Biofilm Reduction Research Articles

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.

Steroidal hydrazones as antimicrobial agents: biological evaluation and molecular docking studies

ABSTRACT Most of pharmaceutical agents display several or even many biological activities. It is obvious that testing even one compound for thousands of biological activities is a practically not reasonable task. Therefore, computer-aided prediction is the method of choice for the selection of the most promising bioassays for particular compounds. Using PASS Online software, we determined the probable antimicrobial activity of the 31 steroid derivatives. Experimental testing of the antimicrobial activity of the tested compounds by microdilution method confirmed the computational predictions. Furthermore, P. aeruginosa and C. albicans biofilm formation was investigated. Compound 11 showed a biofilm reduction by 42.26% at the MIC of the tested compound. The percentages are lower than ketoconazole, but very close to its activity.

Cryptocarya moschata extract decreases single and mixed biofilms on acrylic resins.

This study proposed to assess the effect of Cryptocarya moschata extract on single and mixed biofilms formed on denture base and reline acrylic resin. Single and mixed biofilms of Candida albicans and Streptococcus mutans were formed on the samples and treated with C. moschata extract; Nystatin solution at 100,000 IU/mL or Penicillin antibiotic solution at 100,000 IU/mL; or PBS solution. Antimicrobial activity was analyzed by counting colony-forming units, metabolism assay, assessment of protein components of the biofilm matrix, and of cell viability using confocal laser scanning microscopy (CLSM). Data were submitted to ANOVA and Tukey's post-test (α = 0.05). Cryptocarya moschata extract reduced cell viability of C. albicans and S. mutans single and mixed biofilms formed on samples. For all types of biofilms in the C. moschata group, there was a log reduction of the biofilm, proven by the Alamar Blue assay. Analyzing the extracellular matrix protein components, groups treated with the extract exhibited a lower level of fluorescence compared to the PBS groups. Reduction in thickness biofilm and viable cells was perceptible in the C. moschata group when assessing through CLSM. Cryptocarya moschata extract reduced the single and mixed biofilms of C. albicans and S. mutans on acrylic resins.

In Vitro Assessment of Antifungal and Antibiofilm Efficacy of Commercial Mouthwashes against Candida albicans.

Candida albicans is the most critical fungus causing oral mycosis. Many mouthwashes contain antimicrobial substances, including antifungal agents. This study aimed to investigate the in vitro activity of 15 commercial mouthwashes against 12 strains of C. albicans. The minimal inhibitory concentrations (MICs), minimal fungicidal concentrations (MFCs), and anti-biofilm activity were studied. MICs were determined by the micro-dilution method using 96-well plates, and MFCs were determined by culturing MIC suspensions on Sabouraud dextrose agar. Anti-biofilm activity was evaluated using the crystal violet method. The mouthwashes containing octenidine dihydrochloride (OCT; mean MICs 0.09-0.1%), chlorhexidine digluconate (CHX; MIC 0.12%), and CHX with cetylpyridinium chloride (CPC; MIC 0.13%) exhibited the best activity against C. albicans. The active compound antifungal concentrations were 0.5-0.9 µg/mL for OCT products and 1.1-2.4 µg/mL for CHX rinses. For mouthwashes with CHX + CPC, concentrations were 1.56 µg/mL and 0.65 µg/mL, respectively. Products with polyaminopropyl biguanide (polyhexanide, PHMB; MIC 1.89%) or benzalkonium chloride (BAC; MIC 6.38%) also showed good anti-Candida action. In biofilm reduction studies, mouthwashes with OCT demonstrated the most substantial effect (47-51.1%). Products with CHX (32.1-41.7%), PHMB (38.6%), BAC (35.7%), Scutellaria extract (35.6%), and fluorides + essential oils (33.2%) exhibited moderate antibiofilm activity. The paper also provides an overview of the side effects of CHX, CPC, and OCT. Considering the in vitro activity against Candida albicans, it can be inferred that, clinically, mouthwashes containing OCT are likely to offer the highest effectiveness. Meanwhile, products containing CHX, PHMB, or BAC can be considered as promising alternatives.

The interplay of low H2O2 doses, lytic cyanophage, and Microcystis aeruginosa: Implications for cyanobacterial bloom control and microcystin production/release

Low H2O2 doses can suppress cyanobacterial blooms without damaging non-target species but enable undesirable regrowth. Besides, the role of cyanophage in preventing regrowth after low H2O2 exposure remains unclear. Applying phages to cyanobacteria pre-exposed to low H2O2 in early growth stages may improve host removal and reduce microcystin (MC) production/release. Lytic cyanophage MDM-1 with a 172 PFU/cell burst size, 2-day short latent period against MCs-producing Microcystis, shows high H2O2 stability. Low H2O2 (1 to 2.5 mg/L) doses significantly (p < 0.05) inhibited Microcystis aeruginosa growth rate, biofilm and MCs concentration reduction in a dose-dependent manner but regrowth occurred at all concentrations. Phage treatment eliminated cells without H2O2 pretreatment within 3 days and reduced MC production. H2O2-pretreated M. aeruginosa cells altered the phage dynamics, affecting adsorption, latency, production, and cell lysis in response to H2O2-induced oxidative stress. At 1.5 mg H2O2/L pretreatment, cells were eliminated with reduced MC production, like untreated cells. H2O2 pretreatment with 2.0 and 2.5 mg/L resulted in an extension of the phage absorption phase and the latent period. This was accompanied by a reduction in lysis efficacy, attributed to the increased ROS production. At 2.5 mg H2O2/L, 17.10 % of phages remain un-adsorbed, with cell lysis rate dropped from 0.89 d−1 to 0.26 d−1 compared to the untreated control. The highest phage titer (70 %) was obtained with 1.5 mg/H2O2 pretreated cells. This study emphasizes that low-dose H2O2 eliminates Microcystis but severely affects phage lysis and MCs release depending on H2O2-induced ROS levels. It is a crucial consideration when using phages to control cyanobacterial blooms with H2O2-induced stress.

Characterization of Salmonella ser. Enteritidis-specific bacteriophages and biocontrol strategy to reduce S. Enteritidis on egg products using bacteriophages and essential oil compounds

Salmonella contamination of egg products is a major concern in the poultry industry. This study aimed to characterize newly isolated lytic Salmonella bacteriophages and evaluate the efficacy of Salmonella ser. Enteritidis biofilm reduction using a selected phage (CAU-SEP-3 at 100 MOI), essential oil (EO) compounds (thymol [Thy] and geraniol [Ger]) at 1 × MIC, and the combination of phage and EO compounds on food-contact materials (stainless steel [SS] and polypropylene [PP]) and quail eggs (at 4 and 25 °C). On both the coupons and eggshells, the combination treatment reduced Salmonella biofilms more effectively than either of the single treatments, and no differences in texture were detected after the combination treatment on quail eggs compared with the control. Confocal laser scanning microscopy analysis and three-dimensional imaging using COMSTAT provided visualization of biofilm reduction. Gene expression levels were compared using quantitative real-time PCR analysis, indicating that the combination treatment was the most effective in reducing the avrA, hilA, rpoH, rpoS, sefA, and spvR gene expression levels. A DNAPlotter image of CAU-SEP-3 was generated based on genome sequencing data, revealing that 35 (17.6%) proteins were predicted to be functional proteins, while 147 (82.4%) were annotated as hypothetical proteins. This study demonstrates that the combination of phage and EO compounds is potentially effective in inactivating S. Enteritidis biofilms; furthermore, it may contribute to the safety of future production and processing of eggs.

HOCl-producing electrochemical bandage for treating Pseudomonas aeruginosa-infected murine wounds.

The growing threat of antibiotic-resistant bacterial pathogens necessitates the development of alternative antimicrobial approaches. This is particularly true for chronic wound infections, which commonly harbor biofilm-dwelling bacteria. A novel electrochemical bandage (e-bandage) delivering low-levels of hypochlorous acid (HOCl) was evaluated against Pseudomonas aeruginosa murine wound biofilms. 5 mm skin wounds were created on the dorsum of mice and infected with 106 colony-forming units (CFU) of P. aeruginosa. Biofilms were formed over 2 days, after which e-bandages were placed on the wound beds and covered with Tegaderm. Mice were administered Tegaderm-only (control), non-polarized e-bandage (no HOCl production), or polarized e-bandage (using an HOCl-producing potentiostat), with or without systemic amikacin. Purulence and wound areas were measured before and after treatment. After 48 hours, wounds were harvested for bacterial quantification. Forty-eight hours of polarized e-bandage treatment resulted in mean biofilm reductions of 1.4 log10 CFUs/g (P = 0.0107) vs non-polarized controls and 2.2 log10 CFU/g (P = 0.004) vs Tegaderm-only controls. Amikacin improved CFU reduction in Tegaderm-only (P = 0.0045) and non-polarized control groups (P = 0.0312) but not in the polarized group (P = 0.3876). Compared to the Tegaderm-only group, there was less purulence in the polarized group (P = 0.009). Wound closure was neither impeded nor improved by either polarized or non-polarized e-bandage treatment. Concurrent amikacin did not impact wound closure or purulence. In conclusion, an HOCl-producing e-bandage reduced P. aeruginosa in wound biofilms with no impairment in wound healing, representing a promising antibiotic-free approach for addressing wound infection.

Size-Controlled Synthesis of Gold Nanoparticles Tethering Antimicrobial Peptides with Potent Broad-Spectrum Antimicrobial and Antibiofilm Activities.

New antimicrobials are urgently needed to combat the rising global health concern of antibiotic resistance. Antimicrobial peptides (AMPs) are one of the leading candidates as new antimicrobials since they target bacterial membranes and are therefore less prone to bacterial resistance. However, poor enzymatic stability, high production costs, and toxicity are drawbacks that limit their clinical use. Conjugation of AMPs to gold nanoparticles (NPs) may help to improve enzymatic stability and, thus, their overall antimicrobial efficiency. We did a one-pot synthesis of size-controlled (10 nm) gold NPs selectively conjugated to lipopeptides and determined their antibacterial activity. The conjugates exhibited potent (0.13-1.25 μM) antimicrobial activity against clinical isolates, including Gram-positive methicillin-resistant Staphylococcus aureus (S. aureus) ATCC33593, Gram-negative Escherichia coli (E. coli) CTX-M-14, multidrug-resistant Pseudomonas aeruginosa LESB58 and Acinetobacter baumannii ATCC19606, and showed promising activity (90% inhibition of initial biofilms and 80% reduction of preformed biofilms) against S. aureus and E. coli DH5α biofilms at low micromolar concentrations. The conjugates were stable in rat serum and not toxic to representative mammalian cell lines in vitro (≤64 μM) and in vivo (≤100 μM).

The Effect of Citric and Ascorbic Acids as Anti-Biofilm and Anti-Capsular Agents on Multidrug-Resistant Acinetobacter baumannii

Objective: Acinetobacter baumannii (A. baumannii) is an opportunistic bacterium with multiple virulence factors, including capsule and biofilm, and is known for its high drug resistance. Anti-virulence natural substances have been suggested as novel alternatives to conventional antibiotics. We aimed to evaluate the effect of citric and ascorbic acids as anti-biofilm and anti-capsular agents against multidrug-resistant (MDR) A. baumannii clinical isolates. Materials and Methods: Twenty-eight A. baumannii MDR isolates were collected from different clinical sources. The minimum inhibitory concentration (MIC) of each agent was estimated. Biofilm formation and capsule were investigated phenotypically in the absence and presence of both agents at ½ and ¼ MICs. The presence of 14 adhesive and nonadhesive virulence genes was investigated. Results: Phenotypically, all the isolates were biofilm producers and were capsulated. The MIC of citric acid ranged from 1.25 to 2.5 mg/mL, while that of ascorbic acid was 3 mg/mL for all isolates. Both agents showed significant reduction in biofilm and capsular thinning. Ascorbic acid showed a dose-dependent effect in both biofilm reduction and capsule thinning unlike citric acid. Four genes, papG23, sfa1, fyuA, and cvaC, were absent among all isolates, while iutA was present in 100% of isolates. Other genes showed different distributions among the isolates. These virulence genes were not correlated to the anti-biofilm effect of both agents. Ascorbic acid was observed to have a better effect than citric acid. This can provide a clue for a better treatment regimen including ascorbic acid against MDR A. baumannii infections.

Mechanisms of action of Lactobacillus spp. in the treatment of oral candidiasis.

Candida albicans is often associated with oral candidiasis, and drug-resistance profiles have contributed to an increase in morbidity and mortality. It is known that Lactobacillus spp. acts by competing for adhesion to the epithelium, absorption of nutrients and modulation of the human microbiota. Therefore, they are important to assist in the host's microbiological balance and reduce the growth of Candida spp. Until now, there have been no reports in the literature of reviews correlating to the use of Lactobacillus spp. in the treatment of oral candidiasis. Thus, this review aims to highlight the mechanisms of action of Lactobacillus spp. and methods that can be used in the treatment of oral candidiasis. This is a study carried out through the databases PubMed Central and Scientific Electronic Library Online, using the following keywords: Oral Candidiasis and Lactobacillus. Original articles about oral candidiasis were included, with both in vitro and in vivo analyses, and published from 2012 to 2022. Lactobacillus rhamnosus was the most common microorganism used in the experiments against Candida, acting mainly in the reduction of biofilm, filamentation, and competing for adhesion sites of Candida spp. Among in vivo studies, most researchers used immunosuppressed mouse modelsof Candida infection. The studies showed that Lactobacillus has a great potential as a probiotic, acting mainly in the prevention and treatment of mucosal diseases. Thus, the use of Lactobacillus may be a good strategy for the treatment of oral candidiasis.

Poly(Lysine)-Derived Carbon Quantum Dots Conquer Enterococcus faecalis Biofilm-Induced Persistent Endodontic Infections.

Persistent endodontic infections (PEIs) mediated by bacterial biofilm mainly cause persistent periapical inflammation, resulting in recurrent periapical abscesses and progressive bone destruction. However, conventional root canal disinfectants are highly damaging to the tooth and periodontal tissue and ineffective in treating persistent root canal infections. Antimicrobial materials that are biocompatible with apical tissues and can eliminate PEIs-associated bacteria are urgently needed. Here, ε-poly (L-lysine) derived carbon quantum dots (PL-CQDs) are fabricated using pyrolysis to remove PEIs-associated bacterial biofilms. Due to their ultra-small size, high positive charge, and active reactive oxygen species (ROS) generation capacity, PL-CQDs exhibit highly effective antibacterial activity against Enterococcus faecalis (E. faecalis), which is greatly dependent on PL-CQDs concentrations. 100 µg/mL PL-CQDs could kill E. faecalis in 5 min. Importantly, PL-CQDs effectively achieved a reduction of biofilms in the isolated teeth model, disrupting the dense structure of biofilms. PL-CQDs have acceptable cytocompatibility and hemocompatibility in vitro and good biosafety in vivo. Thus, PL-CQDs provide a new strategy for treating E. faecalis-associated PEIs.

Thymol and carvacrol against Klebsiella: anti-bacterial, anti-biofilm, and synergistic activities-a systematic review.

Klebsiella poses a significant global threat due to its high antibiotic resistance rate. In recent years, researchers have been seeking alternative antimicrobial agents, leading to the introduction of natural compounds such as monoterpenes, specifically thymol and carvacrol. This review aims to illustrate the potential antimicrobial, anti-biofilm, and synergistic traits of thymol and carvacrol in combat against Klebsiella. Searching PubMed, Scopus, and Web of Science, we reviewed available evidence on the antibacterial effects of thymol, carvacrol, or combined with other compounds against Klebsiella until May 2024. Reference checking was performed after the inclusion of studies. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), fractional inhibitory concentration (FIC), and anti-biofilm activity were gathered, and the MBC/MIC ratio was calculated to assess the bactericidal efficacy. We retrieved 38 articles out of 2,652 studies screened. The gathered data assessed the anti-microbial activity of thymol, carvacrol, and both compounds in 17, 10, and 11 studies, respectively. The mean (± standard deviation) non-weighted MIC was 475.46μg/mL (±509.95) out of 60 MIC for thymol and 279.26μg/mL (±434.38) out of 68 MIC for carvacrol. Thymol and carvacrol showed anti-biofilm activities in the forms of disruption, inhibition, and mass reduction of biofilms. The MBC/MIC ratio was lower than 4 in 45 out of 47 cases, showing high bactericidal efficacy. FIC values were gathered for 68 combinations of thymol and carvacrol with other compounds, and they were mostly synergistic or additive. Thymol and carvacrol alone or in combination with other compounds, specifically known antibiotics, show great antimicrobial activity.

In Vitro Study to Assess the Antifungal Effect of Lactoferrin + Econazole/ Econazole in Reduction of Biofilm formed by Fungal Culture of Candida albicans, Candida tropicalis and Candida krusei

In Vitro Study to Assess the Antifungal Effect of Lactoferrin + Econazole/ Econazole in Reduction of Biofilm formed by Fungal Culture of Candida albicans, Candida tropicalis and Candida krusei

Isolation of quinic acid from dropped Citrus reticulata Blanco fruits: its derivatization, antibacterial potential, docking studies, and ADMET profiling.

Citrus reticulata dropped fruits are generally discarded as waste, causing environmental pollution and losses to farmers. In the present study, column chromatography has been used to isolate quinic acid (1,3,4,5-tetrahydroxycyclohexane-1-carboxylic acid) from the ethyl acetate fraction of a methanol extract of citrus fruits dropped in April. Quinic acid is a ubiquitous plant metabolite found in various plants and microorganisms. It is an important precursor in the biosynthesis of aromatic natural compounds. It was further derivatized into 3,4-o-isopropylidenequinic acid 1,5-lactone (QA1), 1,3,4,5-tetraacetoxycyclohexylaceticanhydride (QA2), and cyclohexane-1,2,3,5-tetraone (QA3). These compounds were further tested for their antibacterial potential against the foodborne pathogens Staphylococcus aureus, Bacillus spp., Yersinia enterocolitica, and Escherichia coli. QA1 exhibited maximum antibacterial potential (minimum inhibitory concentration; 80-120μg/mL). QA1 revealed synergistic behavior with streptomycin against all the tested bacterial strains having a fractional inhibitory concentration index ranging from 0.29 to 0.37. It also caused a significant increase in cell constituent release in all the tested bacteria compared to the control, along with prominent biofilm reduction. The results obtained were further checked with computational studies that revealed the best docking score of QA1 (-6.30kcal/mol, -5.8kcal/mol, and -4.70kcal/mol) against β-lactamase, DNA gyrase, and transpeptidase, respectively. The absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis revealed that the drug-like properties of QA1 had an ideal toxicity profile, making it a suitable candidate for the development of antimicrobial drugs.

Anti-Quorum Sensing Efficacy of Mangifera indica Kernel Extract against Biofilm Formation in Pseudomonas aeruginosa

P.aeruginosa (PA) is responsible for causing both acute and chronic infections in immune compromised individuals. Multi-drug resistance among them is a very common phenomenon due to their complex biofilm forming nature enabling the bacteria to evade antibiotic treatment as well as human immune defence mechanism. In the present study, biofilm inhibition in P.aeruginosa was analysed using mango peel (MPE) and kernel extract (MKE). MKE has a greater content of phytoconstituents such as tannin and phenol (1.6458± 0.07 mg g-1 TAE; 1.56± 0.007 mg g-1 GAE) than MPE (0.2938± 0.05 mg g-1 TAE; 1.31± 0.003 mg g-1 GAE). MKE at 12.5-200μg ml-1 showed significant reduction of biofilm (70-75%) and quorum sensing (QS) (35-65%) against PA and C. violaceum whereas MPE showed only 20-23% of biofilm and 5-15% of QS inhibition. Epi-fluorescence and CLSM micrographs demonstrated the efficacy of MKE in inhibiting surface adhesion and biofilm thickness. As a result, MKE at 50μg ml-1 (1/4 BIC) suppressed PA biofilm formation without impairing planktonic cell growth, reducing the possibility of the emergence of multi-drug resistance. Additionally, MKE inhibited the production of pyocyanin and had a negative impact on swarming and twitching motility. Eight distinct phytochemicals were found in MKE after it was characterised, but 2(3h)-furanone, 3-(15-hexadecynylidene)dihydro-4-hydroxy-5-methyl, 4r-(3e,4.alpha.,5.beta) represented 33.75% of the peak area and is presumed to be the antibiofilm compound.

Intermittent alternating magnetic fields diminish metal-associated biofilm in vivo

Prosthetic joint infection (PJI) is a complication of arthroplasty that results in significant morbidity. The presence of biofilm makes treatment difficult, and removal of the prosthesis is frequently required. We have developed a non-invasive approach for biofilm eradication from metal implants using intermittent alternating magnetic fields (iAMF) to generate targeted heating at the implant surface. The goal of this study was to determine whether iAMF demonstrated efficacy in an in vivo implant biofilm infection model. iAMF combined with antibiotics led to enhanced reduction of biofilm on metallic implants in vivo compared to antibiotics or untreated control. iAMF-antibiotic combinations resulted in a > 1 − log further reduction in biofilm burden compared to antibiotics or iAMF alone. This combination effect was seen in both S. aureus and P. aeruginosa and seen with multiple antibiotics used to treat infections with these pathogens. In addition, efficacy was temperature dependent with increasing temperatures resulting in a greater reduction of biofilm. Tissue damage was limited (< 1 mm from implant-tissue interface). This non-invasive approach to eradicating biofilm could serve as a new paradigm in treating PJI.

Bioprospecting of secondary metabolites produced by endophytic actinomycete isolated from Aloe vera

The aim of this work to evaluate the antibacterial action of secondary metabolites produced by endophytic actinomycetes, against isolates of medical interest. For such, the bacteria were isolated from the botanical sample and classical morphological identification was performed. The induction of metabolites production was carried out using the Submerged Fermentation technique, followed by purification of the extract. The evaluation of antibacterial activity was accomplished by using agar diffusion and Minimum Inhibitory Concentration (MIC) assays. Macro and microscopic analysis of the grown microorganism allowed it to be identified as belonging to the genus Streptomyces. Test results demonstrated that the extract was able to inhibit the growth of C. propinquum 431024, with an inhibition zone of 27±0 mm and of C. propinquum 36063, with an inhibition zone of 24±0 mm and MIC of 32.1 µg/mL for boths. The evaluation of biofilm formation resulted in: C. propinquun 421024 as a weak producer and C. propinquun 36063 as a moderate producer. The biofilm interference test showed that compared to the control there was a reduction in biofilm formation of 22% for C. propinquun 421024, as well as a reduction in pre-formed biofilm of 27%. There was a 48% reduction in the formation and 42% in the pre-formed biofilm of C. propinquun 36063. Lastly, it was concluded that the secondary metabolites produced by the endophytic actinomycetes demonstrated an antibiotic potential against clinical strains (nasopharynx) of Corynebacterium propinquum, a rare pathogen described for causing infections in patients with pulmonary involvement, pleural effusion, bacteremia and endocarditis and which presents an emerging antibiotic resistance.

Magnetic‐based photosensitizer to improve the efficiency of antimicrobial photodynamic therapy against mature dental caries‐related biofilms

AbstractAntimicrobial photodynamic therapy (aPDT) shows promise in eliminating oral pathogens without inducing microbial resistance. Yet, it faces limited biofilm penetration by the photosensitizer, which hinders its efficacy against mature, thick biofilms. This study assesses the effectiveness of the MagTBO (magnetic nanoparticles and toluidine‐blue ortho) nanoplatform against mature Streptococcus mutans biofilms associated with dental caries. The study employs constant‐depth film fermenter (CDFF) models, known as “artificial mouth,” to replicate caries processes and allow biofilm growth over teeth. This method enables the evaluation of biofilm‐induced mineral loss under cariogenic challenge over 5 and 10 days. The study shows that MagTBO improves aPDT's effectiveness against highly mature and complex biofilms over 5 and 10 days. However, the biofilm reduction unaffected the mineral content in the underlying dentin. This presents a promising approach for clinical aPDT protocols. However, it is crucial to acknowledge that these findings are based on in vitro studies and may necessitate further clinical confirmation. In summary, our data indicate that magnetic‐based photosensitizers enhance the modulation of pathogenic oral biofilms by aPDT, offering potential advancements in clinical aPDT protocols.

Candida krusei M4CK Produces a Bioemulsifier That Acts on Melaleuca Essential Oil and Aids in Its Antibacterial and Antibiofilm Activity.

Surface-active compounds (SACs) of microbial origin are an active group of biomolecules with potential use in the formulation of emulsions. In this sense, the present study aimed to isolate and select yeasts from fruits that could produce SACs for essential oil emulsions. The Candida krusei M4CK was isolated from the Byrsonima crassifolia fruit to make SACs. This emulsification activity (E24) was equal to or greater 50% in all carbon sources, such as olive oil, sunflower oil, kerosene, hexane, and hexadecane. E24 followed exponential growth according to the growth phase. The stability of emulsions was maintained over a wide range of temperatures, pH, and salinity. The OMBE4CK (melaleuca essential oil emulsion) had better and more significant inhibitory potential for biofilm reduction formation. In addition, bioemulsifier BE4CK alone on Escherichia coli and Pseudomonas aeruginosa biofilm showed few effective results, while there was a significant eradication for Staphylococcus aureus biofilms. The biofilms formed by S. aureus were eradicated in all concentrations of OMBE4CK. At the same time, the preformed biofilm by E. coli and P. aeruginosa were removed entirely at concentrations of 25 mg/mL, 12.5 mg/mL, and 6.25 mg/mL. The results show that the bioemulsifier BE4CK may represent a new potential for antibiofilm application.

2065. Efficacy of D-peptide-conjugated Antisense Compounds Against Pseudomonas aeruginosa

Abstract Background Pseudomonas aeruginosa (PA) causes significant morbidity and mortality in immunocompromised hosts and those with cystic fibrosis. Peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs) are antisense compounds designed to target specific genes and prevent translation. PPMOs with L-isomer peptides (L-PPMOs) were previously shown to have in vitro and in vivo activity. However, L-PPMOs are vulnerable to degradation by host proteases. We hypothesize that PPMOs with a D-isomer peptide (D-PPMOs) may be a more stable and potent alternative. We aimed to characterize the activity of L- and D-isomers in PA strains using planktonic and biofilm assays as well as an infected mouse model. Methods All L- and D-PPMOs were synthesized by Sarepta Therapeutics, Inc. We tested L- and D-isomers of the (RXR)4XB (X for 6-aminohexanoic acid and B for β-Ala) and R6G peptide [(Arg)6-Gly]. PMOs for rpsJ (ribosomal protein) and acpP (fatty acid synthesis protein) were conjugated to the 3’ end of each peptide. Minimum inhibitory concentration (MIC) assays were performed in unique lab and clinical (including MDR) isolates using MOPS medium. Strain PAO1 biofilms were grown in MBEC plates for 24 hours, with PPMOs then dosed every 8 hours for 24 hours, followed by colony enumeration. For in vivo studies, mice were infected with strain PA103 intratracheally and given intranasal PPMO at 6 hours post-infection. Lung burden was determined at 24 hours post-infection. Results MIC values of D-R6G-RpsJ and D-R6G-AcpP were comparable to their L-isomers, but D-RXR-RpsJ showed an improved MIC90 of 0.5 μM compared to the L-RXR-RpsJ MIC90 of 16 μM (Table 1). Both isomers demonstrated reduction of 48-hour biofilm to various degrees. D-PPMO biofilm reduction ranged from 1.5 logs to &amp;gt; 3 logs (D-R6G-AcpP and D-RXR-RpsJ, respectively). L-PPMO biofilm reduction ranged from 2 logs to &amp;gt; 4 logs. D-PPMOs were superior to their L-PPMO counterparts in our delayed in vivo acute pneumonia model, with most D-PPMOs resulting in an additional 50% decrease in lung burden. Conclusion D-PPMOs show similar or improved activity in vitro and in vivo when compared to L-PPMOs at the same dosage. Future studies will investigate the pharmacology of D-PPMOs, as they may represent a more biologically robust alternative to L-PPMOs for PA infections. Disclosures David E. Greenberg, MD, University of Texas Southwestern Medical Center: Dr. Greenberg has numerous patents on PPMOs