Pathogenic Biofilms Research Articles

Novel regimens of phytopolyphenols and celecoxib enhancing efficacy and selectivity of anticancer effects of chemotherapeutic agents on cultured cancer cells

Background/purposeExplorations of novel regimens enhancing efficacy and selectivity of chemotherapeutic agents are urgent to solve the problems of cancer therapy. This study aimed to explore synergistic anticancer effects of novel regimens of phytopolyphenols [curcumin (C), tea polyphenols (G) or GC] with celecoxib (Cl) and ZnSO4. Materials and methodsAntiproliferative effects of drugs on cultured cancer cells and pathogenic biofilms were assayed by MTT and optical density (OD600) respectively; their inhibition on efflux pump (Na+-K+-ATPase) was measured by colorimetric methods. Synergistic (CI < 1) anticancer effects were evaluated by the equations of combination index (CI) and efficacy index (EI). ResultsBoth Cl and methotrexate (MTX) alone exhibited inhibitory effects not only on proliferation and efflux pump of cultured cancer cells but also pathogenic biofilm formation. Phytopolyphenols (P) and MTX potentiated these inhibitory effects of Cl. In addition, novel regimens containing Cl, memantine (Mem) or thioridazine (TRZ) further enhanced not only efficacy and selectivity of anticancer effects but also inhibition on efflux pump and pathogenic biofilm formation of four chemotherapeutic agents (MTX, cisplatin, 5-fluorouracil and doxorubicin) respectively. ConclusionIn this study, novel regimens of phytopolyphenols (P), targeting drugs (T; Cl, Mem or TRZ) and metal ions (M; ZnSO4) so called PTM regimens exerted not only by themselves but also markedly potentiated efficacy and selectivity of anticancer effects of four chemotherapeutic agents. Because of their potent inhibitions on efflux pump and pathogenic biofilm formation, these combinatorial novel regimens were expected to be able to overcome the problems of multidrug resistant cancers and merit for further clinical studies.

Molecular Aspects of the Functioning of Pathogenic Bacteria Biofilm Based on Quorum Sensing (QS) Signal-Response System and Innovative Non-Antibiotic Strategies for Their Elimination.

One of the key mechanisms enabling bacterial cells to create biofilms and regulate crucial life functions in a global and highly synchronized way is a bacterial communication system called quorum sensing (QS). QS is a bacterial cell-to-cell communication process that depends on the bacterial population density and is mediated by small signalling molecules called autoinducers (AIs). In bacteria, QS controls the biofilm formation through the global regulation of gene expression involved in the extracellular polymeric matrix (EPS) synthesis, virulence factor production, stress tolerance and metabolic adaptation. Forming biofilm is one of the crucial mechanisms of bacterial antimicrobial resistance (AMR). A common feature of human pathogens is the ability to form biofilm, which poses a serious medical issue due to their high susceptibility to traditional antibiotics. Because QS is associated with virulence and biofilm formation, there is a belief that inhibition of QS activity called quorum quenching (QQ) may provide alternative therapeutic methods for treating microbial infections. This review summarises recent progress in biofilm research, focusing on the mechanisms by which biofilms, especially those formed by pathogenic bacteria, become resistant to antibiotic treatment. Subsequently, a potential alternative approach to QS inhibition highlighting innovative non-antibiotic strategies to control AMR and biofilm formation of pathogenic bacteria has been discussed.

Efficacy of 38% silver diamine fluoride in reducing gingival inflammation and plaque accumulation in older adults living in retirement-homes: A randomized controlled pilot trial

ObjectivesEmerging from earlier case reports the potential benefits of 38 % silver diamine fluoride (SDF) in addressing pathogenic biofilms and mitigating gingival inflammation and enlargement have sparked interest. Our study aimed to evaluate the efficacy of 38 % SDF in reducing gingival inflammation and plaque accumulation in older adults living in retirement-homes. MethodsThis 7-week randomized, controlled, double-blinded pilot trial employed a parallel assignment design. The study enrolled older adults (aged ≥65) residing in retirement homes in Dallas County, ultimately comprising a cohort of 40 participants who were evenly divided into two arms. The experimental group received SDF treatment, whereas the comparator group received a placebo. Over three consecutive weeks, both groups had solutions applied to the facial surfaces of all their teeth once per week. The primary outcomes measured the change in Löe-Silness Gingival Index (GI) and Silness-Löe Plaque Index (PI) at 7 weeks following baseline treatment. Repeated measures ANOVA was utilized to assess changes over time within each group (n = 15 each). Post-hoc paired t-tests were conducted to compare changes between week 1 and each subsequent follow-up time point (weeks 3, 5, 7), supplemented with 95 % confidence intervals for change from week 1. ResultsIn the SDF group, within-group comparisons demonstrated significant reductions (adjusted p < .05) in GI scores within 3 weeks (-.93±.37), as opposed to week 1 (1.90±.39). Between-group comparisons unveiled reductions in both mean GI (p < .05) and PI (p < .05), indicating less gingival inflammation and plaque accumulation in the SDF group at all time points, commencing at week 3. ConclusionsThis study showed that 38 % SDF was effective in reducing gingival inflammation and plaque accumulation in older adults living in retirement-homes. Clinical significanceOral health in older adults is a public health concern, especially for the medically compromised or those without traditional care. Our findings offer hope for enhancing oral health quality of life by introducing a cost-effective, compliance-free, noninvasive, and accessible therapeutic. Trial registrationNCT03445286.(clinicaltrials.gov)

Surface topography and chemistry of food contact substances, and microbial nutrition affect pathogen persistence and symbiosis in cocktail Listeria monocytogenes biofilms

The foodborne pathogen Listeria monocytogenes (L. monocytogenes) can form very persistent biofilms on food contact substances, either in monospecies, or in conjunction with background microflora. Although some studies have investigated how bacterial symbiosis facilitates L. monocytogenes survival in complex cocktail biofilms, very little is known about how this core symbiotic relationship is affected by environmental factors. Here, we investigate how L. monocytogenes persistence is affected by symbiosis with Escherichia coli O157:H7, Pseudomonas fluorescens, and Ralstonia insidiosa, and how these relationships are impacted by environmental factors, including food contact surface topography and chemistry, and microbial nutrition. We find that symbiosis can significantly enhance L. monocytogenes persistence in four-species cocktail biofilms (5.71 ± 0.03 Log CFU/cm2) by up to 1.9 Log CFU/cm2 compared to monospecies biofilms (3.81 ± 0.08 Log CFU/cm2). We also report that surface topography and chemistry, microbial nutrition, and symbiont species significantly impact the symbiotic relationships involving L. monocytogenes, revealing the adaptability of bacterial symbiosis to changing environmental conditions and the complex nature of cocktail pathogen biofilms. Antagonistic and synergistic interactions involving pathogens in cocktail biofilms, and factors affecting those interactions, are elucidated and can establish a foundation to study symbiosis and its role in mitigating pathogen persistence in food systems, and helping identify unanticipated increased food safety risks of pathogens due to enhanced persistence.

Impairment of Listeria monocytogenes biofilm developed on industrial surfaces by Latilactobacillus curvatus CRL1579 bacteriocin

The effect of lactocin AL705, bacteriocin produced by Latilactobacillus (Lat.) curvatus CRL1579 against Listeria biofilms on stainless steel (SS) and polytetrafluoroethylene (PTFE) coupons at 10 °C was investigated. L. monocytogenes FBUNT showed the greatest adhesion on both surfaces associated to the hydrophobicity of cell surface. Partially purified bacteriocin (800 UA/mL) effectively inhibited L. monocytogenes preformed biofilm through displacement strategy, reducing the pathogen by 5.54 ± 0.26 and 4.74 ± 0.05 log cycles at 3 and 6 days, respectively. The bacteriocin-producer decreased the pathogen biofilm by ∼2.84 log cycles. Control and Bac− treated samples reached cell counts of 7.05 ± 0.18 and 6.79 ± 0.06 log CFU/cm2 after 6 days of incubation. Confocal scanning laser microscopy (CLSM) allowed visualizing the inhibitory effect of lactocin AL705 on L. monocytogenes preformed biofilms under static and hydrodynamic flow conditions. A greater effect of the bacteriocin was found at 3 days independently of the surface matrix and pathogen growth conditions at 10 °C. As a more realistic approach, biofilm displacement strategy under continuous flow conditions showed a significant loss of biomass, mean thickness and substratum coverage of pathogen biofilm. These findings highlight the anti-biofilm capacity of lactocin AL705 and their potential application in food industries.

Strong Activity and No Resistance Induction Exerted by Cell-Free Supernatants from Lacticaseibacillus rhamnosus against Mono-Species and Dual-Species Biofilms of Wound Pathogens in In Vivo-like Conditions.

It is widely agreed that microbial biofilms play a major role in promoting infection and delaying healing of chronic wounds. In the era of microbial resistance, probiotic strains or their metabolic products are emerging as an innovative approach for the treatment of hard-to-heal (chronic) wounds due to their antimicrobial, healing, and host immune-modulatory effects. In this study, we aimed to investigate the potential of cell-free supernatants (CFS) from Lacticaseibacillus rhamnosus GG against mono- and dual-species biofilms of wound pathogens in a 3D in vitro infection model. Mature biofilms of Pseudomonas aeruginosa and Staphylococcus aureus were obtained on collagen scaffolds in the presence of a simulant wound fluid (SWF) and treated with CFS at different doses and time intervals. At 1:4 dilution in SWF, CFS caused a marked reduction in the colony forming-unit (CFU) numbers of bacteria embedded in mono-species biofilms as well as bacteria released by the biofilms in the supernatant. CFU count and electron microscopy imaging also demonstrated a marked antibiofilm effect against dual-species biofilms starting from 8 h of incubation. Furthermore, CFS exhibited acceptable levels of cytotoxicity at 24 h of incubation against HaCaT cells and, differently from ciprofloxacin, failed to induce resistance after 15 passages at sub-inhibitory concentrations. Overall, the results obtained point to L. rhamnosus GG postbiotics as a promising strategy for the treatment of wound biofilms.

Enterococcus mundtii A2 biofilm and its anti-adherence potential against pathogenic microorganisms on stainless steel 316L.

Pathogenic bacterial biofilms present significant challenges, particularly in food safety and material deterioration. Therefore, using Enterococcus mundtii A2, known for its antagonistic activity against pathogen adhesion, could serve as a novel strategy to reduce pathogenic colonization within the food sector. This study aimed to investigate the biofilm-forming ability of E. mundtii A2, isolated from camel milk, on two widely used stainless steels within the agri-food domain and to assess its anti-adhesive properties against various pathogens, especially on stainless steel 316L. Additionally, investigations into auto-aggregation and co-aggregation were also conducted. Plate count methodologies revealed increased biofilm formation by E. mundtii A2 on 316L, followed by 304L. Scanning electron microscopy (SEM) analysis revealed a dense yet thin biofilm layer, playing a critical role in reducing the adhesion of L. monocytogenes CECT 4032 and Staphylococcus aureus CECT 976, with a significant reduction of ≈ 2 Log CFU/cm2. However, Gram-negative strains, P. aeruginosa ATCC 27853 and E. coli ATCC 25922, exhibit modest adhesion reduction (~ 0.7 Log CFU/cm2). The findings demonstrate the potential of applying E. mundtii A2 biofilms as an effective strategy to reduce the adhesion and propagation of potentially pathogenic bacterial species on stainless steel 316L.

An In Vitro Comparative Evaluation of Conventional and Novel Thymus vulgaris Derived Herbal Disinfectant Solutions against Pathogenic Biofilm on Maxillofacial Silicones and Its Impact on Color Stability.

This study aims to assess the antimicrobial efficacy and impact on color stability of Thymus (T.) vulgaris solution compared to conventional disinfectants on maxillofacial silicones. Various solutions were evaluated, including T. vulgaris solutions at 5 and 10%, saline (control), chlorhexidine (4%), and soap water. The substrates were MDX4-4210 silicone elastomers, and the microorganisms tested were Candida (C.) albicans and Staphylococcus (S.) aureus. The viability of microorganisms was determined through an 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) reduction assay, and color stability was measured using a spectrophotometer with X-Rite Europe software. Statistical analysis was performed using the Kruskal-Wallis test, Mann-Whitney U post hoc test, and Wilcoxon Signed Rank test. Soap water demonstrated superior disinfectant action against both microorganisms, while T. vulgaris solutions at 5 and 10% exhibited comparable antimicrobial efficacy. Chlorhexidine and 10% T. vulgaris solution showed minimal color changes in the silicone material. In contrast, soap water and the 5% T. vulgaris solution resulted in clinically unacceptable color alterations. This study underscores the potential of T. vulgaris as an herbal disinfectant for combating microbial biofilms on maxillofacial silicones, particularly at concentrations of 5 and 10%. The importance of maintaining color stability is emphasized, with Chlorhexidine and the 10% T. vulgaris solution demonstrating effective preservation of esthetics. These findings suggest the viability of considering T. vulgaris as an alternative disinfectant in clinical settings for maxillofacial silicone prostheses. Maxillofacial silicones are vital in restoring aesthetic features for individuals with facial trauma, congenital deformities, or post-surgical interventions. Yet, biofilm-related infections jeopardize their durability and visual integrity. Clinically, T. vulgaris signifies a potential advance in prosthodontic care, offering valuable insights for improving antimicrobial performance and aesthetic durability in maxillofacial prostheses. How to cite this article: Peter M, Kanathila H, Bembalagi M, et al. An In Vitro Comparative Evaluation of Conventional and Novel Thymus vulgaris Derived Herbal Disinfectant Solutions against Pathogenic Biofilm on Maxillofacial Silicones and Its Impact on Color Stability. J Contemp Dent Pract 2023;24(12):967-973.

Efficacy of Cold Atmospheric Plasma on Pathogenicity of Oral Microcosm Biofilms

This study aimed to compare the longitudinal efficacy between chlorhexidine gluconate (CHX; 0.12%) and cold atmospheric plasma (CAP) in reducing oral biofilm pathogenicity, utilizing a quantitative light-induced fluorescence-digital (QLF-D) camera. Oral microcosm biofilms were developed for 2 days on 57 hydroxyapatite disks. These biofilms were treated with distilled water for 1 min, CHX for 1 min, and CAP for 2 min over the course of 6 days. The red fluorescence intensities of the biofilms were measured using a QLF-D and expressed as pre- and post-treatment red/green ratios (RatioR/G). The bacterial viability (ratio of the green-stained area to the total stained area, RatioG/G+R) was calculated using live/dead bacterial staining; the total and aciduric bacterial counts were determined. A significant intergroup difference was found between RatioR/G changes according to the treatment period (p &lt; 0.001). The RatioR/G observed within the CAP-treated group was significantly lower compared with the CHX-treated group at every interval of measurement (p &lt; 0.001). The CAP-treated group also exhibited a lower RatioG/G+R and more weakened bacterial aggregation compared with the CHX-treated group (p &lt; 0.05). In the group treated with CAP, the counts of both total and aciduric bacteria were substantially reduced compared with the DW group, with a statistically significant reduction (p &lt; 0.001). Therefore, CAP may be more effective in minimizing oral microcosm biofilm pathogenicity than 0.12% CHX.

LACTIC ACID BACTERIA AND FERMENTED MAIZE SUPERNATANT (Omidun) HAVE ANTI-BIOFILM PROPERTIES AGAINST STAPHYLOCOCCI AND ENTEROAGGREGATIVE Escherichia coli STRAINS

Bacterial infections caused by biofilm forming organisms are of public health concern due to their propensity to contribute to persistent chronic diseases, chiefly because of their ability to resist antibiotics and host immune functions. Probiotics are considered useful therapeutic option in combating pathogenic biofilms. This study evaluates the anti-biofilm properties of potential probiotic Lactic Acid Bacteria (LAB) and fermented maize supernatant (Omidun) against selected biofilm-forming pathogens. Crystal violet biofilm assay was used to determine LAB and Omidun biofilm inhibition and dispersion in selected pathogens (Pseudomonas aeruginosa, Coagulase-negative staphylococci (CoNS), S. aureu and Enteroaggregative Escherichia coli) at different concentration (1%, 10%, 50%, 100%) of neutralized and non-neutralized cell free supernatant (CFS). Percentage biofilm inhibitions and dispersions were evaluated, and data were analysed with ANOVA. Omidun and LAB showed promising biofilm inhibitory and dispersive effect against the selected pathogens. L. plantarum showed the greatest biofilm inhibitory effect (P. aeruginosa: 7.85%, CoNS: 27.75%, S. aureus: 66.90%, EAEC: 39.73%) and dispersive effect (P. aeruginosa: 15.94%, CoNS: 23.27%, S. aureus: 24.90%, EAEC: 32.09%) against the selected pathogens while Omidun showed the least biofilm inhibitory and dispersive effect against the selected pathogens. There was no significance difference in the percentage of biofilm inhibition and dispersion produced under different concentrations, neutralized and non-neutralized state. Pseudomonas aeruginosa was the most resistant pathogen while Enteroaggregative Escherichia coli (EAEC) was the most susceptible. Inhibition and dispersion of biofilm can be mediated by LAB and Omidun, these effects appear to be independent of the produced organic acids

Development of a PVA/PCL/CS-Based Nanofibrous Membrane for Guided Tissue Regeneration and Controlled Delivery of Doxycycline Hydrochloride in Management of Periodontitis: InVivo Evaluation in Rats

Antibiotic administration is an adjacent therapy to guided tissue regeneration (GTR) in the management of periodontitis. This is due to the major role of pathogen biofilm in aggravating periodontal defects. This study aimed to fabricate a GTR membrane for sustained delivery of doxycycline hydrochloride (DOX) while having a space-maintaining function. The membranes were prepared using a polymeric blend of polycaprolactone/polyvinyl alcohol/chitosan by the electrospinning technique. The obtained membranes were characterized in terms of physicochemical and biological properties. Nanofibers showed a mean diameter in the submicron range of < 450 nm while having uniform randomly aligned morphology. The obtained membranes showed high strength and flexibility. A prolonged in vitro release profile during 68 h was observed for manufactured formulations. The prepared membranes showed a cell viability of > 70% at different DOX concentrations. The formulations possessed antimicrobial efficacy against common pathogens responsible for periodontitis. In vivo evaluation also showed prolonged release of DOX for 14 days. The histopathological evaluation confirmed the biocompatibility of the GTR membrane. In conclusion, the developed nanofibrous DOX-loaded GTR membranes may have beneficial characteristics in favour of both sustained antibiotic delivery and periodontal regeneration by space-maintaining function without causing any irritation and tissue damage.

Abietic Acid as a Novel Agent against Ocular Biofilms: An In Vitro and Preliminary In Vivo Investigation.

Biofilm-related ocular infections can lead to vision loss and are difficult to treat with antibiotics due to challenges with application and increasing microbial resistance. In turn, the design and testing of new synthetic drugs is a time- and cost-consuming process. Therefore, in this work, for the first time, we assessed the in vitro efficacy of the plant-based abietic acid molecule, both alone and when introduced to a polymeric cellulose carrier, against biofilms formed by Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans in standard laboratory settings as well as in a self-designed setting using the topologically challenging surface of the artificial eye. These analyses were performed using the standard microdilution method, the biofilm-oriented antiseptic test (BOAT), a modified disk-diffusion method, and eyeball models. Additionally, we assessed the cytotoxicity of abietic acid against eukaryotic cell lines and its anti-staphylococcal efficacy in an in vivo model using Galleria mellonella larvae. We found that abietic acid was more effective against Staphylococcus than Pseudomonas (from two to four times, depending on the test applied) and that it was generally more effective against the tested bacteria (up to four times) than against the fungus C. albicans at concentrations non-cytotoxic to the eukaryotic cell lines and to G. mellonella (256 and 512 µg/mL, respectively). In the in vivo infection model, abietic acid effectively prevented the spread of staphylococcus throughout the larvae organisms, decreasing their lethality by up to 50%. These initial results obtained indicate promising features of abietic acid, which may potentially be applied to treat ocular infections caused by pathogenic biofilms, with higher efficiency manifested against bacterial than fungal biofilms.

Antibiofilm Activity of Eugenol-Loaded Chitosan Coatings against Common Medical-Device-Contaminating Bacteria.

The formation of pathogenic biofilms on medical devices is a major public health concern accounting for over 65% of healthcare-associated infections and causing high infection morbidity, mortality, and a great burden to patients and the healthcare system due to its resistance to treatment. In this study, we developed a chitosan-based antimicrobial coating with embedded mesoporous silica nanoparticles (MSNs) to load and deliver eugenol, an essential oil component, to inhibit the biofilm formation of common bacteria in medical-device-related infections. The eugenol-loaded MSNs were dispersed in a chitosan solution, which was then cross-linked with glutaraldehyde and drop-casted to obtain coatings. The MSNs and coatings were characterized by dynamic light scattering, Brunauer-Emmett-Teller analysis, attenuated-total-reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, 3D optical profilometry, and scanning electron microscopy. The release behavior of eugenol-loaded MSNs and coatings and the antibiofilm and antimicrobial activity of the coatings against adherent Staphylococcus aureus, methicillin-resistant S. aureus, and Pseudomonas aeruginosa were investigated. Eugenol was released from the MSNs and coatings in aqueous conditions in a controlled manner with an initial low release, followed by a peak release, a decrease, and a plateau. While the chitosan coatings alone or with unloaded MSNs demonstrated limited antimicrobial effects and still supported biofilm formation after 24 h, the coating containing eugenol not only reduced biofilm formation but also killed the majority of the attached bacteria. It also showed biocompatibility in indirect contact with NIH/3T3 fibroblasts and a high percentage of live cells in direct contact. However, further investigations into cell proliferation in direct contact are recommended. The findings indicated that the chitosan-based coating with eugenol-loaded MSNs could be developed into an effective strategy to inhibit biofilm formation on medical devices.

Electrochemical Characterization of Two Gut Microbial Strains Cooperatively Promoting Multiple Sclerosis Pathogenesis.

In this study, we explored the extracellular electron transfer (EET) capabilities of two bacterial strains, OTU0001 and OTU0002, which are demonstrated in biofilm formation in mouse gut and the induction of autoimmune diseases like multiple sclerosis. OTU0002 displayed significant electrogenic behaviour, producing microbial current on an indium tin-doped oxide electrode surface, particularly in the presence of glucose, with a current density of 60 nA/cm2. The presence of cell-surface redox substrate potentially mediating EET was revealed by the redox-based staining method and electrochemical voltammetry assay. However, medium swapping analyses and the addition of flavins, a model redox mediator, suggest that the current production is dominated by soluble endogenous redox substrates in OTU0002. Given redox substrates were detected at the cell surface, the secreted redox molecule may interact with the cellular surface of OTU0002. In contrast to OTU0002, OTU0001 did not exhibit notable electrochemical activity, lacking cell-surface redox molecules. Further, the mixture of the two strains did not increase the current production from OTU0001, suggesting that OTU0001 does not support the EET mechanism of OTU0002. The present work revealed the coexistence of EET and non-EET capable pathogens in multi-species biofilm.

Microbial colonization and chemically influenced selective enrichment of bacterial pathogens on polycarbonate plastic.

Plastic pollution in aquatic environments poses significant concerns due to its potential to serve as a refuge for aquatic pathogens. However, the role of plastic surfaces and microbial biofilm interfaces in facilitating pathogen development remains poorly understood. In this study, a microcosm setup was employed to investigate the interactions between plastics and the microbial community and examine the differences in bacterial community composition and potential pathogen occurrences between the plastisphere-biofilm and surrounding seawater. Community composition analysis combined with SEM observations over time indicated that biofilm extracellular polymeric substance formation over 14 days had a link with the relative abundance and succession patterns of pathogen taxa. Colony clusters were observed on biofilms from day 7 and coincided with higher bacterial pathogen dominance. On day 14, pathogen abundance overall decreased with a potentially degrading biofilm. Pseudomonas and Pseudoalteromonas were the dominant potential pathogen groups observed in the microcosm. When further subjected to chemical treatment as an imposed environmental stress over time, biofilm-associated Psuedoalteromonas sharply increased in abundance after three days of exposure, but quickly diminished by 14days in favor of genera such as Acinetobacter, Pseudomonas, and Staphylococcus. These results suggest that environmental plastisphere-biofilms can promote the early selection, enrichment, and spread of pathogenic bacteria in the aquatic environment and could be later worsened under chemical and long-term pressure. This study provided new insights into the succession of pathogens in plastisphere biofilms, contributing to the understanding of pathogen risks involved in emerging plastisphere biofilms in light of global plastic pollution.

Multiple biological characteristics and functions of intestinal biofilm extracellular polymers: friend or foe?

The gut microbiota is vital to human health, and their biofilms significantly impact intestinal immunity and the maintenance of microbial balance. Certain pathogens, however, can employ biofilms to elude identification by the immune system and medical therapy, resulting in intestinal diseases. The biofilm is formed by extracellular polymorphic substances (EPS), which shield microbial pathogens from the host immune system and enhance its antimicrobial resistance. Therefore, investigating the impact of extracellular polysaccharides released by pathogens that form biofilms on virulence and defence mechanisms is crucial. In this review, we provide a comprehensive overview of current pathogenic biofilm research, deal with the role of extracellular polymers in the formation and maintenance of pathogenic biofilm, and elaborate different prevention and treatment strategies to provide an innovative approach to the treatment of intestinal pathogen-based diseases.

Potential Activities of Centella asiatica Leaf Extract against Pathogenic Bacteria-Associated Biofilms and Its Anti-Inflammatory Effects.

The medicinal value of Centella asiatica leaf extract was evaluated as an alternative treatment. The chemical composition of the leaf extract was analyzed, and the biological activities were determined. High-performance liquid chromatography coupled with a photodiode array detector (HPLC-PDA) was used to identify the asiatic acid, madasiatic acid, and madecassic acid/Brahmic acid isolated from the ethanolic extract. The plant extract at 25 mg/disk was found to inhibit both Gram-positive and Gram-negative pathogenic bacteria by the agar disk diffusion test. The MIC and MBC of the ethanolic extracts were better than those of the aqueous extracts. The ethanolic extracts showed antibacterial activity against Gram-positive bacteria with MICs and MBCs ranging from 1.024 to 2.048 mg/mL and 2.048 to 4.096 mg/mL, respectively. The remarkable antibacterial activities were observed against S. mutans. The ethanolic extract at a concentration of 1/2 × MIC exhibited the inhibition effect on S. mutans biofilm formation like the activity of 0.2% chlorhexidine and significantly modified hydrophobicity of the bacterial cell surface. The effects were confirmed via molecular docking analysis. The binding affinities of asiatic acid, madecassic acid, and madasiatic acid with glucosyltransferase C (GtfC) of S. mutans exhibited superior strength in comparison with alpha-acarbose and chlorhexidine. Moreover, the nitric oxide (NO) secretion of RAW247.6 cells was determined after treating the cells with concentrations of the extract. The C. asiatica ethanolic extract can inhibit the secretion of NO, which can inhibit the inflammatory process. The findings indicate the applications of the C. asiatica ethanolic extract as the alternative anti-S. mutans agent and could be used for further formulation for the treatment and prevention of dental diseases and inflammatory injury in the oral cavity.

The effects of antimicrobial peptides buCaTHL4B and Im-4 on infectious root canal biofilms.

The primary cause of pulp and periapical diseases is the invasion of bacteria into the root canal, which results from the continuous destruction of dental hard tissues. Effective management of infections during root canal therapy necessitates effectively irrigation. This study aims to investigate the effects of two antimicrobial peptides (AMPs), buCaTHL4B and Im-4, on root canal biofilms in vitro. Two-species biofilms (Enterococcus faecalis and Fusobacterium nucleatum) were selected and anaerobically cultivated. The following treatments were applied: 10μg/mL buCaTHL4B, 10μg/mL Im-4, 5μg/mL buCaTHL4B, 5μg/mL Im-4, 1μg/mL buCaTHL4B, 1μg/mL Im-4, 1% NaOCl, and sterile water. Each group was treated for 3min. Subsequently, the two strains were co-cultured with 10μg/mL buCaTHL4B, 10μg/mL Im-4, 1% NaOCl, and sterile water for 24, 48, and 72h. The biofilms were examined using confocal laser scanning microscopy (CLSM) with fluorescent staining, and the percentages of dead bacteria were calculated. Quantitative real-time PCR (qRT-PCR) was employed to assess the variations in bacterial proportions during biofilm formation. Compared to 1% NaOCl, 10μg/mL buCaTHL4B or Im-4 exhibited significantly greater bactericidal effects on the two-species biofilms (p < 0.05), leading to their selection for subsequent experiments. Over a 48-hour period, 10μg/mL Im-4 demonstrated a stronger antibiofilm effect than buCaTHL4B (p < 0.05). Following a 24-hour biofilm formation period, the proportion of F. nucleatum decreased while the proportion of E. faecalis increased in the sterile water group. In the buCaTHL4B and 1% NaOCl groups, the proportion of F. nucleatum was lower than that of E. faecalis (p < 0.05), whereas in the Im-4 group, the proportion of F. nucleatum was higher than that of E. faecalis (p < 0.05). The proportions of bacteria in the two AMPs groups gradually stabilized after 24h of treatment. buCaTHL4B and Im-4 exhibited remarkable antibacterial and anti-biofilm capabilities against pathogenic root canal biofilms in vitro, indicating their potential as promising additives to optimize the effectiveness of root canal treatment as alternative irrigants.

Genotypic investigation of drugs resistance and biofilm genes among ciprofloxacin-resistant Pseudomonas aeruginosa isolated from burn patients

Burn patients are the serious targets of hospital-acquired infection occurred by Pseudomonas aeruginosa ( P. aeruginosa) , which is a main cause of burn patients morbidity and mortality, so this study aimed to molecular investigation of genes associated with antibiotic resistance among ciprofloxacin-resistant Pseudomonas aeruginosa. Current study involved 168 burn patients involved 107(63.69%) and 61 (36.3%) were females and male respectively, the results showed 132(78.57%) gram negative bacteria and 27(16.0%) gram positive bacteria while 9(5.3%) no bacterial growth. The results of Vitek-2 compact system recorded 75(44.64%) as P. aeruginosa isolates. Results of ciprofloxacin susceptibility showed 29(38.67%), while 34(45.33%) and 12(16%) of isolates were intermediate and sensitive respectively. Congo red agar assay was applied in current study for qualitative evaluation of pathogenic biofilm were 23/29 (79.31%), and 6/26(20.86%) as high, and moderate biofilm producer among isolates respectively. Result of Polymerase chain reaction (PCR) showed that gyrB was recorded among ciprofloxacin-resistant P. aeruginosa at rate 28/29 (96.55%). At same respect. results of efflux pump genes for oqxA and oqxB genes were detected among this pathogen at rate 26/29 (89.65%) and 29/29(100%) respectively. outer membrane genes, revealed that mexR gene was 27/29 (93.1%), while the spreading of the oprD gene was 26/29(89.65%). Results of molecular detection about colistin resistance genes revealed that the mcr-3 gene was 8/29 (27.58%), but genes of mcr-1 and mcr-2 were no detected in this work, Finally, results showed that 23/29 (79.31%) of ciprofloxacin-resistant P. aeruginosa were harbored pml gene.

Sustainable deployment of host defense peptides for targeted quorum sensing inhibition

The intriguing fact is that exploration of Host Defense Peptides (HDPs), usually known as antimicrobial peptides, has become increasing because of their multifaceted nature, which makes them extremely important for immunity and possible medication. HDPs are short peptides which are produced by the human body as well as other organisms and part of the immune system of the organism that is where they play an essential role. The peptides flexibly promote the antimicrobial resistance to different bacteria, fungi, viruses, and parasites. The main mechanisms work via microorganism cell membrane disruption, perturbation of nucleic acid synthesis, and modulation of the immune response. It is important to mention that the application of HDPs is a fleeting remedy to antibiotics counteracting the development of antibiotics resistance. The fact that they can attack the pathogenic biofilms which are particularly difficult target of conventional therapeutics is undoubtedly additional benefit of using biophotons for clinical purposes – they would be highly helpful in the therapy of chronic diseases and wound healing. HDPs’ sustainability is reinforced by its biodegradability and practically no environmental impacts compared to pharmaceuticals based on the chemical elements that is the major concern in the medical sphere nowadays. Their diverse functions and the respective efficacy against resistant strains are very much active research activities right now, thereby making clear the role of these probiotics in addressing the present and future health hurdles.