Multidrug-resistant Microbes Research Articles

Antimicrobial activities evaluation and phytochemical screening of some selected medicinal plants: A possible alternative in the treatment of multidrug-resistant microbes.

BackgroundFour out of five individuals rely on traditional medicine for their primary healthcare needs. Medicinal plants are endowed with diverse bioactive compounds to treat multidrug-resistant (MDR) microbes. So far, a less thorough examination has been made in this regard. This study aimed to evaluate antimicrobial activity and phytochemical screening of selected medicinal plants against MDR microbes.MethodsIn vitro experimental study was carried out to evaluate antimicrobial effects and phytochemical screening of Rumex abyssinicus, Cucumis pustulatus, Discopodium penninervium, Lippia adoensis, Euphorbia depauperata, Cirsium englerianum, and Polysphaeria aethiopica against MDR bacteria and fungi. Aqueous and 80% methanolic extraction methods were employed for extraction. The susceptibility test, minimum inhibitory concentration, and minimum bactericidal or fungicidal concentration were measured using disc diffusion or broth micro-dilution as per the CLSI protocols.ResultThe 80% methanolic extraction method was a preferred method to aqueous. The phytochemical constituents identified were alkaloids, flavonoids, saponins, phenolic, tannins, terpenoidss, and cardiac glycosides. The hydroalcoholic extract demonstrated an appreciable antimicrobial role against MDR microbes with an MIC value of 1.0–128.0μg/ml and 11-29mm inhibition zone (IZ) in diameter. Extracts obtained from C. englerianum and E. depauperata showed a significant IZ ranged of 26-29mm on MRSA and Streptococcus pyogenes. MDR E. coli and K. pneumoniae showed 12-25mm and 23-28mm IZ in diameter, respectively. T. mentagraphytes was susceptible to all tested extracts. Moreover, S. pyogenes and K. pneumoniae were found the most susceptible bacteria to C. englerianum. Cirsium englerianum, L. adoensis, D. penninervium, and R. abyssinicus demonstrated remarkable antifungal effect against C. albicans and T. mentagrophytes, while R. abyssinicus showed the leading antifungal effect with 32 to 64μg/ml MIC values.ConclusionThe plant extracts have shown appreciable antimicrobial activities comparable to the currently prescribed modern drugs tested. Accordingly, further studies on clinical efficacy trial, safety, toxicity and affordability analyses have to be instigated promptly, so as to head to the final step to synthesize precursor molecules for new effective antimicrobials.

Functionalization of kaolin clay with silver nanoparticles by Murraya koenigii fruit extract-mediated bioreduction process for antimicrobial applications

The emergence of multidrug-resistant microbes and newly outbreaking diseases are one of the major threats before mankind. This paves the way for researchers to explore new antimicrobial agents that possess common day-to-day applications. In this concern, we have fabricated the antimicrobial Ag-kaolin functional nanostructures by simple and sustainable protocol employing Murraya koenigii fruit extract. UV-visible spectra (UV-Vis) of the Ag-kaolin exhibit absorption peak at 430 nm which corresponds to the characteristic surface plasmon resonance of Ag nanoparticles. X-ray diffraction pattern (XRD) shows the diffraction peak at 37.6° confirms their face-centred cubic nature with (111) plane. Furthermore, the formation of Ag-kaolin functional nanostructures was confirmed through a scanning electron microscope (SEM) and energy-dispersive X-ray spectrum (EDX) analysis. The transmission electron microscopic (TEM) studies reveal the effective formation of quasi-spherical monodispersed Ag nanoparticles having 20–30-nm diameters on the kaolin clay. The bio-synthesized Ag-kaolin nanostructures showed excellent antimicrobial activity against pathogenic gram-positive (Staphylococcus aureus, Bacillus subtilis) and gram-negative (Escherichia coli) bacteria respectively with the inhibition zones of 26 mm, 25 mm and 30 mm.

English

The prevalence of the infectious diseases caused by Candida species and other human pathogenic microbes has led to the discovery of some natural agents against multidrug resistant microbes. Therefore, this research was designated to determine the capability of synthesized nanoparticles (NPs) from aqueous extract of leaves and fruits of Casuarina equisetifolia as anticandidal and antibacterial against some microbes. Silver NPs (AgNPs) were successfully gained from aqueous leaves and fruit extracts of C. equisetifolia which is defined on the basis of UV–visible spectroscopy, X-ray diffraction analysis and scanning electron microscope. The results showed that leaves and fruits extracts of C. equisetifolia acts as an excellent capping agent. XRD based on the FWHM analysis showed that AgCl and Ag had an average NPs size of 90.97 nm and 71.28 nm, respectively for fruits and 15.33 nm and 14.01 nm, respectively for leaves. UV–visible spectroscopy showed a maximum absorbance at 442 nm for fruits and 433 nm for leaves. SEM showed that the size of NPs from leaves lied in between of (30 to180 nm) and for fruits (70 to 250 nm). Candida albicans was severely affected by NPs of leaves with inhibition zone (3.03± 1.61 cm) and NPs of fruits had (1.37± 0.15 cm) inhibition zone. Nanoparticles from leaves exhibited maximum activity against P. mirabilis (3.52± 0.13 cm) and low activities against M. luteus (1.50±0.18 cm) inhibition zones. In conclusion, these eco-friendly synthesized AgNPs from leaves and fruits of C. equisetifolia could be used as competitive alternative natural drugs than conventional synthetic chemicals. © 2021 Friends Science Publishers

Resistome and microbial profiling of pediatric patient’s gut infected with multidrug-resistant diarrhoeagenic Enterobacteriaceae using next-generation sequencing; the first study from Pakistan

ABSTRACT A high prevalence of multidrug-resistant (MDR) pathogens has been reported in adult and pediatric populations of Pakistan. However, data describing the effect of MDR microbes on the gut microbiota is scarce. We designed a cross-sectional pediatric study to investigate the effect of MDR microbes’ infection on the gut microbiome and its resistome of children using high-throughput next-generation sequencing (NGS). A cross-sectional study was conducted at a tertiary health care hospital in Peshawar Pakistan, between 5 September 2019 to 15 February 2020. Pediatric patients with acute gastroenteritis (n = 200) were enrolled. All the enrolled pediatric patients underwent initial antimicrobial resistance (AMR) screening using the disk diffusion method. Children with MDR infections were identified and selected for gut microbiome and its resistome profiling using NGS. Out of 200 enrolled pediatric patients, 80 (40%) were found infected with MDR diarrheagenic Enterobacteriaceae consisting of 50 (62.5%) infections caused by extended-spectrum beta-lactamase (ESBL) producing E. coli while 30 (37.5%) by MDR Enterobacter specie. A total of 63 and 17 antibiotic-resistant genes (ARGs) conferring resistance to 7 and 5 classes of antibiotics were identified in the resistomes of MDR diarrheagenic Enterobacteriaceae infected and healthy children, respectively. NGS-based gut microbial profiling of MDR Enterobacter spp., ESBL producing E. coli infected pediatric patients and healthy controls revealed the predominance of Proteobacteria and Actinobacteria, respectively. An increased abundance of several pathogenic gram-negative bacteria namely E. coli, Enterobacter cloacae, and Salmonella enterica was observed in the gut microbiota of children infected with MDR bacterial infections than that of the healthy controls. This work indicates that children with MDR infections have reduced microbial diversity and enriched ARGs than healthy controls. The emergence of MDR bacterial strains and their association with gut dysbiosis needs immediate attention to regulate antibiotics usage in Pakistani children.

The fliK Gene Is Required for the Resistance of Bacillus thuringiensis to Antimicrobial Peptides and Virulence in Drosophila melanogaster.

Antimicrobial peptides (AMPs) are essential effectors of the host innate immune system and they represent promising molecules for the treatment of multidrug resistant microbes. A better understanding of microbial resistance to these defense peptides is thus prerequisite for the control of infectious diseases. Here, using a random mutagenesis approach, we identify the fliK gene, encoding an internal molecular ruler that controls flagella hook length, as an essential element for Bacillus thuringiensis resistance to AMPs in Drosophila. Unlike its parental strain, that is highly virulent to both wild-type and AMPs deficient mutant flies, the fliK deletion mutant is only lethal to the latter’s. In agreement with its conserved function, the fliK mutant is non-flagellated and exhibits highly compromised motility. However, comparative analysis of the fliK mutant phenotype to that of a fla mutant, in which the genes encoding flagella proteins are interrupted, indicate that B. thuringiensis FliK-dependent resistance to AMPs is independent of flagella assembly. As a whole, our results identify FliK as an essential determinant for B. thuringiensis virulence in Drosophila and provide new insights on the mechanisms underlying bacteria resistance to AMPs.

Ocimum gratissimum Capped Sulfur Nanoparticles and Antibacterial Efficacy against Multidrug-Resistant Microbes

This manuscript reports for the first time synthesis of sulfur nanoparticles prepared from thiosulphatepentahydrate ( ) using either oxalic acid alone ( ), or mixture of oxalic acid and aqueous solution of Ocimum gratissimum ( ). The synthesized sulfur nanoparticles were obtained in satisfactory yields, and characterized with techniques such asUV-Vis, XRD, SEM, EDX, TEM, and FT-IR. Presence of capping agents: Oxalic acid and biomolecule contents of Ocimum gratissimum were confirmed by FTIR. Crystallinity, morphology, shapes and elemental compositions of as-prepared nanoparticles were confirmed by XRD, SEM, TEM and EDX, respectively. Antimicrobial activities of the prepared sulfur nanoparticles against five (5) multidrug-resistant microbes were used for this research work. This included Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Salmonella pullorum. The zone of inhibition of the sulfur nanoparticles tested against selected clinical isolates. Staphylococcus aureus was observed to have the highest susceptibility to sulfur nanoparticles ( ) mediated with Ocimum gratissimum plant extract with diameter of 21.0mm; E.coli and Salmonella P. aeruginosa showed resistance. All tested clinical isolates were resistant to the other sulfur nanoparticles (SNP1) synthesized in the absence of Ocimum gratissimum plant extract.

Antibiotics in Prevention and Treatment of Multi-Drug Resistant (MDR) Organisms causing Surgical Site Infection (SSI)

Antibiotics play a vital role in prevention and treatment of various infections. But inappropriate antibiotic choice could lead to emergence of multi-drug resistance (MDR) among microorganisms. Since, the antibiotic susceptibility pattern of organisms could vary from place to place; forming a local prophylaxis and treatment protocol could hugely reduce this global burden. The primary objectives of the study were to observe the frequency of multi-drug resistant organisms causing Surgical Site Infections (SSIs) and to study the pattern of antibiotic usage for the prophylaxis and treatment of SSIs. A descriptive study was carried out in general surgical wards of KR hospital, Mysore for a period of 18 months (2015-2016). The relevant data was collected from the case sheets of patients who were diagnosed with SSI. Pus samples were collected, and culture-sensitivity was done. Collected data were analyzed using relevant statistical tests. A total of 263 study subjects including both males and females were enrolled in the study. Cefotaxime was the most common antibiotic used for pre-surgical prophylaxis (n=221). Out of 263 pus samples 92% were culture positive. The most common organisms causing SSI were E-coli-ESBL (n=73) and MRSA (n=44). About 95% of organisms showed multi-drug resistance. Imipenem, Gentamicin, Piperacillin-Tazobactum and Linezolid were the most common antibiotics used in the treatment of SSIs. The result of the study is alarming. Overall, there is great rise in the prevalence of MDR organisms causing SSIs. The hospital antibiotic policy should be revised in such a way to decrease the emergence of MDR microbes.

Antimicrobial use for pediatric acute respiratory tract infections and the subsequent emergence of multi-drug resistant bacteria

Background: Viruses cause the majority of acute respiratory tract infections (ARTIs). On clinical grounds, differentiation of bacterial vs. viral ARTIs is difficult and warrant costly investigations. In Sri Lanka, ARTIs are commonly treated by family physicians (FP), and severe patients seek inward care. This study was conducted to evaluate the use of antibiotics by FP and by hospital care and the development of antimicrobial resistance (AMR) in children with viral ARTIs. Methods and materials: Nasopharyngeal aspirates of inward patients (1-month to 5-years) with ARTIs were collected in Teaching Hospital, Anuradhapura from March-2013 to August-2014. Using immunofluorescence assay (IFA) specific viral etiology was detected. Phenotypically multi-drug resistant (MDR) bacteria were detected. The use of antibiotics and the development of infectious diseases in the past six months, in the current episode and follow up to 6 months was assessed using questionnaires, telephone interviews, and demonstration of antimicrobials. Multivariate analysis was performed to assess risk factors for the development of MDR microbes. Results: Out of 413 viral etiologies were detected in 40% (165/413). Antibiotics were prescribed in the health care facility for 100% (165/165) of patients with viral ARTIs. Initially, 120 patients were treated by FP, and 100% were on antimicrobials. Following admission, 84 of them were treated with antibiotics. Out of 120, 80 were on co-amoxiclav, 38 were on cephalosporin (cefixime-28; cefuroxime-10), and 2 were on macrolides monotherapy. Everyone was presented to FP on day 1 of illness. Mean ± SD hospital stay for viral ARTIs with and without antimicrobials was 4 ± 1.6 and 4.1 ± 1.8 days and is not significant. Eighty had two episodes of ARTI in the earlier 6-months, and every occasion was treated with antibiotics by FP. In follow up, 102 (75%) and 20 (14.7%) extended-spectrum of beta-lactamases (ESBL) and carbapenemase producers (CRE) were isolated in patients with urinary and other infections. Conclusion: The use of viral diagnostic by FP and in hospitals would be an essential factor in reducing the unnecessary use of antibiotics. The rational antibiotic use will invariably contribute to reduce the cost and to prevent the emergence of ESBL and CRE.

PSVI-14 Effects of saturated fatty acids of 6 to 12 carbons in length on spoilage microbes, zoonotic pathogens and antimicrobial resistant bacteria in air exposed corn silage

Abstract Aerobic exposure of silage during the feed-out phase promotes growth of spoilage as well as pathogenic and multi-drug resistant (MDR) microbes which can risk infection of food-producing animals and the foods they produce. Livestock producers are interested in finding effective yet environmentally friendly interventions to preserve the nutritional value of these spoiled feedstuffs. We investigated the antimicrobial activity of 6 to 12 carbon-containing saturated fatty acids (C6, C8, C10 or C12) added (0.03 g) individually or as 1:1 mixtures of C6:C8:C10:C12 or C8:C10 to 4 g of overnight exposed silage suspended in 10 mL water. Net changes in colony counts, determined as the difference between counts measured after 0 and 24 h aerobic incubation (22oC) of untreated and treated silage suspensions (n = 3/treatment), were subjected to an analysis of variance. Populations of wild-type total aerobes and experimentally-inoculated MDR-Staphylococcus aureus were unaffected by treatment (P > 0.05), decreasing on average (± SD) 0.64 ± 0.40 and 1.09 ± 0.39 log10 CFU/g silage, respectively. Treatment effects (P < 0.05) were observed against experimentally-inoculated Listeria monocytogenes, with the C8:C10 mix decreasing this foodborne pathogen by 0.64 log10 CFU/g compared to a 0.95 log10/g increase in controls. Indigenous yeast and mold, considered responsible for spoilage, were decreased 2.12 and 3.07 log10 CFU/g by the C8 and C8:C10 treatments compared to 0.40 log10 CFU/g increase in controls. Indigenous lactic acid bacteria, considered beneficial, were decreased most potently by the C8 and C8:C10 treatments compared to controls (1.28, 0.66 and 0.37 log10 CFU/g, respectively). Indigenous enterococci decreased in all incubations, including controls (3.03 log10 CFU/g), compared to 4.69 to 5.03 log10 CFU/g decreases in C6, C8, C10, C12 and C8:C10 treatments. Results reveal that some fatty acid treatments inhibited pathogenic and spoilage microbes, yet treatment optimization is needed to avoid adverse effects against beneficial microbes.

Combating Antimicrobial Resistance With New-To-Nature Lanthipeptides Created by Genetic Code Expansion.

Due to the rapid emergence of multi-resistant bacterial strains in recent decades, the commercially available effective antibiotics are becoming increasingly limited. On the other hand, widespread antimicrobial peptides (AMPs) such as the lantibiotic nisin has been used worldwide for more than 40 years without the appearance of significant bacterial resistance. Lantibiotics are ribosomally synthesized antimicrobials generated by posttranslational modifications. Their biotechnological production is of particular interest to redesign natural scaffolds improving their pharmaceutical properties, which has great potential for therapeutic use in human medicine and other areas. However, conventional protein engineering methods are limited to 20 canonical amino acids prescribed by the genetic code. Therefore, the expansion of the genetic code as the most advanced approach in Synthetic Biology allows the addition of new amino acid building blocks (non-canonical amino acids, ncAAs) during protein translation. We now have solid proof-of-principle evidence that bioexpression with these novel building blocks enabled lantibiotics with chemical properties transcending those produced by natural evolution. The unique scaffolds with novel structural and functional properties are the result of this bioengineering. Here we will critically examine and evaluate the use of the expanded genetic code and its alternatives in lantibiotics research over the last 7 years. We anticipate that Synthetic Biology, using engineered lantibiotics and even more complex scaffolds will be a promising tool to address an urgent problem of antibiotic resistance, especially in a class of multi-drug resistant microbes known as superbugs.

Tackling AMR crisis in India: Changing paradigm

Antimicrobial resistance (AMR) is an important public health concern globally. For India, undoubtedly, AMR has had profound impact on its health & socioeconomic parameters. Several hospital and community-based surveys have indicated alarming rise in incidence of multidrug resistant microbes, especially ‘superbugs’, having direct links with antibiotic use/misuse. Additionally, paucity in data with regards to quantification of AMR crisis & its determinants has been concerning. However, the national commitment to address AMR has steadily increased of late, with an oft-restated realization – it is time to act. Recent initiatives like National Policy for Containment of AMR (2011), Chennai Declaration (2012), Anti-microbial Resistance Surveillance and Research Network (2013), The Red Line Campaign (2016), National Action Plan (NAP) for AMR (2017), ICMR Treatment Guidelines for Antimicrobial Use in Common Syndromes (2019) are promising measures expected to have positive impact on both clinical and economic outcome in India. This paper provides a snapshot of major strategies proposed in recent years, including educational and awareness initiatives, infection control guidelines, audit and feedback, antimicrobial stewardship, surveillance projects etc. It also identifies technical challenges & opportunities for improved AMR mitigation in India.

Natural Anti-biofilm Agents: Strategies to Control Biofilm-Forming Pathogens.

Pathogenic microorganisms and their chronic pathogenicity are significant concerns in biomedical research. Biofilm-linked persistent infections are not easy to treat due to resident multidrug-resistant microbes. Low efficiency of various treatments and in vivo toxicity of available antibiotics drive the researchers toward the discovery of many effective natural anti-biofilm agents. Natural extracts and natural product-based anti-biofilm agents are more efficient than the chemically synthesized counterparts with lesser side effects. The present review primarily focuses on various natural anti-biofilm agents, i.e., phytochemicals, biosurfactants, antimicrobial peptides, and microbial enzymes along with their sources, mechanism of action via interfering in the quorum-sensing pathways, disruption of extracellular polymeric substance, adhesion mechanism, and their inhibitory concentrations existing in literature so far. This study provides a better understanding that a particular natural anti-biofilm molecule exhibits a different mode of actions and biofilm inhibitory activity against more than one pathogenic species. This information can be exploited further to improve the therapeutic strategy by a combination of more than one natural anti-biofilm compounds from diverse sources.

Antimicrobial Properties and Application of Polysaccharides and Their Derivatives

With the quick emergence of antibiotic resistance and multi-drug resistant microbes, more and more attention has been paid to the development of new antimicrobial agents that have potential to take the challenge. Polysaccharides, as one of the major classes of biopolymers, were explored for their antimicrobial properties and applications, owing to their easy accessibility, biocompatibility and easy modification. Polysaccharides and their derivatives have variable demonstrations and applications as antimicrobial agents and antimicrobial biomaterials. A variety of polysaccharides, such as chitosan, dextran, hyaluronic acid, cellulose, other plant/animal-derived polysaccharides and their derivatives have been explored for antimicrobial applications. We expect that this review can summarize the important progress of this field and inspire new concepts, which will contribute to the development of novel antimicrobial agents in combating antibiotic resistance and drug-resistant antimicrobial infections.

Metal/metal oxide nanocomposites for bactericidal effect: A review

Many microbial species causing infectious disease all over the world became a social burden and creating threat among community. These microbes possess long lifetime, enhancing mortality and morbidity rate in affected organisms. In this condition, the treatment was ineffective and more chances of spreading of infection into other organisms. Hence, it is necessary to initiate infection control efforts and prevention activities against multidrug resistant microbes, to reduce the death rate of people. Seriously concerning towards this problem progress was shown in developing significant drugs with least side effects. Emergence of nanoparticles and its novelty showed effective role in targeting and destructing microbes well. Further, many research works have shown nanocomposites developed from nanoparticles coupled with other nanoparticles, polymers, carbon material acted as an exotic substance against microbes causing severe loss. However, metal and metal oxide nanocomposites have gained interest due to its small size and enhancing the surface contact with bacteria, producing damage to it. The bactericidal mechanism of metal and metal oxide nanocomposites involve in the production of reactive oxygen species which includes superoxide radical anions, hydrogen peroxide anions and hydrogen peroxide which interact with the cell wall of bacteria causing damage to the cell membrane in turn inhibiting the further growth of cell with leakage of internal cellular components, leading to death of bacteria. This review provides the detailed view on antibacterial activity of metal and metal oxide nanocomposite which possessed novelty due to its physiochemical changes.

Synthesis of Schiff Bases of 4-Amino-5- (2-Hydroxyphenyl)-4H- 1,2,4-Triazole-3-Thiol as Potent Antimicrobial Agents

In recent years, the emergence and rapid spread of multidrug-resistant microbes are increasingly becoming major concerns for public health because infections from such pathogens lead to higher mortality imposing huge healthcare costs. With the currently available drugs becoming ineffective due to the drug resistance developed by pathogens, the synthesis of more powerful antimicrobial agents with a broad spectrum of activity has become a crucial need for the treatment of microbial infections. Some new amino-substituted Schiff bases with triazole ring (4a-c) were prepared by cyclization of potassium 2-(2-hydroxybenzoyl) hydrazinecarbodithioate (2) with hydrazine hydrate followed by condensation with aromatic aldehydes. The newly synthesized compounds were characterized by spectral techniques like FTIR, 1H-NMR, and 13C-NMR. Antimicrobial screening of the synthesized compounds revealed that they possess good to moderate activities against a variety of microorganisms.

Strategies to Prevent Healthcare-Associated Infections: A Narrative Overview.

Healthcare-associated infections (HCAIs) are a major source of morbidity and mortality and are the second most prevalent cause of death. Furthermore, it has been reported that for every one-hundred patients admitted to hospital, seven patients in high-income economies and ten in emerging and low-income economies acquire at least one type of HCAI. Currently, almost all pathogenic microorganisms have developed antimicrobial resistance, and few new antimicrobials are being developed and brought to market. The literature search for this narrative review was performed by searching bibliographic databases (including Google Scholar and PubMed) using the search terms: “Strategies,” “Prevention,” and “Healthcare-Associated Infections,” followed by snowballing references cited by critical articles. We found that although hand hygiene is a centuries-old concept, it is still the primary strategy used around the world to prevent HCAIs. It forms one of a bundle of approaches used to clean and maintain a safe hospital environment and to stop the transmission of contagious and infectious microorganisms, including multidrug-resistant microbes. Finally, antibiotic stewardship also has a crucial role in reducing the impact of HCAIs through conserving currently available antimicrobials.

ECO-FRIENLY SYNTHESIS OF GOLD NANOPARTICLES AND STUDY THEIR EFFECT WITH ANTIBIOTICS AGAINST ACINETOBACTER BAUMANNII

This study was aimed to produce AuNPs biologically using Klebsiella pneumoniae and study their synergistic effect with some antibiotics.Technologies of nanoparticles are quick and are employed in many applications in biomedicine. The potential of metallic nanoparticle as an anti-microbial agent is greatly investigated which considered as an alternative method to reduce the challenges of multi-drug resistance microbes. The present study discusses the novel approach to synthesize nanoparticles involving eco-friendly synthesis of gold nanoparticles using Klebsiella pneumoniae and study their effect as antimicrobial spectrum .Also study synergism effect of gold nanoparticles with antibiotic against Acinetobacter baumannii. These approaches are used to enhance antimicrobial efficacy of nanoparticles by modification of surfaces and to investigate activity of antibiotic delivery.

Evaluation of antimicrobial properties of a novel synthesized nanometric delafossite.

Antibiotics and other antimicrobial compounds are the backbone of clinical medicine. Antimicrobial resistance can cause serious diseases to man. Nanotechnology can improve therapeutic potential of medicinal molecules and related agents. Widespread application of antibiotics and other antimicrobial compounds led to development of multidrug-resistant microbes, so there is need to develop novel therapeutic agents. Novel synthesized nanometric delafossite was assayed against two Gram-positive bacteria (Staphylococcus aureus and Micrococcus luteus), two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae), four opportunistic fungi (Aspergillus flavus, A. fumigatus, A. niger, and Fusarium solani), and four Candida species (C. albicans, C. parapsilosis, C. krusei, and C. tropicalis) using diffusion assay method. The minimum inhibitory concentration (MIC) of the novel synthesized nanometric delafossite was determined using the dilution method. The assayed compounds showed different degrees of antifungal and antibacterial activities, depending on the annealing temperature of preparation of these compounds. Compounds prepared at room temperature showed greater antimicrobial activities than those prepared at higher temperatures. The antimicrobial activity depends also on the susceptibility of the test microbe.

Can medicinal mushrooms have prophylactic or therapeutic effect against COVID-19 and its pneumonic superinfection and complicating inflammation?

Medicinal mushrooms have documented effects against different diseases, including infections and inflammatory disorders. The related Basidiomycota Agaricus blazei Murill (AbM), Hericium erinaceus (HE), and Grifola frondosa (GF) have been shown to exert antimicrobial activity against viral agents, Gram‐positive and Gram‐negative bacteria, and parasites in vitro and in vivo. Since the mechanism is immunomodulatory and not antibiotical, the mushrooms should be active against multi‐drug resistant microbes as well. Moreover, since these Basidiomycota also have anti‐inflammatory properties, they may be suited for treatment of the severe lung inflammation that often follows COVID‐19 infection. An AbM‐based mushroom extract (Andosan™), also containing HE and GF, has been shown to significantly reduce bacteraemia and increase survival in mice with pneumococcal sepsis, and to improve symptoms and quality of life in IBD patients via an anti‐inflammatory effect. Hence, such mushroom extracts could have prophylactic or therapeutic effect against the pneumonic superinfection and severe lung inflammation that often complicates COVID‐19 infection. Here, we review antimicrobial and anti‐inflammatory properties of AbM, HE and GF mushrooms, which could be used for the battle against COVID‐19.

Controlled release and enhanced biological activity of chitosan-fabricated carbenoxolone nanoparticles

Nanotechnology based antimicrobial drugs are developed to enhance their properties to combat multidrug resistant microbes. Carbenoxolone (CBX) is a semi-synthetic derivate of a natural substance from the licorice plant, with anti- (inflammatory, fungal, viral, microbial, fibrotic and cancer) properties. Though used to treat gastric ulcers, its low aqueous stability, low bioavailability and toxicity limited the drug's utility. To enhance its antimicrobial activity and reduce cytotoxicity, a controlled release nanoformulation was developed using natural biodegradable polymer chitosan (CS) as a carrier which is biocompatible, nontoxic with placid antimicrobial property. UV–visible spectroscopy, electron microscopy, and Fourier transform infrared spectroscopy were used for characterization of the resultant CS-CBX nanoparticles (NPs). They were spherical with uniform dispersion, ~200 nm in size with surface charge of +18.6 mV and drug encapsulation of >80%. Drug release kinetics exhibited a controlled release of 86% over 36 h following zero order kinetics. The anti-microbial activity against common pathogenic Gram −ve and +ve bacteria and yeast increased ~2-fold with a concomitant 4-fold reduction in cytotoxicity assessed using human lung adeno carcinoma (A549) cells. This study demonstrates the affirmative aspects of CS-CBX NPs as a promising antibacterial agent and may facilitate repositioning of the drug for diverse applications.