Antibacterial Activity and Mechanism of Oxidized Bacterial Nanocellulose with Different Carboxyl Content.

Oxidized bacterial nanocellulose (OBC) is reported to prevent microbial growth, but its antibacterial characteristics and mechanism are still unclear. Here, the antibacterial mechanism of OBC is explored by detecting and assessing the interaction of OBC with different carboxyl content on Staphylococcus aureus and Escherichia coli. The results show that OBC has strong antibacterial activity and antibiofilm activity against S. aureus and E. coli, which is positively correlated with the carboxyl content of OBC. After OBC treatment, the bacteria adhesion is inhibited and the cell membrane is destroyed leading to increased permeability. Further investigation reveals that the concentration of cyclic diguanosine monophosphate (c-di-GMP) that induced biofilm formation is significantly decreased to 1.81 pmol mg-1 after OBC treatment. In addition, OBC inactivates mature biofilms, with inactivation rates up to 79.3%. This study suggests that OBC has excellent antibacterial and antiadhesion properties, which can increase the cell membrane permeability and inhibit c-di-GMP formation. In addition, OBC also has a strong inactivation effect on mature biofilm, which can be used as an effective antibiofilm agent.

Alhagi maurorum extract modulates quorum sensing genes and biofilm formation in Proteus mirabilis.

Proteus mirabilis (P. mirabilis) is a frequent cause of catheter-associated urinary tract infections. This study aims to investigate the anti-infective effect of Alhagi maurorum extract (AME), the traditional medicinal plant in the middle east, on the biofilm-forming P. mirabilis isolates. Hydroalcoholic extract and oil of A. maurorum were characterized by HPLC and GC-MS. The antiproliferative, anti-biofilm, and bactericidal activity of AME at various concentrations were assessed by turbidity, crystal violet binding, and agar well diffusion assays, respectively. The AME's effect on adhesion and quorum sensing (QS) were investigated by in vitro adhesion assay on cell culture and agar overlay assay using Janthinobacterium lividum (ATCC 12472) as a biosensor strain. In addition, the expression level of selected genes involved in QS and biofilm regulation were determined by quantitative Real-Time PCR. Furthermore, the bladder phantom model was created to evaluate the assays and investigate the catheter's calcium deposition. The most effective chemical compounds found in AME were tamarixetin, quercetin, and trans-anethole. Although AME did not inhibit swarming motility, it reduced biofilm production and exerted a concentration-dependent anti-adhesive and anti-QS activity against P. mirabilis. AME also downregulated the expression level of selected genes involved in biofilm formation and QS. This study showed that AME as a natural compound reduced biofilm formation of P. mirabilis by targeting virulence factor genes, quorum sensing, and other strategies that include preventing the adhesion of P. mirabilis to the cells. The results suggest that A. maurorum extract might have the potential to be considered for preventing UTIs caused by P. mirabilis.

Inhibition of Bacterial Adhesion and Biofilm Formation by Seed-Derived Ethanol Extracts from Persea americana Mill.

The increase in antibiotic resistance demands innovative strategies to combat microorganisms. The current study evaluated the antibacterial and antivirulence effects of ethanol extracts from Persea americana seeds obtained by the Soxhlet (SE) and maceration (MaE) methods. The UHPLC-DAD-QTOF analysis showed mainly the presence of polyphenols and neolignan. Ethanol extracts were not cytotoxic to mammalian cells (CC50 > 500 µg/mL) and displayed a moderate antibacterial activity against Pseudomonas aeruginosa (IC50 = 87 and 187 µg/mL) and Staphylococcus aureus (IC50 = 144 and 159 µg/mL). Interestingly, no antibacterial activity was found against Escherichia coli. SE and MaE extracts were also able to significantly reduce the bacterial adhesion to A549 lung epithelial cells. Additionally, both extracts inhibited the biofilm growth at 24 h and facilitated the release of internal cell components in P. aeruginosa, which might be associated with cell membrane destabilization. Real-time PCR and agarose electrophoresis gel analysis indicated that avocado seed ethanol extracts (64 µg/mL) downregulated virulence-related factors such as mexT and lasA genes. Our results support the potential of bioproducts from P. americana seeds as anti-adhesive and anti-biofilm agents.

In vitro bacterial adherence on teeth submitted to whitening with musa paradisiaca / Adherencia bacteriana in vitro en dientes sometidos a blanqueamiento con musa paradisiaca

Objetive: To compare in vitro bacterial adherence on teeth submitted to whitening with 50% ethanolic extract of Musa paradisiaca and 35% hydrogen peroxide. Material and Methods: The study was experimental and used 18 premolars that were grouped into: G1 (control), G2 (50% ethanol extract of Musa paradisiaca) and G3 (35% hydrogen peroxide). The teeth were then exposed to a Streptococcus mutans culture for 24 hours, followed by centrifugation in thioglycolate broth. A culture on trypticase soy agar was done with a 1 in 100 dilution, and after 48 hours colony forming units (CFU) were counted. Statistical analysis was performed using the ANOVA test, complemented by the Bonferroni post-hoc. Results: Bacterial adherence was 77x105 CFU/ml in Group 3 using 35% hydrogen peroxide, 40x105 CFU/ml in Group 2 using 50% ethanol extract of Musa paradisiaca, and 89x104 CFU/ml in Group 1 (control). The difference between the three groups was significant (p=0.000). Conclusion: Both whitening methods cause bacterial adherence to the tooth surface, although to a lower degree with Musa paradisiaca.eses.

Objetivo: Comparar la adherencia bacteriana in vitro en dientes sometidos a blanqueamiento con extracto etanólico de Musa paradisiaca al 50% y con peróxido de hidrógeno al 35%. Material y Métodos: Comparar la adherencia bacteriana in vitro en dientes sometidos a blanqueamiento con extracto etanólico de Musa paradisiaca al 50% y con peróxido de hidrógeno al 35%.Resultados: La adherencia bacteriana fue de 77x105 UFC/ml con el peróxido de hidrógeno al 35%, de 40x105 UFC/ml con el extracto etanólico de Musa paradisiaca al 50% y de 89x104 UFC/ml con el control. La diferencia fue significativa entre los tres grupos (p=0.000). Conclusión: Ambos métodos de blanqueamiento causan adherencia bacteriana en la superficie dental, siendo menor con Musa paradisiaca.

Nanoapatites Doped and Co-Doped with Noble Metal Ions as Modern Antibiofilm Materials for Biomedical Applications against Drug-Resistant Clinical Strains of Enterococcus faecalis VRE and Staphylococcus aureus MRSA.

The main aim of our research was to investigate antiadhesive and antibiofilm properties of nanocrystalline apatites doped and co-doped with noble metal ions (Ag+, Au+, and Pd2+) against selected drug-resistant strains of Enterococcus faecalis and Staphylococcus aureus. The materials with the structure of apatite (hydroxyapatite, nHAp; hydroxy-chlor-apatites, OH-Cl-Ap) containing 1 mol% and 2 mol% of dopants and co-dopants were successfully obtained by the wet chemistry method. The majority of them contained an additional phase of metallic nanoparticles, in particular, AuNPs and PdNPs, which was confirmed by the XRPD, FTIR, UV-Vis, and SEM-EDS techniques. Extensive microbiological tests of the nanoapatites were carried out determining their MIC, MBC value, and FICI. The antiadhesive and antibiofilm properties of the tested nanoapatites were determined in detail with the use of fluorescence microscopy and computer image analysis. The results showed that almost all tested nanoapatites strongly inhibit adhesion and biofilm production of the tested bacterial strains. Biomaterials have not shown any significant cytotoxic effect on fibroblasts and even increased their survival when co-incubated with bacterial biofilms. Performed analyses confirmed that the nanoapatites doped and co-doped with noble metal ions are safe and excellent antiadhesive and antibiofilm biomaterials with potential use in the future in medical sectors.

Nitric oxide stimulates type IV MSHA pilus retraction in Vibrio cholerae via activation of the phosphodiesterase CdpA.

Bacteria use surface appendages called type IV pili to perform diverse activities including DNA uptake, twitching motility, and attachment to surfaces. The dynamic extension and retraction of pili are often required for these activities, but the stimuli that regulate these dynamics remain poorly characterized. To address this question, we study the bacterial pathogen Vibrio cholerae, which uses mannose-sensitive hemagglutinin (MSHA) pili to attach to surfaces in aquatic environments as the first step in biofilm formation. Here, we use a combination of genetic and cell biological approaches to describe a regulatory pathway that allows V. cholerae to rapidly abort biofilm formation. Specifically, we show that V. cholerae cells retract MSHA pili and detach from a surface in a diffusion-limited, enclosed environment. This response is dependent on the phosphodiesterase CdpA, which decreases intracellular levels of cyclic-di-GMP to induce MSHA pilus retraction. CdpA contains a putative nitric oxide (NO)-sensing NosP domain, and we demonstrate that NO is necessary and sufficient to stimulate CdpA-dependent detachment. Thus, we hypothesize that the endogenous production of NO (or an NO-like molecule) in V. cholerae stimulates the retraction of MSHA pili. These results extend our understanding of how environmental cues can be integrated into the complex regulatory pathways that control pilus dynamic activity and attachment in bacterial species.

Effect of acid-alkali treatment on serum protein adsorption and bacterial adhesion to porous titanium.

Modification of the titanium (Ti) surface is widely known to influence biological reactions such as protein adsorption and bacterial adhesion in vivo, ultimately controlling osseointegration. In this study, we sought to investigate the correlation of protein adsorption and bacterial adhesion with the nanoporous structure of acid-alkali-treated Ti implants, shedding light on the modification of Ti implants to promote osseointegration. We fabricated nontreated porous Ti (NTPT) by powder metallurgy and immersed it in mixed acids and NaOH to obtain acid-alkali-treated porous Ti (AAPT). Nontreated dense sample (NTDT) served as control. Our results showed that nanopores were formed after acid-alkali treatment. AAPT showed a higher specific surface area and became much more hydrophilic than NTPT and NTDT (p < 0.001). Compared to dense samples, porous samples exhibited a lower zeta potential and higher adsorbed protein level at each time point within 120 min (p < 0.001). AAPT formed a thicker protein layer by serum precoating than NTPT and NTDT (p < 0.001). The main adsorbed proteins on AAPT and NTPT were albumin, α1 antitrypsin, transferrin, apolipoprotein A1, complement C3 and haptoglobin α1 chain. The amounts of bacteria adhering to the serum-precoated samples were lower than those adhering to the nonprecoated samples (p < 0.05). Lower-molecular-weight proteins showed higher affinity to porous Ti. In conclusion, acid-alkali treatment facilitated protein adsorption by porous Ti, and the protein coating tended to prevent bacteria from adhering. These findings may be utilized for Ti implant modification aimed at reducing bacterial adhesion and enhancing osseointegration. Graphical abstract.

A Novel Strategy for Creating an Antibacterial Surface Using a Highly Efficient Electrospray-Based Method for Silica Deposition.

Adhesion of bacteria on biomedical implant surfaces is a prerequisite for biofilm formation, which may increase the chances of infection and chronic inflammation. In this study, we employed a novel electrospray-based technique to develop an antibacterial surface by efficiently depositing silica homogeneously onto polyethylene terephthalate (PET) film to achieve hydrophobic and anti-adhesive properties. We evaluated its potential application in inhibiting bacterial adhesion using both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria. These silica-deposited PET surfaces could provide hydrophobic surfaces with a water contact angle greater than 120° as well as increased surface roughness (root mean square roughness value of 82.50 ± 16.22 nm and average roughness value of 65.15 ± 15.26 nm) that could significantly reduce bacterial adhesion by approximately 66.30% and 64.09% for E. coli and S. aureus, respectively, compared with those on plain PET surfaces. Furthermore, we observed that silica-deposited PET surfaces showed no detrimental effects on cell viability in human dermal fibroblasts, as confirmed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide and live/dead assays. Taken together, such approaches that are easy to synthesize, cost effective, and efficient, and could provide innovative strategies for preventing bacterial adhesion on biomedical implant surfaces in the clinical setting.

Dictamnine Inhibits the Adhesion to and Invasion of Uropathogenic Escherichia Coli (UPEC) to Urothelial Cells.

Uropathogenic Escherichia coli (UPEC) is the most common pathogenic bacteria associated with urinary tract infection (UTI). UPEC can cause UTI by adhering to and invading uroepithelial cells. Fimbriae is the most important virulence factor of UPEC, and a potentially promising target in developing novel antibacterial treatments. In this study, the antibacterial properties and effects of the compound dictamnine, extracted from the traditional Chinese medicine Cortex Dictamni, on the bacterial morphology, cell adhesion, and invasion of UPEC were studied. Dictamnine exhibited no obvious antibacterial activity against UPEC, but significantly impeded the ability of UPEC to adhere to and invade uroepithelial cells. RT-qPCR analysis showed that treatment downregulated the expression of type 1 fimbriae, P fimbriae, and curli fimbriae adhesion genes, and also downregulated adhesion-related receptor genes of uroepithelial cells. Transmission electron microscopy showed that dictamnine destroyed the structure of the fimbriae and the surface of the bacteria became smooth. These results suggest that dictamnine may help to prevent UTI by simultaneously targeting UPEC fimbriae and urothelial adhesin receptors, and may have a potential use as a new anti-UPEC drug.

Structural characterization of the carbohydrate and protein part of arabinogalactan protein from Basella alba stem and antiadhesive activity of polysaccharides from B. alba against Helicobacter pylori.

BACKGROUND: Increasing drug resistance of Helicobacter pylori has highlighted the search for natural compounds with antiadhesive properties, interrupting the adhesion of H. pylori to stomach epithelia. Basella alba, a plant widely used in Asian traditional medicine, was investigated for its antiadhesive activity against H. pylori. METHODS: B. alba extract FE was prepared by aqueous extraction. Polysaccharides were isolated from FE by ethanol precipitation and arabinogalactan-protein (AGP) was isolated with Yariv reagent. Carbohydrate analyses was performed by standard methods and sequence analysis of the protein part of AGP by LC-MS. In vitro adhesion assay of fluorescent-labelled H. pylori J99 to human AGS cells was performed by flow cytometric analysis. RESULTS: Raw polysaccharides (BA1) were isolated and 9% of BA1 were identified as AGP (53.1% neutral carbohydrates L-arabinose, D-galactose, rhamnose, 5.4% galacturonic acid, 41.5% protein). After deglycosylation of AGP, the protein part (two bands at 15 and 25 kDa in tricine SDS-PAGE) was shown to contain peptides like ribulose-bisphosphate-carboxylase-large-chain. Histological localization within the stem tissue of B. alba revealed that AGP was mainly located at the procambium ring. Functional assays indicated that neither FE nor BA1 had significant influence on viability of AGS cells or on H. pylori. FE inhibited the bacterial adhesion of H. pylori to AGS cells in a dose dependent manner. Best anti-adhesive effect of ~67% was observed with BA1 at 2 mg/mL. CONCLUSION: The data obtained from this study characterize in part the mucilage and isolated polysaccharides of B. alba. As the polysaccharides interact with the bacterial adhesion, a potential uses a supplemental antiadhesive entity against the recurrence of H. pylori after eradication therapy may be discussed.

A Potential Synbiotic Strategy for the Prevention of Type 2 Diabetes: Lactobacillus paracasei JY062 and Exopolysaccharide Isolated from Lactobacillus plantarum JY039.

The disturbance of intestinal microorganisms and the exacerbation of type 2 diabetes (T2D) are mutually influenced. In this study, the effect of exopolysaccharides (EPS) from Lactobacillus plantarum JY039 on the adhesion of Lactobacillus paracasei JY062 was investigated, as well as their preventive efficacy against T2D. The results showed that the EPS isolated from L. plantarum JY039 effectively improved the adhesion rate of L. paracasei JY062 to Caco-2 cells (1.8 times) and promoted the proliferation of L. paracasei JY062. In the mice experiment, EPS, L. paracasei JY062 and their complex altered the structure of the intestinal microbiota, which elevated the proportion of Bifidobacterium, Faecalibaculum, while inversely decreasing the proportion of Firmicutes, Muribaculaceae, Lachnospiraceae and other bacteria involved in energy metabolism (p < 0.01; p < 0.05); enhanced the intestinal barrier function; promoted secretion of the gut hormone peptide YY (PYY) and glucagon-like peptide-1 (GLP-1); and reduced inflammation by balancing pro-inflammatory factors IL-6, TNF-α and anti-inflammatory factor IL-10 (p < 0.01; p < 0.05). These results illustrate that EPS and L. paracasei JY062 have the synbiotic potential to prevent and alleviate T2D.

Alpha-terpineol grafted acetylated lentinan as an anti-bacterial adhesion agent.

Biomedical implants-associated bacterial infections have become a major threat to human health. Therefore, it is meaningful to develop new antibacterial strategies to solve this problem. In this study, we conjugated acetylated lentinan (AceLNT) with α-terpineol (AceLNT-g-α-ter), a highly effective natural antibacterial compound, to constitute a novel AceLNT-g-α-ter membrane (AceLNT-g-α-terM). Compared with AceLNT membrane (AceLNTM), the adhesion amount of E. coli and P. aeruginosa in AceLNT-g-α-terM decreased by 80% and 85% after 7 d incubation in fluid bacterial medium. Moreover, the number of E. coli and P. aeruginosa biofilm on AceLNT-g-α-terM surface decreased by 70% and 71%. At the meanwhile, α-terpineol grafting modification of AceLNT had limited effect on its stimulating activity on macrophages and had no more cytotoxicity. In summary, our study firstly confirmed that AceLNT-g-α-terM could effectively inhibit gram-negative bacteria adhesion and biofilm formation, and provided a novel strategy for preventing infection of biomedical implants.

Versatile antibacterial surface with amphiphilic quaternized chitin-based derivatives for catheter associated infection prevention.

Microbial colonization of catheter surfaces is responsible for most healthcare-associated infections. Quaternized chitin and chitosan have excellent antimicrobial and biocompatible properties and can be used to provide safe and prolonged protection for biomedical catheters. Herein, we prepared quaternized ß-chitin derivative (QC)- and quaternized chitosan derivative (QCS)-based antimicrobial surfaces. The quaternized polysaccharides modified TPU surfaces exhibited hydrophilicity, good biocompatibility. Among these, QCS2-modified TPU exhibited excellent antibacterial properties against Gram-positive and Gram-negative bacteria, and prevented the adherence of bacteria compared with pristine TPU. The antibacterial activity of QCS2-modified surfaces maintained for 8 weeks under the condition of immersion in serum. An in vivo subcutaneous implantation experiment revealed 99.87% reduction of bacteria and reduced expression of inflammation-related factors in the surrounding tissue five days after implantation with QCS2-modified TPU. Therefore, quaternized polysaccharide-modified surfaces have promising potential in preventing medical catheter-associated infections.

Antibacterial and Antibiofilm Effect of Cell-Free Supernatant of Lactobacillus brevis KCCM 202399 Isolated from Korean Fermented Food against Streptococcus mutans KCTC 5458.

This study aims to determine the antibiofilm effect of cell-free supernatant (CFS) of Lactobacillus brevis strains against Streptococcus mutans strains. To study the antibiofilm mechanism against S. mutans strains, antibacterial effects, cell surface properties (auto-aggregation and cell surface hydrophobicity), exopolysaccharide (EPS) production, and morphological changes were examined. The antibiofilm effect of L. brevis KCCM 202399 CFS as morphological changes were evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), compared with the control treatment. Among the L. brevis strains, L. brevis KCCM 202399 showed the highest antibiofilm effect on S. mutans KCTC 5458. The antibacterial effect of L. brevis KCCM 202399 against S. mutans KCTC 5458 was investigated using the deferred method (16.00 mm). The minimum inhibitory concentration of L. brevis KCCM 202399 against S. mutans KCTC 5458 was 25.00%. Compared with the control treatment, L. brevis KCCM 202399 CFS inhibited the bacterial adhesion of S. mutans KCTC 5458 by decreasing auto-aggregation, cell surface hydrophobicity, and EPS production (45.91%, 40.51%, and 67.44%, respectively). L. brevis KCCM 202399 CFS inhibited and eradicated the S. mutans KCTC 5458 biofilm. Therefore, these results suggest that L. brevis KCCM 202399 CFS may be used to develop oral health in the probiotic industry.

Thermoresponsive Nanostructures: From Mechano-Bactericidal Action to Bacteria Release.

Overuse of antibiotics can increase the risk of notorious antibiotic resistance in bacteria, which has become a growing public health concern worldwide. Featured with the merit of mechanical rupture of bacterial cells, the bioinspired nanopillars are promising alternatives to antibiotics for combating bacterial infections while avoiding antibacterial resistance. However, the resident dead bacterial cells on nanopillars may greatly impair their bactericidal capability and ultimately impede their translational potential toward long-term applications. Here, we show that the functions of bactericidal nanopillars can be significantly broadened by developing a hybrid thermoresponsive polymer@nanopillar-structured surface, which retains all of the attributes of pristine nanopillars and adds one more: releasing dead bacteria. We fabricate this surface through coaxially decorating mechano-bactericidal ZnO nanopillars with thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) brushes. Combining the benefits of ZnO nanopillars and PNIPAAm chains, the antibacterial performances can be controllably regulated between ultrarobust mechano-bactericidal action (∼99%) and remarkable bacteria-releasing efficiency (∼98%). Notably, both the mechanical sterilization against the live bacteria and the controllable release for the pinned dead bacteria solely stem from physical actions, stimulating the exploration of intelligent structure-based bactericidal surfaces with persistent antibacterial properties without the risk of triggering drug resistance.

In vitro activities of cellulase and ceftazidime, alone and in combination against Pseudomonas aeruginosa biofilms.

BACKGROUND: Biofilms are a main pathogenicity feature of Pseudomonas aeruginosa and has a significant role in antibiotic resistance and persistent infections in humans. We investigated the in vitro activities of antibiotic ceftazidime and enzyme cellulase, either alone or in combination against biofilms of P. aeruginosa. RESULTS: Both ceftazidime and cellulase significantly decreased biofilm formation in all strains in a dose-dependent manner. Combination of enzyme at concentrations of 1.25, 2.5, 5, and 10 U/mL tested with 1/16× MIC of antibiotic led to a significant reduction in biofilm biomass. Cellulase showed a significant detachment effect on biofilms at three concentrations of 10 U/mL, 5 U/mL, and 2.5 U/mL. The MIC, MBC, and MBEC values of ceftazidime were 2 to 4 µg/mL, 4 to 8 µg/mL, and 2048 to 8192 µg/mL. When combined with cellulase, the MBECs of antibiotic showed a significant decrease from 32- to 128-fold. CONCLUSIONS: Combination of the ceftazidime and the cellulase had significant anti-biofilm effects, including inhibition of biofilm formation and biofilm eradication in P. aeruginosa. These data suggest that glycoside hydrolase therapy as a novel strategy has the potential to enhance the efficacy of antibiotics and helps to resolve biofilm-associated wound infections caused by this pathogen.

Evaluation of antimicrobial peptide LL-37 for treatment of Staphylococcus aureus biofilm on titanium plate.

ABSTRACT: The antimicrobial peptide LL-37 belongs to the cathelicidin family and is one of the few human bactericidal peptides with potent antistaphylococcal activity. Staphylococcus aureus is one of the main infection bacteria in orthopedic implant therapy. Biofilm formation after bacterial infection brings more and more severe test for clinical antiinfection treatment.However, there are few studies on LL-37 in S. aureus infection of prosthesis. In this work, addition to research the antibacterial activity and the inhibitory effect on bacterial adhesion of LL-37, an in vitro model of S. aureus biofilm formation on titanium alloy surface was established to observe the inhibitory effect of LL-37.The results showed that LL-37 has a strong antibacterial effect on S. aureus in vitro, and the minimum inhibitory concentration (MIC) is about 0.62 µΜ. Moreover, LL-37 has significant impact on the adhesion of S. aureus when the concentration ≥0.16 µM and significant anti-staphylococcal biofilm effects on static biofilm models at the concentration of 0.31 to 10 µM. Additionally, LL-37 at 5 µM had a significant destructive effect on S. aureus biofilm (P < .05) that formed on the titanium alloy surface.This study further confirmed the role of LL-37 in the process of S. aureus infection, including antimicrobial activities, inhibition of bacterial adhesion, and inhibition of mature biofilm. LL-37 can significantly destroy the stable biofilm structure on the titanium alloy surface in vitro, which may provide a new way for refractory infection caused by S. aureus in titanium alloy prosthesis infection.

Are Uropathogenic Bacteria Living in Multispecies Biofilm Susceptible to Active Plant Ingredient-Asiatic Acid?

Urinary tract infections (UTIs) are a serious health problem in the human population due to their chronic and recurrent nature. Bacteria causing UTIs form multispecies biofilms being resistant to the activity of the conventionally used antibiotics. Therefore, compounds of plant origin are currently being searched for, which could constitute an alternative strategy to antibiotic therapy. Our study aimed to determine the activity of asiatic acid (AA) against biofilms formed by uropathogenic Escherichia coli, Enterobacter cloacae, and Pseudomonas aeruginosa. The influence of AA on the survival, biofilm mass formation by bacteria living in mono-, dual-, and triple-species consortia as well as the metabolic activity and bacterial cell morphology were determined. The spectrophotometric methods were used for biofilm mass synthesis and metabolic activity determination. The survival of bacteria was established using the serial dilution assay. The decrease in survival and a weakening of the ability to create biofilms, both single and multi-species, as well as changes in the morphology of bacterial cells were noticed. As AA works best against young biofilms, the use of AA-containing formulations, especially during the initial stages of infection, seems to be reasonable. However, there is a need for further research concerning AA especially regarding its antibacterial mechanisms of action.

Biological and Corrosion Evaluation of In Situ Alloyed NiTi Fabricated through Laser Powder Bed Fusion (LPBF).

In this work, NiTi alloy parts were fabricated using laser powder bed fusion (LBPF) from pre-alloyed NiTi powder and in situ alloyed pure Ni and Ti powders. Comparative research on the corrosive and biological properties of both studied materials was performed. Electrochemical corrosion tests were carried out in phosphate buffered saline at 37 °C, and the degradation rate of the materials was described based on Ni ion release measurements. Cytotoxicity, bacterial growth, and adhesion to the surface of the fabricated coupons were evaluated using L929 cells and spherical Escherichia coli (E. coli) bacteria, respectively. The in situ alloyed NiTi parts exhibit slightly lower corrosion resistance in phosphate buffered saline solution than pre-alloyed NiTi. Moreover, the passive layer formed on in situ alloyed NiTi is weaker than the one formed on the NiTi fabricated from pre-alloyed NiTi powder. Furthermore, in situ alloyed NiTi and NiTi made from pre-alloyed powders have comparable cytotoxicity and biological properties. Overall, the research has shown that nitinol sintered using in situ alloyed pure Ni and Ti is potentially useful for biomedical applications.

Application of Antimicrobial Peptides on Biomedical Implants: Three Ways to Pursue Peptide Coatings.

Biofilm formation and inflammations are number one reasons of implant failure and cause a severe number of postoperative complications every year. To functionalize implant surfaces with antibiotic agents provides perspectives to minimize and/or prevent bacterial adhesion and proliferation. In recent years, antimicrobial peptides (AMP) have been evolved as promising alternatives to commonly used antibiotics, and have been seen as potent candidates for antimicrobial surface coatings. This review aims to summarize recent developments in this field and to highlight examples of the most common techniques used for preparing such AMP-based medical devices. We will report on three different ways to pursue peptide coatings, using either binding sequences (primary approach), linker layers (secondary approach), or loading in matrixes which offer a defined release (tertiary approach). All of them will be discussed in the light of current research in this area.