Antibacterial and antioxidant activities of endophytic fungi and nettle (Urtica dioica L.) leaves as their host.

Nettle (Urtica dioica L), as a plant rich in biologically active compounds, is one of the most important plants used in herbal medicine. Studies have shown that this plant has antioxidant, antiplatelet, hypoglycemic and hypocholesterolemia effects. In this study, we characterized three Alternaria endophytic fungi isolated from their host U. dioica. We hypothesized that these endophytic fungi can produce new bioactive metabolites, which may possess the bioactive property with potential application in the medical and pharmaceutical industries. The antibacterial activity was evaluated against reference and isolated strains, including Methicillin-Resistant Staphylococcus aureus. A wide range of antimicrobial activities similar to those measured in nettle leaves was detected especially for Alternaria sorghi. Furthermore, the highest antioxidant activity detected with DPPH free radical scavenging was measured for A. sorghi and nettle leaves ethyl acetate extracts. In addition, whereas catalase activity was similar in the three isolated fungi and nettle leaves, total thiol content and superoxide dismutase activity were significantly higher in leaves. A. sorghi showed the best activities compared to other isolated fungi. The characterization and further production of bioactive compounds produced by this endophyte should be investigated to fight bacteria and especially those that develop drug multi-resistance.

A Time-Kill Assay Study on the Synergistic Bactericidal Activity of Pomegranate Rind Extract and Zn (II) against Methicillin-Resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa.

There is a need for new antimicrobial systems due to increased global resistance to current antimicrobials. Pomegranate rind extract (PRE) and Zn (II) ions both possess a level of antimicrobial activity and work has previously shown that PRE/Zn (II) in combination possesses synergistic activity against Herpes simplex virus and Micrococcus luteus. Here, we determined whether such synergistic activity extended to other, more pathogenic, bacteria. Reference strains of methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa were cultured and subjected to challenge by PRE, Zn (II), or PRE + Zn (II), in time-kill assays. Data were obtained independently by two researchers using different PRE preparations. Statistically significant synergistic activity for PRE + Zn (II) was shown for all four bacterial strains tested compared to untreated controls, although the extent of efficacy and timescales varied. Zn (II) exerted activity and at 1 h, it was not possible to distinguish with PRE + Zn (II) combination treatment in all cases. PRE alone showed low activity against all four bacteria. Reproducible synergistic bactericidal activity involving PRE and Zn (II) has been confirmed. Potential mechanisms are discussed. The development of a therapeutic system that possesses demonstrable antimicrobial activity is supported which lends itself particularly to topical delivery applications, for example MRSA infections.

Rapid resistance development to three antistaphylococcal therapies in antibiotic-tolerant staphylococcus aureus bacteremia.

Understating how antibiotic tolerance impacts subsequent resistance development in the clinical setting is important to identifying effective therapeutic interventions and prevention measures. This study describes a patient case of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia which rapidly developed resistance to three primary MRSA therapies and identifies genetic and metabolic changes selected in vivo that are associated with rapid resistance evolution. Index blood cultures displayed susceptibility to all (non-beta-lactam) antibiotics with the exception of trimethoprim/ sulfamethoxazole. One month after initial presentation, during the same encounter, blood cultures were again positive for MRSA, now displaying intermediate resistance to vancomycin and ceftaroline and resistance to daptomycin. Two weeks later, blood cultures were positive for a third time, still intermediate resistant to vancomycin and ceftaroline and resistant to daptomycin. Mutations in mprF and vraT were common to all multidrug resistant isolates whereas mutations in tagH, agrB and saeR and secondary mprF mutation emerged sequentially and transiently resulting in distinct in vitro phenotypes. The baseline mutation rate of the patient isolates was unremarkable ruling out the hypermutator phenotype as a contributor to the rapid emergence of resistance. However, the index isolate demonstrated pronounced tolerance to the antibiotic daptomycin, a phenotype that facilitates the subsequent development of resistance during antibiotic exposure. This study exemplifies the capacity of antibiotic-tolerant pathogens to rapidly develop both stable and transient genetic and phenotypic changes, over the course of a single patient encounter.

Preparation and characterization of active oxidized starch films containing licorice residue extracts and its potential against methicillin-resistant S. aureus.

The antibacterial and antioxidant packaging films were fabricated by incorporating licorice residue extracts (LREs) into oxidized starch (OS) films. The bioactive fraction (BF) was firstly obtained from LREs by using bioassay-guided isolation method. The BF showed potent anti-Gram(+) bacteria effects, especially against methicillin-resistant S. aureus (MRSA) with MIC of 32.5 µg/mL. The present results also indicated that the addition of BF could significantly decrease the moisture content, water vapor permeability, light transmittance of OS films. Notably, the antibacterial and antioxidant activities of OS films significantly enhanced with the concentration of BF increasing. Moreover, the films with the highest concentration of BF showed the lowest tensile strength (4.23 MPa) and the highest elongation at break (63.89%). Meanwhile, the bioactive films could release bioactive compounds such as licochalcone A and licochalcone B into the alcoholic and fatty food simulants. Taken together, the active OS films containing LREs have the potential for application in food packaging films, due to its potential against MRSA and antioxidant activity as well as good physicochemical properties.

Bioguided Isolation of Active Compounds from Rhamnus alaternus against Methicillin-Resistant Staphylococcus aureus (MRSA) and Panton-Valentine Leucocidin Positive Strains (MSSA-PVL).

Despite intensified efforts to develop an effective antibiotic, S. aureus is still a major cause of mortality and morbidity worldwide. The multidrug resistance of bacteria has considerably increased the difficulties of scientific research and the concomitant emergence of resistance is to be expected. In this study we have investigated the in vitro activity of 15 ethanol extracts prepared from Moroccan medicinal plants traditionally used for treatment of skin infections. Among the tested species I. viscosa, C. oxyacantha, R. tinctorum, A. herba alba, and B. hispanica showed moderate anti-staphylococcal activity. However, R. alaternus showed promising growth-inhibitory effects against specific pathogenic bacteria especially methicillin-susceptible Staphylococcus aureus Panton-Valentine leucocidin positive (MSSA-PVL) and methicillin-resistant S. aureus (MRSA). The bioguided fractionation of this plant using successive chromatographic separations followed by nuclear magnetic resonance (NMR) and mass spectrometry (MS) including EIMS and HREIMS analysis yielded the emodin (1) and kaempferol (2). Emodin being the most active with MICs ranging between 15.62 and 1.95 µg/mL and showing higher activity against the tested strains in comparison with the crude extract, its mechanism of action and the structure-activity relationship were interestingly discussed. The active compound has not displayed toxicity toward murine macrophage cells. The results obtained in the current study support the traditional uses of R. alaternus and suggest that this species could be a good source for the development of new anti-staphylococcal agents.

Recombinant production of Trx-Ib-AMP4 and Trx-E50-52 antimicrobial peptides and antimicrobial synergistic assessment on the treatment of methicillin-resistant Staphylococcus aureus under in vitro and in vivo situations.

PURPOSE: The production of alternative novel antimicrobial agents is considered an efficient way to cope with multidrug resistance among pathogenic bacteria. E50-52 and Ib-AMP4 antimicrobial peptides (AMPs) have illustrated great proven antibacterial effects. The aim of this study was recombinant production of these AMPs and investigation of their synergistic effects on methicillin-resistant Staphylococcus aureus (MRSA). METHOD: At first, the codon optimized sequences of the Ib-AMP4 (UniProt: 024006 (PRO_0000020721), and E50-52 (UniProtKB: P85148) were individually ligated into the pET-32α vector and transformed into E. coli. After the optimization of production and purification steps, the MIC (Minimum inhibitory concentration), time kill and growth kinetic tests of recombinant proteins were determined against MRSA. Finally, the in vivo wound healing efficiency was tested. RESULTS AND CONCLUSION: The recorded MIC of recombinant Trx-Ib-AMP4, Trx-E50-52 against MRSA bacterium were 0.375 and 0.0875 mg/mL respectively. The combination application of the produced AMPs by the checkerboard method confirmed their synergic activity. The results of the time-kill showed sharply decrease of the number of viable cells with over five time reductions in log10 CFU/mL by the combination of Trx-E50-52 and Trx-IbAMP4 at 2 × MIC within 240 min. The growth kinetic results confirmed the combination of Trx-E50-52 and Trx-IbAMP4 had much greater success in the reduction of over 50 % of MRSA suspensions' turbidity within the first hour. Wound healing assay and histological analysis of infected mice treated with Trx-Ib-AMP4 or Trx-E50-52 compared with those treated with a combination of Trx-Ib-AMP4 and Trx-E50-52 showed significant synergic effects.

In vitro evaluation of loaded chitosan membranes for pain relief and infection prevention.

Wounds resulting from surgeries, implantation of medical devices, and musculoskeletal trauma result in pain and can also result in infection of damaged tissue. Up to 80% of these infections are due to biofilm formation either on the surface of implanted devices or on surrounding wounded tissue. Bacteria within a biofilm have intrinsic growth and development characteristics that allow them to withstand up to 1,000 times the minimum inhibitory concentration of antibiotics, demonstrating the need for new therapeutics to prevent and treat these infections. Cis-2-decenoic acid (C2DA) is known to disperse preformed biofilms and can prevent biofilm formation entirely for some strains of bacteria. Additionally, local anesthetics like bupivacaine have been shown to have antimicrobial effects against multiple bacterial strains. This study sought to evaluate hexanoic acid-treated electrospun chitosan membranes (HA-ESCM) as wound dressings that release C2DA and bupivacaine to simultaneously prevent infection and alleviate pain associated with musculoskeletal trauma. Release profiles of both therapeutics were evaluated, and membranes were tested in vitro against Methicillin-resistant Staphylococcus aureus (MRSA) to determine efficacy in preventing biofilm infection and bacterial growth. Results indicate that membranes release both therapeutics for 72 hr, and release profile can be tailored by loading concentration. Membranes were effective in preventing biofilm growth but were toxic to fibroblasts when loaded with 2.5 or 5 mg of bupivacaine.

A Stable Quaternized Chitosan-Black Phosphorus Nanocomposite for Synergetic Disinfection of Antibiotic-Resistant Pathogens.

Antibiotics are widely used for treatment of bacterial infections, and their overuse has contributed to microbial resistance. Currently, an alternative antibiotic-free therapy for inactivating bacteria is of great interest. Black phosphorus (BP), a biocompatible and nontoxic rising-star two-dimensional layered material, has gained remarkable interest in many bioapplications including biosensing, cancer therapy, drug delivery, and also antibacterial treatment. However, BP nanosheets suffer from instability in ambient environments due to rapid oxidation and degradation. To address this issue, BP nanosheets were modified with quaternized chitosan (QCS) by electrostatic adsorption to prepare a BP-QCS composite for photothermal/pharmaco treatment of bacterial infection. The BP-QCS has obviously enhanced solubility and chemical stability in aqueous suspensions. We have demonstrated that under near-infrared (NIR) irradiation, the BP-QCS can synergistically inactivate more than 95% methicillin-resistant Staphylococcus aureus (S. aureus) (MRSA) and Escherichia coli within 10 min with a dose of only 75 µg/mL in vitro. Meanwhile, the BP-QCS composite under NIR can synergistically inactivate 98% S. aureus in vivo. Furthermore, the BP-QCS suspensions at effective antibacterial concentrations have negligible cytotoxicity and in vivo toxicity.

In vitro and in vivo Antibacterial effect of Commiphora gileadensis Methanolic Extract against Methicillin-Resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa.

BACKGROUND AND OBJECTIVE: Commiphora gileadensis is a plant in the Burseraceae family that grows in the western area of Saudi Arabia. Traditionally, it is used in the treatment of some superficial infections. MATERIALS AND METHODS: The methanolic extract of Commiphora gileadensis isolated from its leaves and branches. The in vitro study was conducted to determine the effect of this extract on Methicillin-Resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa using an agar diffusion and Minimum inhibitory concentration (MIC) methods. The in vivo study was conducted through two different methods. The first method, 20 male Balb c-1 mice were used for the determination of Commiphora gileadensis methanolic extract toxicity (LD50). In the second method, 40 male mice were used and were put into four groups. The first and second groups were injected subcutaneously with 108 CFU of MRSA 1 mL-1, while the third and fourth groups were injected with 108 CFU of Pseudomonas aeruginosa 1 mL-1. The comparison between groups was done by using a t-test (p<0.05). RESULTS: The methanolic extract of Commiphora gileadensis had a greater sensitivity zone on MRSA and Pseudomonas aeruginosa, 7 and 3 mm respectively. The MIC of the extract was 1/8 and 1/2 for MRSA and Pseudomonas aeruginosa respectively. The in vivo study showed that the extract was non-toxic, it also showed that the extract decreased the mortality of mice induced by MRSA injection significantly (p<0.05) While insignificantly with Pseudomonas aeruginosa. CONCLUSION: The total Commiphora gileadensis methanolic extract had an antibacterial effect on MRSA and Pseudomonas aeruginosa. This extract was non-toxic for the mice.

Mild temperature photothermal assisted anti-bacterial and anti-inflammatory nanosystem for synergistic treatment of post-cataract surgery endophthalmitis.

Rationale: Endophthalmitis, which is one of the severest complications of cataract surgeries, can seriously threaten vision and even lead to irreversible blindness owing to its complicated microenvironment, including both local bacterial infection and severe inflammation. It is urgent to develop a comprehensive treatment for both anti-bacterial and anti-inflammatory effects. Methods: Herein, we developed AuAgCu2O-bromfenac sodium nanoparticles (AuAgCu2O-BS NPs), which was designed to combine anti-bacterial and anti-inflammatory effects for integrated therapy of endophthalmitis after cataract surgery. The AuAgCu2O-BS NPs could eradicate methicillin-resistant Staphylococcus aureus (MRSA) bacterial strain relied on their photodynamic effects and the release of metal ions (Ag+ and Cu+) by the hollow AuAgCu2O nanostructures mediated mild photothermal effects. The anti-inflammatory drug, bromfenac sodium, released from the nanoparticles were able to significantly reduce the local inflammation of the endophthalmitis and promote tissue rehabilitation. In vivo bacterial elimination and anti-inflammation were confirmed by a postcataract endophthalmitis rabbit model. Results: Excellent antibacterial ability of AuAgCu2O-BS NPs was verified both in vitro and in vivo. Ophthalmological clinical observation and pathologic histology analysis showed prominent treatment of inflammatory reaction. Importantly, the mild temperature photothermal effect not only promoted the release of metal ions and bromfenac sodium but also avoided the thermal damage of the surrounding tissues, which was more suitable for the practical application of ophthalmology due to the complex structure of the eyeball. Moreover, superior biocompatibility was approved by the preliminary toxicity investigations, including low cytotoxicity, negligible damage to major organs, and stable intraocular pressure. Conclusions: Our studies of nanosystem provide a promising synergic therapeutic strategy for postcataract endophthalmitis treatment with favorable prognosis and promise in clinical translations.

Cochlospermum regium (Schrank) pilger leaf extract inhibit methicillin-resistant Staphylococcus aureus biofilm formation.

ETHNOPHARMACOLOGICAL RELEVANCE: Cochlospermum regium, known as "algodãozinho", is an important plant belonging to Brazilian biodiversity used in traditional medicine to treat infections, wounds and skin conditions. AIM OF THE STUDY: To assess the effects of aqueous and ethanolic extracts from C. regium leaves on methicillin-resistant Staphylococcus aureus planktonic cells and biofilm formation. MATERIAL AND METHODS: The phytochemical characterization of the extracts was carried out by quantification of flavonoids, phenols and tannins and HPLC-DAD. Minimum inhibitory concentrations, cell viability, and enzyme activity inhibition were determined in planktonic cells exposed to C. regium extracts. The effect of the extracts on biofilms was assessed by quantifying colony-forming units (CFUs) and the extracellular matrix, and by visualizing the biofilm structure using scanning electron microscopy. RESULTS: Leaf extract contents showed high concentration of phenols and the gallic and ellagic acids were identified. The extracts showed potent antimicrobial activities at concentrations ranging from 62.5-250 µg/mL, and decreased coagulase activity. In addition, the extracts prevented biofilm formation, and the aqueous extract completely inhibited its formation. CONCLUSIONS: C. regium extracts stand out as promising alternative treatments for the prevention and treatment of methicillin-resistant Staphylococcus aureus infections.

Dual-wavelength photo-killing of methicillin-resistant Staphylococcus aureus.

With the effectiveness of antimicrobials declining as antimicrobial resistance continues to threaten public health, we must look to alternative strategies for the treatment of infections. In this study, we investigated an innovative, drug-free, dual-wavelength irradiation approach that combines 2 wavelengths of light, 460 nm and 405 nm, against methicillin-resistant Staphylococcus aureus (MRSA). MRSA was initially irradiated with 460-nm light (90-360 J/cm2) and subsequently irradiated with aliquots of 405-nm light (54-324 J/cm2). For in vivo studies, mouse skin was abraded and infected with approximately 107 CFUs of MRSA and incubated for 3 hours before irradiating with 460 nm (360 J/cm2) and 405 nm (342 J/cm2). Naive mouse skin was also irradiated to investigate apoptosis. We found that staphyloxanthin, the carotenoid pigment in MRSA cells, promoted resistance to the antimicrobial effects of 405-nm light. In addition, we found that the photolytic effect of 460-nm light on staphyloxanthin attenuated resistance of MRSA to 405-nm light killing. Irradiation of 460 nm alone did not elicit any antimicrobial effect on MRSA. In a proof-of-principle mouse skin abrasion infection model, we observed significant killing of MRSA using the dual-wavelength irradiation approach. However, when either wavelength of light was administered alone, no significant decrease in bacterial viability was observed. Moreover, exposure of the dual-wavelength irradiation to naive mouse skin did not result in any visible apoptosis. In conclusion, a dual-wavelength irradiation strategy may offer an innovative, effective, and safe approach for the treatment of skin infections caused by MRSA.

Phytochemical Characterization and In Vitro Anti-Inflammatory, Antioxidant and Antimicrobial Activity of Combretum collinum Fresen Leaves Extracts from Benin.

Leaves from Combretum collinum Fresen (Combretaceae) are commonly used for the treatment of inflammatory conditions, wound healing and bacterial infections in traditional West African medicine. This research focuses on the characterization of the phenolic profile and lipophilic compounds of leaves extracts of C. collinum. Studies of the in vitro anti-inflammatory activity were performed in TNFα stimulated HaCaT cells and antibacterial activity was evaluated with agar well diffusion and microdilution assays. Antioxidant activity was determined by DPPH and ABTS assays and compared to standards. The phytochemical studies confirmed myricetin-3-O-rhamnoside and myricetin-3-O-glucoside as major components of the leaves extracts, each contributing significantly to the antioxidant activity of the hydrophilic extracts. GC-MS analysis identified 19 substances that were confirmed by comparison with spectral library data and authentic standards. Combretum collinum aqueous leaves extract decreased pro-inflammatory mediators in TNFα stimulated HaCaT cells. Further investigations showed that myricetin-3-O-rhamnoside has an anti-inflammatory effect on IL-8 secretion. In the antimicrobial screening, the largest inhibition zones were found against S. epidermidis, MRSA and S. aureus. MIC values resulted in 275.0 µg/mL for S. epidermidis and 385.5 µg/mL for MRSA. The in vitro anti-inflammatory, antibacterial and antioxidant activity supports topical use of C. collinum leaves extracts in traditional West African medicine.

Phase I, Dose-Escalating Study of the Safety and Pharmacokinetics of Inhaled Dry-Powder Vancomycin (AeroVanc) in Volunteers and Patients with Cystic Fibrosis: a New Approach to Therapy for Methicillin-Resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) has become a significant acute and chronic respiratory pathogen. While vancomycin is effective against MRSA, its relatively poor penetration into lung secretions and dose-limiting renal toxicity make it less effective in the respiratory setting. As inhaled administration of vancomycin would overcome these limitations, we developed a dry powder formulation suitable for inhalation (AeroVanc). Here, we report a phase I, single-dose, dose-escalating study aimed at demonstrating safety and tolerability of AeroVanc. In part I, 18 healthy subjects received a single dose of 16 mg, 32 mg, or 80 mg of AeroVanc. Two subjects also received a 250-mg dose of intravenous vancomycin. In part 2 of the study, 32 mg and 80 mg AeroVanc were administered to subjects with cystic fibrosis as single doses. There were no serious side effects. A small drop in forced expiratory volume in 1 s (FEV1) was observed in 3 subjects with cystic fibrosis, one of whom required salbutamol. Vancomycin was rapidly absorbed after inhalation. Peak and mean plasma concentrations of vancomycin were dose proportional. The average minimum concentration of vancomycin in sputum remained above the usual MIC values for MRSA for up to 24 h (minimum sputum concentration [Cmin], 32-mg dose = 3.05 µg/ml, 80-mg dose = 8.0 µg/ml). In conclusion, AeroVanc was well tolerated and achieved high levels in sputum with a mean systemic absorption of 49%, making it a potential therapeutic strategy for respiratory infection with MRSA.

Self-Assemblies Based on Traditional Medicine Berberine and Cinnamic Acid for Adhesion-Induced Inhibition Multidrug-Resistant Staphylococcus aureus.

S. aureus is resistant to various first-line antibiotics, and seeking multifarious strategies aimed at effective control of antibiotic-resistant behavior is urgently needed. Here, we report a two-component directed self-assembly mode: the phytochemicals berberine and cinnamic acid can directly self-assemble into nanoparticles (NPs) displaying good bacteriostastic activity. Compared with several first-line antibiotics, the obtained nanostructures have a better inhibitory effect on multidrug-resistant S. aureus (MRSA) and stronger ability for biofilm removal. These qualities are attributed to the fact that organic assemblies can first spontaneously adhere to the surface of the bacteria, infiltrate into the cell, and then lead to converging attack against MRSA; thereafter, multipath bactericidal mechanisms of NPs on MRSA are found by both transcriptomic analysis and quantitative Polymerase Chain Reaction analysis. Moreover, when combined with spectral data and single crystal X-ray diffraction, the NPs' self-assembly mechanism governed by hydrogen bonds and π-π stacking interactions is clearly elucidated. These non-covalent interactions induce the NPs' formation of butterfly-like one-dimensional self-assembled units and finally layered three-dimensional spatial configuration. In addition, biocompatibility tests show that the NPs are nonhemolytic with little toxicity in vitro and in vivo. This directed self-assembly mode can offer a new perspective toward the design of biocompatible antimicrobial nanomedicines for clinical translation.

Baicalin suppress growth and virulence-related factors of methicillin-resistant Staphylococcus aureus in vitro and vivo.

A Staphylococcus aureus (S.aureus) was isolated from pigs suffered in pneumonia that can't be cured by antibiotic such as methicillin and vancomycin. It was demonstrated that baicalin, an active natural compound extracted from the traditional Chinese medicinal, possess antimicrobial activity. In the present study, we evaluate it efficacy in vitro and vivo against this isolated methicillin-resistant S.aureus (MRSA). Our findings demonstrated that baicalin can inhibit S. aureus growth in a dose-dependent manner and attenuate the biofilm formation. Scanning electron microscopies showed that cell membrane was damaged and accompany with contents leaks after treated with high concentration of baicalin. In addition, baicalin exerted inhibitory effects on the expression of S.aureus virulence-related factors. Moreover, baicalin treated mice had enhanced survival after a lethal dose of S.aureus infection compared with untreated mice. Simultaneously, the pathological tissue damage and bacterium burden were decrease in baicalin treated mice. These data demonstrated that baicalin displayed a high effectiveness in vitro and vivo against MRSA infection, suggesting that baicalin may potentially be used to treat MRSA infection.

Terminalia ferdinandiana Fruit and Leaf Extracts Inhibit Methicillin-Resistant Staphylococcus aureus Growth.

The development of multiple antibiotic-resistant bacteria has vastly depleted our repertoire of effective antibiotic chemotherapies. The development of multi-ß-lactam-resistant strains are particularly concerning due to our previous reliance on this class of antibiotics because of their initial efficacy and broad-spectrum activity. With increases in extended-spectrum ß-lactam-resistance and an expanded resistance to other classes of antibiotics, there is an urgent need for the development of effective new antibiotic therapies. Terminalia ferdinandiana is an endemic Australian plant known for its high antioxidant and tannin contents. T. ferdinandiana fruit and leaf extracts have strong antibacterial activity against a wide variety of bacterial pathogens. However, T. ferdinandiana extracts have not been tested against ESBL and MRSA antibiotic-resistant pathogens. An objective of this study was to screen T. ferdinandiana fruit and leaf extracts for bacterial growth inhibitory activity by disc diffusion assay against ß-lactam-sensitive and -resistant E. coli strains and against methicillin-sensitive and -resistant S. aureus. The minimum inhibitory concentration (MIC) was quantified by liquid dilution techniques. The fruit methanolic extract, as well as the methanolic, aqueous, and ethyl acetate leaf extracts strongly inhibited the growth of the MRSA, with MICs as low as 223 µg/mL. In contrast, the extracts were ineffective inhibitors of ESBL growth. Metabolomic fingerprint analysis identified a diversity and relative abundance of tannins, flavonoids, and terpenoids, several of which have been reported to inhibit MRSA growth in isolation. All extracts were nontoxic in the Artemia nauplii and HDF toxicity assays, further indicating their potential for medicinal use.

Carbon Nanomaterials and LED Irradiation as Antibacterial Strategies against Gram-Positive Multidrug-Resistant Pathogens.

BACKGROUND: Due to current antibiotic resistance worldwide, there is an urgent need to find new alternative antibacterial approaches capable of dealing with multidrug-resistant pathogens. Most recent studies have demonstrated the antibacterial activity and non-cytotoxicity of carbon nanomaterials such as graphene oxide (GO) and carbon nanofibers (CNFs). On the other hand, light-emitting diodes (LEDs) have shown great potential in a wide range of biomedical applications. METHODS: We investigated a nanotechnological strategy consisting of GO or CNFs combined with light-emitting diod (LED) irradiation as novel nanoweapons against two clinically relevant Gram-positive multidrug-resistant pathogens: methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). The cytotoxicity of GO and CNFs was studied in the presence of human keratinocyte HaCaT cells. RESULTS: GO or CNFs exhibited no cytotoxicity and high antibacterial activity in direct contact with MRSE and MRSA cells. Furthermore, when GO or CNFs were illuminated with LED light, the MRSE and MRSA cells lost viability. The rate of decrease in colony forming units from 0 to 3 h, measured per mL, increased to 98.5 ± 1.6% and 95.8 ± 1.4% for GO and 99.5 ± 0.6% and 99.7 ± 0.2% for CNFs. CONCLUSIONS: This combined antimicrobial approach opens up many biomedical research opportunities and provides an enhanced strategy for the prevention and treatment of Gram-positive multidrug-resistant infections.