Commercial Antibiotics Research Articles

MurC ligase of multi-drug resistant Salmonella Typhi can be inhibited by novel Curcumin derivative: Evidence from molecular docking and dynamics simulations.

Emerging multi-drug resistance in recent Salmonella Typhi isolates, causative agent of enteric Typhoid fever, compelled us to investigate alternative therapeutic strategies. The present study encompassed virtual screening, ADMET screening as well as antibacterial activity prediction to shortlist potent lead molecules whose binding affinities (BAs) were checked against major druggable S. Typhi targets. BA profile revealed a deoxy-tetradeutero- curcumin derivative to be novel bioactive compound having high BA towards UDP-N-acetylmuramate-L-alanine ligase (MurC) protein involved in peptidoglycan synthesis. Molecular docking indicated that our lead {Binding energy (BE)=-8.00±0.02kcal/mol}could competitively bind to MurC with respect to its natural ligand ATP (BE= -7.65±0.19kcal/mol). The lead also possessed superior binding and inhibition profile against MurC than other commercial antibiotics. This BE was contributed by Hydrogen (H-) bonds and numerous non-canonical interactions with the evolutionary conserved active-site residues. From molecular docking and coarse-grained dynamics simulations, it was inferred that the novel curcumin derivative was predicted to be potential competitive inhibitor of ATP for MurC-catalytic domain having low relative RMSF (0.59Å) to inhibit MurC-induced peptidoglycan biosynthesis. The inferences drawn from the study can open new portals for designing efficient therapeutic strategies against S. Typhi.

Formulation, characterization and antimicrobial activity of Rhus coriaria aqueous crude extract

Currently used copper-based pesticides and fungicides caused bacteria and fungi to develop resistance. Therefore, other environmentally friendly methods are being encouraged. Successful biopesticide usage is greatly reliant on suitable development of formulation. Four different surfactants (Emereen 1810, Emereen 1604, Emereen 1820 and Tween 20) were used to formulate Rhus coriaria aqueous extract. Stability, thermostability, particle size distribution, surface tension, shelf life were tested. The formulation was evaluated for its efficacy in controlling two of the most destructive fungi (Fusarium oxysporum (Acc No. KM039054) and Colletotrichum boninense (Acc No. KM039057) and two common bacteria (Xanthomonas vesicatoria (Acc No. KU661975) and Ralstonia solanacearum (Acc No. KT783476) in vitro and in vivo. From the four surfactants Emereen 1820 showed to be the best surfactant and was stable after six months of storage. A surface tension value of nanoemulsion solution was 27.174 mN/m, while particle size was 70.44 nm. Even after incubation and storage for up to twelve months, the formulation was stable and effective as well as efficient as compared to common commercial fungicides and antibiotics. Results indicate that R. coriaria nanoemulsion can effectively be used for the management of tomato pathogens as an eco-friendly approach.

Antibacterial Effect Of Bacillus species Biomolecules (Metabolites, Silver Nanoparticles, And Functionalized Silver Nanoparticles) Against Multi-Drug Resistance Listeria species

The study investigated the anti-listeria activity of Bacillus subtilis (BsaM), Bacillus licheniformis (BlbM) and Bacillus megaterium (BmcM) against seven Listeria species. Metabolites from Bacillus spp. were used for silver nanoparticles (BsaSNPs, BlbSNPs, and BmcSNPs) biosynthesis. The Silver Nanoparticles (SNPs) characterization was done using visual observation, UV-Visible Spectrophotometric, FTIR, SEM, and EDXRF. The anti-listeria synergistic potential of the biosynthesized SNPs and functionalized SNPs against Multidrug resistance (MDR) Listeria strains was evaluated. The BsaM, BlbM, and BmcM had a varied anti- listeria effect against the Listeria spp. 71.43, 100, and 5.71 % of the Listeria spp. were susceptible to the BsaM, BlbM, and BmcM metabolites respectively. The metabolite bio-actively reduced AgNO3 for BsaSNPs, BlbSNPs, and BmcSNPs production. Surface Plasma Resonance (SPR) peaks of 600 nm, 400 and 600 nm, and 600 nm were recorded for BsaSNPs, BlbSNPs, and BmcSNPs. The shape of the SNPs were aggregated, rods, and crystalline. The functional groups present in the nanoparticles were carboxylic acid, amino acid, alcohol, esters, and aldehydes had the highest intensity. BsaSNPs, BlbSNPs, and BmcSNPs had the highest anti-listeria potential of 20.0, 16.0 and 22.0 mm against Listeria innocua LA22A and Listeria ivanovii LA6. Functionalized BsaSNPs, BlbSNPs, and BmcSNPs had the highest anti-listeria activity compared to the metabolites and commercial antibiotics. Ciprofloxacin-BsaSNPs, Erythromycin-FBlbSNPs, and Erythromycin-FBmcSNPS had the highest antagonistic activity (28, 26, and 27 mm) against Listeria ivanovii LA6 respectively. The Bacillus strains’ metabolites, the SNPs, and functionalized SNPs exhibit antimicrobial activities against Multidrug resistance Listeria species. Functionalization improved the anti-listerial ability of the antibiotics. Keywords: Bacillus species, Anti-listeria activity, SNPs, MDR Listeria species, Functionalization.

Enhanced anti-biofilm and biocompatibility of Zn and Mg substituted β-tricalcium phosphate/functionalized multiwalled carbon nanotube composites towards A. baumannii and Methicillin-Resistant Staphylococcus aureus, and MG-63 cells

In this work, Zn and Mg substituted β-tricalcium phosphate/functionalized multiwalled carbon nanotube (f-MWCNT) nanocomposites were prepared by the co-precipitation method. The structural, vibrational, morphological and biological properties of the prepared nanocomposites were studied. The structural study revealed that the increase of Zn concentration shifts the β-tricalcium phosphate planes towards higher angle. Morphological analysis confirmed the formation of hexagonal-shaped particles after substitution of Zn. The particle size of the nanoparticles decreased with the increase of Zn concentration. XPS analysis clearly showed the presence of Zn, Mg, P, Ca, O and C. The Zn (5%) rich nanocomposites have better antibiofilm activity compared to 2% of zinc substituted composite. Also, it has been proven that the prepared nanocomposites have the ability to enhance the bioactivity of commercial antibiotics by means of a decrease in drug resistance. Finally, this study acted as a pioneer to improve drug efficiency and reduced the biofilm formation of certain medically important bacteria. The in-vitro cell viability and anti-biofilm results of zinc (5%) rich nanocomposite confirmed that prepared nanocomposite has biocompatible and enhanced anti-biofilm property, which will be beneficial candidate for biomedical applications.

An in vitro analysis on antagonistic activities of actinomycetes recovered from caves of Garhwal Himalaya against drug resistant pathogens

Antibiotic resistance among bacterial pathogens especially gram-negative bacteria has risen markedly over the last decade. Inadequacy of the commercial antibiotics against multidrug resistant strains of bacteria has necessitated the search for effective antimicrobials from lesser explored ecosystems. Recently, cave actinomycetes have drawn considerable attention as a source of novel antibacterial agents. Garhwal Himalayan region in Uttarakhand abodes several pristine caves which have not been previously explored for their actinomycetes diversity. The present study has been designed to have an insight into the bioactive spectrum of cave actinomycetes of Garhwal Himalaya. In the present study, a total of 103 actinomycetes were isolated from three distinct caves. Streptomyces sp. was found to be the predominant species in all the samples. The recovered actinomycetes were screened for their antibacterial activities with a focus on their activity against MDR E. coli, A. baumannii, S. pyogens, MRSA and VRE. faecalis. Isolates RCM1, RCM14 and SCM1 showed significant antibacterial activities. SCM1 was found to be most promising isolate exhibiting remarkable inhibition against MDR bacterial pathogens.

Ocimum Species: A Review on Chemical Constituents and Antibacterial Activity.

Infection by bacteria is one of the main problems in health. The use of commercial antibiotics is still one of the treatments to overcome these problems. However, high levels of consumption lead to antibiotic resistance. Several types of antibiotics have been reported to experience resistance. One solution that can be given is the use of natural antibacterial products. There have been many studies reporting the potential antibacterial activity of the Ocimum plant. Ocimum is known to be one of the medicinal plants that have been used traditionally by local people. This plant contains components of secondary metabolites such as phenolics, flavonoids, steroids, terpenoids, and alkaloids. Therefore, in this paper, we will discuss five types of Ocimum species, namely O. americanum, O. basilicum, O. gratissimum, O. campechianum, and O. sanctum. The five species are known to contain many chemical constituents and have good antibacterial activity against several pathogenic bacteria.

The synthetic antimicrobial peptide IKR18 displays anti-infectious properties in Galleria mellonella in vivo model

Antimicrobial peptides (AMPs) are promising tools for developing new antibiotics. We described the design of IKR18, an AMP designed with the aid of computational tools. IKR18 showed antimicrobial activity against Gram-negative and Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). CD studies revealed that IKR18 assumes an alpha-helical structure in the membrane-mimetic environment. The action mechanism IKR18 involves damage to the bacteria membrane, as demonstrated by Sytox green uptake. Furthermore, IKR18 displayed synergic and additive effects in combination with antibiotics ciprofloxacin and vancomycin. The peptide showed anti-biofilm activity in concentration and efficiency compared with commercial antibiotics, involving the direct death of bacteria, as confirmed by scanning electron microscopy. The anti-infective activity of IKR18 was demonstrated in the Galleria mellonella model infected with S. aureus, MRSA, and Acinetobacter baumannii. The novel bioinspired peptide, IKR18, proved to be effective in the control of bacterial infection, opening opportunities for the development of further assays, including preclinical models.

Novel Antibacterial, Cytotoxic and Catalytic Activities of Silver Nanoparticles Synthesized from Acidophilic Actinobacterial SL19 with Evidence for Protein as Coating Biomolecule.

Silver nanoparticles (AgNPs) have potential applications in medicine, photocatalysis, agriculture, and cosmetic fields due to their unique physicochemical properties and strong antimicrobial activity. Here, AgNPs were synthesized using actinobacterial SL19 strain, isolated from acidic forest soil in Poland, and confirmed by UV-vis and FTIR spectroscopy, TEM, and zeta potential analysis. The AgNPs were polydispersed, stable, spherical, and small, with an average size of 23 nm. The FTIR study revealed the presence of bonds characteristic of proteins that cover nanoparticles. These proteins were then studied by using liquid chromatography with tandem mass spectrometry (LC-MS/ MS) and identified with the highest similarity to hypothetical protein and porin with molecular masses equal to 41 and 38 kDa, respectively. Our AgNPs exhibited remarkable antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. The combined, synergistic action of these synthesized AgNPs with commercial antibiotics (ampicillin, kanamycin, streptomycin, and tetracycline) enabled dose reductions in both components and increased their antimicrobial efficacy, especially in the case of streptomycin and tetracycline. Furthermore, the in vitro activity of the AgNPs on human cancer cell lines (MCF-7, A375, A549, and HepG2) showed cancer-specific sensitivity, while the genotoxic activity was evaluated by Ames assay, which revealed a lack of mutagenicity on the part of nanoparticles in Salmonella Typhimurium TA98 strain. We also studied the impact of the AgNPs on the catalytic and photocatalytic degradation of methyl orange (MO). The decomposition of MO was observed by a decrease in intensity of absorbance within time. The results of our study proved the easy, fast, and efficient synthesis of AgNPs using acidophilic actinomycete SL19 strain and demonstrated the remarkable potential of these AgNPs as anticancer and antibacterial agents. However, the properties and activity of such particles can vary by biosynthesized batch.

Medical treatment of various diseases through Nagarmotha (Cyperus rotundus) plant

Nagarmotha (Cyperus rotundus) is found throughout India. Its genus name Cyperus is derived from Cypeiros, an ancient Greek name and rotundus from a Latin word for round and refers to the tuber. It is locally known as “Mutha”. The plant is a widely used traditional medicinal herb in India, China, Japan, Korea, Combodia, Nigeria, and Bangladesh. The plant produces rhizomes, tubers, basal bulbs and fibrous roots below ground and rosettes of leaves, scapes and umbels above ground. The rhizomes of nut grass is widely utilized in ancient medication round the world to treat various diseases like constipation, dysentery, abdominal distention, animal tissue stomach ache, chest pains, irregular catamenia, painful catamenia, skin diseases, staphylococcal infection infections, leprosy, sprains and bruises, and fever, analgesic, sedative, medication, anti malarial drug, abdomen disorders, and diarrhoea . Cyperus rotundus has the properties of antimicrobial activity, anti-lesion activity, analgesic activity, anti inflammatory activity, anti diarrhoeal activity, antipyretic activity, medication activity, anti-emetic activity, tranquilizing activity, anti urolithatic activity, antispatic activity, hypolipidaemic activity, wound healing activity, medication activity, inhibitor activity, metastatic tumor activity, antifungal activity, antidiabetic drug activity, anti-obesity activity, antiallergic activity, anti-blood platelet impact, opposing rheumy activity, anti malarial drug activity, gastroprotective activity, hepatoprotective activity, cytoprotective impact, hypotensive activity, ovicidal and larvicidal activity . The petroleum ether extract and essential oil of Cyperus rotundus possessed analgesic activity. Phenols and alkaloids are the active constituents of C. rotundus. Cyperus rotundus preparations (powder in fine suspension, aqueous and alcoholic extracts) exhibited a lipolytic action and mobilized fat from the adipose tissues and thus helping to reduce the obesity. Methanolic extract of the fresh aerial part of the Cyperus rotundus was fractionated by column chromatography method using petroleum ether, chloroform, ethyl acetate and methanol. The ethyl acetate fraction showed potent antibacterial activity compared to control and standard commercial antibiotic tetracycline. It is a widely used plant in traditional medicine around the world for treatment of various diseases. It is deemed with infinite medicinal properties authenticated by the scientific committee. The rhizomes of Cyperus rotundus are used as traditional folk medicine for the treatment of stomach and bowel disorders and inflammatory diseases in Asian countries. The use of the plant as an analgesic, anti-arthritic, antibacterial, anti-cancer, anticandida, anti-convulsant, anti-diabetic, anti-emetic, anti-histaminic, anti-inflammatory, anti-malarial, anti-obesity, anti-pyretic, anti-spastic, gastroprotective, hypotensive, sedative, and tranquilizing agent has been documented by various scientists. Ethnobotanical use of Cyperus rotundus showed that the rhizomes were used to treat aging, apoptosis, atherosclerosis, cancer, cystitis, epilepsy, genotoxicity, hirutism, nociception and prostatitis disorders. The tuber part of Cyperus rotundus is also used for the treatment of dysmenorrheal and menstrual irregularities from ancient times. The rhizome of Cyperus rotundus are α-cyperolone, β-cyperone, ρ-cymol, calcium, camphene, copaene, cyperene, cyperenone, cyperol, cyperolone, caryophyllene, cyperotundone, d-copadiene, d-epoxyguaiene, isocyperol, isokobusone, kobusone, limonene, linoleic-acid, linolenic-acid, mustakone, myristic acid, oleanolic acid, oleic acid, β-pinene, patchoulenone, rotundene, rotundenol, rotundone, α-rotunol, β-rotunol, β-selinene, selinatriene, sitosterol, stearic acid, sugeonol, and sugetriol. Phytochemical constituents of Cyperus rotundus revealed the presence of alkaloids, flavonoids, glycosides, phenols, tannins, steroids, starch and many novel sesquiterpenoids. Sesquiterpene hydrocarbons such as cypera-2,4 (15)-diene, isorotundene, norrotundene and the oxygenated compound cyperadione were isolated and identified.

Synergistic Antibacterial Activity of Ethanolic Extracts of Mondia whytei Roots and Physalis peruviana Leaves against S. aureus and E. coli

Aims: This work investigated the phytochemical constituents and synergistic antibacterial activity of ethanolic extracts of Mondia whytei roots and Physalis peruviana leaves.
 Study Design: This study employed both qualitative and quantitative methods.
 Place and Duration of Study: All research works were performed at the Central Science Laboratories, Faculty of science, Kyambogo University between September 2021 and March 2022.
 Methodology: Standard methods were followed for phytochemical screening of ethanolic extracts of Mondia whytei roots, and Physalis peruviana leaves. The potential synergistic antibacterial activity of ethanolic extracts were evaluated through agar well diffusion assay. The bacteria strains were cultured on Mueller-Hinton agar. Sterile cork borer (6 mm diameter) was used to create the wells on petri discs and filled aseptically with 10 µl of the test extract (100 mg/ml) and Chloramphenicol (0.5 mg/ml) was used as the positive control. The interaction between the extracts and the combined extract was assessed by determining their fractional inhibitory concentration (FIC) index.
 Results: Alkaloids, flavonoids, tannins, saponins, phenols were found to be present in both extracts. Cardiac glycosides, terpenoids, anthraquinnones and steroids were present only in ethanolic extract of Physalis peruviana leaves. The antibacterial activities of Mondia whytei roots extract, Physalis peruviana leaves extract and combined extract were obtained with the following zone of inhibitions; 19.20 ± 0.72 mm, 19.77 ± 0.60 mm, 25.93 ± 0.83 mm for S. aureus and 15.50 ± 0.46 mm, 15.00 ± 0.26 mm, 17.87 ± 0.61 mm for E.coli respectively, as compared with the standard reference antibiotic with zone of inhibitions; 26.00 ± 0.00 mm for S. aureus and 24.00 ± 0.00 mm E. coli. The MICs were determined at 0.1-100 mg/ml, and the FIC index were obtained from the evaluated MIC values with the corresponding values of 0.5 (synergistic) for S. aureus and 1.0 (additive) for E. coli.
 Conclusion: The results obtained from the present study support the traditional claims of using the selected plants to treat bacterial infections. The extracts had low antibacterial activities on the selected human pathogens, Hence, if these extracts are used in unison, greater efficacy could be achieved; further studies should be done using combined extracts combined with commercial antibiotics.

Specific egg yolk antibody raised to biofilm associated protein (Bap) is protective against murine pneumonia caused by Acinetobacter baumannii

Acinetobacter baumannii easily turns into pan drug-resistant (PDR) with a high mortality rate. No effective commercial antibiotic or approved vaccine is available against drug-resistant strains of this pathogen. Egg yolk immunoglobulin (IgY) could be used as a simple and low-cost biotherapeutic against its infections. This study evaluates the prophylactic potential of IgY against A. baumannii in a murine pneumonia model. White Leghorn hens were immunized with intramuscular injection of the recombinant biofilm-associated protein (Bap) from A. baumannii on days 0, 21, 42, and 63. The reactivity and antibiofilm activity of specific IgYs raised against the Bap was evaluated by indirect ELISA and a microtiter plate assay for biofilm formation. The IgYs against Bap were able to decrease the biofilm formation ability of A. baumannii and protect the mice against the challenge of A. baumannii. IgYs antibody raised here shows a good antigen-specificity and protectivity which can be used in passive immunotherapy against A. baumannii. In conclusion, the IgY against biofilm-associated protein proves prophylactic in a murine pneumonia model.

Antibacterial activity of medicinal plants against Streptococcus agalactiae

Streptococcus agalactiae, group B Streptococcus (GBS), infects and causes severe diseases in humans and numerous animal species, including fish, given its ability to cross the host-specific barrier. The emergence of antibiotic resistant GBS strains makes it necessary to look for alternatives to treat and prevent infections that it produces. The aim of the present study was to determine the antibacterial activity of ethanolic and aqueous extracts of medicinal plants from Misiones province, northeast Argentina, against GBS from humans and fish. We used human Streptococcus agalactiae ATCC® BAA-611™ and tilapia Streptococcus agalactiae ATCC® 51487™ strains. Minimum Inhibitory Dose (MID) was determined by the disc diffusion method. Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), MBC/MIC ratio, drug synergism with commercial antibiotics, and resistance assays were determined with extracts that showed antibacterial activity. Medium Lethal Dose 50 (LD50) was determined by the Artemia salina assay. For ethanolic and aqueous Eugenia uniflora L. extracts, we obtained a MID = 0.5 mg.disc-1. For both extracts of Eugenia uniflora L., the MIC and MBC values were 1 mg.mL-1 and 5 mg.mL-1, respectively. The MICI (MBC/MIC ratio) = 5 qualified the action of these extracts as bacteriostatic. The drug synergism assay with ampicillin, erythromycin, and clindamycin combination and extracts showed indifference. The LD50 of the aqueous extract was 0.82 mg.mL-1 indicating moderate toxicity. This work is a first step to identify chemical compounds in native medicinal plants of Misiones, Argentina, that could mean an alternative for the treatment of Streptococcus agalactiae infections.

Potential Bioactive Compounds from Marine Streptomyces sp. and Their In Vitro Antibiofilm and Antibacterial Activities Against Antimicrobial-Resistant Clinical Pathogens.

Antimicrobial resistance issues have risen dramatically in recent years, posing a severe concern to humans worldwide. The urgent need to find novel compounds for pharmaceutical applications prompts the research of under-explored environments such as marine ecosystems. The present study was designed to discover novel secondary metabolites, and we have isolated about 30 actinomycetes from the marine soil samples collected in Thondi (Ramanathapuram, Tamil Nadu, India), where most isolates are associated with the genus Streptomyces. Out of 30, one potentially active strain (Streptomyces sp. SRMA3) was identified using primary and secondary screening methods against the drug-resistant clinical pathogens. The active metabolites extracted from the selected active isolate were subjected to partial purification and characterization using Fourier transform infrared spectrophotometer (FTIR) and gas chromatography-mass spectroscopy (GC-MS) analysis. The minimum inhibitory concentration (MIC) value was determined for the active metabolite. Further, the partially purified active fraction was revealed for its antibacterial and antibiofilm activity against drug-resistant clinical pathogens. Light and fluorescence microscopy detected the viability and adhesion of the biofilm-forming drug-resistant pathogens. Growth curve analysis showed that the active metabolite has the potential to inhibit drug-resistant pathogens. The synergistic effect of active metabolite with commercial antibiotics also revealed that it could enhance the activity of antibiotics in antimicrobial resistance pathogens. This study shows that the isolated Streptomyces sp. SRMA3 is a potentially active strain, and the metabolite derived from this strain has a good antibacterial and antibiofilm activity against antimicrobially resistant clinical pathogens and could be used for various biotechnological applications.

The effect of Ocimum sanctum L. crude extract on haematology of Cyprinus carpio infected by Aeromonas hydrophila

Cyprinus carpio L. is one of the most important freshwater fish and has been intensively cultivated. However, microbial infection become restricting component that can cause economic loss in carp production and the use of commercial antibiotics for therapy produces adverse side effects. This study was conducted to evaluate the potential of Ocimum sanctum L. crude extract on haematology of Cyprinus carpio against A. hydrophila infection. For this purpose, fish that have been infected were immersed in different doses of Ocimum sanctum L. crude extract (50, 150, 250, 350 ppm) and compared with the control group. After 1 week of immersion, total erythrocytes, total leukocytes, and deferential leukocytes (neutrophils, monocytes and lymphocytes) were recorded. The result showed that significant increase of total erythrocytes was obtained at the concentration of 350 ppm Ocimum sanctum L. crude extract. Furthermore, decreasing of the total leukocytes about 55.06×103 to 25.77×103, also decreasing deferential leukocytes (monocytes 40%, neutrophils 31% and lymphocytes 49% from the positive control). These results suggested that 350 ppm of Ocimum sanctum L. crude extract is beneficial to enhance the haematological status of common carp against A. hydrophila.

External oxidant-free and transition metal-free synthesis of 5-amino-1,2,4-thiadiazoles as promising antibacterials against ESKAPE pathogen strains.

A new route to 5-amino-1,2,4-thiadiazole derivatives via reaction of N-chloroamidines with isothiocyanates has been proposed. The advantages of this method are high product yields (up to 93%), the column chromatography-free workup procedure, scalability and the absence of additive oxidizing agents or transition metal catalysts. The 28 examples of 5-amino-1,2,4-thiadiazole derivatives obtaining via the proposing protocol were evaluated in vitro against ESKAPE pathogens strains (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter cloacae). It was found that compounds 5ba, 5bd, 6a, 6d and 6c have potent antibacterial activity (MIC values 0.09-1.5μgmL-1), which is superior to the activity of commercial antibiotics such as pefloxacin (MIC 4-8μgmL-1) and streptomycin (MIC 2-32μgmL-1). The additional cytotoxic assay of hit compounds on PANC-1 cell line demonstrated the low or non-cytotoxicity activity at the same level of concentrations. Thus, these 5 compounds are promising starting point for further antimicrobial drug development.

A 3D calcium-deficient hydroxyapatite-based scaffold with gold nanoparticles effective against Micrococcus luteus as an artificial bone substitute

During implant surgery, microbial contamination of implants is a major issue that must be addressed to avoid acute and chronic post-surgery infection that may result in acute inflammation, a lengthy healing period, and surgical failure. Bacteria and other microbes use reactive oxygen species (ROS) to send signals between microbes for their proliferation and propagation. Therefore, we developed a functional bone substitute comprised of a ceramic scaffold (Calcium-deficient hydroxyapatite, CDHA) and immobilized gold nanoparticles (Au-scaffold) to scavenge microbial ROS and suppress microbial proliferation at early stages. The Au-scaffold can selectively scavenge H2O2 and ∙O2•-, and consequently, effectively inhibit the growth of Micrococcus luteus (M. luteus). In terms of antimicrobial activity, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the Au-scaffold against M. luteus are comparable to commercial antibiotics (e.g., ceftriaxone, ampicillin, streptomycin, gentamycin, and tetracycline). The Au-scaffold also shows higher cell viability than the commercial antibiotics. Thus, with its antimicrobial activity and low toxicity, the developed Au-scaffold has promising potential antibacterial activity against one of the major post-surgical infection bacteria, Micrococcus luteus.

Structure-oriented design strategy to construct NIR AIEgens to selectively combat gram (+) multidrug-resistant bacteria in vivo

Multidrug-resistant (MDR) gram-positive bacteria are an inevitable source of infection for hospitalized patients and one of the reasons for the increased proportion of severe diseases. Therefore, constructing smart agents for specific and effective combating infections in vivo caused by MDR gram-positive strains is very urgent. Herein, we reported a structure-oriented design strategy (SODS) to reasonably construct an organic photo-antimicrobial near-infrared (NIR) AIEgen BDPTV equipped with a phenylboronic acid moiety, which could be bound to the thick peptidoglycan layer of MDR gram-positive bacteria, resulting in a tight distribution with the cell wall in a confined space. Compared to the contrast compounds DQVTA and DPTVN, upon photoirradiation of AIEgen BDPTV, the generation of abundant and highly toxic reactive oxygen species (ROS) irreversibly destroys MDR gram-positive bacteria through photodynamic therapy, which is better than commercial photosensitizers (including methylene blue, chlorin e6, and protoporphyrin IX) and antibiotic (cefoxitin). As a proof of concept, in vitro experimental results showed that methicillin-resistant Staphylococcus aureus (MRSA) were completely killed using AIEgen BDPTV. More importantly, AIEgen BDPTV was capable of successfully combating MRSA-infected wounds of mice, but not Escherichia coli (E. coli)-infected wounds. We hope that this strategy could provide a new method to design powerful AIEgens to avoid the overuse and misuse of antibiotics.

Anti-Microbial Peptides: Strategies of Design and Development and Their Promising Wound-Healing Activities

Current approaches used to overcome microbial infections are becoming inefficient due to the overuse or misuse of antibiotics. Antimicrobial peptides (AMPs) are one of the most promising substitutional candidates for commercial antibiotics. The publications in the field of in silico design of AMPs with focus on the wound-healing AMPs were searched though SCOPUS and PubMed. Through publications, it was reported that a number of AMPs approved for clinical use have also showed efficient wound-healing activity. Todays, the design and production of synthetic types of AMPs have attracted attention in order to expand their applications and to cope with their limitations and adverse effects. In this paper, the currently published researches in the field of AMPs and their wound-healing features were summarized and the strategies used in AMPs design and development have been reviewed. Moreover, different databases and online servers used in this regard were summarized. Design and development of active AMPs, especially those with wound-healing activity, can be performed using bioinformatics servers and software, regarding AMPs structure-activity relationships.

Isolation and characterization of cyromazine degrading Acinetobacter sp. ZX01 from a Chinese ginger cultivated soil.

Cyromazine, a symmetrical triazine insecticide, is used to control dipteran larvae in chicken manure by feeding to the poultry, flies on animals, and leafminers in vegetables. Its extensive use has resulted in the widespread contamination in the environment. In the current study, a cyromazine degrading bacterium (designated strain ZX01) was isolated and characterized from a Chinese ginger cultivated soil by selective enrichment culture method. On the basis of morphological, biochemical characteristics, and 16S rRNA gene sequence, this bacterium showed strong similarity to the Pseudomonadales members and was closely related to the Acinetobacter baumannii group. Spectrophotometric and HPLC analyses revealed that strain ZX01 degraded cyromazine and utilized it as the sole carbon source for its growth. This process hydrolyzes cyromazine to melamine. Strain ZX01 degraded most of the cyromazine in 60h. Besides, its substrate specificity against four symmetrical triazine herbicides, one triazinone herbicide, as well as 10 insecticides and its antibiotic sensitivity towards eight commercial antibiotics were also tested. At the concentration of 100µg/mL for 60h, it could effectively degrade a variety of different pesticides, including atrazine, prometon, simazine, prometryn, enitrothion, diazinon, cypermethrin, and acetamiprid, and the degradation was in the range of 71-87%. In particular, melamine, the main degradation product of cyromazine, was degraded by 47.3%. This microorganism was sensitive to chloramphenicol and tetracycline and intermediate to amoxicillin and trimethoprim. These results highlight that strain ZX01 can be used as a potential biological agent for the remediation of soil, water, or crop contaminated with cyromazine and other symmetrical triazine insecticides.

Effect of a veterinary antibiotic on the growth of regularly consumed Lebanese plants

Aim of study: To investigate the effect of a combined commercial veterinary antibiotic, commonly sold, in different concentrations, on Lens culinaris Medik., Cicer arietinum L., Eruca sativa Mill. and Lepidium sativum L., on germination rates, plant growth traits and rhizospheric bacterial size and diversity. Area of study: Lebanon, soil origin from South Lebanon. Material and methods: The antibiotic phytotoxicity was assayed using seed germination and plant growth tests in a pot experiment conducted in a controlled glasshouse. Rhizospheric bacteria were isolated and identified by assisted laser desorption/ionization spectrometry (MALDI-TOF). Main results: The antibiotic used was species-dependent and negatively affected the plant growth variables causing decrease in root growth and total biomass weight. Regarding crop species, the antibiotic impact was dose-dependent. Arugula and cress were found to be the most sensitive in the tested concentrations, affecting their productivity. In lentil and chickpea, the effects disappeared after the fourth and the first week respectively. In addition, root microbial community was negatively affected in the first 4 weeks in lentil and chickpea. A diversity of growth promoting rhizobacterial genera were identified where some rhizospheric bacteria were more sensitive, while others were resistant to the used antibiotic concentrations. Research highlights: Results highlight the presence of resistant bacteria even in virgin soils. They implicate that the presence of antibiotics in soil leads to biomass reduction in leafy species decreasing the productive capacity of the crops and draw attention to possible transmission to humans consuming these leaves.