Microbial Biofilm Formation Research Articles

Antibiofilm efficacy of Leuconostoc mesenteroides J.27-derived postbiotic and food-grade essential oils against Vibrio parahaemolyticus, Pseudomonas aeruginosa, and Escherichia coli alone and in combination, and their application as a green preservative in the seafood industry

Foodborne pathogen-mediated biofilms in food processing environments are severe threats to human lives. In the interest of human and environmental safety, natural substances with antimicrobial properties and generally regarded as safe (GRAS) status are the futuristic disinfectants of the food industry. In this study, the efficacy of bioactive, soluble products (metabolic by-products) from lactic acid bacteria (LAB) and plant-derived essential oils (EO) were investigated as biocidal agents. The postbiotic produced by kimchi-derived Leuconostoc mesenteroides J.27 isolate was analyzed for its metabolic components to reveal its antimicrobial potential against three pathogenic microorganisms (Vibrio parahaemolyticus, Pseudomonas aeruginosa, and Escherichia coli). Additionally, the efficacy of food-grade EO (eugenol and thymol, respectively) was also assessed in our study. Determination of the minimum inhibitory concentration (MIC) of postbiotic and EO against three tested pathogens revealed that the sub-MIC (0.5 MIC) of postbiotic and EO could efficiently inhibit the biofilm formation on both seafood (squid) and seafood-processing surfaces (rubber and low-density polyethylene plastic). Moreover, the polymerase chain reaction (PCR) analysis confirmed that the LAB J.27 isolate possesses bacteriocin- and enzyme-coding genes. The residual antibacterial activity of the produced postbiotic was maintained over a diverse pH range (pH 1–6) but was entirely abolished at neutral or higher pH values. However, the activity was unaffected by exposure to high temperatures (100 and 121 °C) and storage (30 days). Notably, the leakage of intracellular metabolites, damage to DNA, and the down-regulation of biofilm-associated gene expression in the pathogens increased significantly (p > 0.05) following the combination treatment of postbiotic with thymol compared to postbiotic with eugenol. Nonetheless, all in vitro results indicated the prospective use of combining Leu. mesenteroides J.27-derived postbiotic with both EO as a “green preservative” in the seafood industry to inhibit the formation of pathogenic microbial biofilms.

Effectiveness of Chitosan Coating Catheter in Preventing Catheter- Associated Urinary Tract Infection (CAUTI)

Catheter-associated urinary tract infection (CAUTI) is a serious health issue that develops in hospitalized patients. The number of CAUTI cases could be reduced by preventing microbial adhesion and biofilm formation. Chitosan demonstrates antimicrobial activity against a variety of microorganisms. Coating the surfaces of silicon catheters has been shown to minimize or prevent bacterial adhesion and biofilm formation. In this study, we investigated the efficacy of chitosan, in different molecular sizes, as a polymer-coated silicon catheter. Chitosan of a high (HMw), medium (MMw), and low (LMw) molecular weight, at a pH value of 5.0-6.0, used to coat catheters, was examined using two methods, namely the crystal violet and sonication methods. The first method showed that clinical Klebsiella pneumoniae had a significantly (p<0.05) lower level of bacterial adhesion with MMw chitosan, and Klebsiella pneumoniae ATCC 13883 with LMw of chitosan. Using the sonication method, the MMw chitosan showed a decrease in bacterial viability for the Escherichia coli clinical isolate, Klebsiella pneumoniae reference strain, and Escherichia coli reference strain at to a greater extent than the HMw and LMw. Chitosan with three molecular weights (Mw) showed some antibacterial activity when the time-kill assay was applied. However, overall, HMw chitosan grades were not found to be effective as an antibacterial coating agent, although the MMw and LMw presented a potential antiadhesive polymer material to reduce CAUTI.

Biofilms of pathogenic bacteria and emerging antibiofilm strategies

Biofilms act as physical barriers to the immune system and drugs used by the host, resulting in antimicrobial resistance. Biofilms reduce the chances of eradicating infections and can result in relapses and backsliding after conventional treatment. Biofilms have a big impact on food safety in the food industry; many foodborne outbreaks have been linked to pathogenic bacteria that can form a biofilm. Biofilm-associated infections can cause not only severe symptoms but also serious side effects and even death. The findings of an experimental study of pathogenic bacteria like Pseudomonas aeruginosa, Salmonella enteritidis, and Staphylococcus aureus forming biofilms are presented in this article. The process of biofilm formation and its development phases were displayed with preserved architectonics using light and scanning electron microscopes. The amount of biofilm formed was influenced by the growth medium as well as the incubation conditions and time. Biofilm-forming microbes are a common cause of complicated and recurrent diseases, and they're usually linked to MDR bacteria, which account for nearly 80% of all refractory nosocomial infections. Medical device- and tissue-associated biofilm infections are two types of biofilm infections. Understanding the pathogenesis and factors that contribute to biofilm formation, as well as the disruption and dispersal mechanisms of biofilms, will aid in the development of improved anti-biofilm strategies. Overall, this literature review can serve as a single source of information about microbial biofilm formation and mitigation strategies, which could be extremely useful to biofilm researchers.
 Keywords: biofilm; pathogenic bacteria; infection; anti-biofilm.

Rhizobacteria communities reshaped by red mud based passivators is vital for reducing soil Cd accumulation in edible amaranth

Red mud (RM) was constantly reported to immobilize soil cadmium (Cd) and reduce Cd uptake by crops, but few studies investigated whether and how RM influenced rhizobacteria communities, which was a vital factor determining Cd bioavailability and plant growth. To address this concern, high-throughput sequencing and bioinformatics were used to analyze microbiological mechanisms underlying RM application reducing Cd accumulation in edible amaranth. Based on multiple statistical models (Detrended correspondence analysis, Bray-Curtis, weighted UniFrac, and Phylogenetic tree), this study found that RM reduced Cd content in plants not only through increasing rhizosphere soil pH, but by reshaping rhizobacteria communities. Special taxa (Alphaproteobacteria, Gammaproteobacteria, Actinobacteriota, and Gemmatimonadota) associated with growth promotion, anti-disease ability, and Cd resistance of plants preferentially colonized in the rhizosphere. Moreover, RM distinctly facilitated soil microbes' proliferation and microbial biofilm formation by up-regulating intracellular organic metabolism pathways and down-regulating cell motility metabolic pathways, and these microbial metabolites/microbial biofilm (e.g., organic acid, carbohydrates, proteins, S2−, and PO43−) and microbial cells immobilized rhizosphere soil Cd via the biosorption and chemical chelation. This study revealed an important role of reshaped rhizobacteria communities acting in reducing Cd content in plants after RM application.

Engineered Nanotechnology: An Effective Therapeutic Platform for the Chronic Cutaneous Wound.

The healing of chronic wound infections, especially cutaneous wounds, involves a complex cascade of events demanding mutual interaction between immunity and other natural host processes. Wound infections are caused by the consortia of microbial species that keep on proliferating and produce various types of virulence factors that cause the development of chronic infections. The mono- or polymicrobial nature of surface wound infections is best characterized by its ability to form biofilm that renders antimicrobial resistance to commonly administered drugs due to poor biofilm matrix permeability. With an increasing incidence of chronic wound biofilm infections, there is an urgent need for non-conventional antimicrobial approaches, such as developing nanomaterials that have intrinsic antimicrobial-antibiofilm properties modulating the biochemical or biophysical parameters in the wound microenvironment in order to cause disruption and removal of biofilms, such as designing nanomaterials as efficient drug-delivery vehicles carrying antibiotics, bioactive compounds, growth factor antioxidants or stem cells reaching the infection sites and having a distinct mechanism of action in comparison to antibiotics—functionalized nanoparticles (NPs) for better incursion through the biofilm matrix. NPs are thought to act by modulating the microbial colonization and biofilm formation in wounds due to their differential particle size, shape, surface charge and composition through alterations in bacterial cell membrane composition, as well as their conductivity, loss of respiratory activity, generation of reactive oxygen species (ROS), nitrosation of cysteines of proteins, lipid peroxidation, DNA unwinding and modulation of metabolic pathways. For the treatment of chronic wounds, extensive research is ongoing to explore a variety of nanoplatforms, including metallic and nonmetallic NPs, nanofibers and self-accumulating nanocarriers. As the use of the magnetic nanoparticle (MNP)-entrenched pre-designed hydrogel sheet (MPS) is found to enhance wound healing, the bio-nanocomposites consisting of bacterial cellulose and magnetic nanoparticles (magnetite) are now successfully used for the healing of chronic wounds. With the objective of precise targeting, some kinds of “intelligent” nanoparticles are constructed to react according to the required environment, which are later incorporated in the dressings, so that the wound can be treated with nano-impregnated dressing material in situ. For the effective healing of skin wounds, high-expressing, transiently modified stem cells, controlled by nano 3D architectures, have been developed to encourage angiogenesis and tissue regeneration. In order to overcome the challenge of time and dose constraints during drug administration, the approach of combinatorial nano therapy is adopted, whereby AI will help to exploit the full potential of nanomedicine to treat chronic wounds.

Prevention of medical device infections via multi-action nitric oxide and chlorhexidine diacetate releasing medical grade silicone biointerfaces.

The presence of bacteria and biofilm on medical device surfaces has been linked to serious infections, increased health care costs, and failure of medical devices. Therefore, antimicrobial biointerfaces and medical devices that can thwart microbial attachment and biofilm formation are urgently needed. Both nitric oxide (NO) and chlorhexidine diacetate (CHXD) possess broad-spectrum antibacterial properties. In the past, individual polymer release systems of CHXD and NO donor S-nitroso-N-acetylpenicillamine (SNAP) incorporated polymer platforms have attracted considerable attention for biomedical/therapeutic applications. However, the combination of the two surfaces has not yet been explored. Herein, the synergy of NO and CHXD was evaluated to create an antimicrobial medical-grade silicone rubber. The 10wt% SNAP films were fabricated using solvent casting with a topcoat of CHXD (1, 3, and 5wt%) to generate a dual-active antibacterial interface. Chemiluminescence studies confirmed the NO release from SNAP-CHXD films at physiologically relevant levels (0.5-4× 10-10 mol min-1 cm-2 ) for at least 3 weeks and CHXD release for at least 7 days. Further characterization of the films via SEM-EDS confirmed uniform distribution of SNAP and presence of CHXD within the polymer films without substantial morphological changes, as confirmed by contact angle hysteresis. Moreover, the dual-active SNAP-CHXD films were able to significantly reduce Escherichia coli and Staphylococcus aureus bacteria (>3-log reduction) compared to controls with no explicit toxicity towards mouse fibroblast cells. The synergy between the two potent antimicrobial agents will help combat bacterial contamination on biointerfaces and enhance the longevity of medical devices.

The antimicrobial effect of Rosmarinus officinalis extracts on oral initial adhesion ex vivo

ObjectiveIn the last few decades, there has been a growing worldwide interest in the use of plant extracts for the prevention of oral diseases. The main focus of this interest lies in the identification and isolation of substances that limit the formation of microbial biofilm which plays a major role in the development of caries, periodontitis, and peri-implantitis. In this clinical ex vivo study, we investigated the antimicrobial effects of Rosmarinus officinalis extract against oral microorganisms within in situ initial oral biofilms.Materials and methodsInitial in situ biofilm samples (2 h) from six healthy volunteers were treated ex vivo with R. officinalis extract at concentrations of 20 mg/ml and 30 mg/ml. The number of viable bacterial cells was determined by counting the colony-forming units. All surviving bacteria were isolated in pure cultures and identified using MALDI-TOF and biochemical testing procedures. Additionally, live/dead staining in combination with epifluorescence microscopy was used for visualizing the antimicrobial effects in the initial biofilms.ResultsThe number of colony-forming units in the R. officinalis–treated biofilms was significantly lower than in the untreated controls (p < 0.001). The reduction range of log10 was 1.64–2.78 and 2.41–3.23 for aerobic and anaerobic bacteria, respectively. Regarding the bacterial composition, large intra- and interindividual variability were observed. Except for Campylobacter spp., the average amount of all bacterial taxa was lower after treatment with R. officinalis than in the untreated biofilms. A total of 49 different species were detected in the untreated biofilms, while only 11 bacterial species were detected in the R. officinalis–treated biofilms. Live/dead staining confirmed that the R. officinalis–treated biofilms had significantly lower numbers of surviving bacteria than the untreated biofilms.ConclusionsThe treatment with R. officinalis extract has a significant potential to eliminate microbial oral initial biofilms.Clinical relevanceThe results of this study encourage the use of R. officinalis extracts in biofilm control and thus in the treatment of caries and periodontitis as a herbal adjuvant to synthetic substances.

Antimicrobial and Anti-inflammatory Gallium-Defensin Surface Coatings for Implantable Devices.

Emerging and re-emerging infections are a global threat driven by the development of antimicrobial resistance due to overuse of antimicrobial agents and poor infection control practices. Implantable devices are particularly susceptible to such infections due to the formation of microbial biofilms. Furthermore, the introduction of implants into the body often results in inflammation and foreign body reactions. The antimicrobial and anti-inflammatory properties of gallium (Ga) have been recognized but not yet utilized effectively to improve implantable device integration. Furthermore, defensin (De, hBD-1) has potent antimicrobial activity in vivo as part of the innate immune system; however, this has not been demonstrated as successfully when used in vitro. Here, we combined Ga and De to impart antimicrobial activity and anti-inflammatory properties to polymer-based implantable devices. We fabricated polylactic acid films, which were modified using Ga implantation and subsequently functionalized with De. Ga-ion implantation increased surface roughness and increased stiffness. Ga implantation and defensin immobilization both independently and synergistically introduced antimicrobial activity to the surfaces, significantly reducing total live bacterial biomass. We demonstrated, for the first time, that the antimicrobial effects of De were unlocked by its surface immobilization. Ga implantation of the surface also resulted in reduced foreign body giant cell formation and expression of proinflammatory cytokine IL-1β. Cumulatively, the treated surfaces were able to kill bacteria and reduce inflammation in comparison to the untreated control. These innovative surfaces have the potential to prevent biofilm formation without inducing cellular toxicity or inflammation, which is highly desired for implantable device integration.

Submicron topography design for controlling staphylococcal bacterial adhesion and biofilm formation.

Surface topography modification with nano- or micro-textured structures has been an efficient approach to inhibit microbial adhesion and biofilm formation and thereby to prevent biomaterial-associated infection without modification of surface chemistry/bulk properties of materials and without causing antibiotic resistance. This manuscript focuses on submicron-textured patterns with ordered arrays of pillars on polyurethane (PU) biomaterial surfaces in an effort to understand the effects of surface pillar features and surface properties on adhesion and colonization responses of two staphylococcal strains. Five submicron patterns with a variety of pillar dimensions were designed and fabricated on PU film surfaces and bacterial adhesion and biofilm formation of Staphylococcal strains (Staphylococcus epidermidis RP62A and Staphylococcus aureus Newman D2C) were characterized. Results show that all submicron textured surface significantly reduced bacterial adhesion and inhibited biofilm formation, and bacterial adhesion linearly decreased with the reduction in top surface area fraction. Surface wettability did not show a linear correlation with bacterial adhesion, suggesting that surface contact area dominates bacterial adhesion. From this, it appears that the design of textured patterns should minimize surface area fraction to reduce the bacterial interaction with surfaces but in a way that ensures the mechanical strength of pillars in order to avoid collapse. These findings may provide a rationale for design of polymer surfaces for antifouling medical devices.

Application of proper orthogonal decomposition for evaluation of coherent structures and energy contents in microbial biofilms

Microbial biofilms are structured communities of surface-associated microbial populations embedded in a matrix of extracellular polysaccharides that provide protection for biofilm cells. Among the wide plethora of microbial species adept at forming biofilms, the fungal pathogen Candida albicans (C. albicans), is one of the most notable. C. albicans biofilm development occurs in a series of sequential steps over a period of 24 h. Various quantitative and microscopic methods are available for the monitoring and evaluation of biofilms, including several innovative real-time methods for the evaluation of the cell-to-cell dynamics occurring during biofilm formation. These methods utilize biosensors which capture electrical, acoustic, and reflectance signals in bacterial populations (Li et al., 2021; Li et al., 2020; Kim et al., 2021; Paredes et al., 2021; Reipa et al., 2021). Additionally, machine learning, deep learning and other computational approaches have progressively been incorporated in the field of microbiology (Qu et al., 2019; Goodswen et al., 2021; Zhang et al., 2021; Ghannam and Techtmann, 2021; Rani et al., 2021; Berg et al., 2019) including some studies in biofilms (Buetti-Dinh et al., 2019; Srivastava et al., 2020; Hartmann et al., 2021; Dimauro et al., 2021) but given the potential of machine and deep learning, this niche is in large need of collaborative work between microbiology and engineering or physics experts to propel machine learning to a higher level. Therefore, whilst promising advances have been made, there is an urgent need for extensive development to take place to study and comprehend the complex interaction of microbial pathogens during biofilm formation. Specifically, there is a lot left to be understood about biofilm energy kinetics, and who the active microbial populations are. We infer that biofilm formation is an extremely diverse phenomenon and that each microorganism exerts different pathways to form a biofilm. Thus, we reasoned on the need for a model that would allow us to study the energy kinetics during C. albicans biofilm development. Modal decomposition techniques (MDTs) commonly used in fluid mechanics are gaining popularity outside their original field and might help decipher some of the dynamically relevant structures of biofilm formation. MDTs permit the identification of coherent structures in fluids and have been used in complex applications of information obtained during a particular time-lapse. A common MDT, Proper Orthogonal Decomposition (POD), can be used in reduced order modelling and machine learning applications. POD allows decomposition of a physical field influenced by different variables that may affect its physical properties. We aimed to evaluate the applicability of this technique in the analysis of energy kinetics during microbial biofilm formation, more specifically C. albicans biofilms. Using POD, we were able to easily distinguish visually distinct modes of growth of C. albicans cells in PBS and RPMI in terms of energy accumulation during the kinetic experiment. Comparing both PBS and RPMI, RPMI contains more energetic and dynamically relevant structures than PBS.

Protein O-mannosyltransferase Rv1002c contributes to low cell permeability, biofilm formation in vitro, and mycobacterial survival in mice.

Mycobacterium tuberculosis (M. tuberculosis) Rv1002c encodes the protein O-mannosyltransferase (PMT), which catalyzes the transfer of mannose to serine or threonine residues of proteins. We explored the function of PMT in vitro and in vivo. Rv1002c protein was heterogeneously overexpressed in nonpathogenic Mycobacterium smegmatis (named as MS_Rv1002c). A series of trials including mass spectrometry, transmission electron microscope, biofilm formation and antibiotics susceptibility were performed to explore the function of PMT on bacterial survival in vitro. Mouse experiments were carried out to evaluate the virulence of PMT in vivo. PMT decreased the cell envelope permeability and promoted microbial biofilm formation. PMT enhanced the mycobacterial survival in vivo and inhibited the release of pro-inflammatory cytokines in serum. The function might be associated with an increased abundance of some mannoproteins in culture filtrate (CF). PMT is likely to be involved in mycobacterial survival both in vivo and in vitro due to increasing the mannoproteins abundance in CF.

Antiadherent and antibacterial properties of TiO2-coated and TiO2:Ag-coated stainless steel orthodontic wires against S. mutans bacteria

Purpose Conventional orthodontic treatment with stainless steel orthodontic wires may be detrimental to oral health, as it con-tributes to demineralized lesions and increases adhesion and bacterial biofilm formation, which contributes to cavity development. An alternative that has been investigated to reduce the side effects of orthodontic treatment is the use of coating materials with antimicrobial nanoparticles. This study aims to evaluate the antiadherent and antibacterial properties of TiO2-coated and TiO2:Ag-coated stainless steel orthodontic wires against S. mutans bacteria. Methods In the sol-gel method, TiO2:Ag thin films were deposited on stainless steel orthodontic wires. Coated archwires were analyzed for their antibacterial and antiadherent properties. The evaluation of Streptococcus mutans adhesion to the orthodontic wires’ surface was conducted according to the type of coating used, biofilm formation assay, and measure-ment of the pH of the bacterial community. Results In the microbiological test, the TiO2:Ag coatings revealed a statistically significant difference in terms of microbial adhesion and biofilm formation by Streptococcus mutans. The TiO2:Ag coating on stainless steel wire increased pH levels in the saliva environment. Conclusions It can be concluded that antimicrobial orthodontic wires coated with silver-TiO2 nanoparticles using the sol-gel thin film are a promising choice for improving orthodontic treatment.

Biochar Affects Microbial Attachment and Biofilm Formation Processes in Aerated Subsurface Flow Constructed Wetlands

Biochar Affects Microbial Attachment and Biofilm Formation Processes in Aerated Subsurface Flow Constructed Wetlands

Antibacterial Activity of Bismuth Oxide Nanoparticles Compared to Amikacin against Acinetobacter baumannii and Staphylococcus aureus

In this work, bismuth oxide nanoparticles (Bi2O3 NP) were prepared by laser ablation of a solid target in distilled water. The optical and structural properties of Bi2O3 NPs were studied using UV–VIS spectroscopy, energy‐dispersive X‐ray spectroscopy (EDS), transmission electron microscope (TEM), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR). The results showed that the average particle size is less than 20 nm. The antibacterial activity of the Bi2O3 NPs was determined and compared with amikacin against Acinetobacter baumannii and Staphylococcus aureus. The activity of Bi2O3 NPs was higher than the amikacin. Furthermore, the antibacterial activity of Bi2O3 NPs against S. aureus bacteria was higher than Acinetobacter baumannii; this result was confirmed by studying the effect of Bi2O3 NPs in bacterial biofilm formation in eyes contact lenses using atomic force microscopy (AFM) technique. Taken together, Bi2O3 NPs could be used as a preservative for contact lenses as eye drops to prevent the formation of microbial biofilms in contact lenses.

Influence of Multimedia Reminders on Oral Hygiene Status During Removable Orthodontic Treatment: A Randomized Controlled Trial.

Introduction:Orthodontic appliances complicate daily oral hygiene maintenance and enhance the formation of microbial biofilm on tooth surfaces and orthodontic appliances.Objective:This trial was conducted to assess the effect of reminders on oral hygiene of patients during removable orthodontic treatment.Methods:In this 2-arm parallel randomized controlled trial, 66 orthodontic patients with removable maxillary appliance were randomly allocated with 1:1 ratio to message reminders and the control group. The patients in the messaging group received one or two message reminders and educational videos weekly during the course of treatment. A single blinded examiner measured the plaque index (PI), gingival index (GI), and dental caries index of patients in both groups at baseline (T0) and one (T1), three (T2), and six (T3) months after the first day of treatment to assess their oral hygiene status during treatment.Results:A total of 30 patients in control group and 28 in reminder group completed the study. The PI and GI scores were increased neither in control group nor in message reminder group during T0 and T1, significantly. The PI and GI scores in message reminder group were significantly lower than those in the control group at T2 (PI: P = 0.001, GI: P = 0.003) and T3 (PI: P = 0.024, GI: P = 0.022). Slight significant increasing in the PI and GI score were found during T2 and T3 in message reminder group. Caries index showed no significant difference between two groups during study.Conclusion:It seems that reminders can efficiently promote oral hygiene of patients undergoing removable orthodontic treatment.

Biomimetic of hydroxyapatite with Tridax procumbens leaf extract and investigation of antibiofilm potential in Staphylococcus aureus and Escherichia coli

In the last few decades, hydroxyapatite (HA) has become one of the most highly prized biominerals in the biomedical industry for orthopedic and dental applications. The focus of this research was to synthesize biomimetic HA from Tridax procumbens (TP) leaf extract and investigate their antibiofilm properties. The HA was made using the sol-gel method and the HA-TP biocomposite was made by precipitation method. The d.nm size of HA and HA-TP biocomposite was determined as 193.28 and 258.14 d.nm, respectively. The zeta potential of HA and HA-TP biocomposite was determined as −21.2 and −18.3 mV, respectively, and found highly stable. The FTIR study revealed that phytochemicals of TP were successfully impregnated into HA-TP biocomposite. The HA and HA-TP biocomposite were found spherical and agglomerated from SEM analysis. In HR-TEM analysis, the average diameter of the HA and HA-TP biocomposite were 16.57 – 64.22 nm and 51.71 – 138.68 nm, respectively. According to the EDX analysis, HA is primarily composed of calcium, oxygen, and phosphate, whereas, HA-TP biocomposite is primarily composed of calcium, phosphate, oxygen, and carbon. In the antioxidant assay, the IC50 value (concentration required to scavenge 50% of free radicals) of HA-TP biocomposite was determined as 156.69 ± 14.02 and 180.21 ± 12.84 µg/mL in DPPH and ABTS free radical scavenging assays, respectively. The MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) of as-synthesized HA-TP biocomposite against Staphylococcus aureus – ATCC 13565 and Escherichia coli – MTCC 41 were observed as 181.09 ± 21.47 and 317.30 ± 41.03, and 157.59 ± 32.18 and 264.03 ± 21.58 µg/mL, respectively. The as-synthesized HA-TP biocomposite has detrimentally affected the biofilm formation of both the tested bacteria S. aureus – ATCC 13565 and E. coli – MTCC 41. The study concluded that the as-synthesized HA-TP biocomposite could be highly helpful in the biomedical field for alleviating oxidative-stress-related disorders and inhibiting microbial biofilm formation.

Biofilm Formation and Inhibitory Effect of Essential Oils in Multidrug-Resistant Pseudomonas aeruginosa

Biofilm formation is a major concern in medicine, as well as in the food industry. Some infections related to bacterial biofilms such as Pseudomonas aeruginosa are a real public health challenge. This study aimed to show the activity of essential oils on P. aeruginosa biofilm formation. Pseudomonas aeruginosa isolates consisting of animal (100), environmental (20) and clinical strains (42) were identified by PCR and sequenced. Biofilm formation was assessed by the microplate method. Antibiotic susceptibility testing was performed by using Kirby–Bauer disc-diffusion method. The average biofilm formation percentages vary from 1.2 to 2.1 in 24h and from 2.3 to 3.2 in 48h. The median biofilm formation value was higher in environmental strains (1.4 ± 0.2) than in clinical (1.2 ± 0.4) and animal (1.1 ± 0.4). In decreasing order of importance, the essential oils of Mentha piperita (90 ± 5.12% at 100%), Eucalyptus globulus (34 ± 0.08% at 100%) and Lavandula angustifolia (12 ± 0.71% to 100%) showed distinct inhibitory effects on biofilm formation (p &lt;0.05). The rate of resistance of P. aeruginosa to the antibiotics imipenem, ceftazidime, cefepime, fosfomycin and colistin varied from 12.7% to 48.4% in the biofilm status while that of plankton cells ranged from 2.3% to 15.0%. Moreover, resistance to ticarcillin, ticarcillin clavulanic acid, piperacillin and ciprofloxacin ranged from 56.4% to 83.1% in biofilm and from 29.4% to 51.4% in planktonic cells. In general, biofilm is more resistant to different antibiotics than free cells. The tested essential oils could be an effective natural control against microbial biofilm formation.

Linear-Chain Nanostructured Carbon with a Silver Film Plated on Metal Components Has a Promising Effect for the Treatment of Periprosthetic Joint Infection

Background: Due to the aging of the world population, the number of joint diseases, along with the number of arthroplasties, has increased, simultaneously increasing the amount of complications, including periprosthetic joint infection (PPI). In this study, to combat a PPI, we investigated the antimicrobial properties of the new composite cover for titanium implants, silver-doped carbyne-like carbon (S-CLC) film. Methods: The first assay investigated the antimicrobial activity against Pseudomonas aeruginosa and releasing of silver ions from S-CLC films into growth media covered with S-CLC with a thickness of 1, 2, and 4 mm. The second assay determined the direct antibacterial properties of the S-CLC film’s surface against Staphylococcus aureus, Enterococcus faecalis, or P. aeruginosa. The third assay studied the formation of microbial biofilms of S. aureus or P. aeruginosa on the S-CLC coating. Silver-doped carbyne-like carbon (S-CLC)-covered or titanium plates alone were used as controls. Results: S-CLC films, compared to controls, prevented P. aeruginosa growth on 1 mm thickness agar; had direct antimicrobial properties against S. aureus, E. faecalis, and P. aeruginosa; and could prevent P. aeruginosa biofilm formation. Conclusions: S-CLC films on the Ti surface could successfully fight the most common infectious agent in PPI, and prevented biofilm formation.

A Role for Secreted Immune Effectors in Microbial Biofilm Formation Revealed by Simple In Vitro Assays.

The formation of biofilms is critical for the successful and stable colonization of mucosal surfaces by microbes, which often build three-dimensional environments by exuding exopolysaccharides and other macromolecules such as proteins, lipids, and even DNA. It is not just bacteria, but fungi such as yeast, that form these adherent interacting communities. Historically, biofilms have been studied in the context of pathogenesis, but only recently it has been recognized that important relationships among members of host-associated microbiomes are maintained within the context of biofilms. Host immune responses impact biofilm formation in various ways; for example, it is likely that formation of stable biofilms by non-pathogens improves barrier defenses by not just filling available niche spaces but also by helping to ward off pathogens directly. Recently, it was found that soluble immune effector molecules such as immunoglobulin A (IgA) in mammals serve essential roles in modulating complex biofilm communities in ways that benefit the host. Additional lines of evidence from other secreted immune effectors, such as the variable region-containing chitin-binding proteins (VCBPs) in protochordates, now suggest that this phenomenon is much more widespread than previously recognized. The activity of these immune molecules also likely serves roles beyond those of simple defense strategies; rather, they may be improving the outcome of symbiotic interactions benefiting the host. Thus, traditional immune assays that are aimed at studying the function of secreted immune effectors, such as agglutination assays, should take into account the possibility that the first observation may not be the last if the microbes under study are not directly killed. Here, we describe a series of simple approaches to characterize biofilm formation when bacteria (or yeast) are cultured in the presence of a secreted immune effector. To model this approach, we use microbes isolated from the gut of Ciona robusta, each grown in the presence or absence of VCBPs. The approaches defined here are amenable to diverse model systems and their microbes.

Atmospheric Pressure Plasma Activation of Hydroxyapatite to Improve Fluoride Incorporation and Modulate Bacterial Biofilm.

Despite the technological progress of the last decade, dental caries is still the most frequent oral health threat in children and adults alike. Such a condition has multiple triggers and is caused mainly by enamel degradation under the acidic attack of microbial cells, which compose the biofilm of the dental plaque. The biofilm of the dental plaque is a multispecific microbial consortium that periodically develops on mammalian teeth. It can be partially removed through mechanical forces by individual brushing or in specialized oral care facilities. Inhibition of microbial attachment and biofilm formation, as well as methods to strengthen dental enamel to microbial attack, represent the key factors in caries prevention. The purpose of this study was to elaborate a cold plasma-based method in order to modulate microbial attachment and biofilm formation and to improve the retention of fluoride (F−) in an enamel-like hydroxyapatite (HAP) model sample. Our results showed improved F retention in the HAP model, which correlated with an increased antimicrobial and antibiofilm effect. The obtained cold plasma with a dual effect exhibited through biofilm modulation and enamel strengthening through fluoridation is intended for dental application, such as preventing and treating dental caries and enamel deterioration.