Effective Antibiofilm Agent Research Articles

Synthesis and anti-biofilm activities of dihydro-pyrrol-2-one derivatives on Pseudomonas aeruginosa

Biofilm formation is an important reason for bacterial resistance to antimicrobials. Many compounds with dihydro-pyrrol-2-one (DPO) have antibacterial effects. It is prospective to base on DPO skeleton to design new compounds for biofilm inhibition. DPO was designed by a novel method of tandem cyclization between ethyl glyoxalate and amines, the series of DPO derivatives were synthesized by change of the amines. Their activities were evaluated by the inhibition of biofilm in Pseudomonas aeruginosa. The interaction of DPO derivatives with mannitol dehydrogenase (MDH) or extracellular DNA (eDNA) in the biofilm was simulated by molecular docking to reveal possible mechanism. 19 new DPO derivatives were synthesized and identified, 15 of them had antibacterial activities, but only 5 of them had more than 50% inhibition on biofilm of P. aeruginosa at 50μg/mL. The MDH activity and eDNA content in biofilm decreased significantly after treatment of the DPO derivatives in concentration dependence. The simulation reveals that strong interaction exists between the five DPO derivatives and MDH or eDNA, which are involved in anti-biofilm mechanism. The synthetic method of DPO derivatives is practical to provide effective anti-biofilm agents for P. aeruginosa, and they take effect through inhibition on MDH and eDNA of biofilm.

Usnic acid, a lichen secondary metabolite inhibits Group A Streptococcus biofilms.

Group A Streptococci (GAS) are involved in a number of life threatening diseases and biofilm formation by these pathogens are considered as an important virulence determinant as it mediates antibiotic resistance among them. In the present study, we have explored the ability of (+)-usnic acid, a lichen secondary metabolite, as an antibiofilm agent against four serotypes of Streptococcus pyogenes causing pharyngitis. Usnic acid inhibited the biofilms of M serotypes M56, st38, M89 efficiently and the biofilm of M74 to a lesser extent. Confocal imaging of the treated samples showed that usnic acid reduced the biomass of the biofilms when compared to that of the control. Fourier Transfer Infrared (FT-IR) spectroscopy indicated that usnic acid reduced the cellular components (proteins and fatty acids) of the biofilms. Interestingly, the FT-IR spectrum further revealed that usnic acid probably acted upon the fatty acids of the biofilms as evident from the disappearance of a peak at 2,455-2,100cm(-1) when compared to the control only in serotypes M56, st38 and M89 but not in M74. The present study shows, for the first time, that usnic acid can act as an effective antibiofilm agent against GAS.

One step green synthesis and anti-microbial and anti-biofilm properties of Psidium guajava L. leaf extract-mediated silver nanoparticles

This paper describes a single-step green synthesis of extracellular silver nanoparticles (AgNPs) through an in-situ bio-reduction of aqueous solution of silver nitrate using Psidium guajava L. UV–vis exhibits a characteristic surface plasmon resonance peak at around 487nm. XRD analysis showed crystalline and face-centered cubic geometry of synthesized AgNPs. TEM results revealed stable and spherical particles with a mean diameter size of ~60nm. Fourier transform infrared spectroscopy showed that the nanoparticles were capped with plant bioactive molecules. Phytosynthesized AgNPs showed broad-spectrum anti-microbial activity against Gram-positive, Gram-negative human pathogenic bacteria, and fungi. AgNPs showed prominent ability to inhibit the biofilms formed by Staphylococcus aureus, Escherichia coli and Candida albicans in a laboratory condition through crystal violet assay. The results suggest AgNPs as a promising candidate for the design of an effective antimicrobial and anti-biofilm agent in biomedical field.

Silver–titanium dioxide nanocomposites as effective antimicrobial and antibiofilm agents

Ag–TiO2 nanocomposites were successfully developed from colloidal suspensions containing 750 or 1,500 ppm silver nanoparticles (AgNPs) deposited on 5 % (w/v) titanium dioxide nanoparticles (TiO2NPs) by a chemical reduction approach. The nanocomposites were characterized by diffuse reflectance UV–Vis spectroscopy (DRS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) and dynamic light scattering (DLS). DRS spectra showed an absorption band in visible region with maximum absorbance peaks at 452 and 444 nm attributed to AgNPs plasmon peaks, indicating the formation of small spherical or quasi-spherical Ag nanocrystals in nanocomposites. TEM and SEM analysis proved a nearly spherical morphology of particles (15–30 ± 5 nm average size in diameter). EDX analysis revealed the presence of Ti, O, and Ag in both nanocomposite powders having 1.37 or 2.34 wt% Ag content. DLS analysis yielded a bimodal particle size distribution in a narrow range (31.3 ± 0.5 or 23.4 ± 0.4 nm average particle diameter) and a good polydispersity (0.247 or 0.293 polydispersity index). The nanocomposites were screened for their in vitro antimicrobial activity against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) bacterial and fungal (Candida albicans) reference and clinical strains, in planktonic and adherent state, by qualitative and quantitative assays. The antibacterial activity increased with the increasing AgNPs content, being more intensive for Gram-positive bacteria. Both Ag–TiO2 nanocomposites exhibited a high antibiofilm activity. The obtained results recommend the use of the developed nanocomposites as antimicrobial and antibiofilm agents in practical applications without UV irradiation. The most effective agent proved to be the one with 2.34 wt% AgNPs content.

Inhibitory and Disruptive Effects of Shiitake Mushroom (Lentinula edodes) Essential Oil Extract on Oral Biofilms

Background: The search on natural plant compounds revealed that those compounds can be used for the elimination of oral biofilms as a substitute of current chemical based treatments and is becoming of increasing interest. Objectives: The objective of this study was to investigate the biofilm inhibitory effect and disruptive efficacy of Shiitake mushroom (Lentinula edodes) extracts. Materials and Methods: Essential oils were extracted by hydrodistillation and the components were analyzed by gas chromatography mass-spectroscopy. Biofilm assessments were carried out on four oral pathogens and a mixed culture containing Streptococcus mutans, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. Minimum inhibitory concentrations (MIC), minimum bactericidal concentration (MBC) were determined on planktonic cells and crystal violet assays performed to assess the biofilm inhibition and disruption amount. Results: No inhibitory effect was observed on F. nucleatum biofilms (P > 0.05). Significant disruptive properties on A. actinomycetemcomitans at values lower than the MIC (3.90 µg/mL) was detected (P < 0.05). Shiitake mushroom oil had significant inhibitory and disruptive effects on P. gingivalis (P < 0.05). Furthermore, S. mutans and multispecies biofilms were inhibited at the same concentrations (15.60 - 32.25 µg/mL). Conclusions: Shiitake essential oil is an effective anti-bacterial and anti-biofilm agent on important oral pathogens and has a possible therapeutic potential as an oral anti-biofilm agent.

Melanin mediated synthesis of gold nanoparticles by Yarrowia lipolytica

Yarrowia lipolytica is known to synthesize cell-associated gold nanoparticles. Melanin, a pigment associated with the yeast, was identified as a factor responsible for nanoparticle synthesis. Cell-extracted melanin as well as that induced by incubating cells with 3,4-dihydroxy- l-phenylalanine (l-DOPA) mediated the synthesis of gold nanoparticles (AuNPs). These nanoparticles were characterized by a variety of standard techniques. This report identifies one of the molecular mechanisms involved in nanoparticle synthesis by Y. lipolytica. The nanoparticles thus synthesized were effective antibiofilm agents.

Antimicrobial activity of nanoemulsion on cariogenic planktonic and biofilm organisms

IntroductionNanoemulsions (NE) are a unique class of disinfectants produced by mixing a water immiscible liquid phase into an aqueous phase under high shear forces. NE have antimicrobial properties and are also effective anti-biofilm agents. Materials and methodsThe effectiveness of nanoemulsion and its components was determined against Streptococcus mutans and Lactobacillus casei by live/dead staining. In vitro antimicrobial effectiveness of nanoemulsion against planktonic S. mutans, L. casei, Actinomyces viscosus, Candida albicans and mixed culture was determined by a serial dilution technique to obtain minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC). In addition, efficacy was investigated by kinetics of killing, adherence and biofilm assays. ResultsCompared to its components, nanoemulsion showed notable antimicrobial activity against biofilm organisms, up to 83.0% kill within 1min. NE dilutions ranging from 243 to 19683 were effective against planktonic S. mutans, L. casei, A. viscosus, C. albicans and mixed culture of these four strains as shown through MIC/MBC assays. NE showed antimicrobial activity against planktonic cells at high dilutions, confirmed by time kill studies. The level of adhesion on glass surface was reduced by 94.2–99.5% in nanoemulsion treated groups (p<0.001). 4-Day-old S. mutans, L. casei, A. viscosus, C. albicans and mixed cultures biofilms treated with NE showed reductions of bacterial counts with decreasing dilutions (p<0.001). ConclusionThese results suggest that nanoemulsion has effective anti-cariogenic activity against cariogenic microorganisms and may be a useful medication in the prevention of caries.

The activity of silver against Escherichia coli biofilm is increased by a lipopeptide biosurfactant

Biological contamination of surfaces, both in industry and in health care, plays an important role as a potential vector of disease transmission. Metals have been described to be effective antibiofilm agents, and the efficacy of silver ions as a disinfectant has been known for centuries. The activity of AgNO3 combined with the lipopeptide biosurfactant V9T14 has been studied against a preformed Escherichia coli biofilm on the Calgary Biofilm Device. Results indicated that the activity of silver can be synergistically enhanced by the presence of V9T14, both allowing for a reduction in the quantity of silver used and for greater antimicrobial activity. The concentration of silver needed to obtain this reduction in the silver-biosurfactant solution was from 129- to 258-fold less than the concentration of silver alone. To our knowledge, this is the first time that a synergistic interaction between a lipopeptide biosurfactant and silver has been observed.

Antimicrobial effects of a microemulsion and a nanoemulsion on enteric and other pathogens and biofilms

Some microemulsions and nanoemulsions may have antimicrobial properties and be effective anti-biofilm agents. We examined the abilities of two fine emulsions, designated BCTP and TEOP, to inactivate suspensions of vegetative cells of Salmonella spp. Escherichia coli 0157:H7 (VT-), Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes. BCTP is an O/W nanoemulsion of soybean oil and tri- n-butyl phosphate emulsified with Triton X-100, while TEOP is an O/W microemulsion of ethyl oleate with Tween 80 as emulsifier and n-pentanol as a co-emulsifier. BCTP was effective in reducing the cell numbers of L. monocytogenes, while TEOP was effective against all five organisms investigated. The abilities of these emulsions to reduce preformed biofilms of the five bacteria were also investigated. With the exception of the biofilm formed by L. monocytogenes, which surprisingly was not significantly affected by BCTP, all biofilms were inhibited by both BCTP and TEOP.

Microemulsions are highly effective anti-biofilm agents.

The demonstration of the antibiofilm effects of pharmaceutical microemulsions. Microemulsions were prepared as physically stable oil/water systems. Previous work by this group has shown that microemulsions are highly effective antimembrane agents that result in rapid losses of viability in planktonic populations of Pseudomonas aeruginosa and Staphylococcus aureus. In this experiment a microemulsion preparation was used upon established biofilm cultures of Ps. aeruginosa PA01 for a period of 4 h. The planktonic MIC of sodium pyrithione and the planktonic and biofilm MICs of cetrimide were used as positive controls and a biofilm was exposed to a volume of normal sterile saline as a treatment (negative) control. Results indicate three log-cycle reductions in viability within the microemulsion treated biofilm, as compared to those observed in control treatments of similar biofilms (one log-cycle reduction in viabilities). The results indicate that the microemulsions are highly effective antibiofilm agents. This study suggests that microemulsions may have a role in the treatment of industrial and environmental biofilms.