Greater Antibacterial Effect Research Articles

Antimicrobial Effect of Formononetin Against the Periodental Pathogens Enterococcus faecalis and Candida albicans.

Among the bioactive isoflavones identified from different plants is formononetin. Formononetin's antioxidant, anti-inflammatory, and anti-cancer qualities have all received a lot of attention lately. The goal of the current investigation was to examine formononetin's antifungal and antibacterial activity against Candida albicans and Enterococcus faecalis in vitro, respectively. The present study determined the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and Minimum Fungicidal Concentration (MFC) of formononetin, chlorhexidine, formononetin + chlorhexidine, Formononetin+ nystatin, and nystatin against E. faecalis and C. albicans isolates. Next, SPSS version 25 was used to analyze the data. A significance cutoff of P<0.05 was taken into account. Chlorhexidine + formononetin and formononetin alone had the greatest and lowest minimum inhibitory concentrations (MIC) against E. faecalis, at 6.6 and 18.3 μg/ml, respectively. With MIC values of 0.66 and 8.3 μg/ml against a C. albicans isolate sensitive to nystatin, the combination of formononetin + nystatin and formononetin alone was shown to have the greatest and lowest anti-candida effects. The findings demonstrated a considerably greater antibacterial effect (P<0.05) for the combinations of formononetin + nystatin and chlorhexidine as compared to nystatin and chlorhexidine alone.

The effect of nano silver fluoride, self-assembling peptide and sodium fluoride varnish on salivary cariogenic bacteria: a randomized controlled clinical trial

ObjectivesTo compare the antibacterial effect of Nanosilver Fluoride varnish (NSF) varnish, P11-4 and Sodium Fluoride (NaF) varnish against salivary Streptococcus mutans (S. mutans) and Lactobacilli.Methods66 patients aged 10–24 years old were randomly assigned to receive single application of NSF, P11-4 or NaF varnish. Baseline unstimulated saliva samples were collected before the agents were applied and S.mutans and Lactobacilli colony forming units (CFU) were counted. After one, three and six months, microbiological samples were re-assessed. Groups were compared at each time point and changes across time were assessed. Multivariable linear regression compared the effect of P11-4 and NSF to NaF on salivary S. mutans and Lactobacilli log count at various follow up periods.ResultsThere was a significant difference in salivary S. mutans log count after 1 month between P11-4 (B= -1.29, p = 0.049) and NaF but not at other time points nor between NSF and NaF at any time point. The significant reduction in bacterial counts lasted up to one month in all groups, to three months after using P11-4 and NaF and returned to baseline values after six months.ConclusionIn general, the antimicrobial effect of P11-4 and NSF on salivary S. mutans and Lactobacilli was not significantly different from NaF varnish. P11-4 induced greater reduction more quickly than the two other agents and NSF antibacterial effect was lost after one month.Clinical relevanceNSF varnish and P11-4 have antimicrobial activity that does not significantly differ from NaF by 3 months. P11-4 has the greatest antibacterial effect after one month with sustained effect till 3 months. The antibacterial effect of NSF lasts for one month. NaF remains effective till 3 months.Trial RegistrationThis trial was prospectively registered on the clinicaltrials.gov registry with ID: NCT04929509 on 18/6/2021.

Antibacterial Activity of Robusta Coffee (Coffea Canephora) Husk Extract Against Enterococcus Faecalis and Phorphyromonas Gingivalis: In Vitro Study

Enterococcus faecalis is one of the bacteria that is commonly found in infected root canals, necrotic pulp and failure of root canal treatment, while Phorphyromonas gingivalis play a role in inducing periodontitis. Both bacteria can enter the blood circulation and lead to risk factors for systemic disease such as atherosclerosis. ChKM is the most widely used root canal sterilization, and also 0.2 % chlorhexidine mouthwash for long-term usage. It can destroy a potent cell and is allergenic. Developing an alternative material for root canal sterilization and mouthwash for plaque control is necessary. One of the alternative natural products that is predicted to have antibacterial effect is robusta coffee husk peels. This research aimed to investigate the antibacterial activity of robusta coffee (Coffea canephora) husk extract on E. faecalis and P. gingivalis. The robusta coffee husk was extracted using the maceration process with 96 % ethanol as the solvent. This research is an experimental laboratory, was tested by disk diffusion methods (Kirby-Baurer) using Gram-positive E. faecalis ATCC 29212 and Gram-negative P. gingivalis ATCC 33277 consisted of 6 groups: Aquadest as a negative control group, ChKM (for E.facecalis) and 0.2 % chlorhexidine (for P. gingivalis) as positive control, 4 treatment groups of coffee robusta husk extract with different concentrations there were 250, 250, 500, 750 and 1,000 mg/mL. The antibacterial effect was examined by measuring the clear zone around the disk paper. The results of this study proved the presence of antibacterial activity of coffee robusta husk extract against E. faecalis and P. gingivalis. The higher concentrations followed with a greater antibacterial effect. HIGHLIGHTS Robusta coffee husk extract (Coffea canephora) has an antibacterial property against Gram-positive and Gram-negative bacteria Robusta coffee husk was extracted using the maceration process, and disk diffusion methods (Kirby-Baurer) for antibacterial test Robusta coffee husk extract with a concentration of 1,000 mg/mL showed the greatest inhibition zone. The higher the concentration, the bigger inhibition zone appeared GRAPHICAL ABSTRACT

Durability of photocatalytic ZnO-based surface coatings and preservation of their antibacterial effect after simulated wear

This study focused on antibacterial durability testing of surface coatings based on acrylic matrix-embedded UVA-activated ZnO. Such coatings on stainless steel were treated by dry rubbing, wet rubbing, and abrasive treatment to simulate wearing during everyday touching, cleaning, and aggressive scrubbing. Abrasive treatment caused clear topological changes to the surfaces, flattened the surface at the micrometer scale, and released a significant amount of surface material, which was partly acrylic matrix and partly the embedded ZnO. The highest release of Zn, the most prominent photocatalytic activity under UVA and the greatest antibacterial effect, was observed for abrasively treated surfaces. Although a small amount of surface material was released from surfaces after dry and wet rubbing, no significant increase in Zn release or photocatalytic activity was detected. On the contrary, antibacterial activity after those treatments decreased in comparison with untreated surfaces, likely due to partial surface masking by the released acrylic matrix. In summary, our results indicate that antimicrobial ZnO material immobilized in acrylic matrix creates stable surface coatings that may lose some of their efficacy during daily use and cleaning procedures, but activity of which will be retained during a more aggressive abrasion procedure.

In Vitro Efficacy of Photodynamic Antimicrobial Chemotherapy with TONS504 Using Blue Light Against Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an important causative agent of bacterial keratitis. This study investigates the antibacterial effect of photodynamic antimicrobial chemotherapy (PACT) with the chlorin derivative TONS504 (TONS504-PACT) and a blue light-emitting diode (LED) on P. aeruginosa in vitro. It also explores the synergistic effects of combining TONS504-PACT with EDTA, and compares the antibacterial effects of TONS504-PACT using blue light with those of previously reported red light. To evaluate the antibacterial effects of TONS504-PACT using blue light on P. aeruginosa, PACT with TONS504 (0-100 mg/L) was applied using a 405 nm LED at 0-30 J/cm2 to P. aeruginosa (107-8 CFU/mL). The antibacterial effects were assessed by calculating the survival fraction. Subsequently, to compare the effects of TONS504-PACT using blue light with those of using red light, PACT with TONS504 (10 or 100 mg/L) was conducted using a 405 or 660 nm LED at 30 J/cm2 and evaluated in the same manner. Finally, to investigate the synergistic antibacterial effects of TONS504-PACT with EDTA, PACT with TONS504 (0-100 mg/L) was applied using a 405 nm LED at 5 J/cm2, both with and without EDTA (0.015 M), and its antibacterial effects were similarly assessed. TONS504-PACT using blue light decreased the survival of P. aeruginosa, depending on the light intensity. The greatest antibacterial effect was observed at 10 mg/L and 30 J/cm2, showing a survival fraction of 3.5 × 10-5. TONS504-PACT demonstrated a significantly greater antibacterial effect using blue light than that demonstrated using red light at 10 mg/L, though not at 100 mg/L. The combination of TONS504-PACT using blue light with EDTA significantly enhanced antibacterial effects at all concentrations. These findings confirm the effectiveness of TONS504-PACT using blue light against P. aeruginosa and suggest its potential as a treatment for bacterial keratitis.

Exposure to blue light reduces antimicrobial resistant Pseudomonas aeruginosa isolated from dog ear infections.

Pseudomonas aeruginosa is a leading cause of canine otitis externa. Enrofloxacin is often applied topically to treat this condition, although recalcitrant and recurring infections are common. There is evidence that exposure to blue light (400-470 nm) has a bactericidal effect on P. aeruginosa and other microorganisms. In the present study, we tested the biocidal effect of blue light (375-450 nm), alone or in combination with enrofloxacin, against six isolates of P. aeruginosa from dogs with otitis externa (5 of which were resistant to enrofloxacin). Treatment of planktonic cell cultures with blue light resulted in significant (p < 0.5) reductions in Colony Forming Units (CFU) for all seven strains tested, in some cases below the limit of detection. The greatest bactericidal effect was observed following exposure to light at 405 nm wavelength (p < 0.05). Exposure to blue light for 20 min usually resulted in a greater reduction in Pseudomonas aeruginosa than enrofloxacin treatment, and combination treatment typically resulted in the largest reductions in CFU. Analysis of the genome sequences of these strains established that enrofloxacin resistance was likely the result of a S466F substitution in GyrB. However, there was no clear association between genotype and susceptibility to blue light treatment. These results suggest that blue light treatment, particularly at 405 nm wavelength, and especially in combination with enrofloxacin therapy, could be an effective treatment for otherwise recalcitrant canine otitis externa caused by Pseudomonas aeruginosa. It may also provide a way of extending the usefulness of enrofloxacin therapy which would otherwise be ineffective as a sole therapeutic agent.

Bacterial screening associated with respiratory infection and the synergistic effect of ginger and garlic tea extract conducted at assulfan herbal research center

Respiratory tract infection are the most common infectious diseases in human due to its common mode of transmission and leading a heavy burden to Public Health. The study was aimed to isolate the bacterial pathogens that are associated with respiratory infection and using synergistic effect to evaluate the antibacterial activity of ginger and garlic tea extract of potential isolates. The present study revealed the presence of 41 isolates of respiratory pathogens out of 200 Sample collected from sputum and swab throat. The isolation and identification of target pathogens were done using Cultural and biochemical Characterizations. 7(17.07%), 16(39.02%), 14(34.15%), 3(07.39%) and 1(02.44%) are positive of respectively. For the synergistic antibacterial effect of both methanolic and ethanolic extracts of garlic and ginger tea, all respiratory pathogens that were isolated in the present study were showed the great antibacterial effect except has highest activity of 17±0.7mm at 150mg/ml in methanolic while in ethanolic with 15±0.2 at 100mg/ml. Lowest activity was found to be 07±0.2mm at 50mg/ml for both and .

The first electrochemical N-arylation of chitosan. Antibacterial effect of novel cationic chitosan derivatives

In this study, we present the first electrochemical N-arylation of chitosan, which serves as a straightforward and convenient method for chemical modification of chitosan under mild conditions. Importantly, this method avoids any undesirable depolymerization of the polysaccharide backbone. Through this process, we successfully synthesized chitosan derivatives with varying molecular weights: low, medium, and high. These derivatives exhibited different degrees of substitution, with values of approximately 20 %, 30 %, and 65 %, respectively. Our elaborately designed polymers possess excellent water solubility across a broad pH range, ranging from strongly alkaline to strongly acidic. Furthermore, we conducted an investigation into the antimicrobial activity of the synthesized derivatives against two bacterial strains, namely S. aureus and E. coli. We found that the antimicrobial effectiveness of the polymers strongly relies on both the degree of substitution and the molecular weight of the derivatives. Notably, derivatives with a high degree of substitution and low molecular weight exhibited the most potent antimicrobial activity. Additionally, we explored the formation of nanoparticles through ionic gelation using highly active antimicrobial derivatives. These nanoparticles displayed an even greater antibacterial effect, comparable to that of commercially available antibiotics. Overall, our findings highlight the significance of electrochemical N-arylation as a viable approach for modifying chitosan, yielding chitosan derivatives with desirable properties for potential applications in various fields, particularly in antimicrobial and nanomedicine domains.

The viability of human dental pulp cells and apical papilla cells after treatment with conventional calcium hydroxide and nanoparticulate calcium hydroxide at various concentrations

IntroductionNanoparticulate Ca(OH)2 had greater antibacterial effect than conventional Ca(OH)2. Conversely, a study reported that nanoparticulate Ca(OH)2 had toxicity against murine fibroblast. However, the study of nanoparticulate Ca(OH)2, involving human dental pulp cells (DPCs) and apical papilla cells (APCs) is lacking. The aim of this study is to compare the effects of conventional Ca(OH)2 and nanoparticulate Ca(OH)2 on the viability of DPCs and APCs. MethodsPrimary human DPCs/APCs from the 3rd to 5th passage were divided into control and experimental groups. In the control group, cells were cultured in complete media. In the experimental group, cells were cultured in complete media containing 10, 100, or 1000 μg/mL of either conventional Ca(OH)2 or nanoparticulate Ca(OH)2 for 1, 3, 5, and 7 days. After the treatment period, the cells were tested for viability using MTT assay. ResultsDPCs treated with conventional Ca(OH)2 in all concentrations at day 5 revealed significantly higher proliferation compared to nanoparticulate Ca(OH)2 treated groups. In additions, DPCs treated with 1000 µg/ml nanoparticulate Ca(OH)2 at day7 were significantly lower proliferation compared to DPCs treated with conventional Ca(OH)2. In contrast, APCs treated with 1000 µg/ml nanoparticulated Ca(OH)2 were significantly higher proliferation than APCs treated with 1000 µg/ml conventional Ca(OH)2 at day7. ConclusionsNanoparticulate Ca(OH)2 increased the viability of APCs and can be an alternative choice of intracanal medication for regenerative endodontic procedures. However, Nanoparticulate Ca(OH)2 exerted some effects on DPCs. The use of nanoparticulate Ca(OH)2 has no advantages over the conventional Ca(OH)2 for vital pulp therapy.

Antibacterial activity of Garcinia kola and Hunteria umbellata extracts on bacterial isolates from consumed sachet water in Edo State, Nigeria

"Water is an essential resource and its purity should not be negotiated when it comes to human consumption. This study investigated the antibacterial activity of Garcinia kola and Hunteria umbellata seed and epicarp on some bacterial isolates from sachet water. Duplicate samples of ten brands of sachet water were purchased from sales outlets around Ugbowo community, Benin City. Plate count techniques, minimum inhibitory and minimum bactericidal concentrations of the extracts were adopted in this investigation. Heterotrophic bacterial counts revealed highest range of 3.72±0.50x102 cfu/mL in EJ water and lowest in IB water (0.00±0.0x102 cfu/mL) while total coliform counts revealed its highest value in EJ water (3.62±0.30x102 cfu/mL) and lowest value (0.00±0.0 x102 cfu/mL), in OL, IB, NOS and UNI water. Aeromonas sp., Bacillus sp., Pseudomonas sp., Staphylococcus aereus and Enterobacter sp. were isolated. The antimicrobial susceptibility profile revealed varying zones of inhibition of 4 mm for Aeromonas sp., for Garcinia Kola and 20 mm recorded against Staphylococcus aureus and Bacillus sp. for Hunteria umbellata epicarp extract. The Minimum Inhibitory Concentration of susceptible bacteria to Hunteria umbellata and Garcinia kola extract were 6.25mg/mL and 12.5mg/mL, respectively, except Aeromonas sp. which had 50 mg/mL. Hunteria umbellata epicarp had a greater bactericidal effect of 6.25mg/mL against Staphylococcus aureus, while Garcinia kola had its greatest bactericidal effect on Enterobacter sp. with a minimum bactericidal concentration of 12.5mg/mL. This study has revealed the potentials of Hunteria umbellata epicarp and Garcinia kola as effective natural therapeutic agents against some harmful bacteria, preventing their pathogenic effect. Keywords: Herbal extracts, Hygiene education, Minimum Bactericidal Concentration, Minimum Inhibitory Concentration, Sachet water."

Co-assembled nanocomplexes comprising epigallocatechin gallate and berberine for enhanced antibacterial activity against multidrug resistant Staphylococcus aureus

Berberine (BBR), a major alkaloid in Coptis chinensis, and (-)-epigallocatechin-3-gallate (EGCG), a major catechin in green tea, are two common phytochemicals with numerous health benefits, including antibacterial efficacy. However, the limited bioavailability restricts their application. Advancement in the co-assembly technology to form nanocomposite nanoparticles precisely controls the morphology, electrical charge, and functionalities of the nanomaterials. Here, we have reported a simple one-step method for preparing a novel nanocomposite BBR-EGCG nanoparticles (BBR-EGCG NPs). These BBR-EGCG NPs exhibit improved biocompatibility and greater antibacterial effects both in vitro and in vivo relative to free-BBR and first-line antibiotics (i.e., benzylpenicillin potassium and ciprofloxacin). Furthermore, we demonstrated a synergistic bactericidal effect for BBR when combined with EGCG. We also evaluated the antibacterial activity of BBR and the possible synergism with EGCG in MRSA-infected wounds. A potential mechanism for synergism between S. aureus and MRSA was also explored through ATP determination, the interaction between nanoparticles and bacteria, and, then, transcription analysis. Furthermore, our experiments on S. aureus and MRSA confirmed the biofilm-scavenging effect of BBR-EGCG NPs. More importantly, toxicity analysis revealed that the BBR-EGCG NPs had no toxic effects on the major organs of mice. Finally, we proposed a green method for the fabrication of BBR-EGCG combinations, which may provide an alternative approach to treating infections with MRSA without using antibiotics.

Thymol-Nanoparticles as Effective Biocides against the Quarantine Pathogen Xylella fastidiosa.

Quarantine pathogens require the investigation of new tools for effective plant protection. In particular, research on sustainable agrochemicals is the actual challenge. Plant extracts, essential oils, and gels are natural sources of efficient biocides, such as aromatic secondary metabolites. Thymol is the major phenolic constituent of thyme and oregano essential oils, and it can inhibit many pathogenic microbes. Thymol nanoparticles were obtained through adsorption on CaCO3 nanocrystals, exploiting their carrier action. High loading efficiency and capability were reached as verified through UV and TGA measurements. We report the first study of thymol effect on Xylella fastidiosa, conducing both fluorometric assay and in vitro inhibition assay. The first test confirmed the great antibacterial effect of this compound. Finally, an in vitro test revealed an interesting synergistic action of thymol and nanocarriers, suggesting the potential application of thymol-nanoparticles as effective biocides to control Xylella fastidiosa infection.

Extensive Investigation on the Effect of Niobium Insertion on the Physical and Biological Properties of 45S5 Bioactive Glass for Dental Implant

Dental implants have emerged as one of the most consistent and predictable treatments in the oral surgery field. However, the placement of the implant is sometimes associated with bacterial infection leading to its loss. In this work, we intend to solve this problem through the development of a biomaterial for implant coatings based on 45S5 Bioglass® modified with different amounts of niobium pentoxide (Nb2O5). The structural feature of the glasses, assessed by XRD and FTIR, did not change in spite of Nb2O5 incorporation. The Raman spectra reveal the Nb2O5 incorporation related to the appearance of NbO4 and NbO6 structural units. Since the electrical characteristics of these biomaterials influence their osseointegration ability, AC and DC electrical conductivity were studied by impedance spectroscopy, in the frequency range of 102-106 Hz and temperature range of 200-400 K. The cytotoxicity of glasses was evaluated using the osteosarcoma Saos-2 cells line. The in vitro bioactivity studies and the antibacterial tests against Gram-positive and Gram-negative bacteria revealed that the samples loaded with 2 mol% Nb2O5 had the highest bioactivity and greatest antibacterial effect. Overall, the results showed that the modified 45S5 bioactive glasses can be used as an antibacterial coating material for implants, with high bioactivity, being also non-cytotoxic to mammalian cells.

In vitro comparative study of antimicrobial efficacy of endodontic sealers against common pathogens in the dental pulp.

Different types of bacterial species, Enterococcus faecalis (E. faecalis), Fusobacterium nucleatum (F. nucleatum), and Porphyromonas gingivalis (P. gingivalis), cause pulpal and periradicular diseases. Hence, the antibacterial efficacy of endodontic sealers is of utmost importance from a clinical point of view. The main objective of the study is to test the antibacterial efficacy of endodontic sealers against endo microflora belonging to E. faecalis, F. nucleatum, and P. gingivalis species. The antibacterial effectiveness of five endodontic sealers (AH plus, Apexit, EndoRez, Endomethasone, and Tubliseal) was tested by means of the agar-diffusion test (ADT) and direct contact test (DCT). The bacterial suspension of individual microorganisms was applied separately onto the agar plates for ADT. Subsequently, freshly mixed and set sealer was applied on to the sterile discs. After 48 h of incubation, the inhibition zones were measured. For DCT, the sealers were put in 96-well cell culture plates and overlaid with bacterial suspension and brain heart infusion broth. The bacterial growth density of the liquid was tested by spectrophotometry at 0, 2, 4, 6, and 24 h. The data were analyzed using ANOVA and post hoc Turkey's test. The present study showed that Endomethasone and AH Plus had a good antibacterial effect. In the ADT and DCT, Endomethasone showed the greatest antimicrobial effect against E. faecalis when compared to other endodontic sealers. In the ADT, Apexit had no antimicrobial effect on E. faecalis, whereas AH Plus had the greatest antibacterial effect on F. nucleatum and P gingivalis. Whereas in DCT, EndoRez and Endomethasone showed the greatest effect against F. nucleatum and P. gingivalis.

Antimicrobial Activity of Some Medicinal Herbs to the Treatment of Cutaneous and Mucocutaneous Infections: Preliminary Research

(1) Background: Superficial, including cutaneous and mucocutaneous infections are a current public health problem with universal distribution. One of the main concerns, in the present/future, is fungal/bacterial infections by resistant microorganisms. This study aimed to verify if decoctions of coptidis (Coptis chinensis, Ranunculaceae family), neem (Azadirachta indica, Meliaceae family), and their essential oils (EOs), as well as the EO of manuka (Leptospermum scoparium, Myrtaceae family) have antimicrobial activity against prevalent species of microorganisms responsible for superficial infections. (2) Methods: The antimicrobial activity was determined by the minimum inhibitory concentration (MIC), using broth microdilution method, and minimum lethal concentration (MLC) was determined from subculture of MIC plates. (3) Results: C. chinensis EO and decoction demonstrated some antifungal action against the yeasts and dermatophytes tested. Greatest bactericidal effect against Propionibacterium acnes and some action against Staphylococcus aureus was observed. For A. indica only EO proved activity against dermatophytes and P. acnes. L. scoparium EO showed the broadest antimicrobial spectrum with activity against bacteria, yeasts, and dermatophytes showing greater activity against P. acnes and S. aureus. (4) Conclusions: C. chinensis (EO/decoction), EOs of L. scoparium and A. indica proved in vitro efficacy against fungal, bacterial, or mixed agents of superficial infections, either by sensitive or resistant strains.

Bimetal-doped nanosheet with phototherapeutic potential for clearance of bacterial infection

Phototherapy as a potential alternative has recently emerged for clearance of bacterial infection. However, single photothermal therapy often causes damage to skin and tissues due to excessive temperature. To overcome this deficiency, a bimetal-doped nanosheet (FeS@Cu2O) is successfully devised and fabricated via a hydrothermal method, which possesses photothermal, photodynamic and chemo-dynamic properties. The FeS@Cu2O not only exerts hyperthermal property as a potential photothermal agent, but also can efficiently produce ROS to eliminate bacteria via released bimetal (Fe2+ and Cu+). The antibacterial experiment indicates that the sample has a great antibacterial effect against E. coli and S. aureus. This work provides new ideas for the versatile multimodal synergistic therapy for sterilization.

Dual-Responsive Nanocomposites for Synergistic Antibacterial Therapies Facilitating Bacteria-Infected Wound Healing.

The rising dangers of bacterial infections have created an urgent need for the development of a new generation of antibacterial technologies and therapeutics. Antibacterial photodynamic therapy (PDT), considered as a noninvasive treatment with no drug resistance, has become a new promising photochemistry-involved treatment strategy. Titanium oxide (TiO2 ) is proved to be a very efficient PDT agent among the photosensitive materials, while the property of a large bandgap of TiO2 makes it only be excited by ultraviolet light, which is harmful to organisms. In this work, a novel ligand-to-metal charge transfer (LMCT) mediated TiO2 PDT strategy is proposed via the harmless near-infrared light irradiation. By choosing a mussel-inspired material, polydopamine (PDA) is involved in forming mesoporous TiO2 @PDA nanoparticles (mTiO2 @PDA NPs). The catechol groups of PDA can attach the TiO2 tightly even in colloidal environments, and can also form the LMCT bridge, exciting TiO2 to exert PDT function via 808nm irradiation. Combining the sonodynamic therapy (SDT) of TiO2 and the photothermal therapy properties of PDA, this simple structure mTiO2 @PDA enables synergistic antibacterial applications with multiple functions under the dual excitation of NIR and ultrasound. This reliable all-in-one NPs can achieve great antibacterial effect and a rapid repair of infected wounds.

Bactericidal Effect of Ultrasound-Responsive Microbubbles and Sub-inhibitory Gentamicin against Pseudomonas aeruginosa Biofilms on Substrates With Differing Acoustic Impedance.

The aim of this research was to explore the interaction between ultrasound-activated microbubbles (MBs) and Pseudomonas aeruginosa biofilms, specifically the effects of MB concentration, ultrasound exposure and substrate properties on bactericidal efficacy. Biofilms were grown using a Centre for Disease Control (CDC) bioreactor on polypropylene or stainless-steel coupons as acoustic analogues for soft and hard tissue, respectively. Biofilms were treated with different concentrations of phospholipid-shelled MBs (107-108 MB/mL), a sub-inhibitory concentration of gentamicin (4 µg/mL) and 1-MHz ultrasound with a continuous or pulsed (100-kHz pulse repetition frequency, 25% duty cycle, 0.5-MPa peak-to-peak pressure) wave. The effect of repeated ultrasound exposure with intervals of either 15- or 60-min was also investigated. With polypropylene coupons, the greatest bactericidal effect was achieved with 2×5 min of pulsed ultrasound separated by 60 min and a microbubble concentration of 5×107 MBs/mL. A 0.76 log (83%) additional reduction in the number of bacteria was achieved compared with the use of an antibiotic alone. With stainless-steel coupons, a 67% (0.46 log) reduction was obtained under the same exposure conditions, possibly due to enhancement of a standing wave field which inhibited MB penetration in the biofilm. These findings demonstrate the importance of treatment parameter selection in antimicrobial applications of MBs and ultrasound in different tissue environments.

Antibody-conjugated and streptomycin-chitosan oligosaccharide-modified gold nanoshells for synergistic chemo-photothermal therapy of drug-resistant bacterial infection

Despite the many advanced strategies that are available, rapid gene mutation in multidrug-resistant bacterial infections remains a major challenge. Combining new therapeutic strategies such as chemo-photothermal therapy (PTT) with high antibacterial efficiency against drug-resistant Listeria monocytogenes (LM) is urgently needed. Here, we report synergistic chemo-PTT against drug-resistant LM based on antibody-conjugated and streptomycin-chitosan oligosaccharide-modified gold nanoshells (anti-STR-CO-GNSs) as all-in-one nanotheranostic agents for the first time, which was used for accurate antibacterial applications. The anti-STR-CO-GNSs showed excellent photothermal conversion efficiency (31.97 %) and were responsive to near-infrared (NIR) and pH dual stimuli-triggered antibiotic release, resulting in outstanding chemo-photothermal effects against LM. In vitro chemo-photothermal effect of anti-STR-CO-GNSs with laser irradiation caused a greater antibacterial effect (1.37 %), resulting in more rapid killing of LM and prevention of LM regrowth. Most importantly, the mice receiving the anti-STR-CO-GNSs with laser irradiation specifically at the sites of LM infections healed almost completely, leaving only scars on the surface of the skin and resulting in superior inhibitory effects from combined chemo-PTT. Overall, our findings suggest that chemo-PTT using smart biocompatible anti-STR-CO-GNSs is a favorable potential alternative to combat the increasing threat of drug-resistant LM, which opens a new door for clinical anti-infection therapy in the future.

CONCORDANCE OF METHYLENE BLUE REDUCTION AND MICROBIOLOGICAL TECHNIQUES IN THE ANALYSIS OF RAW AND PROCESSED MILK QUALITY: A COMPARATIVE STUDY

Raw milk is a milk that has not undergone pasteurization for an effective pathogen elimination, thus having a reduced shelf life due to microbial activities. Microorganisms such as bacteria can affect the quality of diary products, hence the need to assess the microbial quality of natural cow milk, pasteurized milk and processed tin-milk which are consumed on daily basis in Nigeria, Africa and the world at large. In this study, raw (unpasteurized) and processed milk samples from two locations (Bogobiri and Watt market) in Calabar municipal were analyzed using methylene blue reduction test (MBRT), total heterotrophic bacterial count (THBC) and total coliform count (TCC). The total Heterotrophic bacterial count ranged from too numerous to count (TNTC) to 3.86 x 106 colony forming unit (CFU)/milliliter (ml) in samples MA (Unpasteurized/Raw cow milk) and MB (Pasteurized cow milk) respectively. There was no fungal growth in five of the samples except MA that had a fungal count that was TNTC. The highest TCC was obtained from sample MA, with a value of 2.96 x 106 CFU/mL while sample MD had the lowest count of one colony. The total microbial count from sample MA was extremely high and above the standard signifying that it is unfit for human consumption. The MBRT result revealed that MD (Processed liquid tin-milk) and MC (Processed liquid tin-milk) gave no methylene blue reduction (excellent quality) while MB (Pasteurized cow milk), ME (Processed liquid tin-milk) and MF (Processed liquid tin-milk) were of fair quality. However, MA gave a poor quality based on the MBR time of between 30 m to 2 h corroborating with the high value of its THBC which was above the standard. Milk being a vital protein source and an excellent medium for microbial growth should be thoroughly treated by sterilization in a bottle as the study revealed that the milk microbial load can be greatly reduced by pasteurization, with sterilization in bottle having a greater bactericidal effect than pasteurization.