α,α-disubstituted β-amino amides eliminate biofilms by membrane disruption and biomass removal.

Bacterial biofilms account for up to 80% of all infections and complicate successful therapies due to their intrinsic tolerance to antibiotics. Biofilms also cause serious problems in the industrial sectors, for instance due to the deterioration of metals or microbial contamination of products. Efforts are put in finding novel strategies in both avoiding and fighting biofilms.

Antibacterial and antibiofilm activity of permanently ionized quaternary ammonium fluoroquinolones.

A series of quaternary ammonium fluoroquinolones was obtained by exhaustive methylation of the amine groups present at the 7-position of fluoroquinolones, including ciprofloxacin, enoxacin, gatifloxacin, lomefloxacin, and norfloxacin. The synthesized molecules were tested for their antibacterial and antibiofilm activities against Gram-positive and Gram-negative human pathogens, i.e.

Food-Grade Bacteria Combat Pathogens by Blocking AHL-Mediated Quorum Sensing and Biofilm Formation.

Disrupting bacterial quorum sensing (QS) signaling is a promising strategy to combat pathogenic biofilms without the development of antibiotic resistance. Here, we report that food-associated bacteria can interfere with the biofilm formation of a Gram-negative pathogenic bacterium by targeting its AHL (acyl-homoserine lactone) QS system. This was demonstrated by screening metabolic end-products of different lactobacilli and propionibacteria using Gram-negative and biofilm-forming as the QS reporter and our anti-QS microscale screening platform with necessary modifications.

Screening of natural compounds identifies ferutinin as an antibacterial and anti-biofilm compound.

Antibacterial screenings are most commonly targeted at planktonic bacteria but less effort is dedicated to the exploration of agents acting on biofilms. Here, a natural compounds library was screened against using a 384-well plate platform to identify compounds preventing biofilm formation. Five structurally diverse hits were selected for follow-up studies: honokiol, tschimganidin, ferutinin, oridonin and deoxyshikonin.

Synthesis and Biological Evaluation of Fingolimod Derivatives as Antibacterial Agents.

We recently identified fingolimod as a potent antibiofilm compound by screening FDA-approved drugs. To study if the antibacterial activity of fingolimod could be further improved and to explore in-depth structure-activity relationships, we synthesized 28 novel fingolimod derivatives and evaluated their efficacy against grown in planktonic/single cell and biofilms. The most effective derivatives were tested on preformed biofilms and against Gram-negative bacteria and , using fingolimod as the reference compound.

Surfaceome and Exoproteome Dynamics in Dual-Species and Biofilms.

Bacterial biofilms are an important underlying cause for chronic infections. By switching into the biofilm state, bacteria can evade host defenses and withstand antibiotic chemotherapy. Despite the fact that biofilms at clinical and environmental settings are mostly composed of multiple microbial species, biofilm research has largely been focused on single-species biofilms.

Surface-Shaving Proteomics of Mycobacterium marinum Identifies Biofilm Subtype-Specific Changes Affecting Virulence, Tolerance, and Persistence.

The complex cell wall and biofilm matrix (ECM) act as key barriers to antibiotics in mycobacteria. Here, the ECM and envelope proteins of Mycobacterium marinum ATCC 927, a nontuberculous mycobacterial model, were monitored over 3 months by label-free proteomics and compared with cell surface proteins on planktonic cells to uncover pathways leading to virulence, tolerance, and persistence. We show that ATCC 927 forms pellicle-type and submerged-type biofilms (PBFs and SBFs, respectively) after 2 weeks and 2 days of growth, respectively, and that the increased CelA1 synthesis in this strain prevents biofilm formation and leads to reduced rifampicin tolerance.

Multisubstituted pyrimidines effectively inhibit bacterial growth and biofilm formation of Staphylococcus aureus.

Biofilms are multicellular communities of microorganisms that generally attach to surfaces in a self-produced matrix. Unlike planktonic cells, biofilms can withstand conventional antibiotics, causing significant challenges in the healthcare system. Currently, new chemical entities are urgently needed to develop novel anti-biofilm agents.

Screening of FDA-Approved Drugs Using a 384-Well Plate-Based Biofilm Platform: The Case of Fingolimod.

In an effort to find new repurposed antibacterial compounds, we performed the screening of an FDA-approved compounds library against American Type Culture Collection (ATCC) 25923. Compounds were evaluated for their capacity to prevent both planktonic growth and biofilm formation as well as to disrupt pre-formed biofilms. One of the identified initial hits was fingolimod (FTY720), an immunomodulator approved for the treatment of multiple sclerosis, which was then selected for follow-up studies.

Combined Effect of Naturally-Derived Biofilm Inhibitors and Differentiated HL-60 Cells in the Prevention of Biofilm Formation.

Nosocomial diseases represent a huge health and economic burden. A significant portion is associated with the use of medical devices, with 80% of these infections being caused by a bacterial biofilm. The insertion of a foreign material usually elicits inflammation, which can result in hampered antimicrobial capacity of the host immunity due to the effort of immune cells being directed to degrade the material.

Chloroquine fumardiamides as novel quorum sensing inhibitors.

Quorum sensing inhibitors (QSIs) that specifically interfere with bacterial cell-to-cell communication are considered as an alternative approach to conventional antibacterial therapy. In our study, a set of twenty-six fumardiamides with a quinoline head-group were evaluated as potential QSIs. Two strains of Gram-negative Chromobacterium violaceum (violacein-producing strain ATCC31532 and violacein-negative, mini-Tn5 mutant derivative CV026) were used as QS reporters for testing anti-QS and bactericidal activity of various quinoline fumardiamides.

Optimization of a High-Throughput 384-Well Plate-Based Screening Platform with ATCC 25923 and ATCC 15442 Biofilms.

In recent years, bacterial infections have become a main concern following the spread of antimicrobial resistance. In addition, bacterial biofilms are known for their high tolerance to antimicrobials and they are regarded as a main cause of recalcitrant infections in humans. Many efforts have been deployed in order to find new antibacterial therapeutic options and the high-throughput screening (HTS) of large libraries of compounds is one of the utilized strategies.

Strategies to Prevent Biofilm Infections on Biomaterials: Effect of Novel Naturally-Derived Biofilm Inhibitors on a Competitive Colonization Model of Titanium by and SaOS-2 Cells.

Biofilm-mediated infection is a major cause of bone prosthesis failure. The lack of molecules able to act in biofilms has driven research aimed at identifying new anti-biofilm agents via chemical screens. However, to be able to accommodate a large number of compounds, the testing conditions of these screenings end up being typically far from the clinical scenario.

Growth Mode and Physiological State of Cells Prior to Biofilm Formation Affect Immune Evasion and Persistence of .

The present study investigated ATCC25923 surfaceomes (cell surface proteins) during prolonged growth by subjecting planktonic and biofilm cultures (initiated from exponential or stationary cells) to label-free quantitative surfaceomics and phenotypic confirmations. The abundance of adhesion, autolytic, hemolytic, and lipolytic proteins decreased over time in both growth modes, while an opposite trend was detected for many tricarboxylic acid (TCA) cycle, reactive oxygen species (ROS) scavenging, Fe-S repair, and peptidolytic moonlighters. In planktonic cells, these changes were accompanied by decreasing and increasing adherence to hydrophobic surface and fibronectin, respectively.

Structural and Functional Dynamics of Biofilms and Biofilm Matrix Proteins on Different Clinical Materials.

Medical device-associated staphylococcal infections are a common and challenging problem. However, detailed knowledge of staphylococcal biofilm dynamics on clinically relevant surfaces is still limited. In the present study, biofilm formation of the ATCC 25923 strain was studied on clinically relevant materials-borosilicate glass, plexiglass, hydroxyapatite, titanium and polystyrene-at 18, 42 and 66 h.

Minimum information guideline for spectrophotometric and fluorometric methods to assess biofilm formation in microplates.

The lack of reproducibility of published studies is one of the major issues facing the scientific community, and the field of biofilm microbiology has been no exception. One effective strategy against this multifaceted problem is the use of minimum information guidelines. This strategy provides a guide for authors and reviewers on the necessary information that a manuscript should include for the experiments in a study to be clearly interpreted and independently reproduced.

Azithromycin-liposomes as a novel approach for localized therapy of cervicovaginal bacterial infections.

Background: Efficient localized cervicovaginal antibacterial therapy, enabling the delivery of antibiotic to the site of action at lower doses while escaping systemic drug effects and reducing the risk of developing microbial resistance, is attracting considerable attention. Liposomes have been shown to allow sustained drug release into vaginal mucosa and improve delivery of antibiotics to bacterial cells and biofilms. Azithromycin (AZI), a potent broad-spectrum macrolide antibiotic, has not yet been investigated for localized therapy of cervicovaginal infections, although it is administered orally for the treatment of sexually transmitted diseases.

Insight into the antimicrobial mechanism of action of β-amino acid derivatives from molecular dynamics simulation: Dancing the can-can at the membrane surface.

The development of antimicrobial agents that target and selectively disrupt biofilms is a pressing issue since, so far, no antibiotics have been developed that achieve this effectively. Previous experimental work has found a promising set of antibacterial peptides: β-amino acid derivatives, relatively small molecules with common structural elements composed of a polar head group and two non-polar hydrocarbon arms. In order to develop insight into possible mechanisms of action of these novel antibacterial agents, we have performed an in silico investigation of four leading β-amino acid derivatives, interacting with models of both bacterial (target) and eukaryotic (host) membranes, using molecular dynamics simulation with a model with all-atom resolution.

Synthesis and biological evaluation of hybrid quinolone-based quaternary ammonium antibacterial agents.

A series of novel fluoroquinolone-Safirinium dye hybrids was synthesized by means of tandem Mannich-electrophilic amination reactions from profluorophoric isoxazolones and antibiotics bearing a secondary amino group at position 7 of the quinoline ring. The obtained fluorescent spiro fused conjugates incorporating quaternary nitrogen atoms were characterized by H NMR, IR, MS, and elemental analysis. All the synthetic analogues (3a-h and 4a-h) were evaluated for their in vitro antimicrobial, bactericidal, and antibiofilm activities against a panel of Gram positive and Gram-negative pathogenic bacteria.

Growth Mode and Carbon Source Impact the Surfaceome Dynamics of GG.

Bacterial biofilms have clear implications in disease and in food applications involving probiotics. Here, we show that switching the carbohydrate source from glucose to fructose increased the biofilm formation and the total surface-antigenicity of a well-known probiotic, GG. Surfaceomes (all cell surface-associated proteins) of GG cells grown with glucose and fructose in planktonic and biofilm cultures were identified and compared, which indicated carbohydrate source-dependent variations, especially during biofilm growth.

Screening of Natural Product Derivatives Identifies Two Structurally Related Flavonoids as Potent Quorum Sensing Inhibitors against Gram-Negative Bacteria.

Owing to the failure of conventional antibiotics in biofilm control, alternative approaches are urgently needed. Inhibition of quorum sensing (QS) represents an attractive target since it is involved in several processes essential for biofilm formation. In this study, a compound library of natural product derivatives ( = 3040) was screened for anti-quorum sensing activity using as reporter bacteria.