Biofilm Reduction Research Articles

Exploration of plasma‐activated water (PAW) as a cleaning‐in‐place (CIP) solution for fouling removal and microbial reduction

AbstractThe rapid fouling and bacterial contamination of equipment, heat exchangers, and pipelines are major concerns in food manufacturing plants. The process of cleaning‐in‐place (CIP) in the food manufacturing industry involves hazardous chemicals such as sulfuric acid, chlorine, sodium hydroxide, and potassium hydroxide. This study aims to investigate the cleaning efficiency of a novel environment‐friendly solution, plasma‐activated water (PAW), for removing dairy and plant‐based fouling and for biofilm reduction. PAW was produced by exposing water to plasma, which is a partially ionized gas generated by applying electricity to air. PAW prepared in this study had a pH, electrical conductivity (EC), and oxidation–reduction potential (ORP) of 2.5 ± 0.1, 1170. 1 ± 202.2 μS/cm, and 589.0 ± 2.4 mV, respectively. Holding PAW at different temperatures (20–75°C) did not change pH, ORP, and EC significantly, while nitrite and nitrate concentrations in PAW did not show a consistent trend with temperature. The treatment time and temperature of PAW were optimized for cleaning fouled coupons (stainless‐steel type 304 and 316) using model fouling fluids (MFF) with dairy (whey) and plant‐based (oat) proteins using full‐factorial design. The optimized PAW combinations (15 min/75°C and 5 min/75°C) were found to be as effective for fouling removal as compared to CIP controls (conventional caustic and acid solutions). Optimized PAW also showed significant biofilm reduction of Listeria innocua on stainless‐steel coupons with/without fouling, with at least 4.4 log and 4.0 log reductions in L. innocua biofilms when attached to MFF‐whey and MFF‐oat, respectively.Practical applicationsPlasma‐activated water (PAW) can inactivate a wide spectrum of microorganisms on various food and food contact surfaces. We propose the use of environment‐friendly plasma‐activated water (PAW), which can be prepared on‐site and on‐demand for cleaning‐in‐place (CIP) operations in the food industry. The results of this study suggest the potential of PAW as a promising CIP alternative for cleaning and sanitizing surfaces soiled by fouling deposits in dairy and plant‐based industries.

Preventive Effect of Ultraviolet Photofunctionalization on Peri-implant Biofilm Formation: An In vivo Randomized Study.

Peri-implant biofilm formation due to local bacterial colonization is one of the important factors for the instability of temporary anchorage devices (TADs). The aim of this study was to quantify and compare the colonization of Streptococcus sanguinis on ultraviolet (UV) treated and untreated titanium TADs. This prospective, in vivo study included 20 subjects requiring orthodontic treatment with first premolar extraction, followed by retraction of the anterior teeth with absolute anchorage using TADs. TADs were placed interdentally, in the keratinized tissue between the upper second premolar and the first molar on the buccal side, at the mucogingival junction. It was a split-mouth study where one side of TAD was UV-treated for 15 min, and the other side was kept untreated as a control. TADs were removed after 6 months for S. sanguinis quantification on both sides and were compared for biofilm reduction. Statistical software was used to perform unpaired t-tests for the individual samples as well as for comparing total UV-treated and untreated samples. P <0.05 was considered significant. The mean bacterial count (per ml) was found to be 2.2 × 106 copy numbers and 8.9 × 106 copy numbers in the UV group and untreated group, respectively. The total count of bacteria was found to be less in the UV-treated group compared to the untreated group. The study concludes that UV photofunctionalization results in a significant reduction of S. sanguinis colony on TADs with reduced chances of failure due to inflammation.

Escherichia coli exopolysaccharides disrupt Pseudomonas aeruginosa biofilm and increase its antibiotic susceptibility

Pseudomonas aeruginosa (P. aeruginosa) is a major pathogen that causes infectious diseases. It has high tendency to form biofilms, resulting in the failure of traditional antibiotic therapies. Inspired by the phenomenon that co-culture of Escherichia coli (E. coli) and P. aeruginosa leads to a biofilm reduction, we reveal that E. coli exopolysaccharides (EPS) can disrupt P. aeruginosa biofilm and increase its antibiotic susceptibility. The results show that E. coli EPS effectively inhibit biofilm formation and disrupt mature biofilms in P. aeruginosa, Staphylococcus aureus, and E. coli itself. The maximal inhibition and disruption rates against P. aeruginosa biofilm are 40 % and 47 %, respectively. Based on the biofilm-disrupting ability of E. coli EPS, we develop an E. coli EPS/antibiotic combining strategy for the treatment of P. aeruginosa biofilms. The combination with E. coli EPS increases the antibacterial efficiency of tobramycin against P. aeruginosa biofilms in vitro and in vivo. This study provides a promising strategy for treating biofilm infections. Statement of significanceBiofilm formation is a leading cause of chronic infections. It blocks antibiotics, increases antibiotic-tolerance, and aids in immune evasion, thus representing a great challenge in clinic. This study proposes a promising approach to combat pathogenic Pseudomonas aeruginosa (P. aeruginosa) biofilms by combining Escherichia coli exopolysaccharides with antibiotics. This strategy shows high efficiency in different P. aeruginosa stains, including two laboratory strains, PAO1 and ATCC 10145, as well as a clinically acquired carbapenem-resistant strain. In addition, in vivo experiments have shown that this approach is effective against implanted P. aeruginosa biofilms and can prevent systemic inflammation in mice. This strategy offers new possibilities to address the clinical failure of conventional antibiotic therapies for microbial biofilms.

Efficacy of Commercially Available Irrigation Solutions on Removal of Staphylococcus Aureus and Biofilm From Porous Titanium Implants: An In Vitro Study

BackgroundPeriprosthetic joint infection remains a major problem. The bactericidal efficacy of commercial irrigation solutions for the treatment of infection is not well established in the presence of porous titanium (Ti) implants. This study compared the in vitro efficacy of five irrigation solutions on infected three-dimensional–printed porous Ti discs. MethodsTitanium discs (2 × 4 mm, 400, 700, and 1,000 μm) were infected with S. aureus (1 × 106 colony-forming unit/mL) and incubated for 3 hours or 3 days to create acute or chronic infection with biofilm. Discs were irrigated with saline, antibiotic, or antiseptic solutions, then repeatedly sonicated. Sonicates were cultured for bacterial quantification. Statistical analyses were performed using one-way analysis of variance (ANOVA), followed by Tukey-Kramer post hoc testing (P < .05 significance). Biofilms were visualized by scanning electron microscopy. ResultsSaline irrigation was ineffective in both groups. In acute infections with 400 μm pores, differences were found with saline versus solution #3 (P = .015) and #4 (P = .015). Solution #4 had the lowest bacterial counts for all pore sizes. For biofilm, irrigation with saline, solutions #1, #2, and #3 inadequately cleared bacteria in all pore sizes. Lower remaining concentrations were observed in #4 with 400μm pores compared to saline (P = .06) and #2 (P = .039). The scanning electron microscopy showed a reduction of biofilm in samples washed with #4. ConclusionsIrrigation of infected porous Ti discs with saline, solutions #1 and #2 failed to reduce the bacterial load. The 400 μm discs consistently had more bacteria despite irrigation, highlighting the difficulty of removing bacteria from small pores. Solutions #3 and #4 reduced bacteria acutely, but only #4 demonstrated efficacy in clearing biofilm compared to saline. These results should be considered when treating periprosthetic joint infection in the presence of porous components and the potential presence of biofilm.

Exploring bio-oil aqueous phase (BOAP) from seaweed biomass as biofilm disruptive agents against foodborne pathogens

Proper preservation of nutrient-rich raw food from microbial contamination is a major challenge faced by the food industry. The use of antibiotics and chemicals to address the issue of contamination in fresh produce and meat has led to antibiotic-resistant pathogens. In the current study, the anti-biofilm effect of bio-oil aqueous phase (BOAP) collected during pyrolysis of seaweed was evaluated against some major food-borne pathogens for its biofilm inhibition and eradication potential in mono- and dual-species biofilms. The results showed that BOAP could eradicate almost 75% of dual-species biofilms. Further, the preservative effect of the BOAP was examined using appropriate food samples (pineapple and prawns). There was profound reduction in the bacterial load in the food samples which shows that BOAP has effective food preservation property. SEM analysis also revealed the drastic reduction in biofilm in BOAP treated food samples. In future, natural preservatives and BOAP can be combined to increase shelf-life of the above food samples.

The effect of different access cavity designs on bacterial biofilm reduction using Er,Cr:YSGG laser in comparison to conventional disinfection protocols. An in vitro study

The effect of different access cavity designs on bacterial biofilm reduction using Er,Cr:YSGG laser in comparison to conventional disinfection protocols. An in vitro study

Bacteriophages and Green Synthesized Zinc Oxide Nanoparticles in Combination Are Efficient against Biofilm Formation of Pseudomonas aeruginosa.

Bacteriophages (phages) are viruses that infect the bacteria within which their reproduction cycle takes place, a process that ends in the lysis and death of the bacterial cell. Some phages are also able to destroy bacterial biofilms. Due to increased antibiotics resistance, Pseudomonas aeruginosa, another biofilm-forming pathogen, is a problem in many parts of the world. Zinc oxide (ZnO) and other metal nanoparticles (NPs) are biologically active and also possess anti-biofilm properties. ZnO-NPs were prepared by the green synthesis method using orange peels. The vibrational peaks of the ZnO-NPs were analyzed using FTIR analysis, and their size and morphological properties were determined using scanning electron microscopy (SEM). The ability of the ZnO-NPs to reduce or eliminate P. aeruginosa biofilm alone or in combination with phages PB10 and PA19 was investigated. The P. aeruginosa cells were effectively killed in the preformed 48 h biofilms during a 24 h incubation with the ZnO-NP-phage combination, in comparison with the control or ZnO-NPs alone. The treatments on growing biofilms were most efficient in the final stages of biofilm development. All five treatment groups showed a significant biofilm reduction compared to the control group (p < 0.0001) at 48 h of incubation. The influence of the ZnO-NPs and phages on the quorum sensing system of P. aeruginosa was monitored by quantitative real-time PCR (qRT-PCR) of the autoinducer biosynthesis gene lasI. While the ZnO-NPs repressed the lasI gene transcription, the phages slightly activated it at 24 and 48 h of incubation. Also, the effect of the ZnO-NPs and phage PA19 on the viability of HFF2 cells was investigated and the results showed that the combination of NPs with PA19 reduced the toxic effect of ZnO-NPs and also stimulated the growth in normal cells.

Evaluation of treatment of methicillin-resistant Staphylococcus aureus biofilms with intermittent electrochemically generated H2O2 or HOCl.

Chronic wound infections can be difficult to treat and may lead to impaired healing and worsened patient outcomes. Novel treatment strategies are needed. This study evaluated the effects of intermittently produced hydrogen peroxide (H2O2) and hypochlorous acid (HOCl), generated via an electrochemical bandage (e-bandage), against methicillin-resistant Staphylococcus aureus biofilms in an agar membrane biofilm model. By changing the working electrode potential, the e-bandage generated either HOCl (1.5 VAg/AgCl) or H2O2 (-0.6 VAg/AgCl). The degree of biocidal activity of intermittent treatment with HOCl and H2O2 correlated with HOCl treatment time; HOCl treatment durations of 0, 1.5, 3, 4.5, and 6 hours (with the rest of the 6-hour total treatment time devoted to H2O2 generation) resulted in mean biofilm reductions of 1.36 ± 0.2, 2.22 ± 0.16, 3.46 ± 0.38, 4.63 ± 0.74, and 7.66 ± 0.5 log CFU/cm2, respectively, vs. non-polarized controls, respectively. However, application of H2O2 immediately after HOCl treatment was detrimental to biofilm removal. For example, 3 hours HOCl treatment followed by 3 hours H2O2 resulted in a 1.90 ± 0.84 log CFU/cm2 lower mean biofilm reduction than 3 hours HOCl treatment followed by 3 hours non-polarization. HOCl generated over 3 hours exhibited biocidal activity for at least 7.5 hours after e-bandage operation ceased; 3 hours of HOCl generation followed by 7.5 hours of non-polarization resulted in a biofilm cell reduction of 7.92 ± 0.12 log CFU/cm2 vs. non-polarized controls. Finally, intermittent treatment with HOCl (i.e., interspersed with periods of e-bandage non-polarization) for various intervals showed similar effects (approximately 6 log CFU/cm2 reduction vs. non-polarized control) to continuous treatment with HOCl for 3 hours, followed by 3 hours of non-polarization. These findings suggest that timing and sequencing of HOCl and H2O2 treatments are crucial for maximizing biofilm control when using an e-bandage strategy.

Antimicrobial efficacy of direct air gas soft jet plasma for the in vitro reduction of oral bacterial biofilms

The aim of this study was to evaluate the antimicrobial efficacy of an air gas soft jet CAP for its potential use in removing oral biofilms, given that plasma-based technologies have emerged as promising methods in periodontology. Two types of biofilms were developed, one by Streptococcus mutans UA 159 bacterial strain and the other by a complex mixture of saliva microorganisms isolated from a patient with periodontitis. This latter biofilm was characterized via Next Generation Sequencing to determine the main bacterial phyla. The CAP source was applied at a distance of 6 mm for different time points. A statistically significant reduction of both CFU count and XTT was already detected after 60 s of CAP treatment. CLSM analysis supported CAP effectiveness in killing the microorganisms inside the biofilm and in reducing the thickness of the biofilm matrix. Cytotoxicity tests demonstrated the possible use of CAP without important side effects towards human gingival fibroblasts cell line. The current study showed that CAP treatment was able to significantly reduce preformed biofilms developed by both S. mutans and microorganisms isolated by a saliva sample. Further studies should be conducted on biofilms developed by additional saliva donors to support the potential of this innovative strategy to counteract oral pathogens responsible for periodontal diseases.

Selective antibacterial and antibiofilm activity of chlorinated hemicyanine against gram-positive bacteria

Antibiotic-free therapies are highly needed due to the limited success of conventional approaches especially against biofilm related infections. In this direction, antimicrobial phototherapy, either in the form of antimicrobial photothermal therapy (aPTT) or antimicrobial photodynamic therapy (aPDT), have appeared to be highly promising candidates in recent years. These are local and promising approaches for antibiotic resistant bacterial infections and biofilms. Organic small photosensitizers (PSs) are extensively preferred in antimicrobial phototherapy applications as they offer a great opportunity to combine therapeutic action (aPTT, aPDT or both) with fluorescence imaging on a single molecule. In this study, the bactericidal effect of cationic chlorinated hemicyanine (Cl-Hem)-based type I PS, which can function as a dual aPDT/aPTT agent, was investigated on both planktonic cells and biofilms of different gram-positive (E. faecalis and S. epidermidis) and gram-negative bacteria (P. aeruginosa and K. pneumoniae) with and without 640 nm laser irradiation. Cl-Hem was shown to induce a selective phototheranostic activity against gram-positive bacteria (E. faecalis and S. epidermidis). Cl-Hem exhibited both dose and laser irradiation time dependent bactericidal effect on planktonic and biofilms of S. epidermidis. These results clearly showed that highly potent Cl-Hem can treat resistant microbial infections, while allowing fluorescence detection at the same time. High biofilm reduction observed with combined aPDT/aPTT action of Cl-Hem together with its non-cytotoxic nature points out that Cl-Hem is a promising PS for antibacterial and antibiofilm treatments.

Effectiveness of different toothbrushing patterns among schoolchildren in an urban area of Argentina.

To identify toothbrushing patterns among schoolchildren with no prior dental hygiene training and associate them with effectiveness for eliminating dental biofilm. Eight calibrated dentists assessed dental biofilm, toothbrushing procedure and dental status and registered: grip, bristle angle with respect to tooth, type of movement, surfaces brushed, simultaneous brushing of both jaws, including all six sextants and duration of brushing dental biofilm before and after brushing was determined in 944 children. Frequency distribution was calculated for nominal variables and central tendency and dispersion for quantitative variables of the toothbrushing procedure. Effectiveness was evaluated in 236 children by calculating differences between biofilm levels before and after brushing using Student's test. A cutoff value was established for the difference in reductions in biofilm levels by means of an ROC curve. The variables including all 6 sextants and bristle angle showed positive association with biofilm reduction. The cutoff point for biofilm reduction for including all 6 sextants was 66.85% (OR 6.4 [3.6-11.38]). The cutoff value for biofilm reduction for bristle angle was 68.35% (OR 3.2 [1.83-5.8]). The variables associated with biofilm reduction can be used to optimize the modality of future educational interventions in schoolchildren.

Biofilm Disruption and Virulence Attenuation Effects of Essential Oil From Endemic Algerian Cistus munbyi (Cistaceae) Against Clinical Strains of Pseudomonas aeruginosa

Background: Pseudomonas aeruginosa is an opportunistic, resistant and highly pathogenic bacteria, responsible for severe nosocomial infections in humans. There is need to search new antimicrobials to target P. aeruginosa strains. Cistus munbyi is used in traditional medicine to manage infections. Objectives: This work aims to investigate the antimicrobial, antibiofilm and other antivirulence effects of essential oil from C. munbyi against P. aeruginosa. Materials and methods: Essential oil (EO) was prepared by hydro-distillation from C. munbyi, characterized by GC–MS and evaluated for its antimicrobial, antibiofilm and anti-virulence effects against clinical isolates of P. aeruginosa. Results: 100% of compounds were identified with Terpinen-4-ol (33.20%), Sabinene (13.20%), α-Thujene (11.30%), and p-Cymene (9.94%) being the major constituents. The EO had good antimicrobial activity determined by diameters of inhibition zones and broth dilution. At minimal inhibitory concentration (MIC), the EO eliminated more that 70% of young biofilms in 19 strains out of 24 tested strains while at 2MIC, only one strain had biofilm inhibition below 70%. The EO eliminated more than 50% of mature biofilms in 13 strains out of 24 tested. Biofilm disruption was concentration-dependent at sub-MIC and indicated good potential of C. munbyi EO as P. aeruginosa antibiofilm agent. Scanning electron microscopy (SEM) images revealed that untreated colonies had a well-developed biofilm while there was significant reduction of biofilms with distorted architecture and cell shrinkage upon treatment with EO. The C. munbyi EO at MIC and sub-MIC was able to reduce quorum-sensing (QS) virulence factors such as pyocyanin production, exopolysaccharides matrix and elastase secretion. Significant QS revealed by reduction of violacein in C. violaceum (CV12472 and CV026) was observed. Conclusion: The overall results show good anti-pseudomonal effects of C. munbyi EO which makes it a potential agent to reduce the spread of infections and resistance to antibiotics from P. aeruginosa strains.

Polish honeys exhibit activity against Pseudomonas aeruginosa isolated from wounds

Pseudomonas aeruginosa is recognized as an opportunistic pathogen and a common contributor to wound infections. This study focused on evaluating the antibacterial activity of selected Polish honeys against P. aeruginosa. Six bacterial strains isolated from wounds and four types of honeys (multifloral, linden, buckwheat, and heather) were utilized. The minimal inhibitory concentrations (MIC) were determined through the micro-dilution method employing 96-well plates, while antibiofilm activity was assessed using fluorescence microscopy after a 4-hour incubation period with the honeys. Results indicated diverse antibacterial efficacy among honeys, with linden and heather honeys demonstrating the most potent activity. Linden honey displayed an average MIC of 20.8%, while heather honey exhibited an MIC of 25%. Both honeys significantly reduced biofilm formation, with linden honey achieving a reduction of 54-67% and heather honey of 45-58%. Buckwheat and multifloral honeys exhibited lower activity, demonstrating average MIC levels of 37.5% and 41.7%, respectively, and a biofilm reduction below 20%. Conclusively, Polish honeys exhibited promising activity against both planktonic and biofilm forms of P. aeruginosa. These findings suggest potential applications in wound healing treatments, emphasizing the need for further research in this area. The study contributes valuable insights to the limited literature on the antibacterial activity of Polish honeys.

Reduction in Pathogenic Biofilms by the Photoactive Composite of Bacterial Cellulose and Nanochitosan Dots under Blue and Green Light.

In this study, nanochitosan dots (ChiDs) were synthesized using gamma rays and encapsulated in bacterial cellulose (BC) polymer matrix for antibiofilm potential in photodynamic therapy. The composites were analyzed for structural changes using SEM, AFM, FTIR, XRD, EPR, and porosity measurements. Additionally, ChiD release was assessed. The results showed that the chemical composition remained unaltered, but ChiD agglomerates embedded in BC changed shape (1.5-2.5 µm). Bacterial cellulose fibers became deformed and interconnected, with increased surface roughness and porosity and decreased crystallinity. No singlet oxygen formation was observed, and the total amount of released ChiD was up to 16.10%. Antibiofilm activity was higher under green light, with reductions ranging from 48 to 57% under blue light and 78 to 85% under green light. Methicillin-resistant Staphylococcus aureus was the most sensitive strain. The new photoactive composite hydrogels show promising potential for combating biofilm-related infections.

Exploring the Potential of Probiotics in Dentistry: A Literature Review

To describe the scientific literature on the uses and application of probiotics in dentistry. An electronic search was carried out without date restriction in the PubMed and Scopus databases. The articles were compiled, and their characteristics, objectives and methods were studied using the following keywords: "probiotics", "S. mutans", "oral health", "biofilm", among others. For the present literature review, 10 studies were chosen that investigate the probiotic action of certain strains such as Lactobaccillus and Bifidobacterium in periodontal and orthodontic treatments, among others. These studies proved their efficacy in different types of presentations such as tablets and yogurt, in different types of populations such as infants, young people and older adults. Finally, a large part of these studies determined biofilm reduction. Based on the research articles, strains such as Lactobaccillus and Bifidobacterium showed positive effects in the reduction of bacterial plaque such as S. mutans in short- and long-term periods in different populations. There is a large production of studies concerning the application of probiotics in dentistry. However, it is necessary to carry out studies with other types of bacteria and different vehicles to determine more precisely which species help to maintain oral health.

A normalized parameter for comparison of biofilm dispersants in vitro

Dispersal of infectious biofilms increases bacterial concentrations in blood. To prevent sepsis, the strength of a dispersant should be limited to allow the immune system to remove dispersed bacteria from blood, preferably without antibiotic administration. Biofilm bacteria are held together by extracellular polymeric substances that can be degraded by dispersants. Currently, comparison of the strength of dispersants is not possible by lack of a suitable comparison parameter. Here, a biofilm dispersal parameter is proposed that accounts for differences in initial biofilm properties, dispersant concentration and exposure time by using PBS as a control and normalizing outcomes with respect to concentration and time. The parameter yielded near-identical values based on dispersant-induced reductions in biomass or biofilm colony-forming-units and appeared strain-dependent across pathogens. The parameter as proposed is largely independent of experimental methods and conditions and suitable for comparing different dispersants with respect to different causative strains in particular types of infection.

The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study.

To evaluate the influence of different preparation tapers on the reduction in planktonic bacteria and biofilms of Enterococcus faecalis and Candida albicans in the apical third (4 mm) of the mesial roots of mandibular molars, correlating decontamination with canal shape. After microtomography analysis for morphological standardization of the canals, 48 mandibular molar roots, each containing two canals (96 canals), were contaminated with E. faecalis and C. albicans and divided into four groups (n = 11) for canal instrumentation using ProDesign Logic 2 files with different tapers G (.03): # 25.03; G (.04): # 25.04; G (.05): # 25.05; and G (.06): # 25.06 and irrigation with 2.5% sodium hypochlorite. Four roots were examined under a scanning electron microscope (SEM) to qualitatively assess biofilm formation. Eight roots were used as the negative control group (samples were not contaminated). Bacteriological samples were taken exclusively from the apical third of the roots before and after chemical-mechanical preparation and bacterial counts were determined (CFU/mL). The final micro-CT scan was used to quantify the volume variation and unprepared canal area in the apical third. Statistical analysis was performed using the Kruskal-Wallis, Student-Newman-Keuls and Wilcoxon tests for analysis of microbiological data. anova and the Tukey or Games-Howell test were used for analysis of micro-CT data and Spearman's test for correlations (α = 5%). All groups showed a significant reduction in bacteria (p < .05), with no statistically significant difference between groups. There was no significant difference in per cent volume increase between groups. The unprepared area (Δ%) was affected by the file used (p = .026) and was significantly lower for G (.06) compared to G (.03). There was no statistically significant correlation among bacterial reduction, volume and unprepared area (p > .05). The different preparation tapers influenced root canal shaping in the apical third but did not improve decontamination in this region.

Imidazolium-Based Main-Chain Copolymers With Alternating Sequences for Broad-Spectrum Bactericidal Activity and Eradication of Bacterial Biofilms.

In response to the escalating challenge of bacterial drug resistance, the imperative to counteract planktonic cell proliferation and eliminate entrenched biofilms underscores the necessity for cationic polymeric antibacterials. However, limited efficacy and cytotoxicity challenge their practical use. Here, novel imidazolium-based main-chain copolymers with imidazolium (PIm+) as the cationic component are introduced. By adjusting precursor molecules, hydrophobicity and cationic density of each unit are fine-tuned, resulting in broad-spectrum bactericidal activity against clinically relevant pathogens. PIm+1 stands out for its potent antibacterial performance, with a minimum inhibitory concentration of 32µg mL-1 against Methicillin-resistant Staphylococcus aureus (MRSA), and substantial biofilm reduction in Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) biofilms. The bactericidal mechanism involves disrupting the outer and cytoplasmic membranes, depolarizing the cytoplasmic membrane, and triggering intracellular reactive oxygen species (ROS) generation. Collectively, this study postulates the potential of imidazolium-based main-chain copolymers, systematically tailored in their sequences, to serve as a promising candidate in combatting drug-resistant bacterial infections.

BolA promotes the generation of multicellular behavior in S. typhimurium by regulating the c-di-GMP pathway genes yeaJ and yhjH

The generation of multicellular behavior enhances the stress adaptability, antibiotic resistance, and pathogenic potential of Salmonella enterica serovar Typhimurium (S. typhimurium), which is challenging for its prevention and control. Therefore, determination of the mechanism of multicellular behavior development is urgently required. Accordingly, this study investigated BolA, a transcription factor that promotes bacterial survival under different stresses. We found that BolA promoted the generation of multicellular behavior. Furthermore, transcriptome analysis revealed that BolA affected the expression of numerous genes, including biofilm formation and motility-related genes. In terms of biofilm formation, compared with the wild-type strain, bolA overexpression (269BolA+) increased the extracellular matrix content (extracellular polysaccharide, extracellular protein, and extracellular DNA (eDNA) by upregulating gene expression, ultimately increasing the biofilm formation ability by 2.56 times. For motility, bolA overexpression inhibited the expression of flagella synthesis genes, resulting in a 91.15 % decrease in motility compared with the wild-type (6 h). Further mechanistic analysis demonstrated that BolA affected the expression of the C-di-GMP pathway genes yeaJ and yhjH, which influenced the generation of multicellular behavior. In terms of biofilms, the extracellular polysaccharide content of 269BolA + ∆Yeaj (bolA overexpression and yeaJ deletion) was reduced by 89.91 % compared with 269BolA+, resulting in a 71.1 % reduction in biofilm forming ability. The motility of the 269∆BolA∆Yhjh (bolA/yhjH double deletion) strain was significantly decreased compared with that of 269∆BolA. Finally, the LacZ gene reporting showed that BolA promoted and inhibited the expression of yeaJ and yhjH, respectively. In conclusion, BolA mainly improves the content of extracellular polysaccharide by promoting the expression of yeaJ, thus enhancing the formation of biofilms. BolA also restricts flagellar synthesis by inhibiting yhjH expression, therefore reducing motility, ultimately promoting multicellular behavior arises. These findings lay a theoretical foundation for the prevention and control of S. typhimurium.

Effectiveness of mechanical and chemical decontamination methods for the treatment of dental implant surfaces affected by peri-implantitis: A systematic review and meta-analysis.

To assess which decontamination method(s) used for the debridement of titanium surfaces (disks and dental implants) contaminated with bacterial, most efficiently eliminate bacterial biofilms. A systematic search was conducted in four electronic databases between January 1, 2010and October 31, 2022. The search strategy followed the PICOS format and included only in vitro studies completed on either dental implant or titanium disk samples. The assessed outcome variable consisted of the most effective method(s)-chemical or mechanical- removing bacterial biofilm from titanium surfaces. A meta-analysis was conducted, and data was summarized through single- and multi-level random effects model (p < .05). The initial search resulted in 5260 articles after the removal of duplicates. After assessment by title, abstract, and full-text review, a total of 13 articles met the inclusion criteria for this review. Different decontamination methods were assessed, including both mechanical and chemical, with the most common method across studies being chlorhexidine (CHX). Significant heterogeneity was noted across the included studies. The meta-analyses only identified a significant difference in biofilm reduction when CHX treatment was compared against PBS. The remaining comparisons did not identify significant differences between the various decontamination methods. The present results do not demonstrate that one method of decontamination is superior in eliminating bacterial biofilm from titanium disk and implant surfaces.