Biofilm Formation Of Pathogens Research Articles

Evaluating the effects of temperature and agitation on biofilm formation of bacterial pathogens isolated from raw cow milk

ObjectivesTo study the effect of agitation and temperature on biofilm formation (cell aggregates embedded within a self-produced matrix) by pathogenic bacteria isolated from Raw cow milk (RCM).MethodsA 40 RCM samples were gathered from eight dairy farms in Riyadh, Saudi Arabia. After bacterial culturing and isolation, gram staining was performed, and all pathogenic, identified using standard criteria established by Food Standards Australia New Zealand (FSANZ), and non-pathogenic bacteria were identified using VITEK-2 and biochemical assays. To evaluate the effects of temperature and agitation on biofilm formation, isolated pathogenic bacteria were incubated for 24 h under the following conditions: 4 °C with no agitation (0 rpm), 15 °C with no agitation, 30 °C with no agitation, 30 °C with 60 rpm agitation, and 30 °C with 120 rpm agitation. Then, biofilms were measured using a crystal violet assay.ResultsOf the eight farm sites, three exhibited non-pathogenic bacterial contamination in their raw milk samples. Of the total of 40 raw milk samples, 15/40 (37.5%; from five farms) were contaminated with pathogenic bacteria. Overall, 346 bacteria were isolated from the 40 samples, with 329/346 (95.1%) considered as non-pathogenic and 17/346 (4.9%) as pathogenic. Most of the isolated pathogenic bacteria exhibited a significant (p < 0.01) increase in biofilm formation when grown at 30 °C compared to 4 °C and when grown with 120 rpm agitation compared to 0 rpm.ConclusionHerein, we highlight the practices of consumers in terms of transporting and storing (temperature and agitation) can significantly impact on the growth of pathogens and biofilm formation in RCM.

Medical Device-Associated Infections Caused by Biofilm-Forming Microbial Pathogens and Controlling Strategies.

Hospital-acquired infections, also known as nosocomial infections, include bloodstream infections, surgical site infections, skin and soft tissue infections, respiratory tract infections, and urinary tract infections. According to reports, Gram-positive and Gram-negative pathogenic bacteria account for up to 70% of nosocomial infections in intensive care unit (ICU) patients. Biofilm production is a main virulence mechanism and a distinguishing feature of bacterial pathogens. Most bacterial pathogens develop biofilms at the solid-liquid and air-liquid interfaces. An essential requirement for biofilm production is the presence of a conditioning film. A conditioning film provides the first surface on which bacteria can adhere and fosters the growth of biofilms by creating a favorable environment. The conditioning film improves microbial adherence by delivering chemical signals or generating microenvironments. Microorganisms use this coating as a nutrient source. The film gathers both inorganic and organic substances from its surroundings, or these substances are generated by microbes in the film. These nutrients boost the initial growth of the adhering bacteria and facilitate biofilm formation by acting as a food source. Coatings with combined antibacterial efficacy and antifouling properties provide further benefits by preventing dead cells and debris from adhering to the surfaces. In the present review, we address numerous pathogenic microbes that form biofilms on the surfaces of biomedical devices. In addition, we explore several efficient smart antiadhesive coatings on the surfaces of biomedical device-relevant materials that manage nosocomial infections caused by biofilm-forming microbial pathogens.

Modern Microbiological Methods to Detect Biofilm Formation in Orthopedy and Suggestions for Antibiotic Therapy, with Particular Emphasis on Prosthetic Joint Infection (PJI).

Biofilm formation is a serious problem that relatively often causes complications in orthopedic surgery. Biofilm-forming pathogens invade implanted foreign bodies and surrounding tissues. Such a condition, if not limited at the appropriate time, often requires reoperation. This can be partially prevented by selecting an appropriate prosthesis material that prevents the development of biofilm. There are many modern techniques available to detect the formed biofilm. By applying them we can identify and visualize biofilm-forming microorganisms. The most common etiological factors associated with biofilms in orthopedics are: Staphylococcus aureus, coagulase-negative Staphylococci (CoNS), and Enterococcus spp., whereas Gram-negative bacilli and Candida spp. also deserve attention. It seems crucial, for therapeutic success, to eradicate the microorganisms able to form biofilm after the implantation of endoprostheses. Planning the effective targeted antimicrobial treatment of postoperative infections requires accurate identification of the microorganism responsible for the complications of the procedure. The modern microbiological testing techniques described in this article show the diagnostic options that can be followed to enable the implementation of effective treatment.

Antifungal, anti-biofilm, and anti-hyphal properties of N-substituted phthalimide derivatives against Candida species.

Candida species comprise a ubiquitous pathogenic fungal genus responsible for causing candidiasis. They are one of the primary causatives of several mucosal and systemic infections in humans and can survive in various environments. In this study, we investigated the antifungal, anti-biofilm, and anti-hyphal effects of six N-substituted phthalimides against three Candida species. Of the derivatives, N-butylphthalimide (NBP) was the most potent, with a minimum inhibitory concentration (MIC) of 100 µg/ml and which dose-dependently inhibited biofilm at sub-inhibitory concentrations (10-50 µg/ml) in both the fluconazole-resistant and fluconazole-sensitive Candida albicans and Candida parapsilosis. NBP also effectively inhibited biofilm formation in other pathogens including uropathogenic Escherichia coli, Staphylococcus epidermidis, Staphylococcus aureus, and Vibrio parahaemolyticus, along with the polymicrobial biofilms of S. epidermidis and C. albicans. NBP markedly inhibited the hyphal formation and cell aggregation of C. albicans and altered its colony morphology in a dose-dependent manner. Gene expression analysis showed that NBP significantly downregulated the expression of important hyphal- and biofilm-associated genes, i.e., ECE1, HWP1, and UME6, upon treatment. NBP also exhibited mild toxicity at concentrations ranging from 2 to 20 µg/ml in a nematode model. Therefore, this study suggests that NBP has anti-biofilm and antifungal potential against various Candida strains.

Lactobacillus acidophilus VB1 co-aggregates and inhibits biofilm formation of chronic otitis media-associated pathogens

This study aims to evaluate the antibacterial activity of Lactobacillus acidophilus, alone and in combination with ciprofloxacin, against otitis media-associated bacteria. L. acidophilus cells were isolated from Vitalactic B (VB), a commercially available probiotic product containing two lactobacilli species, L. acidophilus and Lactiplantibacillus (formerly Lactobacillus) plantarum. The pathogenic bacterial samples were provided by Al-Shams Medical Laboratory (Baqubah, Iraq). Bacterial identification and antibiotic susceptibility testing for 16 antibiotics were performed using the VITEK2 system. The minimum inhibitory concentration of ciprofloxacin was also determined. The antimicrobial activity of L. acidophilus VB1 cell-free supernatant (La-CFS) was evaluated alone and in combination with ciprofloxacin using a checkerboard assay. Our data showed significant differences in the synergistic activity when La-CFS was combined with ciprofloxacin, in comparison to the use of each compound alone, against Pseudomonas aeruginosa SM17 and Proteus mirabilis SM42. However, an antagonistic effect was observed for the combination against Staphylococcus aureus SM23 and Klebsiella pneumoniae SM9. L. acidophilus VB1 was shown to significantly co-aggregate with the pathogenic bacteria, and the highest co-aggregation percentage was observed after 24 h of incubation. The anti-biofilm activities of CFS and biosurfactant (BS) of L. acidophilus VB1 were evaluated, and we found that the minimum biofilm inhibitory concentration that inhibits 50% of bacterial biofilm (MBIC50) of La-CFS was significantly lower than MBIC50 of La-BS against the tested pathogenic bacterial species. Lactobacillus acidophilus, isolated from Vitane Vitalactic B capsules, demonstrated promising antibacterial and anti-biofilm activities against otitis media pathogens, highlighting its potential as an effective complementary/alternative therapeutic strategy to control bacterial ear infections.

Tracking success of interaction of green-synthesized Carbopol nanoemulgel (neomycin-decorated Ag/ZnO nanocomposite) with wound-based MDR bacteria

Abstract Multidrug-resistant wound infections are a global health threat and a leading cause of death, persisting despite available treatments due to antibiotic resistance, biofilms, and ineffective drug delivery systems. The aim of this study is to (i) formulate an innovative nano-drug delivery system (NDDS) based on a Carbopol nanoemulgel (NEG) co-loaded with neomycin-silver/zinc oxide nanocomposite (NC) that could fight clinical MDR and treat biofilm-forming wound pathogens through topical application, and (ii) assess its in vivo wound-healing potential. The silver/zinc oxide (Ag/ZnO) NC was synthesized by co-inoculating the metabolites of Aspergillus welwitschiae and Meyerozyma guilliermondii. The synthesized NC was then conjugated with neomycin and loaded into a Carbopol NEG for efficient topical delivery. The resulting Neo-Ag/ZnO NEG was characterized physicochemically (e.g., UV-visible [UV-Vis] spectrophotometry, field emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared [FTIR] spectroscopy), biologically (e.g., in vitro antimicrobial, antibiofilm, and hemolytic activities), and pharmacologically (e.g., drug content, ex vivo drug release behavior, and in vivo wound-healing potential). The physicochemical analysis confirmed the successful mycosynthesis of the Carbopol NEG-loaded Neo-Ag/ZnO NC. SEM depicted a crystalline polyhedral shape of the small NC (average particle size of 38 nm). FTIR studies showed a slight interaction with the drug and other bioactive moieties in the Carbopol NEG. The Neo content in the Carbopol NEG was as high as 98%, and a maximum release of 81% for Neo, Ag, and ZnO ions was noticed after 12 h. The NDDS appeared hemocompatible and displayed a minimal inhibition concentration of 0.002 µg/mL with the greatest antimicrobial potential against S. aureus (an inhibition zone of 46 mm) compared to other tested wound microbes (p &lt; 0.05). Statistically significant wound-healing activity was found for NDDS (p = 0.0001) in comparison to the control at a concentration of 100 mg/mL. The results showed that this newly developed Carbopol NEG-loaded neo-Ag/ZnO NC appeared promising for controlling resistant skin infections and boosting wound regeneration.

Extracellular host DNA contributes to pathogenic biofilm formation during periodontitis.

Periodontal diseases are known to be associated with polymicrobial biofilms and inflammasome activation. A deeper understanding of the subgingival cytological (micro) landscape, the role of extracellular DNA (eDNA) during periodontitis, and contribution of the host immune eDNA to inflammasome persistence, may improve our understanding of the mechanisms underlaying severe forms of periodontitis. In this work, subgingival biolfilms developing on biologically neutral polyethylene terephthalate films placed in gingival cavities of patients with chronic periodontitis were investigated by confocal laser scanning microscopy (CLSM). This allowed examination of realistic cytological landscapes and visualization of extracellular polymeric substances (EPS) including amyloids, total proteins, carbohydrates and eDNA, as well as comparison with several single-strain in vitro model biofilms produced by oral pathogens such as Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus gordonii, S. sanguinis and S. mitis. Fluorescence in situ hybridization (FISH) analysis was also used to identify eDNA derived from eubacteria, streptococci and members of the Bacteroides-Porphyromonas-Prevotella (BPP) group associated with periodontitis. Analysis of subgingival biofilm EPS revealed low levels of amyloids and high levels of eDNA which appears to be the main matrix component. However, bacterial eDNA contributed less than a third of the total eDNA observed, suggesting that host-derived eDNA released in neutrophil extracellular traps may be of more importance in the development of biofilms causing periodontitis. eDNA derived from host immunocompetent cells activated at the onset of periodontitis may therefore be a major driver of bacterial persistence and pathogenesis.

A survey of multiple candidate probiotic bacteria reveals specificity in the ability to modify the effects of key wound pathogens.

We have evaluated the inhibitory effects of supernatants and lysates derived from several candidate probiotics, on the growth and biofilm formation of wound pathogens, and their ability to protect human primary epidermal keratinocytes from the toxic effects of pathogens. Supernatants (neutralized and non-neutralized) and lysates (via sonication) from Lactiplantibacillus plantarum, Limosilactobacillus reuteri, Bifidobacterium longum, Lacticaseibacillus rhamnosus GG, and Escherichia coli Nissle 1917 were tested for their inhibitory effects against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumanni. The supernatants of L. plantarum, L. rhamnosus, B. longum, and L. rhamnosus GG reduced the growth of S. aureus, E. coli, and A. baumanni. B. longum additionally inhibited P. aeruginosa growth. However, neutralized Lactobacillus supernatants did not inhibit growth and in some cases were stimulatory. Lysates of L. plantarum and L. reuteri inhibited S. pyogenes while B. longum lysates inhibited E. coli and S. aureus growth. E. coli Nissle 1917 lysates enhanced the growth of S. pyogenes and P. aeruginosa. Biofilm formation by E. coli was reduced by lysates of L. reuteri and neutralized supernatants of all candidate probiotics. P. aeruginosa biofilm formation was reduced by E. coli Nissle supernatant but increased by L. plantarum, L. reuteri, and Bifidobacterium longum lysates. L. reuteri decreased the toxic effects of S. aureus on keratinocytes while E. coli Nissle 1917 lysates protected keratinocytes from S. pyogenes toxicity. In conclusion, lactobacilli and E. coli Nissle lysates confer inhibitory effects on pathogenic growth independently of acidification and may beneficially alter the outcome of interactions between host cell-pathogen in a species-specific manner.IMPORTANCEOne of the attributes of probiotics is their ability to inhibit pathogens. For this reason, many lactobacilli have been investigated for their effects as potential topical therapeutics against skin pathogens. However, this field is in its infancy. Even though probiotics are known to be safe when taken orally, the potential safety concerns when applied to potentially compromised skin are unknown. For this reason, we believe that extracts of probiotics will offer advantages over the use of live bacteria. In this study, we have surveyed five candidate probiotics, when used as extracts, in terms of their effects against common wound pathogens. Our data demonstrate that some probiotic extracts promote the growth of pathogens and highlight the need for careful selection of species and strains when probiotics are to be used topically.

Biogenic Synthesis of Selenium and Copper Oxide Nanoparticles and Inhibitory Effect against Multi-Drug Resistant Biofilm-Forming Bacterial Pathogens.

Antimicrobial resistance (AMR), caused by microbial infections, has become a major contributor to morbid rates of mortality worldwide and a serious threat to public health. The exponential increase in resistant pathogen strains including Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) poses significant hurdles in the health sector due to their greater resistance to traditional treatments and medicines. Efforts to tackle infectious diseases caused by resistant microbes have prompted the development of novel antibacterial agents. Herein, we present selenium and copper oxide monometallic nanoparticles (Se-MMNPs and CuO-MMNPs), characterized using various techniques and evaluated for their antibacterial potential via disc diffusion, determination of minimum inhibitory concentration (MIC), antibiofilm, and killing kinetic action. Dynamic light scattering (DLS), scanning electron microscopy (SEM/EDX), and X-ray diffraction (XRD) techniques confirmed the size-distribution, spherical-shape, stability, elemental composition, and structural aspects of the synthesized nanoparticles. The MIC values of Se-MMNPs and CuO-MMNPs against S. aureus and E. coli were determined to be 125 μg/mL and 100 μg/mL, respectively. Time-kill kinetics studies revealed that CuO-MMNPs efficiently mitigate the growth of S. aureus and E. coli within 3 and 3.5 h while Se-MMNPs took 4 and 5 h, respectively. Moreover, CuO-MMNPs demonstrated better inhibition compared to Se-MMNPs. Overall, the proposed materials exhibited promising antibacterial activity against S. aureus and E. coli pathogens.

The optimization of in situ exopolysaccharides production in Lactobacillus helveticus MB2-1 fermented milk and its functional characteristics in vitro

In order to improve the in situ exopolysaccharides (EPS) production of Lactobacillus helveticus MB2-1 fermented milk and explore its functional characteristics, the production optimization conditions, structural characteristics of fermented milk, emulsifying properties, antioxidant, and antibiofilm activities of in situ produced EPS were investigated. The fermentation conditions were optimized using response surface methodology. When the optimal temperature was 37 °C for 8.0 h with 7.0% w/w of inoculum size, the EPS yield could be up to 340 mg L−1. The L. helveticus MB2-1 fermented milk presented better gel structure than the control under the optimized conditions. The in situ produced EPS presented fine emulsifying properties, exhibited potent antioxidant activities as well as obvious antibiofilm activities against foodborne biofilm-forming pathogens. These findings demonstrated that in situ produced EPS in L. helveticus MB2-1 fermented milk has multiple functional qualities and can be a potent ingredient for supplementation and fortification of functional food products.

Probiotic Effect of Streptococcus dentisani on Oral Pathogens: An In Vitro Study.

Probiotics, including Streptococcus dentisani, have been proposed as an alternative to re-establish the ecology of the oral cavity and inhibit the formation of pathogenic biofilms. The main objective of this work was to assess the probiotic ability of S. dentisani against Streptococcus mutans, Streptococcus mitis, and Candida albicans biofilms. The ability of the strains to form a monospecies biofilm and the probiotic potential of S. dentisani using the competition, exclusion, and displacement strategies were determined. All strains were moderate biofilm producers. The ability of S. dentisani to compete with and exclude S. mutans and S. mitis during biofilm formation was not significant. However, S. dentisani significantly reduced pathologic streptococcal biofilms using the displacement strategy. Also S. dentisani reduced the formation of the C. albicans biofilm mainly through competition and displacement. In vitro, S. dentisani exhibited probiotic potential to reduce the formation of potentially pathogenic biofilms. Further investigation is required to understand the biofilm-inhibiting mechanisms exhibited by this probiotic strain.

Antibacterial and antibiofilm activities of iodinated hydrocarbons against Vibrio parahaemolyticus and Staphylococcus aureus

Food-related illnesses have become a growing public concern due to their considerable socioeconomic and medical impacts. Vibrio parahaemolyticus and Staphylococcus aureus have been implicated as causative organisms of food-related infections and poisoning, and both can form biofilms which confer antibiotic resistance. Hence, the need for continuous search for compounds with antibiofilm and antivirulence properties. In this study, 22 iodinated hydrocarbons were screened for their antibiofilm activity, and of these, iodopropynyl butylcarbamate (IPBC) was found to effectively control biofilm formation of both pathogens with a MIC of 50 µg/mL which was bactericidal to V. parahaemolyticus and S. aureus. Microscopic studies confirmed IPBC inhibits biofilm formation of both bacteria and also disrupted their mixed biofilm formation. Furthermore, IPBC suppressed virulence activities such as motility and hemolytic activity of V. parahaemolyticus and the cell surface hydrophobicity of S. aureus. It exhibited a preservative potential against both pathogens in a shrimp model. IPBC disrupted the cell membrane of S. aureus and V. parahaemolyticus and differentially affected gene expressions related to biofilm formation and virulence. Additionally, it displayed broad-spectrum antibiofilm activities against other clinically relevant pathogens. These findings indicate IPBC offers a potential means of controlling infections mediated by Vibrio and Staphylococcus biofilms.

Biofilm Inhibition on Medical Devices and Implants Using Carbon Dots: An Updated Review.

Biofilms are an intricate community of microbes that colonize solid surfaces, communicating via a quorum-sensing mechanism. These microbial aggregates secrete exopolysaccharides facilitating adhesion and conferring resistance to drugs and antimicrobial agents. The escalating global concern over biofilm-related infections on medical devices underscores the severe threat to human health. Carbon dots (CDs) have emerged as a promising substrate to combat microbes and disrupt biofilm matrices. Their numerous advantages such as facile surface functionalization and specific antimicrobial properties, position them as innovative anti-biofilm agents. Due to their minuscule size, CDs can penetrate microbial cells, inhibiting growth via cytoplasmic leakage, reactive oxygen species (ROS) generation, and genetic material fragmentation. Research has demonstrated the efficacy of CDs in inhibiting biofilms formed by key pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Consequently, the development of CD-based coatings and hydrogels holds promise for eradicating biofilm formation, thereby enhancing treatment efficacy, reducing clinical expenses, and minimizing the need for implant revision surgeries. This review provides insights into the mechanisms of biofilm formation on implants, surveys major biofilm-forming pathogens and associated infections, and specifically highlights the anti-biofilm properties of CDs emphasizing their potential as coatings on medical implants.

Current Strategies for Combating Biofilm-Forming Pathogens in Clinical Healthcare-Associated Infections.

The biofilm formation by various pathogens causes chronic infections and poses severe threats to industry, healthcare, and society. They can form biofilm on surfaces of medical implants, heart valves, pacemakers, contact lenses, vascular grafts, urinary catheters, dialysis catheters, etc. These biofilms play a central role in bacterial persistence and antibiotic tolerance. Biofilm formation occurs in a series of steps, and any interference in these steps can prevent its formation. Therefore, the hunt to explore and develop effective anti-biofilm strategies became necessary to decrease the rate of biofilm-related infections. In this review, we highlighted and discussed the current therapeutic approaches to eradicate biofilm formation and combat drug resistance by anti-biofilm drugs, phytocompounds, antimicrobial peptides (AMPs), antimicrobial lipids (AMLs), matrix-degrading enzymes, nanoparticles, phagebiotics, surface coatings, photodynamic therapy (PDT), riboswitches, vaccines, and antibodies. The clinical validation of these findings will provide novel preventive and therapeutic strategies for biofilm-associated infections to the medical world.

Extracellular Proteins Isolated from L. acidophilus as an Osteomicrobiological Therapeutic Agent to Reduce Pathogenic Biofilm Formation, Regulate Chronic Inflammation, and Augment Bone Formation In Vitro (Adv. Healthcare Mater. 9/2024)

Extracellular Proteins Isolated from <i>L. acidophilus</i> as an Osteomicrobiological Therapeutic Agent to Reduce Pathogenic Biofilm Formation, Regulate Chronic Inflammation, and Augment Bone Formation In Vitro (Adv. Healthcare Mater. 9/2024)

Antibacterial and anticancer activities of Nymphaea nauchali rhizome extracts

The present study was conducted to discover the antibacterial and anticancer activities of Nymphaea nauchali rhizome peel and core extracts. Antibacterial activity of ethanol, methanol, and acetone extracts of N. nauchali rhizome peel and inner core extracts has been tested against six biofilm-forming bacterial pathogens, E. coli, P. aeruginosa, E. faecalis, coagulase –ve Staph. aureus, Staph. aureus, and P. vulgaris by agar well diffusion assay. The size of inhibition zones around the wells in the presence of different extracts was used to determine the sensitivity of test bacteria. The anticancer activity of extracts was checked using the MCF-7 cell line, and potency was defined in terms of IC50 values. Methanol, ethanol, and acetone peel extracts showed more antibacterial activities against all test bacteria than inner core extracts. E. faecalis was highly resistant to acetone inner core extracts, and P. aeruginosa showed higher sensitivity to ethanol inner core extract. Ethanolic extracts of rhizome peel and inner core were more effective against the MCF-7 cell line than methanol and acetone extracts. IC50 values of 208.20 μgml−1and 136.16 μgml−1were noted for peel and inner core ethanol extracts, respectively. N. nauchali rhizome can be used as a potential entrant in developing novel antibacterial and anticancer phytoformulations.

Oxygen enrichment mediated by calcium peroxide loaded gelatin methacrylate hydrogel eradicates periodontal biofilms

The low oxygen environment of the periodontal pocket favors pathogenic anaerobes' growth, biofilm formation, and quick recurrence after periodontal treatment. In contrast, oxygen is detrimental to anaerobes, such as Porphyromonas gingivalis (P. gingivalis), since they lack a complete anti-oxidation mechanism to detoxify the oxygen challenge. Therefore, consistently feeding pathogenic anaerobes with abundant oxygen would be an effective strategy to combat them. Here, we reported injectable oxygen-generating hydrogels as oxygen mediators to alleviate the local anaerobic environment and eliminate periodontal pathogens. Gelatin methacrylate (GelMA) hydrogels loaded with calcium peroxide (CPO) possessed excellent injectability and exhibited burst releases of oxygen within 24 h with a 40 % oxygen tension peak. CPO-GelMA hydrogels with CPO concentrations of 5, 10, and 15 % reduced 60, 99, and 89.9 % viable P. gingivalis, respectively. Five percentage CPO-GelMA hydrogel downregulated gingipain and fimA gene expression in P. gingivalis without resistance development. Moreover, the CPO-GelMA hydrogels remarkably prevented biofilm formation and eradicated both monospecies and multispecies bacterial biofilms. In conclusion, CPO-GelMA hydrogels exert remarkable antimicrobial and antibiofilm effects on subgingival biofilms, providing a promising strategy for periodontal treatment.

Silver nanoparticles synthesized from Pseudomonas aeruginosa pyoverdine: Antibiofilm and antivirulence agents

The increasing incidence of antimicrobial resistance exhibited by biofilm-forming microbial pathogens has been recognized as one of the major issues in the healthcare sector. In the present study, nanomaterial-based controlling the biofilm and virulence properties has been considered an alternative approach. Pyoverdine (PVD) isolated from the Pseudomonas aeruginosa was utilized as a biological corona to synthesize silver nanoparticles (AgNPs), which will be helpful in a targeted action to microbial pathogens due to the recognition of the corona of the nanoparticles by the pathogenic membrane. Synthesized PVD-AgNPs were spherical to irregular, with an average size value of 251.87 ± 21.8 nm and zeta potential with a value of −36.51 ± 0.69 mV. The MIC value of PVD-AgNPs towards P. aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Streptococcus mutans, Escherichia coli, and Candida albicans in the standard and host-mimicking media were observed in decreasing order in a multi-fold, such as standard growth media > sputum > synthetic human urine > saliva. Both the initial stage and the well-established biofilms of these microbial pathogens have been effectively inhibited and eradicated by PVD-AgNPs. PVD-AgNPs increase the susceptibility of tetracycline, PVD, and amphotericin B towards established mature mono- and mixed-species biofilms of S. aureus and C. albicans. Additionally, PVD-AgNPs attenuate several virulence properties, such as inhibition of protease activity, motility, and PVD and pyocyanin production in P. aeruginosa. The inhibition of gene expression of biofilm and virulence-associated genes in P. aeruginosa validates its phenotypic effects.

Quantum dots: a next generation approach for pathogenic microbial biofilm inhibition; mechanistic insights, existing challenges, and future potential.

Quantum Dots (QDs) have emerged as versatile nanomaterials with origins spanning organic, inorganic, and natural sources, revolutionizing various biomedical applications, particularly in combating pathogenic biofilm formation. Biofilms, complex structures formed by microbial communities enveloped in exopolysaccharide matrices, pose formidable challenges to traditional antibiotics due to their high tolerance and resistance, exacerbating inefficacy issues in antibiotic treatments. QDs offer a promising solution, employing physical mechanisms like photothermal or photodynamic therapy to disrupt biofilms. Their efficacy is noteworthy, with lower susceptibility to resistance development and broad-spectrum action as compared to conventional antibiotic methods. The stability and durability of QDs ensure sustained biofilm activity, even in challenging environmental conditions. This comprehensive review delves into the synthesis, properties, and applications of Carbon Quantum Dots (CQDs), most widely used QDs, showcasing groundbreaking developments that position these nanomaterials at the forefront of cutting-edge research and innovation. These nanomaterials exhibit multifaceted mechanisms, disrupting cell walls and membranes, generating reactive oxygen species (ROS), and binding to nucleic materials, effectively inhibiting microbial proliferation. This opens transformative possibilities for healthcare interventions by providing insights into biofilm dynamics. However, challenges in size control necessitate ongoing research to refine fabrication techniques, ensure defect-free surfaces, and optimize biological activity. QDs emerge as microscopic yet potent tools, promising to contribute to a brighter future where quantum wonders shape innovative solutions to persistently challenging issues posed by pathogenic biofilms. Henceforth, this review aims to explore QDs as potential agents for inhibiting pathogenic microbial biofilms, elucidating the underlying mechanisms, addressing the current challenges, and highlighting their promising future potential.

Evaluation of Anti-Bacterial and Anti-Biofilm Activity of Native Probiotic Strains of Lactobacillus Extracts.

Lactic acid bacteria produce various beneficial metabolites, including antimicrobial agents. Owing to the fast-rising antibiotic resistance among pathogenic microbes, scientists are exploring antimicrobials beyond antibiotics. In this study, we examined four Lactobacillus strains, namely L. plantarum 42, L. brevis 205, L. rhamnosus 239, and L. delbrueckii 263, isolated from healthy human microbiota, to evaluate their antibacterial and antifungal activity. Lactobacillus strains were cultivated, and the conditioned media were obtained. The supernatant was then used to treat pathogenic bacteria and applied to the growth media containing fungal and bacterial strains. Additionally, the supernatant was separated to achieve the organic and aqueous phases. The two phases were then examined in terms of bacterial and fungal growth rates. Disk diffusion and MIC tests were conducted to determine strains with the most growth inhibition potential. Finally, the potent strains identified through the MIC test were tested on the pathogenic microorganisms to assess their effects on the formation of pathogenic biofilms. The organic phase of L. rhamnosus 239 extracts exhibited the highest antibacterial and antibiofilm effects, while that of L. brevis 205 demonstrated the most effective antifungal impact, with a MIC of 125 µg/mL against Saccharomyces cerevisiae. This study confirms the significant antimicrobial impacts of the lactic acid bacteria strains on pathogenic bacteria and fungi; hence, they could serve as a reliable alternative to antibiotics for a safe and natural protection against pathogenic microorganisms.