration (p < 0.001) and dehydration (p = 0.002). Similarly, disinfectant tolerance was greatest in DSB, followed by 12-day hydrated biofilm and then 3-day biofilm, and it was least in the planktonic bacteria––suggesting that changes to the cell wall may be a key factor for S. aureus biofilm biocide resistance. Our findings shed light on possible new targets to combat biofilm-related infections and hospital dry surface biofilms. Full article

(This article belongs to the Special Issue Molecular Mechanism of Biofilm Infections and the Combat Strategies)

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19 pages, 3098 KiB

Open AccessArticle

Activity of Novel Ultrashort Cyclic Lipopeptides against Biofilm of Candida albicans Isolated from VVC in the Ex Vivo Animal Vaginal Model and BioFlux Biofilm Model—A Pilot Study

by Paulina Czechowicz, Joanna Nowicka, Damian Neubauer, Grzegorz Chodaczek, Paweł Krzyżek and Grażyna Gościniak

Int. J. Mol. Sci. 2022, 23(22), 14453; https://doi.org/10.3390/ijms232214453 - 21 Nov 2022

Cited by 2 | Viewed by 1628

Abstract

In recent years, clinicians and doctors have become increasingly interested in fungal infections, including those affecting the mucous membranes. Vulvovaginal candidiasis (VVC) is no exception. The etiology of this infection remains unexplained to this day, as well as the role and significance of asymptomatic vaginal Candida colonization. There are also indications that in the case of VVC, standard methods of determining drug susceptibility to antifungal drugs may not have a real impact on their clinical effectiveness—which would explain, among other things, treatment failures and relapse rates. The aim of the study was to verify the promising results obtained previously in vitro using standard methods, in a newly developed ex vivo model, using tissue fragments of the mouse vagina. The main goal of the study was to determine whether the selected ultrashort cyclic lipopeptides (USCLs) and their combinations with fluconazole at specific concentrations are equally effective against Candida forming a biofilm directly on the surface of the vaginal epithelium. In addition, the verification was also performed with the use of another model for the study of microorganisms (biofilms) in vitro—the BioFlux system, under microfluidic conditions. The obtained results indicate the ineffectiveness of the tested substances ex vivo at concentrations eradicating biofilm in vitro. Nevertheless, the relatively most favorable and promising results were still obtained in the case of combination therapy—a combination of low concentrations of lipopeptides (mainly linear analogs) with mycostatic fluconazole. Additionally, using BioFlux, it was not possible to confirm the previously obtained results. However, an inhibiting effect of the tested lipopeptides on the development of biofilm under microfluidic conditions was demonstrated. There is an incompatibility between the classic in vitro methods, the newer BioFlux method of biofilm testing, offering many advantages postulated elsewhere, and the ex vivo method. This incompatibility is another argument for the need, on the one hand, to intensify research on the pathomechanism of VVC, and, on the other hand, to verify and maybe modify the standard methods used in the determination of Candida susceptibility. Full article

(This article belongs to the Special Issue Molecular Mechanism of Biofilm Infections and the Combat Strategies)

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17 pages, 2081 KiB

Open AccessArticle

One Step Forward with Dry Surface Biofilm (DSB) of Staphylococcus aureus: TMT-Based Quantitative Proteomic Analysis Reveals Proteomic Shifts between DSB and Hydrated Biofilm

by Md. Arifur Rahman, Ardeshir Amirkhani, Farhana Parvin, Durdana Chowdhury, Mark P. Molloy, Anand Kumar Deva, Karen Vickery and Honghua Hu

Int. J. Mol. Sci. 2022, 23(20), 12238; https://doi.org/10.3390/ijms232012238 - 13 Oct 2022

Cited by 3 | Viewed by 2014

Abstract

The Gram-positive bacterium Staphylococcus aureus is responsible for serious acute and chronic infections worldwide and is well-known for its biofilm formation ability. Recent findings of biofilms on dry hospital surfaces emphasise the failures in current cleaning practices and disinfection and the difficulty in removing these dry surface biofilms (DSBs). Many aspects of the formation of complex DSB biology on environmental surfaces in healthcare settings remains limited. In the present study, we aimed to determine how the protein component varied between DSBs and traditional hydrated biofilm. To do this, biofilms were grown in tryptic soy broth (TSB) on removable polycarbonate coupons in the CDC biofilm reactor over 12 days. Hydrated biofilm (50% TSB for 48 h, the media was then changed every 48 h with 20% TSB, at 37 °C with 130 rpm). DSB biofilm was produced in 5% TSB for 48 h at 35 °C followed by extended periods of dehydration (48, 66, 42 and 66 h at room temperature) interspersed with 6 h of 5% TSB at 35 °C. Then, we constructed a comprehensive reference map of 12-day DSB and 12-day hydrated biofilm associated proteins of S. aureus using a high-throughput tandem mass tag (TMT)-based mass spectrometry. Further pathway analysis of significantly differentially expressed identified proteins revealed that proteins significantly upregulated in 12-day DSB include PTS glucose transporter subunit IIBC (PtaA), UDP-N-acetylmuramate-L-alanine ligase (MurC) and UDP-N-acetylenolpyruvoylglucosamine (MurB) compared to 12-day hydrated biofilm. These three proteins are all linked with peptidoglycan biosynthesis pathway and are responsible for cell-wall formation and thicker EPS matrix deposition. Increased cell-wall formation may contribute to the persistence of DSB on dry surfaces. In contrast, proteins associated with energy metabolisms such as phosphoribosyl transferase (PyrR), glucosamine--fructose-6-phosphate aminotransferase (GlmS), galactose-6-phosphate isomerase (LacA), and argininosuccinate synthase (ArgG) were significantly upregulated whereas ribosomal and ABC transporters were significantly downregulated in the 12-day hydrated biofilm compared to DSB. However, validation by qPCR analysis showed that the levels of gene expression identified were only partially in line with our TMT-MS quantitation analysis. For the first time, a TMT-based proteomics study with DSB has shed novel insights and provided a basis for the identification and study of significant pathways vital for biofilm biology in this reference microorganism. Full article

(This article belongs to the Special Issue Molecular Mechanism of Biofilm Infections and the Combat Strategies)

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Review

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19 pages, 3179 KiB

Open AccessReview

An Overview of the Factors Involved in Biofilm Production by the Enterococcus Genus

by Pavel Șchiopu, Dan Alexandru Toc, Ioana Alina Colosi, Carmen Costache, Giuseppe Ruospo, George Berar, Ștefan-Gabriel Gălbău, Alexandra Cristina Ghilea, Alexandru Botan, Adrian-Gabriel Pană, Vlad Sever Neculicioiu and Doina Adina Todea

Int. J. Mol. Sci. 2023, 24(14), 11577; https://doi.org/10.3390/ijms241411577 - 18 Jul 2023

Cited by 4 | Viewed by 1916

Abstract

Enterococcus species are known for their ability to form biofilms, which contributes to their survival in extreme environments and involvement in persistent bacterial infections, especially in the case of multi-drug-resistant strains. This review aims to provide a comprehensive understanding of the mechanisms underlying biofilm formation in clinically important species such as Enterococcus faecalis and the less studied but increasingly multi-drug-resistant Enterococcus faecium, and explores potential strategies for their eradication. Biofilm formation in Enterococcus involves a complex interplay of genes and virulence factors, including gelatinase, cytolysin, Secreted antigen A, pili, microbial surface components that recognize adhesive matrix molecules (MSCRAMMs), and DNA release. Quorum sensing, a process of intercellular communication, mediated by peptide pheromones such as Cob, Ccf, and Cpd, plays a crucial role in coordinating biofilm development by targeting gene expression and regulation. Additionally, the regulation of extracellular DNA (eDNA) release has emerged as a fundamental component in biofilm formation. In E. faecalis, the autolysin N-acetylglucosaminidase and proteases such as gelatinase and serin protease are key players in this process, influencing biofilm development and virulence. Targeting eDNA may offer a promising avenue for intervention in biofilm-producing E. faecalis infections. Overall, gaining insights into the intricate mechanisms of biofilm formation in Enterococcus may provide directions for anti-biofilm therapeutic research, with the purpose of reducing the burden of Enterococcus-associated infections. Full article

(This article belongs to the Special Issue Molecular Mechanism of Biofilm Infections and the Combat Strategies)

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20 pages, 2258 KiB

Open AccessReview

How Three Self-Secreted Biofilm Exopolysaccharides of Pseudomonas aeruginosa, Psl, Pel, and Alginate, Can Each Be Exploited for Antibiotic Adjuvant Effects in Cystic Fibrosis Lung Infection

by Jonathan Chung, Shafinaz Eisha, Subin Park, Amanda J. Morris and Isaac Martin

Int. J. Mol. Sci. 2023, 24(10), 8709; https://doi.org/10.3390/ijms24108709 - 13 May 2023

Cited by 5 | Viewed by 2592

Abstract

In cystic fibrosis (CF), pulmonary infection with Pseudomonas aeruginosa is a cause of increased morbidity and mortality, especially in patients for whom infection becomes chronic and there is reliance on long-term suppressive therapies. Current antimicrobials, though varied mechanistically and by mode of delivery, are inadequate not only due to their failure to eradicate infection but also because they do not halt the progression of lung function decline over time. One of the reasons for this failure is thought to be the biofilm mode of growth of P. aeruginosa, wherein self-secreted exopolysaccharides (EPSs) provide physical protection against antibiotics and an array of niches with resulting metabolic and phenotypic heterogeneity. The three biofilm-associated EPSs secreted by P. aeruginosa (alginate, Psl, and Pel) are each under investigation and are being exploited in ways that potentiate antibiotics. In this review, we describe the development and structure of P. aeruginosa biofilms before examining each EPS as a potential therapeutic target for combating pulmonary infection with P. aeruginosa in CF, with a particular focus on the current evidence for these emerging therapies and barriers to bringing these therapies into clinic. Full article

(This article belongs to the Special Issue Molecular Mechanism of Biofilm Infections and the Combat Strategies)

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